From 1061d6fe364ddac7458a872839ea9efe8f7600f0 Mon Sep 17 00:00:00 2001 From: Andreas Schwab Date: Mon, 8 Aug 2016 09:29:18 +0200 Subject: [PATCH] arm: mark __startcontext as .cantunwind __startcontext marks the bottom of the call stack of the contexts created by makecontext. [BZ #20435] * sysdeps/unix/sysv/linux/arm/setcontext.S (__startcontext): Mark as .cantunwind. --- sysdeps/unix/sysv/linux/arm/setcontext.S | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S index 603e508..d1f168f 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 -- 2.9.2