Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-21 Thread Arnd Bergmann
On Thu, Feb 21, 2019 at 12:47 AM Kostya Serebryany wrote: > > On Wed, Feb 20, 2019 at 2:12 PM Kostya Serebryany wrote: > > > > On Wed, Feb 20, 2019 at 1:40 PM Arnd Bergmann wrote: > > > > > > On Wed, Feb 20, 2019 at 10:13 PM Arnd Bergmann wrote: > > > > > > > > In the example in

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-21 Thread Andrey Ryabinin
On 2/21/19 6:19 PM, Arnd Bergmann wrote: > On Thu, Feb 21, 2019 at 11:06 AM Andrey Ryabinin > wrote: >> On 2/20/19 8:35 PM, Arnd Bergmann wrote: >>> On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin >>> wrote: On 2/20/19 5:51 PM, Arnd Bergmann wrote: > >>> Maybe bringing it back would be

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-21 Thread Arnd Bergmann
On Thu, Feb 21, 2019 at 11:06 AM Andrey Ryabinin wrote: > On 2/20/19 8:35 PM, Arnd Bergmann wrote: > > On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin > > wrote: > >> On 2/20/19 5:51 PM, Arnd Bergmann wrote: > > Maybe bringing it back would be a compromise? That way it's hidden from > > all

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-21 Thread Andrey Ryabinin
On 2/20/19 8:35 PM, Arnd Bergmann wrote: > On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin > wrote: >> On 2/20/19 5:51 PM, Arnd Bergmann wrote: >>> On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov >>> wrote: >>> I would have to some more research, but I expect several hundred >>> patches

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Kostya Serebryany
On Wed, Feb 20, 2019 at 2:12 PM Kostya Serebryany wrote: > > On Wed, Feb 20, 2019 at 1:40 PM Arnd Bergmann wrote: > > > > On Wed, Feb 20, 2019 at 10:13 PM Arnd Bergmann wrote: > > > > > > In the example in https://bugs.llvm.org/show_bug.cgi?id=38809#c12 > > > (https://godbolt.org/z/ylsGSQ)

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Kostya Serebryany
On Wed, Feb 20, 2019 at 1:40 PM Arnd Bergmann wrote: > > On Wed, Feb 20, 2019 at 10:13 PM Arnd Bergmann wrote: > > > > In the example in https://bugs.llvm.org/show_bug.cgi?id=38809#c12 > > (https://godbolt.org/z/ylsGSQ) there is no inlining, yet clang uses > > over ten times as much stack space

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Arnd Bergmann
On Wed, Feb 20, 2019 at 10:13 PM Arnd Bergmann wrote: > > In the example in https://bugs.llvm.org/show_bug.cgi?id=38809#c12 > (https://godbolt.org/z/ylsGSQ) there is no inlining, yet clang uses > over ten times as much stack space as gcc, for reasons I still > can't explain. My assumption right

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Arnd Bergmann
On Wed, Feb 20, 2019 at 9:02 PM Nick Desaulniers wrote: > > On Wed, Feb 20, 2019 at 10:44 AM Mark Brown wrote: > > > > On Wed, Feb 20, 2019 at 10:07:36AM -0800, Nick Desaulniers wrote: > > > > > I like Evgenii's idea: > > > https://bugs.llvm.org/show_bug.cgi?id=38809#c10 > > > > That's a

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Nick Desaulniers
On Wed, Feb 20, 2019 at 10:44 AM Mark Brown wrote: > > On Wed, Feb 20, 2019 at 10:07:36AM -0800, Nick Desaulniers wrote: > > > I like Evgenii's idea: > > https://bugs.llvm.org/show_bug.cgi?id=38809#c10 > > That's a suggestion to tune the inlining heuristics. Yes; but it will also improve KASAN

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Mark Brown
On Wed, Feb 20, 2019 at 10:07:36AM -0800, Nick Desaulniers wrote: > I like Evgenii's idea: > https://bugs.llvm.org/show_bug.cgi?id=38809#c10 That's a suggestion to tune the inlining heuristics. > While I myself share Arnd's goal of driving compiler warnings to zero, > in general I'd prefer not

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Nick Desaulniers
+ Evgenii On Wed, Feb 20, 2019 at 9:36 AM Arnd Bergmann wrote: > > On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin > wrote: > > On 2/20/19 5:51 PM, Arnd Bergmann wrote: > > > On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov > > > wrote: > > > I would have to some more research, but I expect

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Arnd Bergmann
On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin wrote: > On 2/20/19 5:51 PM, Arnd Bergmann wrote: > > On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov > > wrote: > > I would have to some more research, but I expect several hundred > > patches before we get to a clean randconfig build with a

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Andrey Ryabinin
On 2/20/19 5:51 PM, Arnd Bergmann wrote: > On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov > wrote: >> >> On Tue, Feb 19, 2019 at 10:49 PM Arnd Bergmann wrote: >>> >>> Building an arm64 allmodconfig kernel with clang results in over 140 >>> warnings >>> about overly large stack frames, the

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Arnd Bergmann
On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov wrote: > > On Tue, Feb 19, 2019 at 10:49 PM Arnd Bergmann wrote: > > > > Building an arm64 allmodconfig kernel with clang results in over 140 > > warnings > > about overly large stack frames, the worst ones being: > > > >

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Andrey Konovalov
On Tue, Feb 19, 2019 at 10:49 PM Arnd Bergmann wrote: > > Building an arm64 allmodconfig kernel with clang results in over 140 warnings > about overly large stack frames, the worst ones being: > > drivers/gpu/drm/panel/panel-sitronix-st7789v.c:196:12: error: stack frame > size of 20224 bytes in

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-20 Thread Arnd Bergmann
On Wed, Feb 20, 2019 at 7:44 AM Dmitry Vyukov wrote: > > On Wed, Feb 20, 2019 at 1:34 AM Kostya Serebryany wrote: > > > > On Tue, Feb 19, 2019 at 2:43 PM Nick Desaulniers > > wrote: > > > > > > + Evgenii, Kostya for KASAN > > > > > > On Tue, Feb 19, 2019 at 2:17 PM Qian Cai wrote: > > > > > >

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-19 Thread Dmitry Vyukov
On Wed, Feb 20, 2019 at 1:34 AM Kostya Serebryany wrote: > > On Tue, Feb 19, 2019 at 2:43 PM Nick Desaulniers > wrote: > > > > + Evgenii, Kostya for KASAN > > > > On Tue, Feb 19, 2019 at 2:17 PM Qian Cai wrote: > > > > > > On Tue, 2019-02-19 at 22:49 +0100, Arnd Bergmann wrote: > > > > Building

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-19 Thread Qian Cai
On 2/19/19 7:33 PM, Kostya Serebryany wrote: >>> Well, I am using clang 8.0 on arm64 and running the kernel just fine for a >>> few >>> weeks now and never trigger a single stack overflow (THREAD_SHIFT = 15) >>> because >>> I never use any of those drivers you mentioned above. I don't think

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-19 Thread Kostya Serebryany
On Tue, Feb 19, 2019 at 2:43 PM Nick Desaulniers wrote: > > + Evgenii, Kostya for KASAN > > On Tue, Feb 19, 2019 at 2:17 PM Qian Cai wrote: > > > > On Tue, 2019-02-19 at 22:49 +0100, Arnd Bergmann wrote: > > > Building an arm64 allmodconfig kernel with clang results in over 140 > > > warnings >

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-19 Thread Nick Desaulniers
+ Evgenii, Kostya for KASAN On Tue, Feb 19, 2019 at 2:17 PM Qian Cai wrote: > > On Tue, 2019-02-19 at 22:49 +0100, Arnd Bergmann wrote: > > Building an arm64 allmodconfig kernel with clang results in over 140 > > warnings > > about overly large stack frames, the worst ones being: > > > >

Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier

2019-02-19 Thread Qian Cai
On Tue, 2019-02-19 at 22:49 +0100, Arnd Bergmann wrote: > Building an arm64 allmodconfig kernel with clang results in over 140 warnings > about overly large stack frames, the worst ones being: > > drivers/gpu/drm/panel/panel-sitronix-st7789v.c:196:12: error: stack frame size > of 20224 bytes in