[PATCH 2/4] hurd: Align signal stack pointer after allocating stackframe

[Sergey Bugaev]

sizeof (*stackframe) appears to be divisible by 16, but we should not
rely on that. So make sure to leave enough space for the stackframe
first, and then align the final pointer at 16 bytes.

Checked on x86_64-gnu.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
 sysdeps/mach/hurd/x86/trampoline.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/sysdeps/mach/hurd/x86/trampoline.c 
b/sysdeps/mach/hurd/x86/trampoline.c
index 19bddad8..1f92064e 100644
--- a/sysdeps/mach/hurd/x86/trampoline.c
+++ b/sysdeps/mach/hurd/x86/trampoline.c
@@ -196,15 +196,14 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const 
struct sigaction *action
 #endif
     }
 
+  /* Push the arguments to call `trampoline' on the stack.  */
+  sigsp -= sizeof (*stackframe);
 #ifdef __x86_64__
   /* Align SP at 16 bytes.  Coupled with the fact that sigreturn_addr is
      16-byte aligned within the stackframe struct, this ensures that it ends
      up on a 16-byte aligned address, as required by the ABI.  */
   sigsp = (void *) ((uintptr_t) sigsp & ~15UL);
 #endif
-
-  /* Push the arguments to call `trampoline' on the stack.  */
-  sigsp -= sizeof (*stackframe);
   stackframe = sigsp;
 
   if (_hurdsig_catch_memory_fault (stackframe))
-- 
2.40.1