From: Stephen Rothwell <sfr@canb•auug.org.au>
To: Andrey Ryabinin <aryabinin@virtuozzo•com>
Cc: linux-kernel@vger•kernel.org, Ingo Molnar <mingo@kernel•org>,
Thomas Gleixner <tglx@linutronix•de>,
"H. Peter Anvin" <hpa@zytor•com>,
x86@kernel•org, Andrew Morton <akpm@linux-foundation•org>,
Andy Lutomirski <luto@amacapital•net>,
Andrey Konovalov <andreyknvl@google•com>,
Kostya Serebryany <kcc@google•com>,
Alexander Potapenko <glider@google•com>,
kasan-dev <kasan-dev@googlegroups•com>,
Borislav Petkov <bp@alien8•de>,
Denys Vlasenko <dvlasenk@redhat•com>,
Andi Kleen <ak@linux•intel.com>,
Dmitry Vyukov <dvyukov@google•com>,
Sasha Levin <sasha.levin@oracle•com>,
Wolfram Gloger <wmglo@dent•med.uni-muenchen.de>,
linux-next@vger•kernel.org
Subject: linux-next: build problems (Was: [PATCH v3 1/2] Provide READ_ONCE_NOCHECK())
Date: Thu, 15 Oct 2015 20:18:34 +1100 [thread overview]
Message-ID: <20151015201834.350258bf@canb.auug.org.au> (raw)
In-Reply-To: <1444750088-24444-2-git-send-email-aryabinin@virtuozzo.com>
Hi Andrey,
On Tue, 13 Oct 2015 18:28:07 +0300 Andrey Ryabinin <aryabinin@virtuozzo•com> wrote:
>
> Some code may perform racy by design memory reads. This could be harmless,
> yet such code may produce KASAN warnings.
>
> To hide such accesses from KASAN this patch introduces READ_ONCE_NOCHECK()
> macro. KASAN will not check the memory accessed by READ_ONCE_NOCHECK().
>
> This patch creates __read_once_size_nocheck() a clone of
> __read_once_size_check() (renamed __read_once_size()).
> The only difference between them is 'no_sanitized_address' attribute
> appended to '*_nocheck' function. This attribute tells the compiler that
> instrumentation of memory accesses should not be applied to that function.
> We declare it as static '__maybe_unsed' because GCC is not capable to
> inline such function: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
>
> With KASAN=n READ_ONCE_NOCHECK() is just a clone of READ_ONCE().
>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo•com>
> ---
> include/linux/compiler-gcc.h | 13 ++++++++++
> include/linux/compiler.h | 60 ++++++++++++++++++++++++++++++++++----------
> 2 files changed, 60 insertions(+), 13 deletions(-)
I am pretty sure that this patch is causing quite a bit of compile
breakage in linux-next today. During the day I compile with gcc 4.9.0
and did not see any problems with c86_64 allmodconfig, or i386
defconfig etc, but overnight we compile with older compilers (gcc 4.6.3
in particular) and are getting quite a few errors:
>From an i386 allnoconfig build:
arch/x86/entry/vdso/vdso32.so.dbg: undefined symbols found
/home/kisskb/slave/src/arch/x86/entry/vdso/Makefile:154: recipe for target 'arch/x86/entry/vdso/vdso32.so.dbg' failed
>From an x86_64 allnoconfig build:
arch/x86/entry/vdso/vclock_gettime.o: In function `__read_once_size_check':
vclock_gettime.c:(.text+0x5f): undefined reference to `memcpy'
arch/x86/entry/vdso/vgetcpu.o: In function `__read_once_size_check':
vgetcpu.c:(.text+0x2f): undefined reference to `memcpy'
and several others ...
--
Cheers,
Stephen Rothwell sfr@canb•auug.org.au
next parent reply other threads:[~2015-10-15 9:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1444739750-29241-1-git-send-email-aryabinin@virtuozzo.com>
[not found] ` <1444750088-24444-1-git-send-email-aryabinin@virtuozzo.com>
[not found] ` <1444750088-24444-2-git-send-email-aryabinin@virtuozzo.com>
2015-10-15 9:18 ` Stephen Rothwell [this message]
2015-10-15 10:03 ` linux-next: build problems (Was: [PATCH v3 1/2] Provide READ_ONCE_NOCHECK()) Andrey Ryabinin
2015-10-15 10:19 ` [PATCH] compiler, READ_ONCE: Fix build failure with some older GCC Andrey Ryabinin
2015-10-15 11:30 ` Ingo Molnar
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