linux-kernel - Re: [PATCH v2] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate

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Message-Id: <162470384231.3589875.12558061004579567759.b4-ty@ellerman.id.au>
Date:   Sat, 26 Jun 2021 20:37:22 +1000
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32

On Wed, 23 Jun 2021 05:23:30 +0000 (UTC), Christophe Leroy wrote:
> Trying to use a kprobe on ppc32 results in the below splat:
>     BUG: Unable to handle kernel data access on read at 0x7c0802a6
>     Faulting instruction address: 0xc002e9f0
>     Oops: Kernel access of bad area, sig: 11 [#1]
>     BE PAGE_SIZE=4K PowerPC 44x Platform
>     Modules linked in:
>     CPU: 0 PID: 89 Comm: sh Not tainted 5.13.0-rc1-01824-g3a81c0495fdb #7
>     NIP:  c002e9f0 LR: c0011858 CTR: 00008a47
>     REGS: c292fd50 TRAP: 0300   Not tainted  (5.13.0-rc1-01824-g3a81c0495fdb)
>     MSR:  00009000 <EE,ME>  CR: 24002002  XER: 20000000
>     DEAR: 7c0802a6 ESR: 00000000
>     <snip>
>     NIP [c002e9f0] emulate_step+0x28/0x324
>     LR [c0011858] optinsn_slot+0x128/0x10000
>     Call Trace:
>      opt_pre_handler+0x7c/0xb4 (unreliable)
>      optinsn_slot+0x128/0x10000
>      ret_from_syscall+0x0/0x28
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32
      https://git.kernel.org/powerpc/c/511eea5e2ccdfdbf3d626bde0314e551f247dd18

cheers