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>

4 files changed, 230 insertions, 211 deletions

diff --git a/kernel/events/Makefile b/kernel/events/Makefile
index 89e5e8aa4c36..22d901f9caf4 100644
--- a/kernel/events/Makefile
+++ b/kernel/events/Makefile
@@ -2,5 +2,5 @@ ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_core.o = -pg
 endif
 
-obj-y := core.o ring_buffer.o
+obj-y := core.o ring_buffer.o callchain.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
new file mode 100644
index 000000000000..057e24b665cf
--- /dev/null
+++ b/kernel/events/callchain.c
@@ -0,0 +1,191 @@
+/*
+ * Performance events callchain code, extracted from core.c:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ *
+ * For licensing details see kernel-base/COPYING
+ */
+
+#include <linux/perf_event.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+struct callchain_cpus_entries {
+        struct rcu_head                 rcu_head;
+        struct perf_callchain_entry     *cpu_entries[0];
+};
+
+static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
+static atomic_t nr_callchain_events;
+static DEFINE_MUTEX(callchain_mutex);
+static struct callchain_cpus_entries *callchain_cpus_entries;
+
+
+__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
+{
+}
+
+__weak void perf_callchain_user(struct perf_callchain_entry *entry,
+                                struct pt_regs *regs)
+{
+}
+
+static void release_callchain_buffers_rcu(struct rcu_head *head)
+{
+        struct callchain_cpus_entries *entries;
+        int cpu;
+
+        entries = container_of(head, struct callchain_cpus_entries, rcu_head);
+
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+
+        kfree(entries);
+}
+
+static void release_callchain_buffers(void)
+{
+        struct callchain_cpus_entries *entries;
+
+        entries = callchain_cpus_entries;
+        rcu_assign_pointer(callchain_cpus_entries, NULL);
+        call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
+}
+
+static int alloc_callchain_buffers(void)
+{
+        int cpu;
+        int size;
+        struct callchain_cpus_entries *entries;
+
+        /*
+         * We can't use the percpu allocation API for data that can be
+         * accessed from NMI. Use a temporary manual per cpu allocation
+         * until that gets sorted out.
+         */
+        size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
+
+        entries = kzalloc(size, GFP_KERNEL);
+        if (!entries)
+                return -ENOMEM;
+
+        size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
+
+        for_each_possible_cpu(cpu) {
+                entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
+                                                         cpu_to_node(cpu));
+                if (!entries->cpu_entries[cpu])
+                        goto fail;
+        }
+
+        rcu_assign_pointer(callchain_cpus_entries, entries);
+
+        return 0;
+
+fail:
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+        kfree(entries);
+
+        return -ENOMEM;
+}
+
+int get_callchain_buffers(void)
+{
+        int err = 0;
+        int count;
+
+        mutex_lock(&callchain_mutex);
+
+        count = atomic_inc_return(&nr_callchain_events);
+        if (WARN_ON_ONCE(count < 1)) {
+                err = -EINVAL;
+                goto exit;
+        }
+
+        if (count > 1) {
+                /* If the allocation failed, give up */
+                if (!callchain_cpus_entries)
+                        err = -ENOMEM;
+                goto exit;
+        }
+
+        err = alloc_callchain_buffers();
+        if (err)
+                release_callchain_buffers();
+exit:
+        mutex_unlock(&callchain_mutex);
+
+        return err;
+}
+
+void put_callchain_buffers(void)
+{
+        if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
+                release_callchain_buffers();
+                mutex_unlock(&callchain_mutex);
+        }
+}
+
+static struct perf_callchain_entry *get_callchain_entry(int *rctx)
+{
+        int cpu;
+        struct callchain_cpus_entries *entries;
+
+        *rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
+        if (*rctx == -1)
+                return NULL;
+
+        entries = rcu_dereference(callchain_cpus_entries);
+        if (!entries)
+                return NULL;
+
+        cpu = smp_processor_id();
+
+        return &entries->cpu_entries[cpu][*rctx];
+}
+
+static void
+put_callchain_entry(int rctx)
+{
+        put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
+}
+
+struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+        int rctx;
+        struct perf_callchain_entry *entry;
+
+
+        entry = get_callchain_entry(&rctx);
+        if (rctx == -1)
+                return NULL;
+
+        if (!entry)
+                goto exit_put;
+
+        entry->nr = 0;
+
+        if (!user_mode(regs)) {
+                perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
+                perf_callchain_kernel(entry, regs);
+                if (current->mm)
+                        regs = task_pt_regs(current);
+                else
+                        regs = NULL;
+        }
+
+        if (regs) {
+                perf_callchain_store(entry, PERF_CONTEXT_USER);
+                perf_callchain_user(entry, regs);
+        }
+
+exit_put:
+        put_callchain_entry(rctx);
+
+        return entry;
+}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0e8457da6f95..eadac69265fc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2570,215 +2570,6 @@ static u64 perf_event_read(struct perf_event *event)
 }
 
 /*
- * Callchain support
- */
-
-struct callchain_cpus_entries {
-        struct rcu_head                 rcu_head;
-        struct perf_callchain_entry     *cpu_entries[0];
-};
-
-static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
-static atomic_t nr_callchain_events;
-static DEFINE_MUTEX(callchain_mutex);
-struct callchain_cpus_entries *callchain_cpus_entries;
-
-
-__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
-                                  struct pt_regs *regs)
-{
-}
-
-__weak void perf_callchain_user(struct perf_callchain_entry *entry,
-                                struct pt_regs *regs)
-{
-}
-
-static void release_callchain_buffers_rcu(struct rcu_head *head)
-{
-        struct callchain_cpus_entries *entries;
-        int cpu;
-
-        entries = container_of(head, struct callchain_cpus_entries, rcu_head);
-
-        for_each_possible_cpu(cpu)
-                kfree(entries->cpu_entries[cpu]);
-
-        kfree(entries);
-}
-
-static void release_callchain_buffers(void)
-{
-        struct callchain_cpus_entries *entries;
-
-        entries = callchain_cpus_entries;
-        rcu_assign_pointer(callchain_cpus_entries, NULL);
-        call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
-}
-
-static int alloc_callchain_buffers(void)
-{
-        int cpu;
-        int size;
-        struct callchain_cpus_entries *entries;
-
-        /*
-         * We can't use the percpu allocation API for data that can be
-         * accessed from NMI. Use a temporary manual per cpu allocation
-         * until that gets sorted out.
-         */
-        size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
-
-        entries = kzalloc(size, GFP_KERNEL);
-        if (!entries)
-                return -ENOMEM;
-
-        size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
-
-        for_each_possible_cpu(cpu) {
-                entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
-                                                         cpu_to_node(cpu));
-                if (!entries->cpu_entries[cpu])
-                        goto fail;
-        }
-
-        rcu_assign_pointer(callchain_cpus_entries, entries);
-
-        return 0;
-
-fail:
-        for_each_possible_cpu(cpu)
-                kfree(entries->cpu_entries[cpu]);
-        kfree(entries);
-
-        return -ENOMEM;
-}
-
-static int get_callchain_buffers(void)
-{
-        int err = 0;
-        int count;
-
-        mutex_lock(&callchain_mutex);
-
-        count = atomic_inc_return(&nr_callchain_events);
-        if (WARN_ON_ONCE(count < 1)) {
-                err = -EINVAL;
-                goto exit;
-        }
-
-        if (count > 1) {
-                /* If the allocation failed, give up */
-                if (!callchain_cpus_entries)
-                        err = -ENOMEM;
-                goto exit;
-        }
-
-        err = alloc_callchain_buffers();
-        if (err)
-                release_callchain_buffers();
-exit:
-        mutex_unlock(&callchain_mutex);
-
-        return err;
-}
-
-static void put_callchain_buffers(void)
-{
-        if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
-                release_callchain_buffers();
-                mutex_unlock(&callchain_mutex);
-        }
-}
-
-static int get_recursion_context(int *recursion)
-{
-        int rctx;
-
-        if (in_nmi())
-                rctx = 3;
-        else if (in_irq())
-                rctx = 2;
-        else if (in_softirq())
-                rctx = 1;
-        else
-                rctx = 0;
-
-        if (recursion[rctx])
-                return -1;
-
-        recursion[rctx]++;
-        barrier();
-
-        return rctx;
-}
-
-static inline void put_recursion_context(int *recursion, int rctx)
-{
-        barrier();
-        recursion[rctx]--;
-}
-
-static struct perf_callchain_entry *get_callchain_entry(int *rctx)
-{
-        int cpu;
-        struct callchain_cpus_entries *entries;
-
-        *rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
-        if (*rctx == -1)
-                return NULL;
-
-        entries = rcu_dereference(callchain_cpus_entries);
-        if (!entries)
-                return NULL;
-
-        cpu = smp_processor_id();
-
-        return &entries->cpu_entries[cpu][*rctx];
-}
-
-static void
-put_callchain_entry(int rctx)
-{
-        put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
-}
-
-static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
-{
-        int rctx;
-        struct perf_callchain_entry *entry;
-
-
-        entry = get_callchain_entry(&rctx);
-        if (rctx == -1)
-                return NULL;
-
-        if (!entry)
-                goto exit_put;
-
-        entry->nr = 0;
-
-        if (!user_mode(regs)) {
-                perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
-                perf_callchain_kernel(entry, regs);
-                if (current->mm)
-                        regs = task_pt_regs(current);
-                else
-                        regs = NULL;
-        }
-
-        if (regs) {
-                perf_callchain_store(entry, PERF_CONTEXT_USER);
-                perf_callchain_user(entry, regs);
-        }
-
-exit_put:
-        put_callchain_entry(rctx);
-
-        return entry;
-}
-
-/*
  * Initialize the perf_event context in a task_struct:
  */
 static void __perf_event_init_context(struct perf_event_context *ctx)
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 09097dd8116c..be4a43f6de4f 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -1,6 +1,10 @@
 #ifndef _KERNEL_EVENTS_INTERNAL_H
 #define _KERNEL_EVENTS_INTERNAL_H
 
+#include <linux/hardirq.h>
+
+/* Buffer handling */
+
 #define RING_BUFFER_WRITABLE            0x01
 
 struct ring_buffer {
@@ -64,7 +68,7 @@ static inline int page_order(struct ring_buffer *rb)
 }
 #endif
 
-static unsigned long perf_data_size(struct ring_buffer *rb)
+static inline unsigned long perf_data_size(struct ring_buffer *rb)
 {
         return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
 }
@@ -93,4 +97,37 @@ __output_copy(struct perf_output_handle *handle,
         } while (len);
 }
 
+/* Callchain handling */
+extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
+extern int get_callchain_buffers(void);
+extern void put_callchain_buffers(void);
+
+static inline int get_recursion_context(int *recursion)
+{
+        int rctx;
+
+        if (in_nmi())
+                rctx = 3;
+        else if (in_irq())
+                rctx = 2;
+        else if (in_softirq())
+                rctx = 1;
+        else
+                rctx = 0;
+
+        if (recursion[rctx])
+                return -1;
+
+        recursion[rctx]++;
+        barrier();
+
+        return rctx;
+}
+
+static inline void put_recursion_context(int *recursion, int rctx)
+{
+        barrier();
+        recursion[rctx]--;
+}
+
 #endif /* _KERNEL_EVENTS_INTERNAL_H */