[PATCH, AArch64] Sync merge libffi - fix call frame information in ffi_closure_SYSV

[Yufeng Zhang]

Hi,

The attached patch fixes a bug in ./src/aarch64/sysv.S:ffi_closure_SYSV 
where stack unwinding information was not generated correctly.  The 
change has been reviewed, approved and merged into the stand-alone 
libffi release tree**.

OK for the trunk?

Thanks,
Yufeng

** http://github.com/atgreen/libffi


2014-02-28  Yufeng Zhang  <yufeng.zh...@arm.com>

        * src/aarch64/sysv.S (ffi_closure_SYSV): Use x29 as the
        main CFA reg; update cfi_rel_offset.diff --git a/libffi/src/aarch64/sysv.S b/libffi/src/aarch64/sysv.S
index b8cd421..ffb16f8 100644
--- a/libffi/src/aarch64/sysv.S
+++ b/libffi/src/aarch64/sysv.S
@@ -231,13 +231,13 @@ ffi_closure_SYSV:
         cfi_rel_offset (x30, 8)
 
         mov     x29, sp
+        cfi_def_cfa_register (x29)
 
         sub     sp, sp, #ffi_closure_SYSV_FS
-       cfi_adjust_cfa_offset (ffi_closure_SYSV_FS)
 
         stp     x21, x22, [x29, #-16]
-        cfi_rel_offset (x21, 0)
-        cfi_rel_offset (x22, 8)
+        cfi_rel_offset (x21, -16)
+        cfi_rel_offset (x22, -8)
 
         /* Load x21 with &call_context.  */
         mov     x21, sp
@@ -295,7 +295,7 @@ ffi_closure_SYSV:
         cfi_restore (x22)
 
         mov     sp, x29
-       cfi_adjust_cfa_offset (-ffi_closure_SYSV_FS)
+        cfi_def_cfa_register (sp)
 
         ldp     x29, x30, [sp], #16
        cfi_adjust_cfa_offset (-16)