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Message-ID: <1c583986-74f8-4829-883b-390dc49ddabb@email.android.com> Date: Fri, 28 Feb 2014 07:13:06 -0800 From: "H. Peter Anvin" <hpa@...or.com> To: Vince Weaver <vincent.weaver@...ne.edu>, Steven Rostedt <rostedt@...dmis.org> CC: Peter Zijlstra <peterz@...radead.org>, Linux Kernel <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com> Subject: Re: perf_fuzzer compiled for x32 causes reboot If I'm reading this right we end up going from the page fault tracepoint to copy_from_user_nmi() without going through NMI, and the cr2 corruption is obvious. I guess the assumption that only the NMI path needed to save cr2 is flawed? On February 28, 2014 7:07:29 AM PST, Vince Weaver <vincent.weaver@...ne.edu> wrote: >On Fri, 28 Feb 2014, Steven Rostedt wrote: > >> Interesting. Are you doing a perf function trace? >> >> And just in case, can you add this patch and make sure the copy is >> called by NMI. > >199.900682: function: trace_do_page_fault >199.900683: page_fault_user: address=__per_cpu_end >ip=__per_cpu_end error_code=0x6 >199.900683: function: perf_swevent_get_recursion_context >199.900684: function: perf_tp_event >199.900684: function: perf_swevent_event >199.900684: function: perf_swevent_overflow >199.900684: function: __perf_event_overflow >199.900685: function: perf_prepare_sample >199.900685: function: >__perf_event_header__init_id >199.900685: function: task_tgid_nr_ns >199.900685: function: perf_event_tid >199.900686: function: __task_pid_nr_ns >199.900686: function: perf_callchain >199.900687: function: copy_from_user_nmi >199.900687: function: trace_do_page_fault >199.900687: page_fault_kernel: address=irq_stack_union >ip=copy_user_generic_string error_code=0x0 >199.900688: function: __do_page_fault >199.900688: function: bad_area_nosemaphore >199.900688: function: __bad_area_nosemaphore >199.900689: function: no_context >199.900689: function: fixup_exception >199.900689: function: >search_exception_tables >199.900689: function: search_extable >199.900691: function: copy_user_handle_tail >199.900691: function: trace_do_page_fault >199.900691: page_fault_kernel: address=irq_stack_union >ip=copy_user_handle_tail error_code=0x0 >199.900691: function: __do_page_fault >199.900692: function: bad_area_nosemaphore >199.900692: function: __bad_area_nosemaphore >199.900692: function: no_context >199.900692: function: fixup_exception >199.900692: function: >search_exception_tables >199.900692: function: search_extable >199.900693: function: save_stack_trace >199.900693: function: dump_trace >199.900694: function: print_context_stack >199.900694: function: __kernel_text_address >199.900694: function: is_module_text_address >199.900695: function: __module_text_address >199.900695: function: __module_address >199.900695: function: __kernel_text_address >199.900695: function: is_module_text_address >199.900696: function: __module_text_address >199.900696: function: __module_address >... >199.900705: function: __kernel_text_address >199.900809: kernel_stack: <stack trace> >=> perf_callchain (ffffffff810d35a2) >=> perf_prepare_sample (ffffffff810cfae3) >=> __perf_event_overflow (ffffffff810d02f4) >=> perf_swevent_overflow (ffffffff810d04e3) >=> perf_swevent_event (ffffffff810d0574) >=> perf_tp_event (ffffffff810d070c) >=> perf_trace_x86_exceptions (ffffffff810341b6) >=> trace_do_page_fault (ffffffff81537702) >=> trace_page_fault (ffffffff81534772) >199.900810: function: perf_output_begin >199.900810: function: __do_page_fault >199.900810: function: __perf_sw_event >199.900810: function: >perf_swevent_get_recursion_context >199.900811: function: down_read_trylock >199.900811: function: _cond_resched >199.900811: function: find_vma >199.900811: function: bad_area >199.900812: function: up_read >199.900812: function: __bad_area_nosemaphore >199.900812: function: is_prefetch >199.900812: function: convert_ip_to_linear >199.900813: function: unhandled_signal >199.900813: function: __printk_ratelimit >199.900813: function: _raw_spin_trylock >199.900813: function: _raw_spin_unlock_irqrestore >199.900814: function: printk >199.900814: function: vprintk_emit -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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