Fix CFI annotations in p256-x86_64-asm.pl.
This was caught by in-progress work to test unwind information. It was
incorrect at two instructions: immediately before we jump to
.Lpoint_double_shortcut$x. This is needed because
ecp_nistz256_point_add$x tries to be clever about not unwinding the
stack frame in its tail call.
It's also unlikely that the SEH handlers in this file are correct at
this point, but that will be handled separately while overhauling
everything else here. (For Win64, probably the only ABI-compliant option
is to just properly unwind the stack frame. Without a custom handler,
Win64 unwind codes are very restrictive.)
Bug: 181
Change-Id: I9f576d868850312d6c14d1386f8fbfa85021b347
Reviewed-on: https://boringssl-review.googlesource.com/c/33946
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/fipsmodule/ec/asm/p256-x86_64-asm.pl b/crypto/fipsmodule/ec/asm/p256-x86_64-asm.pl
index 1dc257d..ab62a28 100755
--- a/crypto/fipsmodule/ec/asm/p256-x86_64-asm.pl
+++ b/crypto/fipsmodule/ec/asm/p256-x86_64-asm.pl
@@ -3114,7 +3114,9 @@
movq %xmm1, $a_ptr # restore $a_ptr
movq %xmm0, $r_ptr # restore $r_ptr
add \$`32*(18-5)`, %rsp # difference in frame sizes
+.cfi_adjust_cfa_offset `-32*(18-5)`
jmp .Lpoint_double_shortcut$x
+.cfi_adjust_cfa_offset `32*(18-5)`
.align 32
.Ladd_proceed$x:
