Re: [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS

[Stephane Eranian]

This assumes struct pt_regs is somehow exported to userland.
Is that the case?

I would clearly spell out that the REGS are the interrupted REGS,
not the overflow REGS. Maybe PERF_SAMPLE_IREGS.

On Wed, Mar 3, 2010 at 8:39 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> Simply copy out the provided pt_regs in a u64 aligned fashion.
>
> XXX: do task_pt_regs() and get_irq_regs() always clear everything or
> Â Â are we now leaking data?
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> ---
> Âinclude/linux/perf_event.h | Â Â5 ++++-
> Âkernel/perf_event.c    Â|  17 +++++++++++++++++
> Â2 files changed, 21 insertions(+), 1 deletion(-)
>
> Index: linux-2.6/include/linux/perf_event.h
> ===================================================================
> --- linux-2.6.orig/include/linux/perf_event.h
> +++ linux-2.6/include/linux/perf_event.h
> @@ -125,8 +125,9 @@ enum perf_event_sample_format {
> Â Â Â ÂPERF_SAMPLE_PERIOD Â Â Â Â Â Â Â Â Â Â Â= 1U << 8,
> Â Â Â ÂPERF_SAMPLE_STREAM_ID Â Â Â Â Â Â Â Â Â = 1U << 9,
> Â Â Â ÂPERF_SAMPLE_RAW Â Â Â Â Â Â Â Â Â Â Â Â = 1U << 10,
> + Â Â Â PERF_SAMPLE_REGS Â Â Â Â Â Â Â Â Â Â Â Â= 1U << 11,
>
> - Â Â Â PERF_SAMPLE_MAX = 1U << 11, Â Â Â Â Â Â /* non-ABI */
> + Â Â Â PERF_SAMPLE_MAX = 1U << 12, Â Â Â Â Â Â /* non-ABI */
> Â};
>
> Â/*
> @@ -392,6 +393,7 @@ enum perf_event_type {
> Â Â Â Â * Â Â Â{ u64 Â Â Â Â Â Â Â Â Â period; Â } && PERF_SAMPLE_PERIOD
> Â Â Â Â *
>     *   Â{ struct read_format  Âvalues;  } && PERF_SAMPLE_READ
> +    Â*   Â{ struct pt_regs    Âregs;   } && PERF_SAMPLE_REGS
> Â Â Â Â *
> Â Â Â Â * Â Â Â{ u64 Â Â Â Â Â Â Â Â Â nr,
> Â Â Â Â * Â Â Â Âu64 Â Â Â Â Â Â Â Â Â ips[nr]; Â} && PERF_SAMPLE_CALLCHAIN
> @@ -800,6 +802,7 @@ struct perf_sample_data {
> Â Â Â Âu64 Â Â Â Â Â Â Â Â Â Â Â Â Â Â period;
>    Âstruct perf_callchain_entry   *callchain;
>    Âstruct perf_raw_record     Â*raw;
> +    struct pt_regs         Â*regs;
> Â};
>
> Âstatic inline
> Index: linux-2.6/kernel/perf_event.c
> ===================================================================
> --- linux-2.6.orig/kernel/perf_event.c
> +++ linux-2.6/kernel/perf_event.c
> @@ -3176,6 +3176,17 @@ void perf_output_sample(struct perf_outp
> Â Â Â Âif (sample_type & PERF_SAMPLE_READ)
> Â Â Â Â Â Â Â Âperf_output_read(handle, event);
>
> + Â Â Â if (sample_type & PERF_SAMPLE_REGS) {
> + Â Â Â Â Â Â Â int size = DIV_ROUND_UP(sizeof(struct pt_regs), sizeof(u64)) -
> + Â Â Â Â Â Â Â Â Â Â Â Â Âsizeof(struct pt_regs);
> +
> + Â Â Â Â Â Â Â perf_output_put(handle, *data->regs);
> + Â Â Â Â Â Â Â if (size) {
> + Â Â Â Â Â Â Â Â Â Â Â u64 zero = 0;
> + Â Â Â Â Â Â Â Â Â Â Â perf_output_copy(handle, &zero, size);
> + Â Â Â Â Â Â Â }
> + Â Â Â }
> +
> Â Â Â Âif (sample_type & PERF_SAMPLE_CALLCHAIN) {
> Â Â Â Â Â Â Â Âif (data->callchain) {
> Â Â Â Â Â Â Â Â Â Â Â Âint size = 1;
> @@ -3273,6 +3284,12 @@ void perf_prepare_sample(struct perf_eve
> Â Â Â Âif (sample_type & PERF_SAMPLE_READ)
> Â Â Â Â Â Â Â Âheader->size += perf_event_read_size(event);
>
> + Â Â Â if (sample_type & PERF_SAMPLE_REGS) {
> + Â Â Â Â Â Â Â data->regs = regs;
> + Â Â Â Â Â Â Â header->size += DIV_ROUND_UP(sizeof(struct pt_regs),
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âsizeof(u64));
> + Â Â Â }
> +
> Â Â Â Âif (sample_type & PERF_SAMPLE_CALLCHAIN) {
> Â Â Â Â Â Â Â Âint size = 1;
>
>
> --
>
>



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Stephane Eranian | EMEA Software Engineering
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