[PATCH] x86-64: Properly align La_x86_64_retval to VEC_SIZE [BZ #22715]

["H.J. Lu" <hongjiu dot lu at intel dot com>]

_dl_runtime_profile calls _dl_call_pltexit, passing a pointer to
La_x86_64_retval which is allocated on stack.  The lrv_vector0
field in La_x86_64_retval must be aligned to size of vector register.
When allocating stack space for La_x86_64_retval, we need to make sure
that the address of La_x86_64_retval + RV_VECTOR0_OFFSET is aligned to
VEC_SIZE.  This patch checks the alignment of the lrv_vector0 field
and pads the stack space if needed.

Tested with x32 and x86-64 on SSE4, AVX and AVX512 machines.

OK for master?

H.J.
---
	[BZ #22715]
	* sysdeps/x86_64/dl-trampoline.h (_dl_runtime_profile): Properly
	align La_x86_64_retval to VEC_SIZE.
---
 sysdeps/x86_64/dl-trampoline.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
index 15edf49674..298cfb3d99 100644
--- a/sysdeps/x86_64/dl-trampoline.h
+++ b/sysdeps/x86_64/dl-trampoline.h
@@ -440,8 +440,16 @@ _dl_runtime_profile:
 # ifdef RESTORE_AVX
 	/* sizeof(La_x86_64_retval).  Need extra space for 2 SSE
 	   registers to detect if xmm0/xmm1 registers are changed
-	   by audit module.  */
-	sub $(LRV_SIZE + XMM_SIZE*2), %RSP_LP
+	   by audit module.  Since rsp is aligned to VEC_SIZE, we
+	   need to make sure that the address of La_x86_64_retval +
+	   LRV_VECTOR0_OFFSET is aligned to VEC_SIZE.  */
+#  define LRV_SPACE (LRV_SIZE + XMM_SIZE*2)
+#  define LRV_MISALIGNED ((LRV_SIZE + LRV_VECTOR0_OFFSET) & (VEC_SIZE - 1))
+#  if LRV_MISALIGNED == 0
+	sub $LRV_SPACE, %RSP_LP
+#  else
+	sub $(LRV_SPACE + VEC_SIZE - LRV_MISALIGNED), %RSP_LP
+#  endif
 # else
 	sub $LRV_SIZE, %RSP_LP	# sizeof(La_x86_64_retval)
 # endif
-- 
2.14.3