[PATCH] ARM64: implement TASK_SIZE_OF

[PATCH] ARM64: implement TASK_SIZE_OF

[Colin Cross]

include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
is not set by the architecture headers.  TASK_SIZE uses the
current task to determine the size of the virtual address space.
On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
64-bit process from a 32-bit process to return EOF when it reads
past 0xffffffff.

Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
test_tsk_thread_flag instead of test_thread_flag.

Cc: stable at vger.kernel.org
Signed-off-by: Colin Cross <ccross@android.com>
---
 arch/arm64/include/asm/memory.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 993bce527b85..902eb708804a 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -56,6 +56,8 @@
 #define TASK_SIZE_32		UL(0x100000000)
 #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) ? \
+				TASK_SIZE_32 : TASK_SIZE_64)
 #else
 #define TASK_SIZE		TASK_SIZE_64
 #endif /* CONFIG_COMPAT */
-- 
2.0.0.526.g5318336

[PATCH] ARM64: implement TASK_SIZE_OF

[Will Deacon]

Hi Colin,

On Wed, Jun 18, 2014 at 09:10:09PM +0100, Colin Cross wrote:
> include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
> is not set by the architecture headers.  TASK_SIZE uses the
> current task to determine the size of the virtual address space.
> On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
> 64-bit process from a 32-bit process to return EOF when it reads
> past 0xffffffff.
> 
> Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
> test_tsk_thread_flag instead of test_thread_flag.

Looks sane to me.

  Acked-by: Will Deacon <will.deacon@arm.com>

I take it you're being bitten by this in real software, hence the CC stable
tag?

Will

[PATCH] ARM64: implement TASK_SIZE_OF

[Colin Cross]

On Fri, Jun 20, 2014 at 1:25 AM, Will Deacon <will.deacon@arm.com> wrote:
> Hi Colin,
>
> On Wed, Jun 18, 2014 at 09:10:09PM +0100, Colin Cross wrote:
>> include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
>> is not set by the architecture headers.  TASK_SIZE uses the
>> current task to determine the size of the virtual address space.
>> On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
>> 64-bit process from a 32-bit process to return EOF when it reads
>> past 0xffffffff.
>>
>> Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
>> test_tsk_thread_flag instead of test_thread_flag.
>
> Looks sane to me.
>
>   Acked-by: Will Deacon <will.deacon@arm.com>
>
> I take it you're being bitten by this in real software, hence the CC stable
> tag?
>
> Will

Yes, it causes memory statistics produced by Android's procrank tool
to be completely wrong.  It applies cleanly to at least 3.10.44,
3.12.22, and 3.14.8.

[PATCH] ARM64: implement TASK_SIZE_OF

[Catalin Marinas]

On Wed, Jun 18, 2014 at 09:10:09PM +0100, Colin Cross wrote:
> include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
> is not set by the architecture headers.  TASK_SIZE uses the
> current task to determine the size of the virtual address space.
> On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
> 64-bit process from a 32-bit process to return EOF when it reads
> past 0xffffffff.
> 
> Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
> test_tsk_thread_flag instead of test_thread_flag.
> 
> Cc: stable at vger.kernel.org
> Signed-off-by: Colin Cross <ccross@android.com>

Thanks. Applied.

-- 
Catalin