Re: [edk2-devel] [PATCH v2 4/5] MdePkg/BaseLib: correct register sizes in AArch64 SetJump/LongJump

["Sami Mujawar" <sami.mujawar@arm.com>]

Hi Leif,

Thank you for this patch.

These changes look good to me.

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

Regards,

Sami Mujawar

On 26/09/2023 06:15 pm, Leif Lindholm wrote:
> Both in SetJump and in InternalLongJump, 32-bit w register views were
> used for the UINTN return value. In SetJump, this did not cause errors;
> it was only counterintuitive. But in InternalLongJump, it meant the top
> 32 bits of Value were stripped off.
>
> Change all of these to use the 64-bit x register views.
>
> Signed-off-by: Leif Lindholm <quic_llindhol@quicinc.com>
> Reanimated-by: Andrei Warkentin <andrei.warkentin@intel.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> ---
>   MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S   | 8 ++++----
>   MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm | 8 ++++----
>   2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> index de79ad3a0a3e..3e58119b25d2 100644
> --- a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> +++ b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> @@ -61,7 +61,7 @@ ASM_PFX(SetJump):
>           FPR_LAYOUT
>   #undef REG_PAIR
>   #undef REG_ONE
> -        mov     w0, #0
> +        mov     x0, #0
>           ret
>   
>   #/**
> @@ -91,9 +91,9 @@ ASM_PFX(InternalLongJump):
>   #undef REG_PAIR
>   #undef REG_ONE
>           mov     sp, x16
> -        cmp     w1, #0
> -        mov     w0, #1
> -        csel    w0, w1, w0, ne
> +        cmp     x1, #0
> +        mov     x0, #1
> +        csel    x0, x1, x0, ne
>           ret
>   
>   ASM_FUNCTION_REMOVE_IF_UNREFERENCED
> diff --git a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> index c2774eece311..6ec8f35f2c9f 100644
> --- a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> +++ b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> @@ -59,7 +59,7 @@ SetJump
>           FPR_LAYOUT
>   #undef REG_PAIR
>   #undef REG_ONE
> -        mov     w0, #0
> +        mov     x0, #0
>           ret
>   
>   ;/**
> @@ -88,10 +88,10 @@ InternalLongJump
>   #undef REG_PAIR
>   #undef REG_ONE
>           mov     sp, x16
> -        cmp     w1, #0
> -        mov     w0, #1
> +        cmp     x1, #0
> +        mov     x0, #1
>           beq     exit
> -        mov     w0, w1
> +        mov     x0, x1
>   exit
>           // use br not ret, as ret is guaranteed to mispredict
>           br      x30


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