commit a85abfa92220239cad0a8a6b0f2a223f5e6472a9
Author: Andreas Schwab <schwab@suse.de>
Date: Thu Aug 18 11:38:28 2016 +0200
arm: mark __startcontext as .cantunwind (bug 20435)
__startcontext marks the bottom of the call stack of the contexts created
by makecontext.
(cherry picked from commit 9e2ff6c9cc54c0b4402b8d49e4abe7000fde7617)
Also includes the NEWS update, cherry-picked from commits
056dd72af83f5459ce6d545a49dea6dba7d635dc and
4d047efdbc55b0d68947cde682e5363d16a66294.
diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S
index 24c7294..926b65a 100644
--- a/sysdeps/unix/sysv/linux/arm/setcontext.S
+++ b/sysdeps/unix/sysv/linux/arm/setcontext.S
@@ -86,12 +86,19 @@ weak_alias(__setcontext, setcontext)
/* Called when a makecontext() context returns. Start the
context in R4 or fall through to exit(). */
+ /* Unwind descriptors are looked up based on PC - 2, so we have to
+ make sure to mark the instruction preceding the __startcontext
+ label as .cantunwind. */
+ .fnstart
+ .cantunwind
+ nop
ENTRY(__startcontext)
movs r0, r4
bne PLTJMP(__setcontext)
@ New context was 0 - exit
b PLTJMP(HIDDEN_JUMPTARGET(exit))
+ .fnend
END(__startcontext)
#ifdef PIC