Andrey Ryabinin <ryabinin....@gmail.com> writes:
> 2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>:
>> We add enable/disable callbacks in this patch which architecture
>> can implemement. We will use this in the later patches for architecture
>> like ppc64, that cannot have early zero page kasan shadow region for the
>> entire virtual address space. Such architectures also cannot use
>> inline kasan support.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
>> ---
>> mm/kasan/kasan.c | 9 +++++++++
>> mm/kasan/kasan.h | 15 +++++++++++++++
>> 2 files changed, 24 insertions(+)
>>
>> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
>> index 7b28e9cdf1c7..e4d33afd0eaf 100644
>> --- a/mm/kasan/kasan.c
>> +++ b/mm/kasan/kasan.c
>> @@ -43,6 +43,9 @@ static void kasan_poison_shadow(const void *address,
>> size_t size, u8 value)
>> {
>> void *shadow_start, *shadow_end;
>>
>> + if (!kasan_enabled())
>> + return;
>> +
>
> By the time this function called we already should have shadow,
> so it should be safe to remove this check.
>
I remember hitting that call before enabling kasan completely. Will
check that again.
>
>> shadow_start = kasan_mem_to_shadow(address);
>> shadow_end = kasan_mem_to_shadow(address + size);
>>
>> @@ -51,6 +54,9 @@ static void kasan_poison_shadow(const void *address,
>> size_t size, u8 value)
>>
>> void kasan_unpoison_shadow(const void *address, size_t size)
>> {
>> + if (!kasan_enabled())
>> + return;
>> +
>
> Ditto.
>
>> kasan_poison_shadow(address, size, 0);
>>
>> if (size & KASAN_SHADOW_MASK) {
>> @@ -238,6 +244,9 @@ static __always_inline void check_memory_region(unsigned
>> long addr,
>> {
>> struct kasan_access_info info;
>>
>> + if (!kasan_enabled())
>> + return;
>> +
>> if (unlikely(size == 0))
>> return;
>>
>> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
>> index a6b46cc94907..deb547d5a916 100644
>> --- a/mm/kasan/kasan.h
>> +++ b/mm/kasan/kasan.h
>> @@ -68,6 +68,21 @@ static inline bool kasan_report_enabled(void)
>> return !current->kasan_depth;
>> }
>>
>> +#ifndef kasan_enabled
>> +/*
>> + * Some archs may want to disable kasan callbacks.
>> + */
>> +static inline bool kasan_enabled(void)
>> +{
>> + return true;
>> +}
>> +#define kasan_enabled kasan_enabled
>
> Why we need this define?
That is to make sure that we don't endup with different definition of
kasan_enabled due to header include errors. Once we select a
particular definition of the overloaded function, it is always good to mark
the function as defined, so that checks like #ifndef kasan_enabled will
always fail.
>
>> +#else
>> +#ifdef CONFIG_KASAN_INLINE
>> +#error "Kasan inline support cannot work with KASAN arch hooks"
>> +#endif
>> +#endif
>> +
>> void kasan_report(unsigned long addr, size_t size,
>> bool is_write, unsigned long ip);
>>
>> --
>> 2.5.0
>>
-aneesh
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