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    Subject[tip:perf/core] perf, x86: P4 PMU -- do a real check for ESCR address being in hash
    Commit-ID:  623aab896ee1a532cb540bcf0d5ae8a88275afd5
    Gitweb: http://git.kernel.org/tip/623aab896ee1a532cb540bcf0d5ae8a88275afd5
    Author: Cyrill Gorcunov <gorcunov@openvz.org>
    AuthorDate: Wed, 19 May 2010 01:19:17 +0400
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Wed, 19 May 2010 09:41:05 +0200

    perf, x86: P4 PMU -- do a real check for ESCR address being in hash

    To prevent from clashes in future code modifications
    do a real check for ESCR address being in hash. At
    moment the callers are known to pass sane values but
    better to be on a safe side.

    And comment fix.

    Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    CC: Lin Ming <ming.m.lin@intel.com>
    CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
    CC: Frederic Weisbecker <fweisbec@gmail.com>
    LKML-Reference: <20100518212439.004503600@openvz.org>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/kernel/cpu/perf_event_p4.c | 7 ++++---
    1 files changed, 4 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
    index 87e1803..5f8e36d 100644
    --- a/arch/x86/kernel/cpu/perf_event_p4.c
    +++ b/arch/x86/kernel/cpu/perf_event_p4.c
    @@ -670,7 +670,7 @@ static void p4_pmu_swap_config_ts(struct hw_perf_event *hwc, int cpu)

    /*
    * ESCR address hashing is tricky, ESCRs are not sequential
    - * in memory but all starts from MSR_P4_BSU_ESCR0 (0x03e0) and
    + * in memory but all starts from MSR_P4_BSU_ESCR0 (0x03a0) and
    * the metric between any ESCRs is laid in range [0xa0,0xe1]
    *
    * so we make ~70% filled hashtable
    @@ -735,8 +735,9 @@ static int p4_get_escr_idx(unsigned int addr)
    {
    unsigned int idx = P4_ESCR_MSR_IDX(addr);

    - if (unlikely(idx >= P4_ESCR_MSR_TABLE_SIZE ||
    - !p4_escr_table[idx])) {
    + if (unlikely(idx >= P4_ESCR_MSR_TABLE_SIZE ||
    + !p4_escr_table[idx] ||
    + p4_escr_table[idx] != addr)) {
    WARN_ONCE(1, "P4 PMU: Wrong address passed: %x\n", addr);
    return -1;
    }

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