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

[Andy Lutomirski]

I added a commit message :)

On Wed, Nov 1, 2017 at 3:31 AM, Borislav Petkov <bp@xxxxxxx> wrote:
> On Thu, Oct 26, 2017 at 01:26:50AM -0700, Andy Lutomirski wrote:
>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
>> ---
>>  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@xxxxxxx>
>
> --
> Regards/Gruss,
>     Boris.
>
> SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton, HRB 21284 (AG NÃrnberg)
> --