[Linux-Xtensa] [PATCH] xtensa: fix get_wchan

Max Filippov jcmvbkbc at gmail.com
Thu Feb 7 20:33:36 UTC 2019


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 at vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc at gmail.com>
---
 arch/xtensa/kernel/process.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 74969a437a37..2e73395f0560 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -321,8 +321,8 @@ 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;
 }
-- 
2.11.0



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