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    Subject[PATCH 3.14 073/100] sparc64: Fix pcr_ops initialization and usage bugs.
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "David S. Miller" <davem@davemloft.net>

    [ Upstream commit 8bccf5b313180faefce38e0d1140f76e0f327d28 ]

    Christopher reports that perf_event_print_debug() can crash in uniprocessor
    builds. The crash is due to pcr_ops being NULL.

    This happens because pcr_arch_init() is only invoked by smp_cpus_done() which
    only executes in SMP builds.

    init_hw_perf_events() is closely intertwined with pcr_ops being setup properly,
    therefore:

    1) Call pcr_arch_init() early on from init_hw_perf_events(), instead of
    from smp_cpus_done().

    2) Do not hook up a PMU type if pcr_ops is NULL after pcr_arch_init().

    3) Move init_hw_perf_events to a later initcall so that it we will be
    sure to invoke pcr_arch_init() after all cpus are brought up.

    Finally, guard the one naked sequence of pcr_ops dereferences in
    __global_pmu_self() with an appropriate NULL check.

    Reported-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/sparc/kernel/perf_event.c | 7 +++++--
    arch/sparc/kernel/process_64.c | 3 +++
    arch/sparc/kernel/smp_64.c | 1 -
    3 files changed, 8 insertions(+), 3 deletions(-)

    --- a/arch/sparc/kernel/perf_event.c
    +++ b/arch/sparc/kernel/perf_event.c
    @@ -1671,9 +1671,12 @@ static bool __init supported_pmu(void)

    int __init init_hw_perf_events(void)
    {
    + int err;
    +
    pr_info("Performance events: ");

    - if (!supported_pmu()) {
    + err = pcr_arch_init();
    + if (err || !supported_pmu()) {
    pr_cont("No support for PMU type '%s'\n", sparc_pmu_type);
    return 0;
    }
    @@ -1685,7 +1688,7 @@ int __init init_hw_perf_events(void)

    return 0;
    }
    -early_initcall(init_hw_perf_events);
    +pure_initcall(init_hw_perf_events);

    void perf_callchain_kernel(struct perf_callchain_entry *entry,
    struct pt_regs *regs)
    --- a/arch/sparc/kernel/process_64.c
    +++ b/arch/sparc/kernel/process_64.c
    @@ -306,6 +306,9 @@ static void __global_pmu_self(int this_c
    struct global_pmu_snapshot *pp;
    int i, num;

    + if (!pcr_ops)
    + return;
    +
    pp = &global_cpu_snapshot[this_cpu].pmu;

    num = 1;
    --- a/arch/sparc/kernel/smp_64.c
    +++ b/arch/sparc/kernel/smp_64.c
    @@ -1395,7 +1395,6 @@ void __cpu_die(unsigned int cpu)

    void __init smp_cpus_done(unsigned int max_cpus)
    {
    - pcr_arch_init();
    }

    void smp_send_reschedule(int cpu)



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