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xtensa: fix get_wchan

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commit d90b88fd3653f1fb66ecc6571b860d5a5749fa56 upstream.

Stack unwinding is implemented incorrectly in xtensa get_wchan: instead
of extracting a0 and a1 registers from the spill location under the
stack pointer it extracts a word pointed to by the stack pointer and
subtracts 4 or 3 from it.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Max Filippov 2019-01-02 01:08:32 -08:00 committed by Greg Kroah-Hartman
parent af46f4c037
commit 1b0322ebab
1 changed files with 2 additions and 2 deletions
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4
arch/xtensa/kernel/process.c
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@ -314,8 +314,8 @@ unsigned long get_wchan(struct task_struct *p)
/* Stack layout: sp-4: ra, sp-3: sp' */
pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
sp = *(unsigned long *)sp - 3;
pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp);
sp = SPILL_SLOT(sp, 1);
} while (count++ < 16);
return 0;
}