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linux/arch/metag
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James Hogan a21f68bd8c metag: Fix KSTK_EIP() and KSTK_ESP() macros 
commit c2996cb29b upstream.

The KSTK_EIP() and KSTK_ESP() macros should return the user program
counter (PC) and stack pointer (A0StP) of the given task. These are used
to determine which VMA corresponds to the user stack in
/proc/<pid>/maps, and for the user PC & A0StP in /proc/<pid>/stat.

However for Meta the PC & A0StP from the task's kernel context are used,
resulting in broken output. For example in following /proc/<pid>/maps
output, the 3afff000-3b021000 VMA should be described as the stack:

  # cat /proc/self/maps
  ...
  100b0000-100b1000 rwxp 00000000 00:00 0          [heap]
  3afff000-3b021000 rwxp 00000000 00:00 0

And in the following /proc/<pid>/stat output, the PC is in kernel code
(1074234964 = 0x40078654) and the A0StP is in the kernel heap
(1335981392 = 0x4fa17550):

  # cat /proc/self/stat
  51 (cat) R ... 1335981392 1074234964 ...

Fix the definitions of KSTK_EIP() and KSTK_ESP() to use
task_pt_regs(tsk)->ctx rather than (tsk)->thread.kernel_context. This
gets the registers from the user context stored after the thread info at
the base of the kernel stack, which is from the last entry into the
kernel from userland, regardless of where in the kernel the task may
have been interrupted, which results in the following more correct
/proc/<pid>/maps output:

  # cat /proc/self/maps
  ...
  0800b000-08070000 r-xp 00000000 00:02 207        /lib/libuClibc-0.9.34-git.so
  ...
  100b0000-100b1000 rwxp 00000000 00:00 0          [heap]
  3afff000-3b021000 rwxp 00000000 00:00 0          [stack]

And /proc/<pid>/stat now correctly reports the PC in libuClibc
(134320308 = 0x80190b4) and the A0StP in the [stack] region (989864576 =
0x3b002280):

  # cat /proc/self/stat
  51 (cat) R ... 989864576 134320308 ...

Reported-by: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Reported-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
History 2015-03-18 09:58:55 +00:00
..
boot metag: tz1090: instantiate gpio-tz1090-pdc 2013-07-22 10:55:31 +01:00
configs metag: minimal TZ1090 (Comet) SoC infrastructure 2013-06-13 12:14:07 +01:00
include metag: Fix KSTK_EIP() and KSTK_ESP() macros 2015-03-18 09:58:55 +00:00
kernel of/fdt: consolidate built-in dtb section variables 2014-04-30 00:59:13 -05:00
lib metag: move EXPORT_SYMBOL(csum_partial) to metag_ksyms.c 2013-07-04 10:00:02 +01:00
mm vm: add VM_FAULT_SIGSEGV handling support 2015-02-04 10:58:27 +00:00
oprofile metag: OProfile support 2013-03-15 13:21:05 +00:00
tbx metag: handle low level kicks directly 2013-11-06 10:40:02 +00:00
Kconfig Kconfig: rename HAS_IOPORT to HAS_IOPORT_MAP 2014-04-07 16:36:11 -07:00
Kconfig.debug consolidate per-arch stack overflow debugging options 2013-07-04 11:25:39 -07:00
Kconfig.soc metag: tz1090: select and instantiate gpio-tz1090 2013-07-22 10:55:31 +01:00
Makefile metag: minimal TZ1090 (Comet) SoC infrastructure 2013-06-13 12:14:07 +01:00