From: Peter Zijlstra <peterz@infradead.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Dmitry Vyukov' <dvyukov@google.com>,
Marco Elver <elver@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH 3/3] asm-generic, x86: Add bitops instrumentation for KASAN
Date: Wed, 29 May 2019 14:01:18 +0200 [thread overview]
Message-ID: <20190529120118.GQ2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <a0157a8d778a48b7ba3935f3e6840d30@AcuMS.aculab.com>
On Wed, May 29, 2019 at 11:20:56AM +0000, David Laight wrote:
> From: Dmitry Vyukov
> > Sent: 29 May 2019 11:57
> > Interesting. Does an address passed to bitops also should be aligned,
> > or alignment is supposed to be handled by bitops themselves?
>
> The bitops are defined on 'long []' and it is expected to be aligned.
> Any code that casts the argument is likely to be broken on big-endian.
> I did a quick grep a few weeks ago and found some very dubious code.
> Not all the casts seemed to be on code that was LE only (although
> I didn't try to find out what the casts were from).
>
> The alignment trap on x86 could be avoided by only ever requesting 32bit
> cycles - and assuming the buffer is always 32bit aligned (eg int []).
> But on BE passing an 'int []' is just so wrong ....
Right, but as argued elsewhere, I feel we should clean up the dubious
code instead of enabling it.
next prev parent reply other threads:[~2019-05-29 12:01 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-28 16:32 [PATCH 1/3] lib/test_kasan: Add bitops tests Marco Elver
2019-05-28 16:32 ` Marco Elver
2019-05-28 16:32 ` [PATCH 2/3] tools/objtool: add kasan_check_* to uaccess whitelist Marco Elver
2019-05-28 16:32 ` Marco Elver
2019-05-28 17:19 ` Peter Zijlstra
2019-05-28 17:19 ` Peter Zijlstra
2019-05-29 8:54 ` Dmitry Vyukov
2019-05-29 8:54 ` Dmitry Vyukov
2019-05-29 9:46 ` Marco Elver
2019-05-29 9:46 ` Marco Elver
2019-05-29 9:58 ` Peter Zijlstra
2019-05-29 9:58 ` Peter Zijlstra
2019-05-28 16:32 ` [PATCH 3/3] asm-generic, x86: Add bitops instrumentation for KASAN Marco Elver
2019-05-28 16:32 ` Marco Elver
2019-05-28 16:50 ` Mark Rutland
2019-05-28 16:50 ` Mark Rutland
2019-05-29 8:53 ` Dmitry Vyukov
2019-05-29 8:53 ` Dmitry Vyukov
2019-05-29 9:20 ` Marco Elver
2019-05-29 9:20 ` Marco Elver
2019-05-29 10:01 ` Peter Zijlstra
2019-05-29 10:01 ` Peter Zijlstra
2019-05-29 10:16 ` Marco Elver
2019-05-29 10:16 ` Marco Elver
2019-05-29 10:30 ` Peter Zijlstra
2019-05-29 10:30 ` Peter Zijlstra
2019-05-29 10:57 ` Dmitry Vyukov
2019-05-29 10:57 ` Dmitry Vyukov
2019-05-29 11:20 ` David Laight
2019-05-29 11:20 ` David Laight
2019-05-29 12:01 ` Peter Zijlstra [this message]
2019-05-29 12:01 ` Peter Zijlstra
2019-05-29 11:23 ` Andrey Ryabinin
2019-05-29 11:23 ` Andrey Ryabinin
2019-05-29 11:29 ` Dmitry Vyukov
2019-05-29 11:29 ` Dmitry Vyukov
2019-05-29 12:01 ` Peter Zijlstra
2019-05-29 12:01 ` Peter Zijlstra
2019-05-29 13:26 ` Mark Rutland
2019-05-29 13:26 ` Mark Rutland
2019-05-28 16:50 ` [PATCH 1/3] lib/test_kasan: Add bitops tests Mark Rutland
2019-05-28 16:50 ` Mark Rutland
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