| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 098/127] sparc64: Fix pcr_ops initialization and usage bugs. | Date | Tue, 28 Oct 2014 11:35:33 +0800 |
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3.16-stable review patch. If anyone has any objections, please let me know.
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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) static 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 @@ static int __init init_hw_perf_events(vo 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 @@ -312,6 +312,9 @@ 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 @@ -1383,7 +1383,6 @@ 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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