Re: [PATCH 04/13] x86/crypto/aesni-intel_avx: Standardize stack alignment prologue

[Peter Zijlstra]

On Wed, Feb 24, 2021 at 10:29:17AM -0600, Josh Poimboeuf wrote:
> Use RBP instead of R14 for saving the old stack pointer before
> realignment.  This resembles what compilers normally do.
> 
> This enables ORC unwinding by allowing objtool to understand the stack
> realignment.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
>  arch/x86/crypto/aesni-intel_avx-x86_64.S | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/crypto/aesni-intel_avx-x86_64.S b/arch/x86/crypto/aesni-intel_avx-x86_64.S
> index 188f1848a730..98e3552b6e03 100644
> --- a/arch/x86/crypto/aesni-intel_avx-x86_64.S
> +++ b/arch/x86/crypto/aesni-intel_avx-x86_64.S
> @@ -251,22 +251,20 @@ VARIABLE_OFFSET = 16*8
>  .macro FUNC_SAVE
>          push    %r12
>          push    %r13
> -        push    %r14
>          push    %r15
>  
> -        mov     %rsp, %r14
> -
> -
> +	push	%rbp
> +	mov	%rsp, %rbp
>  
>          sub     $VARIABLE_OFFSET, %rsp
>          and     $~63, %rsp                    # align rsp to 64 bytes
>  .endm
>  
>  .macro FUNC_RESTORE
> -        mov     %r14, %rsp
> +        mov     %rbp, %rsp
> +	pop	%rbp
>  
>          pop     %r15
> -        pop     %r14
>          pop     %r13
>          pop     %r12
>  .endm

Urgh, I was about to say your patch is whitespace damaged, but it's the
original file :-/