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From: Will Deacon <will.deacon@arm.com>
To: Eric Dumazet <edumazet@google.com>
Cc: Wei Wei <dotweiba@gmail.com>,
	Willem de Bruijn <willemb@google.com>,
	netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>,
	David Miller <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone()
Date: Fri, 20 Oct 2017 10:18:23 +0100	[thread overview]
Message-ID: <20171020091823.GA18282@arm.com> (raw)
In-Reply-To: <CANn89iKj45+zqMt7XqPkCG+8PQwhzjHUBZ0vu-REvZWs1HuqOw@mail.gmail.com>

On Thu, Oct 19, 2017 at 10:34:54PM -0700, Eric Dumazet wrote:
> On Thu, Oct 19, 2017 at 8:13 PM, Wei Wei <dotweiba@gmail.com> wrote:
> > Code: f9406680 8b010000 91009000 f9800011 (885f7c01)
> > All code
> > ========
> >    0:   80 66 40 f9             andb   $0xf9,0x40(%rsi)
> >    4:   00 00                   add    %al,(%rax)
> >    6:   01 8b 00 90 00 91       add    %ecx,-0x6eff7000(%rbx)
> >    c:   11 00                   adc    %eax,(%rax)
> >    e:   80 f9 01                cmp    $0x1,%cl
> >   11:   7c 5f                   jl     0x72
> >   13:*  88 00                   mov    %al,(%rax)               <-- trapping instruction
> >   15:   00 00                   add    %al,(%rax)
> >         ...
> >
> > Code starting with the faulting instruction
> > ===========================================
> >    0:   01 7c 5f 88             add    %edi,-0x78(%rdi,%rbx,2)
> >    4:   00 00                   add    %al,(%rax)
> >         ...
> > —[ end trace 261e7ac1458ccc0a ]---
> >
> 
> I thought it was happening on arm64 ?
> 
> This is x86_64 disassembly :/

I guess they forgot the ARCH/CROSS_COMPILE env vars for decodecode. here
you go:

Code: f9406680 8b010000 91009000 f9800011 (885f7c01)
All code
========
   0:	f9406680 	ldr	x0, [x20,#200]
   4:	8b010000 	add	x0, x0, x1
   8:	91009000 	add	x0, x0, #0x24
   c:	f9800011 	prfm	pstl1strm, [x0]
  10:*	885f7c01 	ldxr	w1, [x0]		<-- trapping instruction

Code starting with the faulting instruction
===========================================
   0:	885f7c01 	ldxr	w1, [x0]

so it's faulting on the load part of an atomic rmw.

Will

WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone()
Date: Fri, 20 Oct 2017 10:18:23 +0100	[thread overview]
Message-ID: <20171020091823.GA18282@arm.com> (raw)
In-Reply-To: <CANn89iKj45+zqMt7XqPkCG+8PQwhzjHUBZ0vu-REvZWs1HuqOw@mail.gmail.com>

On Thu, Oct 19, 2017 at 10:34:54PM -0700, Eric Dumazet wrote:
> On Thu, Oct 19, 2017 at 8:13 PM, Wei Wei <dotweiba@gmail.com> wrote:
> > Code: f9406680 8b010000 91009000 f9800011 (885f7c01)
> > All code
> > ========
> >    0:   80 66 40 f9             andb   $0xf9,0x40(%rsi)
> >    4:   00 00                   add    %al,(%rax)
> >    6:   01 8b 00 90 00 91       add    %ecx,-0x6eff7000(%rbx)
> >    c:   11 00                   adc    %eax,(%rax)
> >    e:   80 f9 01                cmp    $0x1,%cl
> >   11:   7c 5f                   jl     0x72
> >   13:*  88 00                   mov    %al,(%rax)               <-- trapping instruction
> >   15:   00 00                   add    %al,(%rax)
> >         ...
> >
> > Code starting with the faulting instruction
> > ===========================================
> >    0:   01 7c 5f 88             add    %edi,-0x78(%rdi,%rbx,2)
> >    4:   00 00                   add    %al,(%rax)
> >         ...
> > ?[ end trace 261e7ac1458ccc0a ]---
> >
> 
> I thought it was happening on arm64 ?
> 
> This is x86_64 disassembly :/

I guess they forgot the ARCH/CROSS_COMPILE env vars for decodecode. here
you go:

Code: f9406680 8b010000 91009000 f9800011 (885f7c01)
All code
========
   0:	f9406680 	ldr	x0, [x20,#200]
   4:	8b010000 	add	x0, x0, x1
   8:	91009000 	add	x0, x0, #0x24
   c:	f9800011 	prfm	pstl1strm, [x0]
  10:*	885f7c01 	ldxr	w1, [x0]		<-- trapping instruction

Code starting with the faulting instruction
===========================================
   0:	885f7c01 	ldxr	w1, [x0]

so it's faulting on the load part of an atomic rmw.

Will

  reply	other threads:[~2017-10-20  9:18 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-20  2:16 v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone() Wei Wei
2017-10-20  2:16 ` Wei Wei
2017-10-20  2:53 ` Eric Dumazet
2017-10-20  2:53   ` Eric Dumazet
2017-10-20  3:13   ` Wei Wei
2017-10-20  3:13     ` Wei Wei
2017-10-20  5:34     ` Eric Dumazet
2017-10-20  5:34       ` Eric Dumazet
2017-10-20  9:18       ` Will Deacon [this message]
2017-10-20  9:18         ` Will Deacon
2017-10-20 11:14 ` Mark Rutland
2017-10-20 11:14   ` Mark Rutland
2017-10-20 14:40   ` Wei Wei
2017-10-20 14:40     ` Wei Wei
2017-10-20 15:11     ` Mark Rutland
2017-10-20 15:11       ` Mark Rutland
2017-10-20 15:14     ` Dmitry Vyukov
2017-10-20 15:14       ` Dmitry Vyukov
2017-10-20 15:39       ` Willem de Bruijn
2017-10-20 15:39         ` Willem de Bruijn
2017-10-22  1:56         ` Wei Wei
2017-10-22  1:56           ` Wei Wei
2017-10-25 18:24           ` Willem de Bruijn
2017-10-25 18:24             ` Willem de Bruijn
2017-10-25 18:49             ` Willem de Bruijn
2017-10-25 18:49               ` Willem de Bruijn
2017-10-25 19:01               ` Eric Dumazet
2017-10-25 19:01                 ` Eric Dumazet
2017-10-26  5:38                 ` Jason Wang
2017-10-26  5:38                   ` Jason Wang
2017-10-26 15:24               ` David Laight
2017-10-26 15:24                 ` David Laight
2017-10-26 15:24                 ` David Laight

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