[Mesa-dev] [PATCH 03/39] llvmpipe: Fix overflow for 32 bits available memory computation

[Rob Herring]

On Tue, May 17, 2016 at 11:35 AM, Axel Davy <axel.davy at ens.fr> wrote:
> On 16/05/2016 23:28, Rob Herring wrote:
>>
>> On Sun, May 15, 2016 at 5:45 AM, Axel Davy <axel.davy at ens.fr> wrote:
>>>
>>> And cap to 2 GB on 32 bits.
>>>
>>> Fixes https://bugs.freedesktop.org/show_bug.cgi?id=94561
>>>
>>> Signed-off-by: Axel Davy <axel.davy at ens.fr>
>>> ---
>>>   src/gallium/auxiliary/os/os_misc.c       | 2 +-
>>>   src/gallium/drivers/llvmpipe/lp_screen.c | 5 +++++
>>>   2 files changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/gallium/auxiliary/os/os_misc.c
>>> b/src/gallium/auxiliary/os/os_misc.c
>>> index d6b83e9..cf2ef95 100644
>>> --- a/src/gallium/auxiliary/os/os_misc.c
>>> +++ b/src/gallium/auxiliary/os/os_misc.c
>>> @@ -117,7 +117,7 @@ os_get_total_physical_memory(uint64_t *size)
>>>      const long phys_pages = sysconf(_SC_PHYS_PAGES);
>>>      const long page_size = sysconf(_SC_PAGE_SIZE);
>>>
>>> -   *size = phys_pages * page_size;
>>> +   *size = (int64_t)phys_pages * (int64_t)page_size;
>>>      return (phys_pages > 0 && page_size > 0);
>>>   #elif defined(PIPE_OS_APPLE) || defined(PIPE_OS_BSD)
>>>      size_t len = sizeof(*size);
>>> diff --git a/src/gallium/drivers/llvmpipe/lp_screen.c
>>> b/src/gallium/drivers/llvmpipe/lp_screen.c
>>> index 4f61de8..2f84b75 100644
>>> --- a/src/gallium/drivers/llvmpipe/lp_screen.c
>>> +++ b/src/gallium/drivers/llvmpipe/lp_screen.c
>>> @@ -279,6 +279,11 @@ llvmpipe_get_param(struct pipe_screen *screen, enum
>>> pipe_cap param)
>>>         if (!os_get_total_physical_memory(&system_memory))
>>>            return 0;
>>>
>>> +#ifdef PIPE_ARCH_X86
>>> +      /* cap to 2 GB on 32 bits system */
>>
>> What about non-x86 32-bit systems?
>>
>> Rob
>>
> Do you have a suggestion for a better check ?

if (sizeof(void *) == 4)
    /* cap to 2 GB on 32 bits system */
    system_memory = MIN2(system_memory, 2048);

>
>
> I could add in p_config.h a PIPE_ARCH_32 (and PIPE_ARCH_64), but I'm not
> sure what to put in there,
>
> since it is possible to have a 32 bits processor with 64 bits memory
> addressing.

Yes, but userspace can still only see 32-bits worth in that case. I
don't see how that matters here.

Rob