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From 15c7c4d39b317f0d902ef28fd43eca5c3369f891 Mon Sep 17 00:00:00 2001

From: Max Filippov <jcmvbkbc@gmail.com>

Date: Sat, 15 Aug 2015 05:12:11 +0300

Subject: [PATCH 3/3] xtensa: fix _Unwind_GetCFA

​

Returning context->cfa in _Unwind_GetCFA makes CFA point one stack frame

higher than what was actually used by code at context->ra. This results

in invalid CFA value in signal frames and premature unwinding completion

in forced unwinding used by uClibc NPTL thread cancellation.

Returning context->sp from _Unwind_GetCFA makes all CFA values valid and

matching code that used them.

​

2015-08-18  Max Filippov  <jcmvbkbc@gmail.com>

libgcc/

    * config/xtensa/unwind-dw2-xtensa.c (_Unwind_GetCFA): Return

    context->sp instead of context->cfa.

​

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

---

Backported from: r226964

​

 libgcc/config/xtensa/unwind-dw2-xtensa.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

​

diff --git a/libgcc/config/xtensa/unwind-dw2-xtensa.c b/libgcc/config/xtensa/unwind-dw2-xtensa.c

index 35f7797..ef6b900 100644

--- a/libgcc/config/xtensa/unwind-dw2-xtensa.c

+++ b/libgcc/config/xtensa/unwind-dw2-xtensa.c

@@ -130,7 +130,7 @@ _Unwind_GetGR (struct _Unwind_Context *context, int index)

 _Unwind_Word

 _Unwind_GetCFA (struct _Unwind_Context *context)

 {

-  return (_Unwind_Ptr) context->cfa;

+  return (_Unwind_Ptr) context->sp;

 }

 /* Overwrite the saved value for register INDEX in CONTEXT with VAL.  */

-- 

1.8.1.4

​