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    Subject[PATCH] perf, ibs: Check syscall attribute flags
    On 06.09.12 21:56:45, Robert Richter wrote:
    > I tested the patch and it runs ok with my kernel patch that checks
    > syscall attributes for ibs. perf tools falls back and clears
    > exclude_guest/_host bits in attr.

    This is the patch that checks syscall attributes for ibs. Should be
    for tip:perf/urgent for ABI compatibility.

    -Robert


    From 1d037614edef576da441936bd8c917d31f57b179 Mon Sep 17 00:00:00 2001
    From: Robert Richter <robert.richter@amd.com>
    Date: Wed, 25 Jul 2012 19:12:45 +0200
    Subject: [PATCH] perf, ibs: Check syscall attribute flags

    Current implementation simply ignores attribute flags. Thus, there is
    no notification to userland of unsupported features. Check syscall's
    attribute flags to let userland know if a feature is supported by the
    kernel. This is also needed to distinguish between future kernels what
    might support a feature.

    Cc: <stable@vger.kernel.org> v3.5..
    Signed-off-by: Robert Richter <robert.richter@amd.com>
    ---
    arch/x86/kernel/cpu/perf_event_amd_ibs.c | 11 +++++++++++
    include/linux/perf_event.h | 2 ++
    2 files changed, 13 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
    index 7bfb5be..0456061 100644
    --- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
    +++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
    @@ -215,6 +215,14 @@ static int perf_ibs_init(struct perf_event *event)
    struct perf_ibs *perf_ibs;
    u64 max_cnt, config;
    int ret;
    + struct perf_event_attr notsupp = {
    + .exclude_user = 1,
    + .exclude_kernel = 1,
    + .exclude_hv = 1,
    + .exclude_idle = 1,
    + .exclude_host = 1,
    + .exclude_guest = 1,
    + };

    perf_ibs = get_ibs_pmu(event->attr.type);
    if (perf_ibs) {
    @@ -229,6 +237,9 @@ static int perf_ibs_init(struct perf_event *event)
    if (event->pmu != &perf_ibs->pmu)
    return -ENOENT;

    + if (perf_flags(&event->attr) & perf_flags(&notsupp))
    + return -EINVAL;
    +
    if (config & ~perf_ibs->config_mask)
    return -EINVAL;

    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 28f9cee..c36a04f 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -304,6 +304,8 @@ struct perf_event_attr {
    __u32 __reserved_2;
    };

    +#define perf_flags(attr) (*(&(attr)->read_format + 1))
    +
    /*
    * Ioctls that can be done on a perf event fd:
    */
    --
    1.7.8.6



    --
    Advanced Micro Devices, Inc.
    Operating System Research Center



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