[PATCH v2 1/4] arm64/signal: Raise limit on stack frames

[Catalin Marinas]

On Mon, Aug 15, 2022 at 02:28:31PM +0100, Mark Brown wrote:
> The signal code has a limit of 64K on the size of a stack frame that it
> will generate, if this limit is exceeded then a process will be killed if
> it receives a signal. Unfortunately with the advent of SME this limit is
> too small - the maximum possible size of the ZA register alone is 64K. This
> is not an issue for practical systems at present but is easily seen using
> virtual platforms.
> 
> Raise the limit to 256K, this is substantially more than could be used by
> any current architecture extension.
> 
> Signed-off-by: Mark Brown <broonie at kernel.org>
> ---
>  arch/arm64/kernel/signal.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index 3e6d0352d7d3..a410c980e50e 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -91,7 +91,7 @@ static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
>   * not taken into account.  This limit is not a guarantee and is
>   * NOT ABI.
>   */
> -#define SIGFRAME_MAXSZ SZ_64K
> +#define SIGFRAME_MAXSZ (SZ_64K * 4)

Why not SZ_256K?

Otherwise it looks fine:

Acked-by: Catalin Marinas <catalin.marinas at arm.com>