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 2011-10-16 17:15:04 +02:00 committed by Ingo Molnar
parent efc96737bd
commit 9251f904f9
4 changed files with 230 additions and 211 deletions

View file

@ -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

191
kernel/events/callchain.c Normal file
View file

@ -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;
}

View file

@ -2569,215 +2569,6 @@ static u64 perf_event_read(struct perf_event *event)
return perf_event_count(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:
*/

View file

@ -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 */