From: David Long <dave.long@linaro.org>
To: Li Bin <huawei.libin@huawei.com>, James Morse <james.morse@arm.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Petr Mladek" <pmladek@suse.com>, "Feng Kan" <fkan@apm.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will.deacon@arm.com>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"John Blackwood" <john.blackwood@ccur.com>,
"Pratyush Anand" <panand@redhat.com>,
"Zi Shen Lim" <zlim.lnx@gmail.com>,
"Dave P Martin" <Dave.Martin@arm.com>,
"Yang Shi" <yang.shi@linaro.org>,
"Vladimir Murzin" <Vladimir.Murzin@arm.com>,
"Steve Capper" <steve.capper@linaro.org>,
"Kees Cook" <keescook@chromium.org>,
"Suzuki K. Poulose" <suzuki.poulose@arm.com>,
"Marc Zyngier" <marc.zyngier@arm.com>,
"Mark Brown" <broonie@kernel.org>,
"Sandeepa Prabhu" <sandeepa.s.prabhu@gmail.com>,
"William Cohen" <wcohen@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
linux-arm-kernel@lists.infradead.org,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org,
"Mark Salyzyn" <salyzyn@android.com>,
"Balamurugan Shanmugam" <bshanmugam@apm.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Robin Murphy" <Robin.Murphy@arm.com>,
"Jens Wiklander" <jens.wiklander@linaro.org>,
"Christoffer Dall" <christoffer.dall@linaro.org>
Subject: Re: [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support
Date: Fri, 13 May 2016 16:02:12 -0400 [thread overview]
Message-ID: <573632C4.9010501@linaro.org> (raw)
In-Reply-To: <5733E9E0.1060504@huawei.com>
On 05/11/2016 10:26 PM, Li Bin wrote:
>
>
> on 2016/5/11 23:33, James Morse wrote:
>> Hi David,
>>
>> On 27/04/16 19:52, David Long wrote:
>>> From: "David A. Long" <dave.long@linaro.org>
>>>
>>> This patchset is heavily based on Sandeepa Prabhu's ARM v8 kprobes patches,
>>> first seen in October 2013. This version attempts to address concerns raised by
>>> reviewers and also fixes problems discovered during testing.
>>>
>>> This patchset adds support for kernel probes(kprobes), jump probes(jprobes)
>>> and return probes(kretprobes) support for ARM64.
>>>
>>> The kprobes mechanism makes use of software breakpoint and single stepping
>>> support available in the ARM v8 kernel.
>>
>> I applied this series on v4.6-rc7, and built the sample kprobes. They work fine,
>> unless I throw ftrace into the mix too.
>>
>> I enabled the function_graph tracer, then tried to load the jprobe example module:
>> -------------------------%<-------------------------
>> root@ubuntu:/sys/kernel/debug/tracing# insmod /root/jprobe_example.ko
>> Planted jprobe at ffffff80080c8f20, handler addr ffffff8000bb3000
>> root@ubuntu:/sys/kernel/debug/tracing# jprobe: clone_flags = 0x1200011, stack_st
>> art = 0x0 stack_size = 0x0
>> Bad mode in Synchronous Abort handler detected, code 0x86000005 -- IABT (current
>> EL)
>> CPU: 5 PID: 1047 Comm: systemd-udevd Not tainted 4.6.0-rc7+ #4064
>> Hardware name: ARM Juno development board (r1) (DT)
>> task: ffffffc975948300 ti: ffffffc974e4c000 task.ti: ffffffc974e4c000
>> PC is at 0x0
>> LR is at 0x0
>>
>> pc : [<0000000000000000>] lr : [<0000000000000000>] pstate: 60000145
>> sp : ffffffc974e4ff00
>> x29: 0000000001200011 x28: ffffffc974e4c000
>> x27: ffffff80088d0000 x26: 00000000000000dc
>> x25: 0000000000000120 x24: 0000000000000015
>> x23: 0000000060000000 x22: 0000007fa1b40e60
>> x21: 0000007fa1ce70d0 x20: 0000000000000000
>> x19: 0000000000000000 x18: 0000000000000a03
>> x17: 0000007fa1b40d90 x16: ffffff80080c9708
>> x15: 003b9aca00000000 x14: 0000007fddb7e5c0
>> x13: 0000007fa1b40e2c x12: 0000000000d00ff0
>> x11: ffffff8009c4d000 x10: ffffff800920c000
>> x9 : ffffff8008f5c000 x8 : ffffffc976c06800
>> x7 : 000000000006daf2 x6 : 0000000000000015
>> x5 : 0000000000000004 x4 : ffffffc96e8690a0
>> x3 : 0000001ed7cbab74 x2 : ffffffc96e869000
>> x1 : 0000000000000000 x0 : 0000000000000000
>>
>> Internal error: Oops - bad mode: 0 [#1] PREEMPT SMP
>> Modules linked in: jprobe_example
>> CPU: 5 PID: 1047 Comm: systemd-udevd Not tainted 4.6.0-rc7+ #4064
>> Hardware name: ARM Juno development board (r1) (DT)
>> task: ffffffc975948300 ti: ffffffc974e4c000 task.ti: ffffffc974e4c000
>> PC is at 0x0
>> LR is at 0x0
>>
>> pc : [<0000000000000000>] lr : [<0000000000000000>] pstate: 60000145
>> sp : ffffffc974e4ff00
>> x29: 0000000001200011 x28: ffffffc974e4c000
>> x27: ffffff80088d0000 x26: 00000000000000dc
>> x25: 0000000000000120 x24: 0000000000000015
>> x23: 0000000060000000 x22: 0000007fa1b40e60
>> x21: 0000007fa1ce70d0 x20: 0000000000000000
>> x19: 0000000000000000 x18: 0000000000000a03
>> x17: 0000007fa1b40d90 x16: ffffff80080c9708
>> x15: 003b9aca00000000 x14: 0000007fddb7e5c0
>> x13: 0000007fa1b40e2c x12: 0000000000d00ff0
>> x11: ffffff8009c4d000 x10: ffffff800920c000
>> x9 : ffffff8008f5c000 x8 : ffffffc976c06800
>> x7 : 000000000006daf2 x6 : 0000000000000015
>> x5 : 0000000000000004 x4 : ffffffc96e8690a0
>> x3 : 0000001ed7cbab74 x2 : ffffffc96e869000
>> x1 : 0000000000000000 x0 : 0000000000000000
>>
>> Process systemd-udevd (pid: 1047, stack limit = 0xffffffc974e4c020)
>> Stack: (0xffffffc974e4ff00 to 0xffffffc974e50000)
>> ff00: 0000000000000417 0000007fa1ce76f0 00000000000000dc 0000000000000417
>> ff20: 00000000ffffffff 0000007fddb7ecf8 0000000000000005 ffffffffffffffff
>> ff40: 00000000ff000001 003b9aca00000000 000000555b3868b0 0000007fa1b40d90
>> ff60: 0000000000000a03 0000007fddb7e5c0 0000000000000000 0000007fddb7e5e0
>> ff80: 000000555b358000 000000558f56f0e0 0000000000000000 000000558f574f00
>> ffa0: 000000558f574f00 00000000000004fa 000000558f56f010 0000007fddb7e600
>> ffc0: 0000007fa1b40e2c 0000007fddb7e5c0 0000007fa1b40e60 0000000060000000
>> ffe0: 0000000001200011 00000000000000dc 0004000084000200 0800000002000000
>> Call trace:
>> [< (null)>] (null)
>> Code: bad PC value
>> ---[ end trace 35d24aad799c2941 ]---
>> -------------------------%<-------------------------
>>
>
> To solve this, it should pause function tracing before the jprobe handler is called
> and unpause it before it returns back to the function it probed.
>
> diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c
> index db2d95c..b21ed00 100644
> --- a/arch/arm64/kernel/kprobes.c
> +++ b/arch/arm64/kernel/kprobes.c
> @@ -714,6 +714,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
>
> instruction_pointer_set(regs, (long)jp->entry);
> preempt_disable();
> + pause_graph_tracing();
> return 1;
> }
>
> @@ -757,6 +758,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
> show_regs(regs);
> BUG();
> }
> + unpause_graph_tracing();
> *regs = kcb->jprobe_saved_regs;
> memcpy((void *)stack_addr, kcb->jprobes_stack,
> MIN_STACK_SIZE(stack_addr));
>
>
> Li Bin
>
>>
>> Thanks,
>>
>>
>> James
Thanks for the suggested fix.
-dl
next prev parent reply other threads:[~2016-05-13 20:02 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 18:52 [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support David Long
2016-04-27 18:52 ` [PATCH v12 01/10] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature David Long
2016-04-28 16:08 ` Marc Zyngier
2016-05-13 19:07 ` David Long
2016-05-17 9:14 ` Huang Shijie
2016-05-20 4:18 ` David Long
2016-04-27 18:52 ` [PATCH v12 02/10] arm64: Add more test functions to insn.c David Long
2016-04-27 18:52 ` [PATCH v12 03/10] arm64: add conditional instruction simulation support David Long
2016-04-27 18:52 ` [PATCH v12 04/10] arm64: Blacklist non-kprobe-able symbols David Long
2016-04-27 18:53 ` [PATCH v12 05/10] arm64: Kprobes with single stepping support David Long
2016-05-12 15:01 ` James Morse
2016-05-18 4:04 ` Masami Hiramatsu
2016-05-20 5:16 ` David Long
2016-05-17 8:58 ` Huang Shijie
2016-05-18 3:29 ` Masami Hiramatsu
2016-05-26 19:25 ` David Long
2016-05-26 15:40 ` David Long
2016-05-17 9:10 ` Huang Shijie
2016-06-01 5:15 ` David Long
2016-04-27 18:53 ` [PATCH v12 06/10] arm64: Treat all entry code as non-kprobe-able David Long
2016-05-12 14:49 ` James Morse
2016-05-20 5:28 ` David Long
2016-05-26 15:26 ` David Long
2016-04-27 18:53 ` [PATCH v12 07/10] arm64: kprobes instruction simulation support David Long
2016-05-19 1:52 ` Huang Shijie
2016-05-26 19:28 ` David Long
2016-04-27 18:53 ` [PATCH v12 08/10] arm64: Add trampoline code for kretprobes David Long
2016-04-27 18:53 ` [PATCH v12 09/10] arm64: Add kernel return probes support (kretprobes) David Long
2016-04-27 18:53 ` [PATCH v12 10/10] kprobes: Add arm64 case in kprobe example module David Long
2016-05-17 9:57 ` Huang Shijie
2016-05-17 10:24 ` Mark Brown
2016-05-18 1:31 ` Huang Shijie
2016-05-11 15:33 ` [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support James Morse
2016-05-12 2:26 ` Li Bin
2016-05-13 20:02 ` David Long [this message]
2016-05-18 2:24 ` Huang Shijie
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