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    Subject[PATCH 30/32] perf,perf/x86: add hook perf_event_arch_exec
    Date
    perf_event context switches events to newly exec'ed tasks using
    perf_event_exec. Add a hook for such path.

    In x86, perf_event_arch_exec is used to synchronize the software
    cache of the PQR_ASSOC msr, setting the right RMID for the new task.

    Reviewed-by: Stephane Eranian <eranian@google.com>
    Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
    ---
    arch/x86/include/asm/perf_event.h | 2 ++
    include/linux/perf_event.h | 5 +++++
    kernel/events/core.c | 1 +
    3 files changed, 8 insertions(+)

    diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
    index 99fc206..c13f501 100644
    --- a/arch/x86/include/asm/perf_event.h
    +++ b/arch/x86/include/asm/perf_event.h
    @@ -332,6 +332,8 @@ extern struct cftype perf_event_cgrp_arch_subsys_cftypes[];
    .dfl_cftypes = perf_event_cgrp_arch_subsys_cftypes, \
    .legacy_cftypes = perf_event_cgrp_arch_subsys_cftypes,

    +#define perf_event_arch_exec pqr_update
    +
    #else

    #define PERF_CGROUP_ARCH_CGRP_SUBSYS_ATTS
    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 9c973bd..99b4393 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -1289,4 +1289,9 @@ static struct device_attribute format_attr_##_name = __ATTR_RO(_name)
    #define PERF_CGROUP_ARCH_CGRP_SUBSYS_ATTS
    #endif

    +#ifndef perf_event_arch_exec
    +#define perf_event_arch_exec() do { } while (0)
    +#endif
    +
    +
    #endif /* _LINUX_PERF_EVENT_H */
    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index cfffa50..5c675b4 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -3248,6 +3248,7 @@ void perf_event_exec(void)
    for_each_task_context_nr(ctxn)
    perf_event_enable_on_exec(ctxn);
    rcu_read_unlock();
    + perf_event_arch_exec();
    }

    struct perf_read_data {
    --
    2.8.0.rc3.226.g39d4020
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