Messages in this thread | | | Subject | Re: [PATCH v2 1/2] arm64/crash_core: Export KERNELPACMASK in vmcoreinfo | From | Amit Kachhap <> | Date | Wed, 6 May 2020 18:34:20 +0530 |
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Hi,
On 5/6/20 6:01 PM, Will Deacon wrote: > On Wed, May 06, 2020 at 05:32:56PM +0530, Amit Kachhap wrote: >> On 5/4/20 10:47 PM, Will Deacon wrote: >>> On Mon, Apr 27, 2020 at 11:55:01AM +0530, Amit Daniel Kachhap wrote: >>>> diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h >>>> index eece20d..32d5900 100644 >>>> --- a/arch/arm64/include/asm/compiler.h >>>> +++ b/arch/arm64/include/asm/compiler.h >>>> @@ -19,6 +19,9 @@ >>>> #define __builtin_return_address(val) \ >>>> (void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val))) >>>> +#else /* !CONFIG_ARM64_PTR_AUTH */ >>>> +#define ptrauth_user_pac_mask() 0ULL >>>> +#define ptrauth_kernel_pac_mask() 0ULL >>> >>> This doesn't look quite right to me, since you still have to take into >>> account the case where CONFIG_ARM64_PTR_AUTH=y but the feature is not >>> available at runtime: >> >> Yes agree with you here. However the config gaurd is saving some extra >> computation for __builtin_return_address. There are some compiler >> support being added in __builtin_extract_return_address to mask the PAC. >> Hopefully that will improve this code. In the meantime let it be like this. > > Does the extra computation matter? Isn't it just a couple of instructions?
ok sure. I will push v3 as you suggested.
Thanks, Amit
> > Will >
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