perf: Carve out callchain functionality
Split the callchain code from the perf events core into a new kernel/events/callchain.c file. This simplifies a bit the big core.c Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Stephane Eranian <eranian@google.com> [keep ctx recursion handling inline and use internal headers] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1318778104-17152-1-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Borislav Petkov
committed by
Ingo Molnar
Ingo Molnar
parent
efc96737bd
commit
9251f904f9
@@ -2569,215 +2569,6 @@ static u64 perf_event_read(struct perf_event *event)
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return perf_event_count(event);
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}
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/*
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* Callchain support
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*/
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struct callchain_cpus_entries {
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struct rcu_head rcu_head;
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struct perf_callchain_entry *cpu_entries[0];
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};
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static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
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static atomic_t nr_callchain_events;
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static DEFINE_MUTEX(callchain_mutex);
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struct callchain_cpus_entries *callchain_cpus_entries;
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__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
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struct pt_regs *regs)
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{
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}
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__weak void perf_callchain_user(struct perf_callchain_entry *entry,
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struct pt_regs *regs)
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{
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}
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static void release_callchain_buffers_rcu(struct rcu_head *head)
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{
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struct callchain_cpus_entries *entries;
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int cpu;
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entries = container_of(head, struct callchain_cpus_entries, rcu_head);
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for_each_possible_cpu(cpu)
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kfree(entries->cpu_entries[cpu]);
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kfree(entries);
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}
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static void release_callchain_buffers(void)
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{
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struct callchain_cpus_entries *entries;
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entries = callchain_cpus_entries;
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rcu_assign_pointer(callchain_cpus_entries, NULL);
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call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
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}
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static int alloc_callchain_buffers(void)
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{
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int cpu;
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int size;
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struct callchain_cpus_entries *entries;
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/*
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* We can't use the percpu allocation API for data that can be
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* accessed from NMI. Use a temporary manual per cpu allocation
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* until that gets sorted out.
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*/
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size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
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entries = kzalloc(size, GFP_KERNEL);
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if (!entries)
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return -ENOMEM;
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size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
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for_each_possible_cpu(cpu) {
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entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
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cpu_to_node(cpu));
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if (!entries->cpu_entries[cpu])
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goto fail;
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}
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rcu_assign_pointer(callchain_cpus_entries, entries);
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return 0;
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fail:
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for_each_possible_cpu(cpu)
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kfree(entries->cpu_entries[cpu]);
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kfree(entries);
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return -ENOMEM;
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}
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static int get_callchain_buffers(void)
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{
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int err = 0;
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int count;
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mutex_lock(&callchain_mutex);
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count = atomic_inc_return(&nr_callchain_events);
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if (WARN_ON_ONCE(count < 1)) {
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err = -EINVAL;
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goto exit;
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}
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if (count > 1) {
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/* If the allocation failed, give up */
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if (!callchain_cpus_entries)
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err = -ENOMEM;
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goto exit;
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}
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err = alloc_callchain_buffers();
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if (err)
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release_callchain_buffers();
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exit:
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mutex_unlock(&callchain_mutex);
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return err;
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}
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static void put_callchain_buffers(void)
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{
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if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
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release_callchain_buffers();
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mutex_unlock(&callchain_mutex);
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}
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}
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static int get_recursion_context(int *recursion)
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{
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int rctx;
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if (in_nmi())
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rctx = 3;
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else if (in_irq())
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rctx = 2;
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else if (in_softirq())
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rctx = 1;
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else
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rctx = 0;
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if (recursion[rctx])
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return -1;
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recursion[rctx]++;
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barrier();
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return rctx;
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}
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static inline void put_recursion_context(int *recursion, int rctx)
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{
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barrier();
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recursion[rctx]--;
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}
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static struct perf_callchain_entry *get_callchain_entry(int *rctx)
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{
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int cpu;
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struct callchain_cpus_entries *entries;
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*rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
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if (*rctx == -1)
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return NULL;
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entries = rcu_dereference(callchain_cpus_entries);
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if (!entries)
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return NULL;
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cpu = smp_processor_id();
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return &entries->cpu_entries[cpu][*rctx];
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}
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static void
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put_callchain_entry(int rctx)
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{
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put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
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}
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static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
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{
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int rctx;
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struct perf_callchain_entry *entry;
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entry = get_callchain_entry(&rctx);
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if (rctx == -1)
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return NULL;
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if (!entry)
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goto exit_put;
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entry->nr = 0;
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if (!user_mode(regs)) {
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perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
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perf_callchain_kernel(entry, regs);
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if (current->mm)
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regs = task_pt_regs(current);
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else
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regs = NULL;
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}
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if (regs) {
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perf_callchain_store(entry, PERF_CONTEXT_USER);
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perf_callchain_user(entry, regs);
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}
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exit_put:
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put_callchain_entry(rctx);
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return entry;
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}
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/*
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* Initialize the perf_event context in a task_struct:
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*/
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