On Fri, Dec 04, 2015 at 03:59:42AM -0800, tip-bot for Andi Kleen wrote:
> Commit-ID: 07b41f5cf37b34ef3de4f40fbaf8547abe690abb
> Gitweb: http://git.kernel.org/tip/07b41f5cf37b34ef3de4f40fbaf8547abe690abb
> Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> AuthorDate: Tue, 1 Dec 2015 17:00:59 -0800
> Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Fri, 4 Dec 2015 10:58:34 +0100
>
> x86, tracing, perf: Add trace point for MSR accesses
>
> For debugging low level code interacting with the CPU it is often
> useful to trace the MSR read/writes. This gives a concise summary of
> PMU and other operations.
>
> perf has an ad-hoc way to do this using trace_printk, but it's
> somewhat limited (and also now spews ugly boot messages when enabled)
>
> Instead define real trace points for all MSR accesses.
>
> This adds three new trace points: read_msr and write_msr and rdpmc.
>
> They also report if the access faulted (if *_safe is used)
>
> This allows filtering and triggering on specific MSR values, which
> allows various more advanced debugging techniques.
>
> All the values are well defined in the CPU documentation.
>
> The trace can be post processed with
> Documentation/trace/postprocess/decode_msr.py to add symbolic MSR
> names to the trace.
>
> I only added it to native MSR accesses in C, not paravirtualized or in
> entry*.S (which is not too interesting)
>
> Originally the patch kit moved the MSRs out of line. This uses an
> alternative approach recommended by Steven Rostedt of only moving the
> trace calls out of line, but open coding the access to the jump label.
>
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Mike Galbraith <efault@xxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Stephane Eranian <eranian@xxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/1449018060-1742-3-git-send-email-andi@xxxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
...
> diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c
> index 4362373..004c861 100644
> --- a/arch/x86/lib/msr.c
> +++ b/arch/x86/lib/msr.c
> @@ -1,6 +1,8 @@
> #include <linux/module.h>
> #include <linux/preempt.h>
> #include <asm/msr.h>
> +#define CREATE_TRACE_POINTS
> +#include <asm/msr-trace.h>
>
> struct msr *msrs_alloc(void)
> {
> @@ -108,3 +110,27 @@ int msr_clear_bit(u32 msr, u8 bit)
> {
> return __flip_bit(msr, bit, false);
> }
> +
> +#ifdef CONFIG_TRACEPOINTS
> +void do_trace_write_msr(unsigned msr, u64 val, int failed)
> +{
> + trace_write_msr(msr, val, failed);
> +}
> +EXPORT_SYMBOL(do_trace_write_msr);
> +EXPORT_TRACEPOINT_SYMBOL(write_msr);
> +
> +void do_trace_read_msr(unsigned msr, u64 val, int failed)
> +{
> + trace_read_msr(msr, val, failed);
> +}
> +EXPORT_SYMBOL(do_trace_read_msr);
> +EXPORT_TRACEPOINT_SYMBOL(read_msr);
> +
> +void do_trace_rdpmc(unsigned counter, u64 val, int failed)
> +{
> + trace_rdpmc(counter, val, failed);
> +}
> +EXPORT_SYMBOL(do_trace_rdpmc);
> +EXPORT_TRACEPOINT_SYMBOL(rdpmc);
Any particular reason why those are EXPORT_SYMBOL and not
EXPORT_SYMBOL_GPL?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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