Re: [PATCH] tcg/arm: Increase stack alignment for function generation

[Peter Maydell]

On Wed, 1 Sept 2021 at 18:01, Richard W.M. Jones <rjones@redhat.com> wrote:
>
> This avoids the following assertion when the kernel initializes X.509
> certificates:
>
> [    7.315373] Loading compiled-in X.509 certificates
> qemu-system-arm: ../tcg/tcg.c:3063: temp_allocate_frame: Assertion `align <= 
> TCG_TARGET_STACK_ALIGN' failed.
>
> Fixes: commit c1c091948ae
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1999878
> Cc: qemu-stable@nongnu.org
> Tested-by: Richard W.M. Jones <rjones@redhat.com>
> Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
> ---
>  tcg/arm/tcg-target.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tcg/arm/tcg-target.h b/tcg/arm/tcg-target.h
> index d113b7f8db..09df3b39a1 100644
> --- a/tcg/arm/tcg-target.h
> +++ b/tcg/arm/tcg-target.h
> @@ -115,7 +115,7 @@ extern bool use_neon_instructions;
>  #endif
>
>  /* used for function call generation */
> -#define TCG_TARGET_STACK_ALIGN         8
> +#define TCG_TARGET_STACK_ALIGN          16
>  #define TCG_TARGET_CALL_ALIGN_ARGS     1
>  #define TCG_TARGET_CALL_STACK_OFFSET   0

The 32-bit Arm procedure call standard only guarantees 8-alignment
of SP, not 16-alignment, so I suspect this is not the correct fix.

-- PMM