[RFC V1 11/11] perf: Capture branch privilege information
James Clark
james.clark at arm.com
Tue Jan 25 07:39:24 PST 2022
On 24/01/2022 04:30, Anshuman Khandual wrote:
> Platforms like arm64 could capture privilege level information for all the
> branch records. Hence this adds a new element in the struct branch_entry to
> record the privilege level information, which could be requested through a
> new event.attr.branch_sample_type flag PERF_SAMPLE_BRANCH_PRIV_SAVE. While
> here, update the BRBE driver as required.
>
> Cc: Will Deacon <will at kernel.org>
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: Peter Zijlstra <peterz at infradead.org>
> Cc: Ingo Molnar <mingo at redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme at kernel.org>
> Cc: Jiri Olsa <jolsa at redhat.com>
> Cc: Namhyung Kim <namhyung at kernel.org>
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: linux-perf-users at vger.kernel.org
> Cc: linux-kernel at vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
> ---
> drivers/perf/arm_pmu_brbe.c | 28 ++++++++++++++++++++++++
> include/linux/perf_event.h | 5 +++++
> include/uapi/linux/perf_event.h | 13 ++++++++++-
> tools/include/uapi/linux/perf_event.h | 13 ++++++++++-
> tools/perf/Documentation/perf-record.txt | 1 +
> tools/perf/util/parse-branch-options.c | 1 +
> 6 files changed, 59 insertions(+), 2 deletions(-)
>
[...]
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index 361fdc6b87a0..4d77710f7a4e 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -204,6 +204,8 @@ enum perf_branch_sample_type_shift {
>
> PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT = 17, /* save low level index of raw branch records */
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT = 18, /* save privillege mode */
privillege -> privilege
> +
> PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> };
>
> @@ -233,6 +235,8 @@ enum perf_branch_sample_type {
>
> PERF_SAMPLE_BRANCH_HW_INDEX = 1U << PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT,
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE = 1U << PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT,
> +
Can you also add the new entry to the perf verbose printer otherwise it looks like
it's not being set on branch_sample_type
(as in when using ./perf record -j any_call,u,priv -vvv):
static void __p_branch_sample_type(char *buf, size_t size, u64 value)
{
#define bit_name(n) { PERF_SAMPLE_BRANCH_##n, #n }
struct bit_names bits[] = {
bit_name(USER), bit_name(KERNEL), bit_name(HV), bit_name(ANY),
bit_name(ANY_CALL), bit_name(ANY_RETURN), bit_name(IND_CALL),
bit_name(ABORT_TX), bit_name(IN_TX), bit_name(NO_TX),
bit_name(COND), bit_name(CALL_STACK), bit_name(IND_JUMP),
bit_name(CALL), bit_name(NO_FLAGS), bit_name(NO_CYCLES),
bit_name(HW_INDEX),
{ .name = NULL, }
};
#undef bit_name
__p_bits(buf, size, value, bits);
}
PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT is also missing so it probably makes sense to add it
at the same time as that was expanded for BRBE.
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> };
>
> @@ -265,6 +269,12 @@ enum {
> PERF_BR_MAX,
> };
>
> +enum {
> + PERF_BR_USER = 0,
> + PERF_BR_KERNEL = 1,
> + PERF_BR_HV = 2,
> +};
> +
> #define PERF_SAMPLE_BRANCH_PLM_ALL \
> (PERF_SAMPLE_BRANCH_USER|\
> PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -1377,7 +1387,8 @@ struct perf_branch_entry {
> abort:1, /* transaction abort */
> cycles:16, /* cycle count to last branch */
> type:6, /* branch type */
> - reserved:38;
> + priv:2, /* privilege level */
> + reserved:36;
> };
>
> union perf_sample_weight {
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index 9a82b8aaed93..a2208400b0b9 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -204,6 +204,8 @@ enum perf_branch_sample_type_shift {
>
> PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT = 17, /* save low level index of raw branch records */
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT = 18, /* save privillege mode */
> +
> PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> };
>
> @@ -233,6 +235,8 @@ enum perf_branch_sample_type {
>
> PERF_SAMPLE_BRANCH_HW_INDEX = 1U << PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT,
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE = 1U << PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT,
> +
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> };
>
> @@ -265,6 +269,12 @@ enum {
> PERF_BR_MAX,
> };
>
> +enum {
> + PERF_BR_USER = 0,
> + PERF_BR_KERNEL = 1,
> + PERF_BR_HV = 2,
> +};
> +
> #define PERF_SAMPLE_BRANCH_PLM_ALL \
> (PERF_SAMPLE_BRANCH_USER|\
> PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -1377,7 +1387,8 @@ struct perf_branch_entry {
> abort:1, /* transaction abort */
> cycles:16, /* cycle count to last branch */
> type:6, /* branch type */
> - reserved:38;
> + priv:2, /* privilege level */
> + reserved:36;
> };
>
> union perf_sample_weight {
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 9ccc75935bc5..3e33686977a1 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -387,6 +387,7 @@ following filters are defined:
> - abort_tx: only when the target is a hardware transaction abort
> - cond: conditional branches
> - save_type: save branch type during sampling in case binary is not available later
> + - priv: save privilege state during sampling in case binary is not available later
>
> +
> The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
> diff --git a/tools/perf/util/parse-branch-options.c b/tools/perf/util/parse-branch-options.c
> index bb4aa88c50a8..00588b9db474 100644
> --- a/tools/perf/util/parse-branch-options.c
> +++ b/tools/perf/util/parse-branch-options.c
> @@ -32,6 +32,7 @@ static const struct branch_mode branch_modes[] = {
> BRANCH_OPT("call", PERF_SAMPLE_BRANCH_CALL),
> BRANCH_OPT("save_type", PERF_SAMPLE_BRANCH_TYPE_SAVE),
> BRANCH_OPT("stack", PERF_SAMPLE_BRANCH_CALL_STACK),
> + BRANCH_OPT("priv", PERF_SAMPLE_BRANCH_PRIV_SAVE),
> BRANCH_END
> };
>
>
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