On 05/27/2016 08:06 AM, Peter Maydell wrote:
@@ -31,6 +32,8 @@ safe_syscall_base:
* does not list any ABI differences regarding stack alignment.)
*/
push %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset rbp,-16
While this is correct, there are two other directives that make it easier to
describe changes without having to compute globally correct constants. Here
they would be:
.cfi_adjust_cfa_offset 8
Add 8 to the offset, i.e. decrement the SP by 8.
.cfi_rel_offset rbp, 0
Save rbp at the current top-of-stack.
The assembler will compute the absolute values from these relative values.
Using them makes it easy to see from a narrow window of code that the
annotations are correct.
Otherwise,
Reviewed-by: Richard Henderson <r...@twiddle.net>
r~
