[PATCH 5.0 38/46] xtensa: fix get_wchan

Greg Kroah-Hartman
2019-03-08T12:53:09Z

From: Max Filippov <jcmvbkbc@gmail.com>

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>

---
arch/xtensa/kernel/process.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -321,8 +321,8 @@ unsigned long get_wchan(struct task_stru

/* 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;
}