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authorAndreas Schwab <schwab@suse.de>2016-08-18 11:38:28 +0200
committerMike Frysinger <vapier@gentoo.org>2016-11-12 00:44:38 -0500
commitcafa0319f8ff701b7edd56e3e244e79abcf84748 (patch)
tree52ede1544ee195d4adc141c3e04098cfde6179c2
parent2b1222a9337b2f1fc6ce8b9704ebe5265fa592d6 (diff)
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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.

(cherry picked from commit 23446cad92195d8c50092410b4f72ca7f6d1d2f1)
-rw-r--r--sysdeps/unix/sysv/linux/arm/setcontext.S7
1 files changed, 7 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S
index 603e508858..d1f168fece 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