[PATCH v4 10/12] arm64: BTI: Reset BTYPE when skipping emulated instructions

Catalin Marinas catalin.marinas at arm.com
Tue Jan 14 09:36:28 PST 2020


On Wed, Dec 11, 2019 at 03:42:04PM +0000, Mark Brown wrote:
> From: Dave Martin <Dave.Martin at arm.com>
> 
> Since normal execution of any non-branch instruction resets the
> PSTATE BTYPE field to 0, so do the same thing when emulating a
> trapped instruction.
> 
> Branches don't trap directly, so we should never need to assign a
> non-zero value to BTYPE here.
> 
> Signed-off-by: Dave Martin <Dave.Martin at arm.com>
> Signed-off-by: Mark Brown <broonie at kernel.org>
> ---
>  arch/arm64/kernel/traps.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index bf79d8024fbe..9fc05ae500e6 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -332,6 +332,8 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
>  
>  	if (regs->pstate & PSR_MODE32_BIT)

Same comment as on a previous patch, compat_user_mode() could be used.

Other than this:

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



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