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Re: Backporting KAsan patches to 4.9 branch

On 09/18/2014 01:57 PM, Jakub Jelinek wrote:
> On Thu, Sep 18, 2014 at 01:46:21PM +0400, Yury Gribov wrote:
>> Kernel Asan patches are currently being discussed in LKML. One of the points>> raised during review was that KAsan requires GCC 5.0 which is presumably >> unstable (e.g. compilation of kernel modules has been broken for two months
>> due to
>> Would it make sense to backport Kasan-related patches to 4.9 branch to make
>> this feature more accessible to kernel developers? Quick analysis showed
>> that at the very least this would require
>> ...
>> Is it ok to backport these to 4.9? Note that I would discard patches for
>> other sanitizers (UBsan, Tsan).
> I'd say so, if it doesn't need any library changes
> (especially not any ABI
> visible ones, guess bugfixes could be acceptable).

Finally got time to look into this. I've successfully backported 22 patches to 4.9:
* bugfixes (12 patches)
* install Asan headers (1 patch)
* libsanitizer merge (1 patch) - this is questionable, see below for discussion
* instrumentation with calls (1 patch)
* optimize strlen instrumentation (1 patch)
* move inlining to sanopt pass (2 patches)
* Kasan (2 patches)

One problem is that for BUILT_IN_ASAN_REPORT_{LOAD,STORE}_N patch I need libsanitizer APIs (__asan_loadN, __asan_storeN) which were introduced in a giant libsanitizer merge in 5.0. In current patchset I backport the whole merge patch (and a bunch of cherry-picks which followed it) but it changes libsanitizer ABI (new version of __asan_init_vXXX, etc.) which is probably undesirable. Another option would be to backport just the necessary minimum (__asan_loadN, __asan_storeN). How should I proceed?

Another question: Should I update patch CL dates for backported patches? If not - should I insert them to CLs in chronological order or just stack on top of previous contents?


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