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linux/arch/x86/entry
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Steven Rostedt (Red Hat) 21be088c36 ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it 
commit 847fa1a6d3 upstream.

With new binutils, gcc may get smart with its optimization and change a jmp
from a 5 byte jump to a 2 byte one even though it was jumping to a global
function. But that global function existed within a 2 byte radius, and gcc
was able to optimize it. Unfortunately, that jump was also being modified
when function graph tracing begins. Since ftrace expected that jump to be 5
bytes, but it was only two, it overwrote code after the jump, causing a
crash.

This was fixed for x86_64 with commit 8329e818f1, with the same subject as
this commit, but nothing was done for x86_32.

Fixes: d61f82d066 ("ftrace: use dynamic patching for updating mcount calls")
Reported-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2017-01-09 08:32:23 +01:00
..
syscalls x86, pkeys: remove cruft from never-merged syscalls 2016-10-17 14:16:13 -07:00
vdso KVM updates for v4.9-rc1 2016-10-06 10:49:01 -07:00
vsyscall Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-07-29 17:38:46 -07:00
calling.h x86/asm/entry: Remove unused SAVE_ALL/RESTORE_ALL macros for !CONFIG_x86_64 2016-01-19 08:24:03 +01:00
common.c x86/entry: Get rid of pt_regs_to_thread_info() 2016-09-15 08:25:12 +02:00
entry_32.S ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it 2017-01-09 08:32:23 +01:00
entry_64.S Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-10-14 14:26:58 -07:00
entry_64_compat.S x86/asm/entry/32: Simplify pushes of zeroed pt_regs->REGs 2016-05-03 08:19:40 +02:00
Makefile x86/build: Fix build with older GCC versions 2016-10-25 11:44:25 +02:00
syscall_32.c x86/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
syscall_64.c x86/entry/64: Always run ptregs-using syscalls on the slow path 2016-01-29 09:46:38 +01:00
thunk_32.S x86: move exports to actual definitions 2016-08-07 23:47:15 -04:00
thunk_64.S x86: move exports to actual definitions 2016-08-07 23:47:15 -04:00