i386: Remove _Unwind_Frames_Increment

Message ID 20180720181531.GA66979@intel.com
State New
Headers show
Series
  • i386: Remove _Unwind_Frames_Increment
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Commit Message

H.J. Lu July 20, 2018, 6:15 p.m.
Tested on CET SDV using the CET kernel on cet branch at:

https://github.com/yyu168/linux_cet/tree/cet

OK for trunk and GCC 8 branch?

Thanks.


H.J.
---
The CET kernel has been changed to place a restore token on shadow stack
for signal handler to enhance security.  It is usually transparent to user
programs since kernel will pop the restore token when signal handler
returns.  But when an exception is thrown from a signal handler, now
we need to remove _Unwind_Frames_Increment to pop the the restore token
from shadow stack.  Otherwise, we get

FAIL: g++.dg/torture/pr85334.C   -O0  execution test
FAIL: g++.dg/torture/pr85334.C   -O1  execution test
FAIL: g++.dg/torture/pr85334.C   -O2  execution test
FAIL: g++.dg/torture/pr85334.C   -O3 -g  execution test
FAIL: g++.dg/torture/pr85334.C   -Os  execution test
FAIL: g++.dg/torture/pr85334.C   -O2 -flto -fno-use-linker-plugin -flto-partition=none  execution test

	PR libgcc/85334
	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
	Removed.
---
 libgcc/config/i386/shadow-stack-unwind.h | 5 -----
 1 file changed, 5 deletions(-)

-- 
2.17.1

Patch

diff --git a/libgcc/config/i386/shadow-stack-unwind.h b/libgcc/config/i386/shadow-stack-unwind.h
index a32f3e74b52..40f48df2aec 100644
--- a/libgcc/config/i386/shadow-stack-unwind.h
+++ b/libgcc/config/i386/shadow-stack-unwind.h
@@ -49,8 +49,3 @@  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 	}					\
     }						\
     while (0)
-
-/* Increment frame count.  Skip signal frames.  */
-#undef _Unwind_Frames_Increment
-#define _Unwind_Frames_Increment(context, frames) \
-  if (!_Unwind_IsSignalFrame (context)) frames++