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[COMMITTED] alpha: Fix signal thunk unwind info
- From: Richard Henderson <rth at twiddle dot net>
- To: libc-ports at sourceware dot org
- Cc: alpha at gentoo dot org, mattst88 at gmail dot com
- Date: Sat, 16 Nov 2013 11:11:24 +1000
- Subject: [COMMITTED] alpha: Fix signal thunk unwind info
- Authentication-results: sourceware.org; auth=none
---
I'm still testing this same patch applied to 2.18. I don't plan on
backporting it further. Gentoo can do that if it wishes, but I hope
most of their users will update all the way to the most recent.
r~
ports/ChangeLog.alpha | 5 +++++
ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S | 18 ++++++++++++++----
2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/ports/ChangeLog.alpha b/ports/ChangeLog.alpha
index 07f5dfb..8f97951 100644
--- a/ports/ChangeLog.alpha
+++ b/ports/ChangeLog.alpha
@@ -1,3 +1,8 @@
+2013-11-16 Richard Henderson <rth@redhat.com>
+
+ * sysdeps/unix/sysv/linux/alpha/rt_sigaction.S: Include a nop
+ before each signal thunk.
+
2013-10-30 Mike Frysinger <vapier@gentoo.org>
* sysdeps/alpha/configure.in: Moved to ...
diff --git a/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S b/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S
index 3d291fd..6efa738 100644
--- a/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S
+++ b/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S
@@ -83,14 +83,21 @@ PSEUDO_END(__syscall_rt_sigaction)
cfi_offset (64, \base + 2 * 8)
.endm
- .align 4
-
cfi_startproc
cfi_return_column (64)
.cfi_signal_frame
SIGCONTEXT_REGS -648
-
cfi_def_cfa_offset (648)
+
+ /* While this frame is marked as a signal frame, that only applies
+ to how this return address is handled for the outer frame.
+ The return address that arrived here, from the inner frame, is
+ not marked as a signal frame and so the unwinder still tries to
+ subtract 1 to examine the presumed call insn. Thus we must
+ extend the unwind info to a nop before the start. */
+ nop
+ .align 4
+
__syscall_sigreturn:
mov sp, a0
ldi v0, __NR_sigreturn
@@ -98,8 +105,11 @@ __syscall_sigreturn:
.size __syscall_sigreturn, .-__syscall_sigreturn
.type __syscall_sigreturn, @function
- .align 4
+ /* See above wrt including the nop. */
cfi_def_cfa_offset (176 + 648)
+ nop
+ .align 4
+
__syscall_rt_sigreturn:
mov sp,a0
ldi v0,__NR_rt_sigreturn
--
1.8.3.1