Align stack to 16 bytes when calling __setcontext

Don't use pop to restore %rdi so that stack is aligned to 16 bytes when calling __setcontext. [BZ #18661] * sysdeps/unix/sysv/linux/x86_64/__start_context.S (__start_context): Don't use pop to restore %rdi so that stack is aligned to 16 bytes when calling __setcontext.
git-mirror · Aug 5, 2015 · 8e1f346 · 8e1f346
1 parent 3b8d2eb
commit 8e1f346
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diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,10 @@
+2015-08-05  H.J. Lu  <hongjiu.lu@intel.com>
+
+	[BZ #18661]
+	* sysdeps/unix/sysv/linux/x86_64/__start_context.S
+	(__start_context): Don't use pop to restore %rdi so that stack
+	is aligned to 16 bytes when calling __setcontext.
+
 2015-08-05  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S: Compile

diff --git a/sysdeps/unix/sysv/linux/x86_64/__start_context.S b/sysdeps/unix/sysv/linux/x86_64/__start_context.S
@@ -31,8 +31,8 @@ ENTRY(__start_context)
 	   on the stack pointer for the next context.  */
 	movq	%rbx, %rsp
 
-	popq	%rdi			/* This is the next context.  */
-	cfi_adjust_cfa_offset(-8)
+	/* Don't use pop here so that stack is aligned to 16 bytes.  */
+	movq	(%rsp), %rdi		/* This is the next context.  */
 	testq	%rdi, %rdi
 	je	2f			/* If it is zero exit.  */