linux/tools/objtool/check.c

2475 lines
58 KiB

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details [based] [from] [clk] [highbank] [c] you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 355 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-19 15:51:43 +02:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Assume unannotated UD2 instructions are dead ends Arnd reported some false positive warnings with GCC 7: drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16 drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set() drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove() drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable() drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart() When GCC 7 detects a potential divide-by-zero condition, it sometimes inserts a UD2 instruction for the case where the divisor is zero, instead of letting the hardware trap on the divide instruction. Objtool doesn't consider UD2 to be fatal unless it's annotated with unreachable(). So it considers the GCC-generated UD2 to be non-fatal, and it tries to follow the control flow past the UD2 and gets confused. Previously, objtool *did* assume UD2 was always a dead end. That changed with the following commit: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") The motivation behind that change was that Peter was planning on using UD2 for __WARN(), which is *not* a dead end. However, it turns out that some emulators rely on UD2 being fatal, so he ended up using 'ud0' instead: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") For GCC 4.5+, it should be safe to go back to the previous assumption that UD2 is fatal, even when it's not annotated with unreachable(). But for pre-4.5 versions of GCC, the unreachable() macro isn't supported, so such cases of UD2 need to be explicitly annotated as reachable. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-27 15:56:53 -05:00
objtool: Assume unannotated UD2 instructions are dead ends Arnd reported some false positive warnings with GCC 7: drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16 drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set() drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove() drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable() drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart() When GCC 7 detects a potential divide-by-zero condition, it sometimes inserts a UD2 instruction for the case where the divisor is zero, instead of letting the hardware trap on the divide instruction. Objtool doesn't consider UD2 to be fatal unless it's annotated with unreachable(). So it considers the GCC-generated UD2 to be non-fatal, and it tries to follow the control flow past the UD2 and gets confused. Previously, objtool *did* assume UD2 was always a dead end. That changed with the following commit: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") The motivation behind that change was that Peter was planning on using UD2 for __WARN(), which is *not* a dead end. However, it turns out that some emulators rely on UD2 being fatal, so he ended up using 'ud0' instead: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") For GCC 4.5+, it should be safe to go back to the previous assumption that UD2 is fatal, even when it's not annotated with unreachable(). But for pre-4.5 versions of GCC, the unreachable() macro isn't supported, so such cases of UD2 need to be explicitly annotated as reachable. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-27 15:56:53 -05:00
objtool: Assume unannotated UD2 instructions are dead ends Arnd reported some false positive warnings with GCC 7: drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16 drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set() drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove() drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable() drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart() When GCC 7 detects a potential divide-by-zero condition, it sometimes inserts a UD2 instruction for the case where the divisor is zero, instead of letting the hardware trap on the divide instruction. Objtool doesn't consider UD2 to be fatal unless it's annotated with unreachable(). So it considers the GCC-generated UD2 to be non-fatal, and it tries to follow the control flow past the UD2 and gets confused. Previously, objtool *did* assume UD2 was always a dead end. That changed with the following commit: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") The motivation behind that change was that Peter was planning on using UD2 for __WARN(), which is *not* a dead end. However, it turns out that some emulators rely on UD2 being fatal, so he ended up using 'ud0' instead: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") For GCC 4.5+, it should be safe to go back to the previous assumption that UD2 is fatal, even when it's not annotated with unreachable(). But for pre-4.5 versions of GCC, the unreachable() macro isn't supported, so such cases of UD2 need to be explicitly annotated as reachable. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-27 15:56:53 -05:00
objtool: Assume unannotated UD2 instructions are dead ends Arnd reported some false positive warnings with GCC 7: drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16 drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set() drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove() drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable() drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart() When GCC 7 detects a potential divide-by-zero condition, it sometimes inserts a UD2 instruction for the case where the divisor is zero, instead of letting the hardware trap on the divide instruction. Objtool doesn't consider UD2 to be fatal unless it's annotated with unreachable(). So it considers the GCC-generated UD2 to be non-fatal, and it tries to follow the control flow past the UD2 and gets confused. Previously, objtool *did* assume UD2 was always a dead end. That changed with the following commit: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") The motivation behind that change was that Peter was planning on using UD2 for __WARN(), which is *not* a dead end. However, it turns out that some emulators rely on UD2 being fatal, so he ended up using 'ud0' instead: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") For GCC 4.5+, it should be safe to go back to the previous assumption that UD2 is fatal, even when it's not annotated with unreachable(). But for pre-4.5 versions of GCC, the unreachable() macro isn't supported, so such cases of UD2 need to be explicitly annotated as reachable. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-27 15:56:53 -05:00
objtool: Fix GCC 8 cold subfunction detection for aliased functions The kbuild test robot reported the following issue: kernel/time/posix-stubs.o: warning: objtool: sys_ni_posix_timers.cold.1()+0x0: unreachable instruction This file creates symbol aliases for the sys_ni_posix_timers() function. So there are multiple ELF function symbols for the same function: 23: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_create 24: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 sys_ni_posix_timers 25: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __ia32_sys_timer_create 26: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_gettime Here's the corresponding cold subfunction: 11: 0000000000000000 45 FUNC LOCAL DEFAULT 6 sys_ni_posix_timers.cold.1 When analyzing overlapping functions, objtool only looks at the first one in the symbol list. The rest of the functions are basically ignored because they point to instructions which have already been analyzed. So in this case it analyzes the __x64_sys_timer_create() function, but then it fails to recognize that its cold subfunction is sys_ni_posix_timers.cold.1(), because the names are different. Make the subfunction detection a little smarter by associating each subfunction with the first function which jumps to it, since that's the one which will be analyzed. Unfortunately we still have to leave the original subfunction detection code in place, thanks to GCC switch tables. (See the comment for more details.) Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/d3ba52662cbc8e3a64a3b64d44b4efc5674fd9ab.1527855808.git.jpoimboe@redhat.com
2018-06-01 07:23:51 -05:00
objtool: Fix GCC 8 cold subfunction detection for aliased functions The kbuild test robot reported the following issue: kernel/time/posix-stubs.o: warning: objtool: sys_ni_posix_timers.cold.1()+0x0: unreachable instruction This file creates symbol aliases for the sys_ni_posix_timers() function. So there are multiple ELF function symbols for the same function: 23: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_create 24: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 sys_ni_posix_timers 25: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __ia32_sys_timer_create 26: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_gettime Here's the corresponding cold subfunction: 11: 0000000000000000 45 FUNC LOCAL DEFAULT 6 sys_ni_posix_timers.cold.1 When analyzing overlapping functions, objtool only looks at the first one in the symbol list. The rest of the functions are basically ignored because they point to instructions which have already been analyzed. So in this case it analyzes the __x64_sys_timer_create() function, but then it fails to recognize that its cold subfunction is sys_ni_posix_timers.cold.1(), because the names are different. Make the subfunction detection a little smarter by associating each subfunction with the first function which jumps to it, since that's the one which will be analyzed. Unfortunately we still have to leave the original subfunction detection code in place, thanks to GCC switch tables. (See the comment for more details.) Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/d3ba52662cbc8e3a64a3b64d44b4efc5674fd9ab.1527855808.git.jpoimboe@redhat.com
2018-06-01 07:23:51 -05:00
objtool: Fix GCC 8 cold subfunction detection for aliased functions The kbuild test robot reported the following issue: kernel/time/posix-stubs.o: warning: objtool: sys_ni_posix_timers.cold.1()+0x0: unreachable instruction This file creates symbol aliases for the sys_ni_posix_timers() function. So there are multiple ELF function symbols for the same function: 23: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_create 24: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 sys_ni_posix_timers 25: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __ia32_sys_timer_create 26: 0000000000000150 26 FUNC GLOBAL DEFAULT 1 __x64_sys_timer_gettime Here's the corresponding cold subfunction: 11: 0000000000000000 45 FUNC LOCAL DEFAULT 6 sys_ni_posix_timers.cold.1 When analyzing overlapping functions, objtool only looks at the first one in the symbol list. The rest of the functions are basically ignored because they point to instructions which have already been analyzed. So in this case it analyzes the __x64_sys_timer_create() function, but then it fails to recognize that its cold subfunction is sys_ni_posix_timers.cold.1(), because the names are different. Make the subfunction detection a little smarter by associating each subfunction with the first function which jumps to it, since that's the one which will be analyzed. Unfortunately we still have to leave the original subfunction detection code in place, thanks to GCC switch tables. (See the comment for more details.) Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/d3ba52662cbc8e3a64a3b64d44b4efc5674fd9ab.1527855808.git.jpoimboe@redhat.com
2018-06-01 07:23:51 -05:00
objtool: Support GCC 8 switch tables With GCC 8, some issues were found with the objtool switch table detection. 1) In the .rodata section, immediately after the switch table, there can be another object which contains a pointer to the function which had the switch statement. In this case objtool wrongly considers the function pointer to be part of the switch table. Fix it by: a) making sure there are no pointers to the beginning of the function; and b) making sure there are no gaps in the switch table. Only the former was needed, the latter adds additional protection for future optimizations. 2) In find_switch_table(), case 1 and case 2 are missing the check to ensure that the .rodata switch table data is anonymous, i.e. that it isn't already associated with an ELF symbol. Fix it by adding the same find_symbol_containing() check which is used for case 3. This fixes the following warnings with GCC 8: drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72 net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48 drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24 drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32 drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: damian <damian.tometzki@icloud.com> Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-10 17:48:49 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Support GCC 8 switch tables With GCC 8, some issues were found with the objtool switch table detection. 1) In the .rodata section, immediately after the switch table, there can be another object which contains a pointer to the function which had the switch statement. In this case objtool wrongly considers the function pointer to be part of the switch table. Fix it by: a) making sure there are no pointers to the beginning of the function; and b) making sure there are no gaps in the switch table. Only the former was needed, the latter adds additional protection for future optimizations. 2) In find_switch_table(), case 1 and case 2 are missing the check to ensure that the .rodata switch table data is anonymous, i.e. that it isn't already associated with an ELF symbol. Fix it by adding the same find_symbol_containing() check which is used for case 3. This fixes the following warnings with GCC 8: drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72 net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48 drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24 drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32 drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: damian <damian.tometzki@icloud.com> Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-10 17:48:49 -05:00
objtool: Support GCC 8 switch tables With GCC 8, some issues were found with the objtool switch table detection. 1) In the .rodata section, immediately after the switch table, there can be another object which contains a pointer to the function which had the switch statement. In this case objtool wrongly considers the function pointer to be part of the switch table. Fix it by: a) making sure there are no pointers to the beginning of the function; and b) making sure there are no gaps in the switch table. Only the former was needed, the latter adds additional protection for future optimizations. 2) In find_switch_table(), case 1 and case 2 are missing the check to ensure that the .rodata switch table data is anonymous, i.e. that it isn't already associated with an ELF symbol. Fix it by adding the same find_symbol_containing() check which is used for case 3. This fixes the following warnings with GCC 8: drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72 net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48 drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24 drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32 drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: damian <damian.tometzki@icloud.com> Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-10 17:48:49 -05:00
objtool: Support GCC 8 switch tables With GCC 8, some issues were found with the objtool switch table detection. 1) In the .rodata section, immediately after the switch table, there can be another object which contains a pointer to the function which had the switch statement. In this case objtool wrongly considers the function pointer to be part of the switch table. Fix it by: a) making sure there are no pointers to the beginning of the function; and b) making sure there are no gaps in the switch table. Only the former was needed, the latter adds additional protection for future optimizations. 2) In find_switch_table(), case 1 and case 2 are missing the check to ensure that the .rodata switch table data is anonymous, i.e. that it isn't already associated with an ELF symbol. Fix it by adding the same find_symbol_containing() check which is used for case 3. This fixes the following warnings with GCC 8: drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72 net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48 drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24 drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32 drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: damian <damian.tometzki@icloud.com> Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-10 17:48:49 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Detect RIP-relative switch table references Typically a switch table can be found by detecting a .rodata access followed an indirect jump: 1969: 4a 8b 0c e5 00 00 00 mov 0x0(,%r12,8),%rcx 1970: 00 196d: R_X86_64_32S .rodata+0x438 1971: e9 00 00 00 00 jmpq 1976 <dispc_runtime_suspend+0xb6a> 1972: R_X86_64_PC32 __x86_indirect_thunk_rcx-0x4 Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata access uses RIP-relative addressing: 19bd: 48 8b 3d 00 00 00 00 mov 0x0(%rip),%rdi # 19c4 <dispc_runtime_suspend+0xbb8> 19c0: R_X86_64_PC32 .rodata+0x45c 19c4: e9 00 00 00 00 jmpq 19c9 <dispc_runtime_suspend+0xbbd> 19c5: R_X86_64_PC32 __x86_indirect_thunk_rdi-0x4 In this case the relocation addend needs to be adjusted accordingly in order to find the location of the switch table. The fix is for case 3 (as described in the comments), but also make the existing case 1 & 2 checks more precise by only adjusting the addend for R_X86_64_PC32 relocations. This fixes the following warnings: drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 08:53:24 -05:00
objtool: Detect RIP-relative switch table references, part 2 With the following commit: fd35c88b7417 ("objtool: Support GCC 8 switch tables") I added a "can't find switch jump table" warning, to stop covering up silent failures if add_switch_table() can't find anything. That warning found yet another bug in the objtool switch table detection logic. For cases 1 and 2 (as described in the comments of find_switch_table()), the find_symbol_containing() check doesn't adjust the offset for RIP-relative switch jumps. Incidentally, this bug was already fixed for case 3 with: 6f5ec2993b1f ("objtool: Detect RIP-relative switch table references") However, that commit missed the fix for cases 1 and 2. The different cases are now starting to look more and more alike. So fix the bug by consolidating them into a single case, by checking the original dynamic jump instruction in the case 3 loop. This also simplifies the code and makes it more robust against future switch table detection issues -- of which I'm sure there will be many... Switch table detection has been the most fragile area of objtool, by far. I long for the day when we'll have a GCC plugin for annotating switch tables. Linus asked me to delay such a plugin due to the flakiness of the plugin infrastructure in older versions of GCC, so this rickety code is what we're stuck with for now. At least the code is now a little simpler than it was. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-18 15:10:34 -05:00
objtool: Detect RIP-relative switch table references, part 2 With the following commit: fd35c88b7417 ("objtool: Support GCC 8 switch tables") I added a "can't find switch jump table" warning, to stop covering up silent failures if add_switch_table() can't find anything. That warning found yet another bug in the objtool switch table detection logic. For cases 1 and 2 (as described in the comments of find_switch_table()), the find_symbol_containing() check doesn't adjust the offset for RIP-relative switch jumps. Incidentally, this bug was already fixed for case 3 with: 6f5ec2993b1f ("objtool: Detect RIP-relative switch table references") However, that commit missed the fix for cases 1 and 2. The different cases are now starting to look more and more alike. So fix the bug by consolidating them into a single case, by checking the original dynamic jump instruction in the case 3 loop. This also simplifies the code and makes it more robust against future switch table detection issues -- of which I'm sure there will be many... Switch table detection has been the most fragile area of objtool, by far. I long for the day when we'll have a GCC plugin for annotating switch tables. Linus asked me to delay such a plugin due to the flakiness of the plugin infrastructure in older versions of GCC, so this rickety code is what we're stuck with for now. At least the code is now a little simpler than it was. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-18 15:10:34 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Detect RIP-relative switch table references Typically a switch table can be found by detecting a .rodata access followed an indirect jump: 1969: 4a 8b 0c e5 00 00 00 mov 0x0(,%r12,8),%rcx 1970: 00 196d: R_X86_64_32S .rodata+0x438 1971: e9 00 00 00 00 jmpq 1976 <dispc_runtime_suspend+0xb6a> 1972: R_X86_64_PC32 __x86_indirect_thunk_rcx-0x4 Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata access uses RIP-relative addressing: 19bd: 48 8b 3d 00 00 00 00 mov 0x0(%rip),%rdi # 19c4 <dispc_runtime_suspend+0xbb8> 19c0: R_X86_64_PC32 .rodata+0x45c 19c4: e9 00 00 00 00 jmpq 19c9 <dispc_runtime_suspend+0xbbd> 19c5: R_X86_64_PC32 __x86_indirect_thunk_rdi-0x4 In this case the relocation addend needs to be adjusted accordingly in order to find the location of the switch table. The fix is for case 3 (as described in the comments), but also make the existing case 1 & 2 checks more precise by only adjusting the addend for R_X86_64_PC32 relocations. This fixes the following warnings: drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 08:53:24 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Detect RIP-relative switch table references Typically a switch table can be found by detecting a .rodata access followed an indirect jump: 1969: 4a 8b 0c e5 00 00 00 mov 0x0(,%r12,8),%rcx 1970: 00 196d: R_X86_64_32S .rodata+0x438 1971: e9 00 00 00 00 jmpq 1976 <dispc_runtime_suspend+0xb6a> 1972: R_X86_64_PC32 __x86_indirect_thunk_rcx-0x4 Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata access uses RIP-relative addressing: 19bd: 48 8b 3d 00 00 00 00 mov 0x0(%rip),%rdi # 19c4 <dispc_runtime_suspend+0xbb8> 19c0: R_X86_64_PC32 .rodata+0x45c 19c4: e9 00 00 00 00 jmpq 19c9 <dispc_runtime_suspend+0xbbd> 19c5: R_X86_64_PC32 __x86_indirect_thunk_rdi-0x4 In this case the relocation addend needs to be adjusted accordingly in order to find the location of the switch table. The fix is for case 3 (as described in the comments), but also make the existing case 1 & 2 checks more precise by only adjusting the addend for R_X86_64_PC32 relocations. This fixes the following warnings: drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 08:53:24 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Detect RIP-relative switch table references, part 2 With the following commit: fd35c88b7417 ("objtool: Support GCC 8 switch tables") I added a "can't find switch jump table" warning, to stop covering up silent failures if add_switch_table() can't find anything. That warning found yet another bug in the objtool switch table detection logic. For cases 1 and 2 (as described in the comments of find_switch_table()), the find_symbol_containing() check doesn't adjust the offset for RIP-relative switch jumps. Incidentally, this bug was already fixed for case 3 with: 6f5ec2993b1f ("objtool: Detect RIP-relative switch table references") However, that commit missed the fix for cases 1 and 2. The different cases are now starting to look more and more alike. So fix the bug by consolidating them into a single case, by checking the original dynamic jump instruction in the case 3 loop. This also simplifies the code and makes it more robust against future switch table detection issues -- of which I'm sure there will be many... Switch table detection has been the most fragile area of objtool, by far. I long for the day when we'll have a GCC plugin for annotating switch tables. Linus asked me to delay such a plugin due to the flakiness of the plugin infrastructure in older versions of GCC, so this rickety code is what we're stuck with for now. At least the code is now a little simpler than it was. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-18 15:10:34 -05:00
objtool: Detect RIP-relative switch table references Typically a switch table can be found by detecting a .rodata access followed an indirect jump: 1969: 4a 8b 0c e5 00 00 00 mov 0x0(,%r12,8),%rcx 1970: 00 196d: R_X86_64_32S .rodata+0x438 1971: e9 00 00 00 00 jmpq 1976 <dispc_runtime_suspend+0xb6a> 1972: R_X86_64_PC32 __x86_indirect_thunk_rcx-0x4 Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata access uses RIP-relative addressing: 19bd: 48 8b 3d 00 00 00 00 mov 0x0(%rip),%rdi # 19c4 <dispc_runtime_suspend+0xbb8> 19c0: R_X86_64_PC32 .rodata+0x45c 19c4: e9 00 00 00 00 jmpq 19c9 <dispc_runtime_suspend+0xbbd> 19c5: R_X86_64_PC32 __x86_indirect_thunk_rdi-0x4 In this case the relocation addend needs to be adjusted accordingly in order to find the location of the switch table. The fix is for case 3 (as described in the comments), but also make the existing case 1 & 2 checks more precise by only adjusting the addend for R_X86_64_PC32 relocations. This fixes the following warnings: drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 08:53:24 -05:00
objtool: Detect RIP-relative switch table references, part 2 With the following commit: fd35c88b7417 ("objtool: Support GCC 8 switch tables") I added a "can't find switch jump table" warning, to stop covering up silent failures if add_switch_table() can't find anything. That warning found yet another bug in the objtool switch table detection logic. For cases 1 and 2 (as described in the comments of find_switch_table()), the find_symbol_containing() check doesn't adjust the offset for RIP-relative switch jumps. Incidentally, this bug was already fixed for case 3 with: 6f5ec2993b1f ("objtool: Detect RIP-relative switch table references") However, that commit missed the fix for cases 1 and 2. The different cases are now starting to look more and more alike. So fix the bug by consolidating them into a single case, by checking the original dynamic jump instruction in the case 3 loop. This also simplifies the code and makes it more robust against future switch table detection issues -- of which I'm sure there will be many... Switch table detection has been the most fragile area of objtool, by far. I long for the day when we'll have a GCC plugin for annotating switch tables. Linus asked me to delay such a plugin due to the flakiness of the plugin infrastructure in older versions of GCC, so this rickety code is what we're stuck with for now. At least the code is now a little simpler than it was. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-18 15:10:34 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-09-07 08:12:01 -05:00
objtool: Handle another GCC stack pointer adjustment bug The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-20 16:24:32 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle another GCC stack pointer adjustment bug The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-20 16:24:32 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle another GCC stack pointer adjustment bug The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-20 16:24:32 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle another GCC stack pointer adjustment bug The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-20 16:24:32 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Handle GCC stack pointer adjustment bug Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:51:03 -05:00
objtool: Fix function fallthrough detection When a function falls through to the next function due to a compiler bug, objtool prints some obscure warnings. For example: drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8 Instead it should be printing: drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages() This used to work, but was broken by the following commit: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") The padding nops at the end of a function aren't actually part of the function, as defined by the symbol table. So the 'func' variable in validate_branch() is getting cleared to NULL when a padding nop is encountered, breaking the fallthrough detection. If the current instruction doesn't have a function associated with it, just consider it to be part of the previously detected function by not overwriting the previous value of 'func'. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-05-13 12:01:32 -05:00
objtool: Add --backtrace support For when you want to know the path that reached your fail state: $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user() arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func) 0000000000000000 <__clear_user>: 0: e8 00 00 00 00 callq 5 <__clear_user+0x5> 1: R_X86_64_PLT32 __fentry__-0x4 5: 90 nop 6: 90 nop 7: 90 nop 8: 48 89 f0 mov %rsi,%rax b: 48 c1 ee 03 shr $0x3,%rsi f: 83 e0 07 and $0x7,%eax 12: 48 89 f1 mov %rsi,%rcx 15: 48 85 c9 test %rcx,%rcx 18: 74 0f je 29 <__clear_user+0x29> 1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 21: 48 83 c7 08 add $0x8,%rdi 25: ff c9 dec %ecx 27: 75 f1 jne 1a <__clear_user+0x1a> 29: 48 89 c1 mov %rax,%rcx 2c: 85 c9 test %ecx,%ecx 2e: 74 0a je 3a <__clear_user+0x3a> 30: c6 07 00 movb $0x0,(%rdi) 33: 48 ff c7 inc %rdi 36: ff c9 dec %ecx 38: 75 f6 jne 30 <__clear_user+0x30> 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 48 89 c8 mov %rcx,%rax 40: c3 retq Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-01 11:15:49 +01:00
objtool: Add --backtrace support For when you want to know the path that reached your fail state: $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user() arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func) 0000000000000000 <__clear_user>: 0: e8 00 00 00 00 callq 5 <__clear_user+0x5> 1: R_X86_64_PLT32 __fentry__-0x4 5: 90 nop 6: 90 nop 7: 90 nop 8: 48 89 f0 mov %rsi,%rax b: 48 c1 ee 03 shr $0x3,%rsi f: 83 e0 07 and $0x7,%eax 12: 48 89 f1 mov %rsi,%rcx 15: 48 85 c9 test %rcx,%rcx 18: 74 0f je 29 <__clear_user+0x29> 1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 21: 48 83 c7 08 add $0x8,%rdi 25: ff c9 dec %ecx 27: 75 f1 jne 1a <__clear_user+0x1a> 29: 48 89 c1 mov %rax,%rcx 2c: 85 c9 test %ecx,%ecx 2e: 74 0a je 3a <__clear_user+0x3a> 30: c6 07 00 movb $0x0,(%rdi) 33: 48 ff c7 inc %rdi 36: ff c9 dec %ecx 38: 75 f6 jne 30 <__clear_user+0x30> 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 48 89 c8 mov %rcx,%rax 40: c3 retq Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-01 11:15:49 +01:00
objtool: Add --backtrace support For when you want to know the path that reached your fail state: $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user() arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func) 0000000000000000 <__clear_user>: 0: e8 00 00 00 00 callq 5 <__clear_user+0x5> 1: R_X86_64_PLT32 __fentry__-0x4 5: 90 nop 6: 90 nop 7: 90 nop 8: 48 89 f0 mov %rsi,%rax b: 48 c1 ee 03 shr $0x3,%rsi f: 83 e0 07 and $0x7,%eax 12: 48 89 f1 mov %rsi,%rcx 15: 48 85 c9 test %rcx,%rcx 18: 74 0f je 29 <__clear_user+0x29> 1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 21: 48 83 c7 08 add $0x8,%rdi 25: ff c9 dec %ecx 27: 75 f1 jne 1a <__clear_user+0x1a> 29: 48 89 c1 mov %rax,%rcx 2c: 85 c9 test %ecx,%ecx 2e: 74 0a je 3a <__clear_user+0x3a> 30: c6 07 00 movb $0x0,(%rdi) 33: 48 ff c7 inc %rdi 36: ff c9 dec %ecx 38: 75 f6 jne 30 <__clear_user+0x30> 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 48 89 c8 mov %rcx,%rax 40: c3 retq Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-01 11:15:49 +01:00
objtool: Add --backtrace support For when you want to know the path that reached your fail state: $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user() arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func) 0000000000000000 <__clear_user>: 0: e8 00 00 00 00 callq 5 <__clear_user+0x5> 1: R_X86_64_PLT32 __fentry__-0x4 5: 90 nop 6: 90 nop 7: 90 nop 8: 48 89 f0 mov %rsi,%rax b: 48 c1 ee 03 shr $0x3,%rsi f: 83 e0 07 and $0x7,%eax 12: 48 89 f1 mov %rsi,%rcx 15: 48 85 c9 test %rcx,%rcx 18: 74 0f je 29 <__clear_user+0x29> 1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 21: 48 83 c7 08 add $0x8,%rdi 25: ff c9 dec %ecx 27: 75 f1 jne 1a <__clear_user+0x1a> 29: 48 89 c1 mov %rax,%rcx 2c: 85 c9 test %ecx,%ecx 2e: 74 0a je 3a <__clear_user+0x3a> 30: c6 07 00 movb $0x0,(%rdi) 33: 48 ff c7 inc %rdi 36: ff c9 dec %ecx 38: 75 f6 jne 30 <__clear_user+0x30> 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 48 89 c8 mov %rcx,%rax 40: c3 retq Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-01 11:15:49 +01:00