From: Dmitry Vyukov <dvyukov@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Julien Thierry <julien.thierry@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@amacapital.net>,
Ingo Molnar <mingo@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
valentin.schneider@arm.com, Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Denys Vlasenko <dvlasenk@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>
Subject: Re: [PATCH 1/8] kasan,x86: Frob kasan_report() in an exception
Date: Wed, 6 Mar 2019 15:40:51 +0100 [thread overview]
Message-ID: <CACT4Y+YmQBc67hU2exY5=tAVG1jWNUeZ7FAm+GGgqDvOH7cu1A@mail.gmail.com> (raw)
In-Reply-To: <20190306143439.GY32534@hirez.programming.kicks-ass.net>
On Wed, Mar 6, 2019 at 3:34 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Mar 06, 2019 at 03:12:37PM +0100, Peter Zijlstra wrote:
> > On Wed, Mar 06, 2019 at 03:01:33PM +0100, Dmitry Vyukov wrote:
> > > On Wed, Mar 6, 2019 at 2:57 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > > I've not found callers of __asan_report_load* with AC=1 in the kernel
> > > > yet. Under what condtions does GCC emit calls to these functions?
> > >
> > > CONFIG_KASAN_INLINE=y
> > > Then compiler inlines fast path into generated code and only calls
> > > into runtime to report errors (also, faster, this should be a default
> > > for anything other than tiny ROM controllers).
> >
> > *sigh*, clearly I've not build enough kernels yet... Lemme go try that.
>
> mm/kasan/generic_report.o: warning: objtool: __asan_report_load1_noabort()+0x0: call to __fentry__() with UACCESS enabled
>
> You want to do:
>
> CFLAGS_REMOVE_f= -pg
>
> like generic.o has?
This should not matter for KASAN itself.
KASAN will call into function tracer, and function tracer will call
into KASAN, but unless function tracer is badly broken and causes a
KASAN report on every invocation, the recursion will end (function
tracer will get to the _report_ function). So we only disabled -pg for
fast paths.
But if it makes things simpler for the objtool, then I think we can
disable function tracer for generic_report.c too.
next prev parent reply other threads:[~2019-03-06 14:41 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 14:54 [PATCH 0/8] objtool: UACCESS validation v2 Peter Zijlstra
2019-02-28 14:54 ` [PATCH 1/8] kasan,x86: Frob kasan_report() in an exception Peter Zijlstra
2019-02-28 15:22 ` Dmitry Vyukov
2019-02-28 15:45 ` Peter Zijlstra
2019-02-28 15:52 ` Dmitry Vyukov
2019-02-28 16:01 ` Andrey Ryabinin
2019-02-28 16:03 ` Dmitry Vyukov
2019-02-28 17:46 ` Peter Zijlstra
2019-02-28 18:18 ` Dmitry Vyukov
2019-03-01 14:45 ` Peter Zijlstra
2019-03-01 15:06 ` Dmitry Vyukov
2019-03-01 15:23 ` Peter Zijlstra
2019-03-06 13:13 ` Peter Zijlstra
2019-03-06 13:39 ` Dmitry Vyukov
2019-03-06 13:57 ` Peter Zijlstra
2019-03-06 14:01 ` Dmitry Vyukov
2019-03-06 14:12 ` Peter Zijlstra
2019-03-06 14:34 ` Peter Zijlstra
2019-03-06 14:40 ` Dmitry Vyukov [this message]
2019-03-06 14:41 ` Dmitry Vyukov
2019-03-06 14:55 ` Peter Zijlstra
2019-03-06 15:01 ` Dmitry Vyukov
2019-03-06 17:14 ` Peter Zijlstra
2019-03-06 17:27 ` Linus Torvalds
2019-03-06 17:37 ` Peter Zijlstra
2019-03-06 17:59 ` Linus Torvalds
2019-03-07 13:49 ` Peter Zijlstra
2019-02-28 14:54 ` [PATCH 2/8] x86/ia32: Fix ia32_restore_sigcontext AC leak Peter Zijlstra
2019-02-28 14:54 ` [PATCH 3/8] objtool: Set insn->func for alternatives Peter Zijlstra
2019-02-28 14:54 ` [PATCH 4/8] objtool: Hande function aliases Peter Zijlstra
2019-02-28 14:54 ` [PATCH 5/8] objtool: Rewrite add_ignores() Peter Zijlstra
2019-02-28 14:54 ` [PATCH 6/8] i915,uaccess: Fix redundant CLAC Peter Zijlstra
2019-02-28 15:10 ` Chris Wilson
2019-02-28 15:24 ` Peter Zijlstra
2019-02-28 16:49 ` Linus Torvalds
2019-02-28 17:51 ` Peter Zijlstra
2019-02-28 18:01 ` Peter Zijlstra
2019-02-28 18:29 ` Linus Torvalds
2019-02-28 19:01 ` Peter Zijlstra
2019-03-01 10:34 ` Peter Zijlstra
2019-03-01 12:27 ` Peter Zijlstra
2019-03-01 12:57 ` Peter Zijlstra
2019-03-01 14:38 ` Peter Zijlstra
2019-03-01 15:27 ` Andy Lutomirski
2019-03-01 16:15 ` Linus Torvalds
2019-03-01 16:17 ` Linus Torvalds
2019-02-28 14:54 ` [PATCH 7/8] objtool: Add UACCESS validation Peter Zijlstra
2019-02-28 14:54 ` [PATCH 8/8] objtool: Add Direction Flag validation Peter Zijlstra
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