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authorRichard Henderson <rth@twiddle.net>2013-11-16 06:34:39 +1000
committerRichard Henderson <rth@twiddle.net>2013-11-16 06:34:39 +1000
commit027e32bd42314e17095ba39df82ef293f4a72c09 (patch)
treecd0c821a2b2aec5754a6ae66b34a09b0c45d97d4 /ports/sysdeps/unix
parent1820b143aa651d619a768708f08b129aa45043c2 (diff)
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alpha: Fix signal thunk unwind info
Diffstat (limited to 'ports/sysdeps/unix')
-rw-r--r--ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S18
1 files changed, 14 insertions, 4 deletions
diff --git a/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S b/ports/sysdeps/unix/sysv/linux/alpha/rt_sigaction.S
index 3d291fd0b4..6efa7386d5 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