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Subject[PATCH 2/2] perf: Carve out callchain functionality
Date
From: Borislav Petkov <borislav.petkov@amd.com>

Move callchain-related code into its own module:
kernel/events/callchain.c

No functionality change.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
---
include/linux/perf_event.h | 7 +-
kernel/events/Makefile | 2 +-
kernel/events/callchain.c | 182 +++++++++++++++++++++++++++++++++
kernel/events/core.c | 237 +++++--------------------------------------
4 files changed, 217 insertions(+), 211 deletions(-)
create mode 100644 kernel/events/callchain.c
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 687f852..7978850 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -961,7 +961,6 @@ enum event_type_t {
};

#ifdef CONFIG_PERF_EVENTS
-
extern struct list_head pmus;
extern int perf_pmu_register(struct pmu *pmu, char *name, int type);
extern void perf_pmu_unregister(struct pmu *pmu);
@@ -1201,6 +1200,12 @@ static inline void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
extern int
task_function_call(struct task_struct *p, int (*func) (void *info), void *info);
extern u64 perf_event_time(struct perf_event *event);
+
+extern int get_recursion_context(int *recursion);
+extern inline void put_recursion_context(int *recursion, int rctx);
+extern void put_callchain_buffers(void);
+extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
+extern int get_callchain_buffers(void);
#else
static inline void
perf_event_task_sched_in(struct task_struct *task) { }
diff --git a/kernel/events/Makefile b/kernel/events/Makefile
index 21b7da7..ca16be2 100644
--- a/kernel/events/Makefile
+++ b/kernel/events/Makefile
@@ -2,6 +2,6 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_core.o = -pg
endif

-obj-y := core.o
+obj-y := core.o callchain.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_CGROUP_PERF) += cgroup.o
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
new file mode 100644
index 0000000..0b495fc
--- /dev/null
+++ b/kernel/events/callchain.c
@@ -0,0 +1,182 @@
+#include <linux/slab.h>
+#include <linux/hardirq.h>
+#include <linux/perf_event.h>
+/*
+ * 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;
+}
+
+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 b65905f..364cad6 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2070,6 +2070,34 @@ out:
local_irq_restore(flags);
}

+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;
+}
+
+inline void put_recursion_context(int *recursion, int rctx)
+{
+ barrier();
+ recursion[rctx]--;
+}
+
/*
* Cross CPU call to read the hardware event
*/
@@ -2136,215 +2164,6 @@ 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)
--
1.7.4.rc2


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