On 01/04/2019 11:59, Catalin Marinas wrote: > On Mon, Apr 01, 2019 at 11:32:01AM +0100, Vincenzo Frascino wrote: >> Currently, compat tasks running on arm64 can allocate memory up to >> TASK_SIZE_32 (UL(0x100000000)). >> >> This means that mmap() allocations, if we treat them as returning an >> array, are not compliant with the sections 6.5.8 of the C standard >> (C99) which states that: "If the expression P points to an element of >> an array object and the expression Q points to the last element of the >> same array object, the pointer expression Q+1 compares greater than P". >> >> Redefine TASK_SIZE_32 to address the issue. >> >> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> >> Cc: Will Deacon <will.deacon@xxxxxxx> >> Cc: Jann Horn <jannh@xxxxxxxxxx> >> Reported-by: Jann Horn <jannh@xxxxxxxxxx> >> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> >> --- >> arch/arm64/include/asm/processor.h | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h >> index 5d9ce62bdebd..f8235f7df29b 100644 >> --- a/arch/arm64/include/asm/processor.h >> +++ b/arch/arm64/include/asm/processor.h >> @@ -57,7 +57,11 @@ >> #define TASK_SIZE_64 (UL(1) << vabits_user) >> >> #ifdef CONFIG_COMPAT >> +#ifdef CONFIG_ARM64_64K_PAGES >> #define TASK_SIZE_32 UL(0x100000000) >> +#else >> +#define TASK_SIZE_32 (UL(0x100000000) - PAGE_SIZE) >> +#endif /* CONFIG_ARM64_64K_PAGES */ > > I'd add a comment above stating that with the 64K page configuration, > the last page is occupied by the compat vectors page. > Ok, I will post v2 shortly. -- Regards, Vincenzo
