Messages in this thread | | | Date | Mon, 21 May 2012 15:19:32 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 04/17] perf: Add ability to attach user stack dump to sample |
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On Wed, May 02, 2012 at 01:37:05PM +0200, Jiri Olsa wrote: > Introducing new sample_type bit PERF_SAMPLE_STACK. Once set, > the sample_stack value determines the stack which is going > to be attached. > > Currently only user level stack is supported, specified by > PERF_SAMPLE_STACK_USER bit in sample_stack value. When set, > the sample_stack_user value determines the size of the > stack dump. > > Beeing able to dump parts of the user stack, starting from the > stack pointer, will be useful to make a post mortem dwarf CFI > based stack unwinding. > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Signed-off-by: Jiri Olsa <jolsa@redhat.com> > --- > include/linux/perf_event.h | 20 ++++++++- > kernel/events/core.c | 103 ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 122 insertions(+), 1 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index dcda0f16..2e5f486 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -131,8 +131,9 @@ enum perf_event_sample_format { > PERF_SAMPLE_RAW = 1U << 10, > PERF_SAMPLE_BRANCH_STACK = 1U << 11, > PERF_SAMPLE_REGS = 1U << 12, > + PERF_SAMPLE_STACK = 1U << 13, > > - PERF_SAMPLE_MAX = 1U << 13, /* non-ABI */ > + PERF_SAMPLE_MAX = 1U << 14, /* non-ABI */ > }; > > /* > @@ -173,6 +174,15 @@ enum perf_sample_regs { > }; > > /* > + * Values for sample_stack when PERF_SAMPLE_STACK is set. > + * Defines stack dump to be attached to the sample. > + */ > +enum perf_sample_stack { > + PERF_SAMPLE_STACK_USER = 1U << 0, /* user stack */ > + PERF_SAMPLE_STACK_MAX = 1U << 1, /* non-ABI */
Same problem than with regs, this doesn't allow several stack dumps types in a single sample.
> +}; > + > +/* > * The format of the data returned by read() on a perf event fd, > * as specified by attr.read_format: > * > @@ -291,6 +301,14 @@ struct perf_event_attr { > * See asm/perf_regs.h for details. > */ > __u64 sample_regs_user; > + > + __u64 sample_stack; /* enum perf_sample_stack */ > + > + /* > + * Defines size of the user stack to dump on samples, > + * for sample_stack PERF_SAMPLE_STACK_USER settings. > + */ > + __u64 sample_stack_user;
Do we need PERF_SAMPLE_STACK when we can already set 0 in sample_stack_user?
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