| Message ID | 20190401103201.9268-1-vincenzo.frascino@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: compat: Reduce address limit | expand |
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@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Jann Horn <jannh@google.com> > Reported-by: Jann Horn <jannh@google.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > 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.
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@arm.com> >> Cc: Will Deacon <will.deacon@arm.com> >> Cc: Jann Horn <jannh@google.com> >> Reported-by: Jann Horn <jannh@google.com> >> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> >> --- >> 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.
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 */ #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ TASK_SIZE_32 : TASK_SIZE_64) #define TASK_SIZE_OF(tsk) (test_tsk_thread_flag(tsk, TIF_32BIT) ? \
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@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Jann Horn <jannh@google.com> Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- arch/arm64/include/asm/processor.h | 4 ++++ 1 file changed, 4 insertions(+)