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| Started by | James Morse <james.morse@arm.com> |
|---|---|
| First post | 2016-05-11 17:40 +0200 |
| Last post | 2016-05-13 22:10 +0200 |
| Articles | 3 — 3 participants |
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Re: [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support James Morse <james.morse@arm.com> - 2016-05-11 17:40 +0200
Re: [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support Li Bin <huawei.libin@huawei.com> - 2016-05-12 04:30 +0200
Re: [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support David Long <dave.long@linaro.org> - 2016-05-13 22:10 +0200
| From | James Morse <james.morse@arm.com> |
|---|---|
| Date | 2016-05-11 17:40 +0200 |
| Subject | Re: [PATCH v12 00/10] arm64: Add kernel probes (kprobes) support |
| Message-ID | <rxEoW-2BM-31@gated-at.bofh.it> |
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 ]--- -------------------------%<------------------------- Thanks, James
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| From | Li Bin <huawei.libin@huawei.com> |
|---|---|
| Date | 2016-05-12 04:30 +0200 |
| Message-ID | <rxOxY-4mk-3@gated-at.bofh.it> |
| In reply to | #1399273 |
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
>
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> .
>
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| From | David Long <dave.long@linaro.org> |
|---|---|
| Date | 2016-05-13 22:10 +0200 |
| Message-ID | <ryrzk-24Y-9@gated-at.bofh.it> |
| In reply to | #1399645 |
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
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