linux/kernel/profile.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/kernel/profile.c
 *  Simple profiling. Manages a direct-mapped profile hit count buffer,
 *  with configurable resolution, support for restricting the cpus on
 *  which profiling is done, and switching between cpu time and
 *  schedule() calls via kernel command line parameters passed at boot.
 *
 *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
 *	Red Hat, July 2004
 *  Consolidation of architecture support code for profiling,
 *	Nadia Yvette Chambers, Oracle, July 2004
 *  Amortized hit count accounting via per-cpu open-addressed hashtables
 *	to resolve timer interrupt livelocks, Nadia Yvette Chambers,
 *	Oracle, 2004
 */

#include <linux/export.h>
#include <linux/profile.h>
#include <linux/memblock.h>
#include <linux/notifier.h>
#include <linux/mm.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/highmem.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/sched/stat.h>

#include <asm/sections.h>
#include <asm/irq_regs.h>
#include <asm/ptrace.h>

struct profile_hit { … };
#define PROFILE_GRPSHIFT …
#define PROFILE_GRPSZ …
#define NR_PROFILE_HIT …
#define NR_PROFILE_GRP …

static atomic_t *prof_buffer;
static unsigned long prof_len;
static unsigned short int prof_shift;

int prof_on __read_mostly;
EXPORT_SYMBOL_GPL(…);

int profile_setup(char *str)
{ … }
__setup(…);


int __ref profile_init(void)
{ … }

static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
{ … }

void profile_hits(int type, void *__pc, unsigned int nr_hits)
{ … }
EXPORT_SYMBOL_GPL(…);

void profile_tick(int type)
{ … }

#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>

/*
 * This function accesses profiling information. The returned data is
 * binary: the sampling step and the actual contents of the profile
 * buffer. Use of the program readprofile is recommended in order to
 * get meaningful info out of these data.
 */
static ssize_t
read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{ … }

/* default is to not implement this call */
int __weak setup_profiling_timer(unsigned mult)
{ … }

/*
 * Writing to /proc/profile resets the counters
 *
 * Writing a 'profiling multiplier' value into it also re-sets the profiling
 * interrupt frequency, on architectures that support this.
 */
static ssize_t write_profile(struct file *file, const char __user *buf,
			     size_t count, loff_t *ppos)
{ … }

static const struct proc_ops profile_proc_ops = …;

int __ref create_proc_profile(void)
{ … }
subsys_initcall(create_proc_profile);
#endif /* CONFIG_PROC_FS */