From: Peter Zijlstra <peterz@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
kernel test robot <lkp@intel.com>, LKP <lkp@01.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-arch <linux-arch@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@kernel.org>, Nadav Amit <namit@vmware.com>
Subject: Re: 1808d65b55 ("asm-generic/tlb: Remove arch_tlb*_mmu()"): BUG: KASAN: stack-out-of-bounds in __change_page_attr_set_clr
Date: Fri, 12 Apr 2019 20:15:57 +0200 [thread overview]
Message-ID: <20190412181557.GC12232@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5890.1555087830@warthog.procyon.org.uk>
On Fri, Apr 12, 2019 at 05:50:30PM +0100, David Howells wrote:
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> > We should never have stack alignment bigger than 16 bytes. And
> > preferably not even that.
>
> At least one arch I know of (FRV) had instructions that could atomically
> load/store register pairs or register quads, but they had to be pair- or
> quad-aligned (ie. 8- or 16-byte), which made for more efficient code if you
> could use them.
>
> I don't know whether any arch we currently support has features like this (I
> know some have multi-reg load/stores, but they seem to require only
> word-alignment).
ARC (iirc) has u64 atomics with natural alignment requirements but
alignof(u64)=4 due it being a 32bit arch. Which is awkward.
ARMv7 can also do u64 ops when aligned right, but I forgot if they have
proper alignment or not.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: lkp@lists.01.org
Subject: Re: 1808d65b55 ("asm-generic/tlb: Remove arch_tlb*_mmu()"): BUG: KASAN: stack-out-of-bounds in __change_page_attr_set_clr
Date: Fri, 12 Apr 2019 20:15:57 +0200 [thread overview]
Message-ID: <20190412181557.GC12232@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5890.1555087830@warthog.procyon.org.uk>
[-- Attachment #1: Type: text/plain, Size: 886 bytes --]
On Fri, Apr 12, 2019 at 05:50:30PM +0100, David Howells wrote:
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> > We should never have stack alignment bigger than 16 bytes. And
> > preferably not even that.
>
> At least one arch I know of (FRV) had instructions that could atomically
> load/store register pairs or register quads, but they had to be pair- or
> quad-aligned (ie. 8- or 16-byte), which made for more efficient code if you
> could use them.
>
> I don't know whether any arch we currently support has features like this (I
> know some have multi-reg load/stores, but they seem to require only
> word-alignment).
ARC (iirc) has u64 atomics with natural alignment requirements but
alignof(u64)=4 due it being a 32bit arch. Which is awkward.
ARMv7 can also do u64 ops when aligned right, but I forgot if they have
proper alignment or not.
next prev parent reply other threads:[~2019-04-12 18:15 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 14:55 1808d65b55 ("asm-generic/tlb: Remove arch_tlb*_mmu()"): BUG: KASAN: stack-out-of-bounds in __change_page_attr_set_clr kernel test robot
2019-04-10 14:55 ` kernel test robot
2019-04-11 19:39 ` Peter Zijlstra
2019-04-11 19:39 ` Peter Zijlstra
2019-04-11 19:54 ` Peter Zijlstra
2019-04-11 19:54 ` Peter Zijlstra
2019-04-11 21:13 ` Peter Zijlstra
2019-04-11 21:13 ` Peter Zijlstra
2019-04-12 10:56 ` Peter Zijlstra
2019-04-12 10:56 ` Peter Zijlstra
2019-04-12 11:17 ` Peter Zijlstra
2019-04-12 11:17 ` Peter Zijlstra
2019-04-12 15:11 ` Nadav Amit
2019-04-12 15:11 ` Nadav Amit
2019-04-12 15:18 ` Nadav Amit
2019-04-12 15:18 ` Nadav Amit
2019-04-12 17:05 ` Nadav Amit
2019-04-12 17:05 ` Nadav Amit
2019-04-12 17:14 ` Andy Lutomirski
2019-04-12 17:14 ` Andy Lutomirski
2019-04-12 17:49 ` Nadav Amit
2019-04-12 17:49 ` Nadav Amit
2019-04-12 18:13 ` Peter Zijlstra
2019-04-12 18:13 ` Peter Zijlstra
2019-04-12 18:19 ` Peter Zijlstra
2019-04-12 18:19 ` Peter Zijlstra
2019-04-12 19:42 ` Nadav Amit
2019-04-12 19:42 ` Nadav Amit
2019-04-12 15:32 ` Linus Torvalds
2019-04-12 15:32 ` Linus Torvalds
2019-04-12 16:50 ` David Howells
2019-04-12 16:50 ` David Howells
2019-04-12 18:15 ` Peter Zijlstra [this message]
2019-04-12 18:15 ` Peter Zijlstra
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