Messages in this thread | | | Date | Mon, 3 Sep 2012 13:28:15 +0800 | From | wyang1 <> | Subject | Re: [PATCH 1/1] x86/oprofile: Fix the calltrace upon profiling some specified events with oprofile |
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On 08/28/2012 05:17 PM, Robert Richter wrote: > On 27.08.12 09:32:13, Wei.Yang@windriver.com wrote: >> From: Wei Yang<Wei.Yang@windriver.com> >> >> Upon enabling the call-graph functionality of oprofile, A few minutes >> later the following calltrace will always occur. >> >> BUG: unable to handle kernel paging request at 656d6153 > This is probably the same I found to yesterday. Will test your fix.
OK, I have already tested it on some boards based on intel atom e6xx and intel atom n4xx & d5xx.
Thanks Wei > -Robert > >> IP: [<c10050f5>] print_context_stack+0x55/0x110 >> *pde = 00000000 >> Oops: 0000 [#1] PREEMPT SMP >> Modules linked in: >> Pid: 0, comm: swapper/0 Not tainted 3.6.0-rc3-WR5.0+snapshot-20120820_standard >> EIP: 0060:[<c10050f5>] EFLAGS: 00010093 CPU: 0 >> EIP is at print_context_stack+0x55/0x110 >> EAX: 656d7ffc EBX: 656d6153 ECX: c1837ee0 EDX: 656d6153 >> ESI: 00000000 EDI: ffffe000 EBP: f600deac ESP: f600de88 >> DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 >> CR0: 8005003b CR2: 656d6153 CR3: 01934000 CR4: 000007d0 >> DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 >> DR6: ffff0ff0 DR7: 00000400 >> Process swapper/0 (pid: 0, ti=f600c000 task=c18411a0 task.ti=c1836000) >> Stack: >> 1a7f76ea 656d7ffc 656d6000 c1837ee0 ffffe000 c1837ee0 656d6153 c188e27c >> 656d6000 f600dedc c10040f8 c188e27c f600def0 00000000 f600dec8 c1837ee0 >> 00000000 f600ded4 c1837ee0 f600dfc4 0000001f f600df08 c1564d22 00000000 >> Call Trace: >> [<c10040f8>] dump_trace+0x68/0xf0 >> [<c1564d22>] x86_backtrace+0xb2/0xc0 >> [<c1562dd2>] oprofile_add_sample+0xa2/0xc0 >> [<c1003fbf>] ? do_softirq+0x6f/0xa0 >> [<c1566519>] ppro_check_ctrs+0x79/0x100 >> [<c15664a0>] ? ppro_shutdown+0x60/0x60 >> [<c156552f>] profile_exceptions_notify+0x8f/0xb0 >> [<c1672248>] nmi_handle.isra.0+0x48/0x70 >> [<c1672343>] do_nmi+0xd3/0x3c0 >> [<c1033d39>] ? __local_bh_enable+0x29/0x70 >> [<c1034620>] ? ftrace_define_fields_irq_handler_entry+0x80/0x80 >> [<c1671a0d>] nmi_stack_correct+0x28/0x2d >> [<c1034620>] ? ftrace_define_fields_irq_handler_entry+0x80/0x80 >> [<c1003fbf>] ? do_softirq+0x6f/0xa0 >> <IRQ> >> [<c1034ad5>] irq_exit+0x65/0x70 >> [<c16776f9>] smp_apic_timer_interrupt+0x59/0x89 >> [<c16717da>] apic_timer_interrupt+0x2a/0x30 >> [<c135164d>] ? acpi_idle_enter_bm+0x245/0x273 >> [<c14f3a25>] cpuidle_enter+0x15/0x20 >> [<c14f4070>] cpuidle_idle_call+0xa0/0x320 >> [<c1009705>] cpu_idle+0x55/0xb0 >> [<c16519a8>] rest_init+0x6c/0x74 >> [<c18a291b>] start_kernel+0x2ec/0x2f3 >> [<c18a2467>] ? repair_env_string+0x51/0x51 >> [<c18a22a2>] i386_start_kernel+0x78/0x7d >> Code: e0 ff ff 89 7d ec 74 5a 8d b4 26 00 00 00 00 8d bc 27 00 00 >> 00 00 39 f3 72 0c 8b 45 f0 8d 64 24 18 5b 5e 5f 5d c3 3b 5d ec 72 >> ef<8b> 3b 89 f8 89 7d dc e8 ef 40 04 00 85 c0 74 20 8b 40 >> EIP: [<c10050f5>] print_context_stack+0x55/0x110 SS:ESP 0068:f600de88 >> CR2: 00000000656d6153 >> ---[ end trace 751c9b47c6ff5e29 ]--- >> >> Let's assume a scenario that do_softirq() switches the stack to a soft irq >> stack, and the soft irq stack is totally empty. At this moment, a nmi interrupt >> occurs, subsequently, CPU does not automatically save SS and SP registers >> and switch any stack, but instead only stores EFLAGS, CS and IP to the soft irq >> stack. since the CPU is in kernel mode when the NMI exception occurs. >> the layout of the current soft irq stack is this: >> >> +--------------+<-----the top of soft irq >> | EFLAGS | >> +--------------+ >> | CS | >> +--------------+ >> | IP | >> +--------------+ >> | SAVE_ALL | >> +--------------+ >> >> but the return value of the function kernel_stack_pointer() is'®s->sp' >> (for x86_32 CPU), which is invoked by the x86_backtrace function. Since >> the type of regs pointer is a pt_regs structure, the return value is not >> in the range of the soft irq stack, as the SP register is not save in the >> soft irq stack. Therefore, we need to check if the return value of the function >> resides in valid range. Additionally, the changes has no impact on the normal >> NMI exception. >> >> Signed-off-by: Yang Wei<wei.yang@windriver.com> >> --- >> arch/x86/oprofile/backtrace.c | 10 ++++++++++ >> 1 files changed, 10 insertions(+), 0 deletions(-) >> >> diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c >> index d6aa6e8..a5fca0b 100644 >> --- a/arch/x86/oprofile/backtrace.c >> +++ b/arch/x86/oprofile/backtrace.c >> @@ -17,6 +17,11 @@ >> #include<asm/ptrace.h> >> #include<asm/stacktrace.h> >> >> +static inline int valid_stack_ptr(struct thread_info *tinfo, void *p) >> +{ >> + void *t = tinfo; >> + return p> t + sizeof(struct thread_info)&& p< t + THREAD_SIZE; >> +} >> static int backtrace_stack(void *data, char *name) >> { >> /* Yes, we want all stacks */ >> @@ -110,9 +115,14 @@ void >> x86_backtrace(struct pt_regs * const regs, unsigned int depth) >> { >> struct stack_frame *head = (struct stack_frame *)frame_pointer(regs); >> + struct thread_info *context; >> >> if (!user_mode_vm(regs)) { >> unsigned long stack = kernel_stack_pointer(regs); >> + context = (struct thread_info *) >> + (stack& (~(THREAD_SIZE - 1))); >> + if (!valid_stack_ptr(context, (void *)stack)) >> + return; >> if (depth) >> dump_trace(NULL, regs, (unsigned long *)stack, 0, >> &backtrace_ops,&depth); >> -- >> 1.7.0.2 >> >>
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