[glibc/release/2.34/master] powerpc64[le]: Allocate extra stack frame on syscall.S

[Matheus Castanho <mscastanho@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5daf13b1e637eec0f7a2de05b177cb0d76479aa2

commit 5daf13b1e637eec0f7a2de05b177cb0d76479aa2
Author: Matheus Castanho <msc@linux.ibm.com>
Date:   Wed Dec 1 11:14:40 2021 -0300

    powerpc64[le]: Allocate extra stack frame on syscall.S
    
    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)

Diff:
---
 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 a29652feaf..a5497c8370 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 defined(USE_PPC_SCV) && !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