On 3/16/20 10:22 AM, Mark Rutland wrote: > Hi Vincenzo, > > On Mon, Mar 16, 2020 at 09:42:32AM +0000, Vincenzo Frascino wrote: >> On 3/15/20 6:30 PM, Catalin Marinas wrote: >>> On Fri, Mar 13, 2020 at 03:43:37PM +0000, Vincenzo Frascino wrote: >>>> --- /dev/null >>>> +++ b/arch/arm64/include/asm/vdso/processor.h >>>> @@ -0,0 +1,31 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>>> +/* >>>> + * Copyright (C) 2020 ARM Ltd. >>>> + */ >>>> +#ifndef __ASM_VDSO_PROCESSOR_H >>>> +#define __ASM_VDSO_PROCESSOR_H >>>> + >>>> +#ifndef __ASSEMBLY__ >>>> + >>>> +#include <asm/page-def.h> >>>> + >>>> +#ifdef CONFIG_COMPAT >>>> +#if defined(CONFIG_ARM64_64K_PAGES) && defined(CONFIG_KUSER_HELPERS) >>>> +/* >>>> + * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied >>>> + * by the compat vectors page. >>>> + */ >>>> +#define TASK_SIZE_32 UL(0x100000000) >>>> +#else >>>> +#define TASK_SIZE_32 (UL(0x100000000) - PAGE_SIZE) >>>> +#endif /* CONFIG_ARM64_64K_PAGES */ >>>> +#endif /* CONFIG_COMPAT */ >>> >>> Just curious, what's TASK_SIZE_32 used for in the vDSO code? You don't >>> seem to move TASK_SIZE. >>> >> >> I tried to fine grain the headers as much as I could in order to avoid >> unneeded/unwanted inclusions: >> * TASK_SIZE_32 is used to verify ABI consistency on vdso32 (please refer to >> arch/arm64/kernel/vdso32/vgettimeofday.c). >> * TASK_SIZE is not required by the vdso library hence it is not present in >> these headers. > > It would be worth noting the former point in the commit message, since > it can be surprising. > Sure it is a good point, I will add this to the commit message. > I also think it's worth keeping the definitions together if that's easy, > as it makes it easier to navigate the codebase, even if TASK_SIZE isn't > necessary for the VDSO itself. This can't be done because TASK_SIZE on arm64 requires test_thread_flag() with is not suited for vDSO. In other words can cause the same problem we are trying to solve. > > Thanks, > Mark. > -- Regards, Vincenzo
