queue-4.9/xtensa-fix-get_wchan.patch

   1 From d90b88fd3653f1fb66ecc6571b860d5a5749fa56 Mon Sep 17 00:00:00 2001
   2 From: Max Filippov <jcmvbkbc@gmail.com>
   3 Date: Wed, 2 Jan 2019 01:08:32 -0800
   4 Subject: xtensa: fix get_wchan
   5
   6 From: Max Filippov <jcmvbkbc@gmail.com>
   7
   8 commit d90b88fd3653f1fb66ecc6571b860d5a5749fa56 upstream.
   9
  10 Stack unwinding is implemented incorrectly in xtensa get_wchan: instead
  11 of extracting a0 and a1 registers from the spill location under the
  12 stack pointer it extracts a word pointed to by the stack pointer and
  13 subtracts 4 or 3 from it.
  14
  15 Cc: stable@vger.kernel.org
  16 Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18
  19 ---
  20  arch/xtensa/kernel/process.c |    4 ++--
  21  1 file changed, 2 insertions(+), 2 deletions(-)
  22
  23 --- a/arch/xtensa/kernel/process.c
  24 +++ b/arch/xtensa/kernel/process.c
  25 @@ -311,8 +311,8 @@ unsigned long get_wchan(struct task_stru
  26
  27                 /* Stack layout: sp-4: ra, sp-3: sp' */
  28
  29 -               pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
  30 -               sp = *(unsigned long *)sp - 3;
  31 +               pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp);
  32 +               sp = SPILL_SLOT(sp, 1);
  33         } while (count++ < 16);
  34         return 0;
  35  }