[COMMITTED 2.33, 2.34] powerpc64[le]: Allocate extra stack frame on syscall.S

[Matheus Castanho <msc@linux.ibm.com>]

The syscall function does not allocate the extra stack frame for scv like other
assembly syscalls using DO_CALL_SCV. So after commit d120fb9941 changed the
offset that is used to save LR, syscall ended up using an invalid offset,
causing regressions on powerpc64. So make sure the extra stack frame is
allocated in syscall.S as well to make it consistent with other uses of
DO_CALL_SCV and avoid similar issues in the future.

Tested on powerpc, powerpc64, and powerpc64le (with and without scv)

Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com>

(cherry picked from commit ae91d3df24a4a1b1f264d101a71a298bff310d14)
---
 sysdeps/unix/sysv/linux/powerpc/syscall.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sysdeps/unix/sysv/linux/powerpc/syscall.S b/sysdeps/unix/sysv/linux/powerpc/syscall.S
index d6ec87f006..d06e776ca4 100644
--- a/sysdeps/unix/sysv/linux/powerpc/syscall.S
+++ b/sysdeps/unix/sysv/linux/powerpc/syscall.S
@@ -27,7 +27,11 @@ ENTRY (syscall)
 	mr   r8,r9
 #if !IS_IN(rtld) && (defined(__PPC64__) || defined(__powerpc64__))
 	CHECK_SCV_SUPPORT r9 0f
+	stdu r1,-SCV_FRAME_SIZE(r1)
+	cfi_adjust_cfa_offset(SCV_FRAME_SIZE)
 	DO_CALL_SCV
+	addi r1,r1,SCV_FRAME_SIZE
+	cfi_adjust_cfa_offset(-SCV_FRAME_SIZE)
 	RET_SCV
 	b 1f
 #endif
--
2.31.1