Re: [PATCH 18/18] x86/traps: Use a new on_thread_stack() helper to clean up an assertion

Borislav Petkov
2017-11-01T10:31:08Z

On Thu, Oct 26, 2017 at 01:26:50AM -0700, Andy Lutomirski wrote:
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> arch/x86/include/asm/processor.h | 6 ++++++
> arch/x86/kernel/traps.c | 3 +--
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 562c575d8bc3..26fc33231cbd 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -541,6 +541,12 @@ static inline unsigned long current_top_of_stack(void)
> #endif
> }
>
> +static inline bool on_thread_stack(void)
> +{
> + return (unsigned long)(current_top_of_stack() -
> + current_stack_pointer) < THREAD_SIZE;
> +}
> +
> #ifdef CONFIG_PARAVIRT
> #include <asm/paravirt.h>
> #else
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 67db4f43309e..42a9c4458f5d 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -141,8 +141,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
> * will catch asm bugs and any attempt to use ist_preempt_enable
> * from double_fault.
> */
> - BUG_ON((unsigned long)(current_top_of_stack() -
> - current_stack_pointer) >= THREAD_SIZE);
> + BUG_ON(!on_thread_stack());
>
> preempt_enable_no_resched();
> }
> --

Having a commit message is always better. Other than that:

Reviewed-by: Borislav Petkov <bp@suse.de>

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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