Messages in this thread | | | Date | Wed, 15 Apr 2015 09:22:37 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH 07/18 v3] tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values |
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On 04/02/2015 09:38 PM, Steven Rostedt wrote: > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org> > > Several tracepoints use the helper functions __print_symbolic() or > __print_flags() and pass in enums that do the mapping between the > binary data stored and the value to print. This works well for reading > the ASCII trace files, but when the data is read via userspace tools > such as perf and trace-cmd, the conversion of the binary value to a > human string format is lost if an enum is used, as userspace does not > have access to what the ENUM is. > > For example, the tracepoint trace_tlb_flush() has: > > __print_symbolic(REC->reason, > { TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" }, > { TLB_REMOTE_SHOOTDOWN, "remote shootdown" }, > { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, > { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" }) > > Which maps the enum values to the strings they represent. But perf and > trace-cmd do no know what value TLB_LOCAL_MM_SHOOTDOWN is, and would > not be able to map it. > > With TRACE_DEFINE_ENUM(), developers can place these in the event header > files and ftrace will convert the enums to their values: > > By adding: > > TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH); > TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN); > TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN); > TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN); > > $ cat /sys/kernel/debug/tracing/events/tlb/tlb_flush/format > [...] > __print_symbolic(REC->reason, > { 0, "flush on task switch" }, > { 1, "remote shootdown" }, > { 2, "local shootdown" }, > { 3, "local mm shootdown" }) > > The above is what userspace expects to see, and tools do not need to > be modified to parse them. > > Cc: Guilherme Cox <cox@computer.org> > Cc: Tony Luck <tony.luck@gmail.com> > Cc: Xie XiuQi <xiexiuqi@huawei.com> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> > ---
Hey Steven,
I'm seeing the following when booting:
[ 10.678876] BUG: KASan: out of bounds access in trace_event_enum_update+0xb1d/0xb70 at addr ffffffffa6c4dc68 [ 10.680222] Read of size 1 by task swapper/0/1 [ 10.680222] Address belongs to variable print_fmt_9p_client_req+0x848/0x880 [ 10.680222] CPU: 19 PID: 1 Comm: swapper/0 Not tainted 4.0.0-next-20150415-sasha-00064-g7858a62 #2147 [ 10.680222] ffffffffa6c4dc68 00000000915e69dc ffff88004e8efb18 ffffffffa1b4f7a6 [ 10.680222] 0000000000000000 ffff88004e8efba8 ffff88004e8efb98 ffffffff976544b1 [ 10.680222] ffff88004e8efbd8 ffffffff990134a4 0000000000000282 ffffffffa444e381 [ 10.680222] Call Trace: [ 10.680222] dump_stack (lib/dump_stack.c:52) [ 10.680222] kasan_report_error (mm/kasan/report.c:132 mm/kasan/report.c:193) [ 10.680222] ? snprintf (lib/vsprintf.c:2069) [ 10.680222] ? vsprintf (lib/vsprintf.c:2069) [ 10.680222] ? trace_event_enum_update (kernel/trace/trace_events.c:1807) [ 10.680222] __asan_report_load1_noabort (mm/kasan/report.c:230 mm/kasan/report.c:248) [ 10.680222] ? trace_event_enum_update (kernel/trace/trace_events.c:1807) [ 10.680222] trace_event_enum_update (kernel/trace/trace_events.c:1807) [ 10.680222] tracer_init_tracefs (kernel/trace/trace.c:4122 kernel/trace/trace.c:6750 kernel/trace/trace.c:6848) [ 10.680222] ? clear_boot_tracer (kernel/trace/trace.c:6825) [ 10.680222] ? clear_boot_tracer (kernel/trace/trace.c:6825) [ 10.680222] do_one_initcall (init/main.c:788) [ 10.680222] ? try_to_run_init_process (init/main.c:777) [ 10.680222] ? parse_args (kernel/params.c:131 kernel/params.c:216) [ 10.680222] ? trace_hardirqs_on (kernel/locking/lockdep.c:2630) [ 10.680222] kernel_init_freeable (init/main.c:853 init/main.c:861 init/main.c:880 init/main.c:1001) [ 10.680222] ? local_clock (kernel/sched/clock.c:392) [ 10.680222] ? start_kernel (init/main.c:973) [ 10.680222] ? finish_task_switch (kernel/sched/core.c:2249) [ 10.680222] ? finish_task_switch (include/linux/tick.h:186 kernel/sched/core.c:2263) [ 10.680222] ? finish_task_switch (kernel/sched/sched.h:1077 kernel/sched/core.c:2245) [ 10.680222] ? rest_init (init/main.c:928) [ 10.680222] kernel_init (init/main.c:933) [ 10.680222] ? rest_init (init/main.c:928) [ 10.680222] ret_from_fork (arch/x86/kernel/entry_64.S:631) [ 10.680222] ? rest_init (init/main.c:928) [ 10.680222] Memory state around the buggy address: [ 10.680222] ffffffffa6c4db00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 10.680222] ffffffffa6c4db80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 10.680222] >ffffffffa6c4dc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa [ 10.680222] ^ [ 10.680222] ffffffffa6c4dc80: fa fa fa fa 00 00 00 00 fa fa fa fa 00 00 00 00 [ 10.680222] ffffffffa6c4dd00: fa fa fa fa 00 00 00 00 fa fa fa fa 00 00 00 00
Thanks, Sasha
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