Release 4.15 kernel/events/callchain.c

/*
 * 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
 *  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 <linux/sched/task_stack.h>

#include "internal.h"


struct callchain_cpus_entries {
	
struct rcu_head			rcu_head;
	
struct perf_callchain_entry	*cpu_entries[0];
};


int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;

int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;



static inline size_t perf_callchain_entry__sizeof(void)
{
	return (sizeof(struct perf_callchain_entry) +
		sizeof(__u64) * (sysctl_perf_event_max_stack +
				 sysctl_perf_event_max_contexts_per_stack));
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Arnaldo Carvalho de Melo
29
100.00%
2
100.00%
Total
29
100.00%
2
100.00%

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_ctx *entry,
				  struct pt_regs *regs)
{
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
14
93.33%
1
50.00%
Arnaldo Carvalho de Melo
1
6.67%
1
50.00%
Total
15
100.00%
2
100.00%



__weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
				struct pt_regs *regs)
{
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
14
93.33%
1
50.00%
Arnaldo Carvalho de Melo
1
6.67%
1
50.00%
Total
15
100.00%
2
100.00%



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);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
50
100.00%
1
100.00%
Total
50
100.00%
1
100.00%



static void release_callchain_buffers(void)
{
	struct callchain_cpus_entries *entries;

	entries = callchain_cpus_entries;
	RCU_INIT_POINTER(callchain_cpus_entries, NULL);
	call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
33
97.06%
1
50.00%
Andreea-Cristina Bernat
1
2.94%
1
50.00%
Total
34
100.00%
2
100.00%



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 = perf_callchain_entry__sizeof() * 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;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
129
98.47%
1
50.00%
Arnaldo Carvalho de Melo
2
1.53%
1
50.00%
Total
131
100.00%
2
100.00%



int get_callchain_buffers(int event_max_stack)
{
	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;
		/*
                 * If requesting per event more than the global cap,
                 * return a different error to help userspace figure
                 * this out.
                 *
                 * And also do it here so that we have &callchain_mutex held.
                 */
		if (event_max_stack > sysctl_perf_event_max_stack)
			err = -EOVERFLOW;
		goto exit;
	}

	err = alloc_callchain_buffers();
exit:
	if (err)
		atomic_dec(&nr_callchain_events);

	mutex_unlock(&callchain_mutex);

	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
79
72.48%
1
25.00%
Frédéric Weisbecker
16
14.68%
2
50.00%
Arnaldo Carvalho de Melo
14
12.84%
1
25.00%
Total
109
100.00%
4
100.00%



void put_callchain_buffers(void)
{
	if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
		release_callchain_buffers();
		mutex_unlock(&callchain_mutex);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
29
100.00%
1
100.00%
Total
29
100.00%
1
100.00%



static struct perf_callchain_entry *get_callchain_entry(int *rctx)
{
	int cpu;
	struct callchain_cpus_entries *entries;

	*rctx = get_recursion_context(this_cpu_ptr(callchain_recursion));
	if (*rctx == -1)
		return NULL;

	entries = rcu_dereference(callchain_cpus_entries);
	if (!entries)
		return NULL;

	cpu = smp_processor_id();

	return (((void *)entries->cpu_entries[cpu]) +
		(*rctx * perf_callchain_entry__sizeof()));
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
71
82.56%
1
33.33%
Arnaldo Carvalho de Melo
14
16.28%
1
33.33%
Christoph Lameter
1
1.16%
1
33.33%
Total
86
100.00%
3
100.00%


static void

put_callchain_entry(int rctx)
{
	put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
18
94.74%
1
50.00%
Christoph Lameter
1
5.26%
1
50.00%
Total
19
100.00%
2
100.00%


struct perf_callchain_entry *

perf_callchain(struct perf_event *event, struct pt_regs *regs)
{
	bool kernel = !event->attr.exclude_callchain_kernel;
	bool user   = !event->attr.exclude_callchain_user;
	/* Disallow cross-task user callchains. */
	bool crosstask = event->ctx->task && event->ctx->task != current;
	const u32 max_stack = event->attr.sample_max_stack;

	if (!kernel && !user)
		return NULL;

	return get_perf_callchain(regs, 0, kernel, user, max_stack, crosstask, true);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Alexei Starovoitov
37
39.36%
1
16.67%
Frédéric Weisbecker
29
30.85%
1
16.67%
Arnaldo Carvalho de Melo
12
12.77%
2
33.33%
Borislav Petkov
11
11.70%
1
16.67%
Andrey Vagin
5
5.32%
1
16.67%
Total
94
100.00%
6
100.00%


struct perf_callchain_entry *

get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
		   u32 max_stack, bool crosstask, bool add_mark)
{
	struct perf_callchain_entry *entry;
	struct perf_callchain_entry_ctx ctx;
	int rctx;

	entry = get_callchain_entry(&rctx);
	if (rctx == -1)
		return NULL;

	if (!entry)
		goto exit_put;

	ctx.entry     = entry;
	ctx.max_stack = max_stack;
	ctx.nr	      = entry->nr = init_nr;
	ctx.contexts       = 0;
	ctx.contexts_maxed = false;

	if (kernel && !user_mode(regs)) {
		if (add_mark)
			perf_callchain_store_context(&ctx, PERF_CONTEXT_KERNEL);
		perf_callchain_kernel(&ctx, regs);
	}

	if (user) {
		if (!user_mode(regs)) {
			if  (current->mm)
				regs = task_pt_regs(current);
			else
				regs = NULL;
		}

		if (regs) {
			mm_segment_t fs;

			if (crosstask)
				goto exit_put;

			if (add_mark)
				perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);

			fs = get_fs();
			set_fs(USER_DS);
			perf_callchain_user(&ctx, regs);
			set_fs(fs);
		}
	}

exit_put:
	put_callchain_entry(rctx);

	return entry;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
98
42.79%
1
11.11%
Arnaldo Carvalho de Melo
45
19.65%
4
44.44%
Alexei Starovoitov
44
19.21%
1
11.11%
Will Deacon
18
7.86%
1
11.11%
Frédéric Weisbecker
18
7.86%
1
11.11%
Andrey Vagin
6
2.62%
1
11.11%
Total
229
100.00%
9
100.00%

/*
 * Used for sysctl_perf_event_max_stack and
 * sysctl_perf_event_max_contexts_per_stack.
 */


int perf_event_max_stack_handler(struct ctl_table *table, int write,
				 void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int *value = table->data;
	int new_value = *value, ret;
	struct ctl_table new_table = *table;

	new_table.data = &new_value;
	ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
	if (ret || !write)
		return ret;

	mutex_lock(&callchain_mutex);
	if (atomic_read(&nr_callchain_events))
		ret = -EBUSY;
	else
		*value = new_value;

	mutex_unlock(&callchain_mutex);

	return ret;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Arnaldo Carvalho de Melo
116
100.00%
2
100.00%
Total
116
100.00%
2
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Borislav Petkov
599
58.38%
1
5.56%
Arnaldo Carvalho de Melo
247
24.07%
7
38.89%
Alexei Starovoitov
81
7.89%
1
5.56%
Frédéric Weisbecker
63
6.14%
3
16.67%
Will Deacon
18
1.75%
1
5.56%
Andrey Vagin
11
1.07%
1
5.56%
Ingo Molnar
3
0.29%
1
5.56%
Christoph Lameter
2
0.19%
1
5.56%
Peter Zijlstra
1
0.10%
1
5.56%
Andreea-Cristina Bernat
1
0.10%
1
5.56%
Total
1026
100.00%
18
100.00%
Directory: kernel/events

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.