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Thu, 5 Aug 2021 11:52:03 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4GgP5v1hyjz9sST; Thu, 5 Aug 2021 11:52:03 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id DC22D8B7BD; Thu, 5 Aug 2021 11:52:02 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id QxKh0RqSaX8k; Thu, 5 Aug 2021 11:52:02 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 6F8EE8B7C0; Thu, 5 Aug 2021 11:51:56 +0200 (CEST) Subject: Re: [PATCH] powerpc/kprobes: Fix kprobe Oops happens in booke To: Pu Lehui , oleg@redhat.com, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, naveen.n.rao@linux.vnet.ibm.com, mhiramat@kernel.org, peterz@infradead.org, npiggin@gmail.com, ruscur@russell.cc References: <20210804143735.148547-1-pulehui@huawei.com> From: Christophe Leroy Message-ID: <021cf081-77a9-8e4e-a246-4faaf3937dbe@csgroup.eu> Date: Thu, 5 Aug 2021 11:51:57 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210804143735.148547-1-pulehui@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: zhangjinhao2@huawei.com, xukuohai@huawei.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 04/08/2021 à 16:37, Pu Lehui a écrit : > When using kprobe on powerpc booke series processor, Oops happens > as show bellow: > > [ 35.861352] Oops: Exception in kernel mode, sig: 5 [#1] > [ 35.861676] BE PAGE_SIZE=4K SMP NR_CPUS=24 QEMU e500 > [ 35.861905] Modules linked in: > [ 35.862144] CPU: 0 PID: 76 Comm: sh Not tainted 5.14.0-rc3-00060-g7e96bf476270 #18 > [ 35.862610] NIP: c0b96470 LR: c00107b4 CTR: c0161c80 > [ 35.862805] REGS: c387fe70 TRAP: 0700 Not tainted (5.14.0-rc3-00060-g7e96bf476270) > [ 35.863198] MSR: 00029002 CR: 24022824 XER: 20000000 > [ 35.863577] > [ 35.863577] GPR00: c0015218 c387ff20 c313e300 c387ff50 00000004 40000002 40000000 0a1a2cce > [ 35.863577] GPR08: 00000000 00000004 00000000 59764000 24022422 102490c2 00000000 00000000 > [ 35.863577] GPR16: 00000000 00000000 00000040 10240000 10240000 10240000 10240000 10220000 > [ 35.863577] GPR24: ffffffff 10240000 00000000 00000000 bfc655e8 00000800 c387ff50 00000000 > [ 35.865367] NIP [c0b96470] schedule+0x0/0x130 > [ 35.865606] LR [c00107b4] interrupt_exit_user_prepare_main+0xf4/0x100 > [ 35.865974] Call Trace: > [ 35.866142] [c387ff20] [c0053224] irq_exit+0x114/0x120 (unreliable) > [ 35.866472] [c387ff40] [c0015218] interrupt_return+0x14/0x13c > [ 35.866728] --- interrupt: 900 at 0x100af3dc > [ 35.866963] NIP: 100af3dc LR: 100de020 CTR: 00000000 > [ 35.867177] REGS: c387ff50 TRAP: 0900 Not tainted (5.14.0-rc3-00060-g7e96bf476270) > [ 35.867488] MSR: 0002f902 CR: 20022422 XER: 20000000 > [ 35.867808] > [ 35.867808] GPR00: c001509c bfc65570 1024b4d0 00000000 100de020 20022422 bfc655a8 100af3dc > [ 35.867808] GPR08: 0002f902 00000000 00000000 00000000 72656773 102490c2 00000000 00000000 > [ 35.867808] GPR16: 00000000 00000000 00000040 10240000 10240000 10240000 10240000 10220000 > [ 35.867808] GPR24: ffffffff 10240000 00000000 00000000 bfc655e8 10245910 ffffffff 00000001 > [ 35.869406] NIP [100af3dc] 0x100af3dc > [ 35.869578] LR [100de020] 0x100de020 > [ 35.869751] --- interrupt: 900 > [ 35.870001] Instruction dump: > [ 35.870283] 40c20010 815e0518 714a0100 41e2fd04 39200000 913e00c0 3b1e0450 4bfffd80 > [ 35.870666] 0fe00000 92a10024 4bfff1a9 60000000 <7fe00008> 7c0802a6 93e1001c 7c5f1378 > [ 35.871339] ---[ end trace 23ff848139efa9b9 ]--- > > There is no real mode for booke arch and the MMU translation is > always on. The corresponding MSR_IS/MSR_DS bit in booke is used > to switch the address space, but not for real mode judgment. Can you explain more the link between that explanation and the Oops itself ? > > Fixes: 21f8b2fa3ca5 ("powerpc/kprobes: Ignore traps that happened in real mode") > Signed-off-by: Pu Lehui > --- > arch/powerpc/include/asm/ptrace.h | 6 ++++++ > arch/powerpc/kernel/kprobes.c | 5 +---- > 2 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h > index 3e5d470a6155..4aec1a97024b 100644 > --- a/arch/powerpc/include/asm/ptrace.h > +++ b/arch/powerpc/include/asm/ptrace.h > @@ -187,6 +187,12 @@ static inline unsigned long frame_pointer(struct pt_regs *regs) > #define user_mode(regs) (((regs)->msr & MSR_PR) != 0) > #endif > > +#ifdef CONFIG_BOOKE > +#define real_mode(regs) 0 > +#else > +#define real_mode(regs) (!((regs)->msr & MSR_IR) || !((regs)->msr & MSR_DR)) > +#endif > + You don't need an #ifdef stuff here, you can base your testing on IS_ENABLED(CONFIG_BOOKE) > #define force_successful_syscall_return() \ > do { \ > set_thread_flag(TIF_NOERROR); \ > diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c > index cbc28d1a2e1b..fac9a5974718 100644 > --- a/arch/powerpc/kernel/kprobes.c > +++ b/arch/powerpc/kernel/kprobes.c > @@ -289,10 +289,7 @@ int kprobe_handler(struct pt_regs *regs) > unsigned int *addr = (unsigned int *)regs->nip; > struct kprobe_ctlblk *kcb; > > - if (user_mode(regs)) > - return 0; > - > - if (!(regs->msr & MSR_IR) || !(regs->msr & MSR_DR)) > + if (user_mode(regs) || real_mode(regs)) > return 0; > > /* >