tools/perf/tests/code-reading.c - kernel/lockdown - Git at Google

 #include <linux/types.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <ctype.h>
 #include <string.h>

 #include "parse-events.h"
 #include "evlist.h"
 #include "evsel.h"
 #include "thread_map.h"
 #include "cpumap.h"
 #include "machine.h"
 #include "event.h"
 #include "thread.h"

 #include "tests.h"

 #define BUFSZ	1024
 #define READLEN	128

 struct state {
 	u64 done[1024];
 	size_t done_cnt;
 };

 static unsigned int hex(char c)
 {
 	if (c >= '0' && c <= '9')
 		return c - '0';
 	if (c >= 'a' && c <= 'f')
 		return c - 'a' + 10;
 	return c - 'A' + 10;
 }

 static void read_objdump_line(const char *line, size_t line_len, void **buf,
 			      size_t *len)
 {
 	const char *p;
 	size_t i;

 	/* Skip to a colon */
 	p = strchr(line, ':');
 	if (!p)
 		return;
 	i = p + 1 - line;

 	/* Read bytes */
 	while (*len) {
 		char c1, c2;

 		/* Skip spaces */
 		for (; i < line_len; i++) {
 			if (!isspace(line[i]))
 				break;
 		}
 		/* Get 2 hex digits */
 		if (i >= line_len || !isxdigit(line[i]))
 			break;
 		c1 = line[i++];
 		if (i >= line_len || !isxdigit(line[i]))
 			break;
 		c2 = line[i++];
 		/* Followed by a space */
 		if (i < line_len && line[i] && !isspace(line[i]))
 			break;
 		/* Store byte */
 		*(unsigned char *)*buf = (hex(c1) << 4) | hex(c2);
 		*buf += 1;
 		*len -= 1;
 	}
 }

 static int read_objdump_output(FILE *f, void **buf, size_t *len)
 {
 	char *line = NULL;
 	size_t line_len;
 	ssize_t ret;
 	int err = 0;

 	while (1) {
 		ret = getline(&line, &line_len, f);
 		if (feof(f))
 			break;
 		if (ret < 0) {
 			pr_debug("getline failed\n");
 			err = -1;
 			break;
 		}
 		read_objdump_line(line, ret, buf, len);
 	}

 	free(line);

 	return err;
 }

 static int read_via_objdump(const char *filename, u64 addr, void *buf,
 			    size_t len)
 {
 	char cmd[PATH_MAX * 2];
 	const char *fmt;
 	FILE *f;
 	int ret;

 	fmt = "%s -d --start-address=0x%"PRIx64" --stop-address=0x%"PRIx64" %s";
 	ret = snprintf(cmd, sizeof(cmd), fmt, "objdump", addr, addr + len,
 		       filename);
 	if (ret <= 0 || (size_t)ret >= sizeof(cmd))
 		return -1;

 	pr_debug("Objdump command is: %s\n", cmd);

 	/* Ignore objdump errors */
 	strcat(cmd, " 2>/dev/null");

 	f = popen(cmd, "r");
 	if (!f) {
 		pr_debug("popen failed\n");
 		return -1;
 	}

 	ret = read_objdump_output(f, &buf, &len);
 	if (len) {
 		pr_debug("objdump read too few bytes\n");
 		if (!ret)
 			ret = len;
 	}

 	pclose(f);

 	return ret;
 }

 static int read_object_code(u64 addr, size_t len, u8 cpumode,
 			    struct thread *thread, struct state *state)
 {
 	struct addr_location al;
 	unsigned char buf1[BUFSZ];
 	unsigned char buf2[BUFSZ];
 	size_t ret_len;
 	u64 objdump_addr;
 	int ret;

 	pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);

 	thread__find_addr_map(thread, cpumode, MAP__FUNCTION, addr, &al);
 	if (!al.map || !al.map->dso) {
 		pr_debug("thread__find_addr_map failed\n");
 		return -1;
 	}

 	pr_debug("File is: %s\n", al.map->dso->long_name);

 	if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
 	    !dso__is_kcore(al.map->dso)) {
 		pr_debug("Unexpected kernel address - skipping\n");
 		return 0;
 	}

 	pr_debug("On file address is: %#"PRIx64"\n", al.addr);

 	if (len > BUFSZ)
 		len = BUFSZ;

 	/* Do not go off the map */
 	if (addr + len > al.map->end)
 		len = al.map->end - addr;

 	/* Read the object code using perf */
 	ret_len = dso__data_read_offset(al.map->dso, thread->mg->machine,
 					al.addr, buf1, len);
 	if (ret_len != len) {
 		pr_debug("dso__data_read_offset failed\n");
 		return -1;
 	}

 	/*
 	 * Converting addresses for use by objdump requires more information.
 	 * map__load() does that.  See map__rip_2objdump() for details.
 	 */
 	if (map__load(al.map, NULL))
 		return -1;

 	/* objdump struggles with kcore - try each map only once */
 	if (dso__is_kcore(al.map->dso)) {
 		size_t d;

 		for (d = 0; d < state->done_cnt; d++) {
 			if (state->done[d] == al.map->start) {
 				pr_debug("kcore map tested already");
 				pr_debug(" - skipping\n");
 				return 0;
 			}
 		}
 		if (state->done_cnt >= ARRAY_SIZE(state->done)) {
 			pr_debug("Too many kcore maps - skipping\n");
 			return 0;
 		}
 		state->done[state->done_cnt++] = al.map->start;
 	}

 	/* Read the object code using objdump */
 	objdump_addr = map__rip_2objdump(al.map, al.addr);
 	ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
 	if (ret > 0) {
 		/*
 		 * The kernel maps are inaccurate - assume objdump is right in
 		 * that case.
 		 */
 		if (cpumode == PERF_RECORD_MISC_KERNEL ||
 		    cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
 			len -= ret;
 			if (len) {
 				pr_debug("Reducing len to %zu\n", len);
 			} else if (dso__is_kcore(al.map->dso)) {
 				/*
 				 * objdump cannot handle very large segments
 				 * that may be found in kcore.
 				 */
 				pr_debug("objdump failed for kcore");
 				pr_debug(" - skipping\n");
 				return 0;
 			} else {
 				return -1;
 			}
 		}
 	}
 	if (ret < 0) {
 		pr_debug("read_via_objdump failed\n");
 		return -1;
 	}

 	/* The results should be identical */
 	if (memcmp(buf1, buf2, len)) {
 		pr_debug("Bytes read differ from those read by objdump\n");
 		return -1;
 	}
 	pr_debug("Bytes read match those read by objdump\n");

 	return 0;
 }

 static int process_sample_event(struct machine *machine,
 				struct perf_evlist *evlist,
 				union perf_event *event, struct state *state)
 {
 	struct perf_sample sample;
 	struct thread *thread;
 	u8 cpumode;

 	if (perf_evlist__parse_sample(evlist, event, &sample)) {
 		pr_debug("perf_evlist__parse_sample failed\n");
 		return -1;
 	}

 	thread = machine__findnew_thread(machine, sample.pid, sample.tid);
 	if (!thread) {
 		pr_debug("machine__findnew_thread failed\n");
 		return -1;
 	}

 	cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

 	return read_object_code(sample.ip, READLEN, cpumode, thread, state);
 }

 static int process_event(struct machine *machine, struct perf_evlist *evlist,
 			 union perf_event *event, struct state *state)
 {
 	if (event->header.type == PERF_RECORD_SAMPLE)
 		return process_sample_event(machine, evlist, event, state);

 	if (event->header.type == PERF_RECORD_THROTTLE ||
 	    event->header.type == PERF_RECORD_UNTHROTTLE)
 		return 0;

 	if (event->header.type < PERF_RECORD_MAX) {
 		int ret;

 		ret = machine__process_event(machine, event, NULL);
 		if (ret < 0)
 			pr_debug("machine__process_event failed, event type %u\n",
 				 event->header.type);
 		return ret;
 	}

 	return 0;
 }

 static int process_events(struct machine *machine, struct perf_evlist *evlist,
 			  struct state *state)
 {
 	union perf_event *event;
 	int i, ret;

 	for (i = 0; i < evlist->nr_mmaps; i++) {
 		while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
 			ret = process_event(machine, evlist, event, state);
 			perf_evlist__mmap_consume(evlist, i);
 			if (ret < 0)
 				return ret;
 		}
 	}
 	return 0;
 }

 static int comp(const void *a, const void *b)
 {
 	return *(int *)a - *(int *)b;
 }

 static void do_sort_something(void)
 {
 	int buf[40960], i;

 	for (i = 0; i < (int)ARRAY_SIZE(buf); i++)
 		buf[i] = ARRAY_SIZE(buf) - i - 1;

 	qsort(buf, ARRAY_SIZE(buf), sizeof(int), comp);

 	for (i = 0; i < (int)ARRAY_SIZE(buf); i++) {
 		if (buf[i] != i) {
 			pr_debug("qsort failed\n");
 			break;
 		}
 	}
 }

 static void sort_something(void)
 {
 	int i;

 	for (i = 0; i < 10; i++)
 		do_sort_something();
 }

 static void syscall_something(void)
 {
 	int pipefd[2];
 	int i;

 	for (i = 0; i < 1000; i++) {
 		if (pipe(pipefd) < 0) {
 			pr_debug("pipe failed\n");
 			break;
 		}
 		close(pipefd[1]);
 		close(pipefd[0]);
 	}
 }

 static void fs_something(void)
 {
 	const char *test_file_name = "temp-perf-code-reading-test-file--";
 	FILE *f;
 	int i;

 	for (i = 0; i < 1000; i++) {
 		f = fopen(test_file_name, "w+");
 		if (f) {
 			fclose(f);
 			unlink(test_file_name);
 		}
 	}
 }

 static void do_something(void)
 {
 	fs_something();

 	sort_something();

 	syscall_something();
 }

 enum {
 	TEST_CODE_READING_OK,
 	TEST_CODE_READING_NO_VMLINUX,
 	TEST_CODE_READING_NO_KCORE,
 	TEST_CODE_READING_NO_ACCESS,
 	TEST_CODE_READING_NO_KERNEL_OBJ,
 };

 static int do_test_code_reading(bool try_kcore)
 {
 	struct machines machines;
 	struct machine *machine;
 	struct thread *thread;
 	struct record_opts opts = {
 		.mmap_pages	     = UINT_MAX,
 		.user_freq	     = UINT_MAX,
 		.user_interval	     = ULLONG_MAX,
 		.freq		     = 4000,
 		.target		     = {
 			.uses_mmap   = true,
 		},
 	};
 	struct state state = {
 		.done_cnt = 0,
 	};
 	struct thread_map *threads = NULL;
 	struct cpu_map *cpus = NULL;
 	struct perf_evlist *evlist = NULL;
 	struct perf_evsel *evsel = NULL;
 	int err = -1, ret;
 	pid_t pid;
 	struct map *map;
 	bool have_vmlinux, have_kcore, excl_kernel = false;

 	pid = getpid();

 	machines__init(&machines);
 	machine = &machines.host;

 	ret = machine__create_kernel_maps(machine);
 	if (ret < 0) {
 		pr_debug("machine__create_kernel_maps failed\n");
 		goto out_err;
 	}

 	/* Force the use of kallsyms instead of vmlinux to try kcore */
 	if (try_kcore)
 		symbol_conf.kallsyms_name = "/proc/kallsyms";

 	/* Load kernel map */
 	map = machine->vmlinux_maps[MAP__FUNCTION];
 	ret = map__load(map, NULL);
 	if (ret < 0) {
 		pr_debug("map__load failed\n");
 		goto out_err;
 	}
 	have_vmlinux = dso__is_vmlinux(map->dso);
 	have_kcore = dso__is_kcore(map->dso);

 	/* 2nd time through we just try kcore */
 	if (try_kcore && !have_kcore)
 		return TEST_CODE_READING_NO_KCORE;

 	/* No point getting kernel events if there is no kernel object */
 	if (!have_vmlinux && !have_kcore)
 		excl_kernel = true;

 	threads = thread_map__new_by_tid(pid);
 	if (!threads) {
 		pr_debug("thread_map__new_by_tid failed\n");
 		goto out_err;
 	}

 	ret = perf_event__synthesize_thread_map(NULL, threads,
 						perf_event__process, machine, false);
 	if (ret < 0) {
 		pr_debug("perf_event__synthesize_thread_map failed\n");
 		goto out_err;
 	}

 	thread = machine__findnew_thread(machine, pid, pid);
 	if (!thread) {
 		pr_debug("machine__findnew_thread failed\n");
 		goto out_err;
 	}

 	cpus = cpu_map__new(NULL);
 	if (!cpus) {
 		pr_debug("cpu_map__new failed\n");
 		goto out_err;
 	}

 	while (1) {
 		const char *str;

 		evlist = perf_evlist__new();
 		if (!evlist) {
 			pr_debug("perf_evlist__new failed\n");
 			goto out_err;
 		}

 		perf_evlist__set_maps(evlist, cpus, threads);

 		if (excl_kernel)
 			str = "cycles:u";
 		else
 			str = "cycles";
 		pr_debug("Parsing event '%s'\n", str);
 		ret = parse_events(evlist, str);
 		if (ret < 0) {
 			pr_debug("parse_events failed\n");
 			goto out_err;
 		}

 		perf_evlist__config(evlist, &opts);

 		evsel = perf_evlist__first(evlist);

 		evsel->attr.comm = 1;
 		evsel->attr.disabled = 1;
 		evsel->attr.enable_on_exec = 0;

 		ret = perf_evlist__open(evlist);
 		if (ret < 0) {
 			if (!excl_kernel) {
 				excl_kernel = true;
 				perf_evlist__set_maps(evlist, NULL, NULL);
 				perf_evlist__delete(evlist);
 				evlist = NULL;
 				continue;
 			}
 			pr_debug("perf_evlist__open failed\n");
 			goto out_err;
 		}
 		break;
 	}

 	ret = perf_evlist__mmap(evlist, UINT_MAX, false);
 	if (ret < 0) {
 		pr_debug("perf_evlist__mmap failed\n");
 		goto out_err;
 	}

 	perf_evlist__enable(evlist);

 	do_something();

 	perf_evlist__disable(evlist);

 	ret = process_events(machine, evlist, &state);
 	if (ret < 0)
 		goto out_err;

 	if (!have_vmlinux && !have_kcore && !try_kcore)
 		err = TEST_CODE_READING_NO_KERNEL_OBJ;
 	else if (!have_vmlinux && !try_kcore)
 		err = TEST_CODE_READING_NO_VMLINUX;
 	else if (excl_kernel)
 		err = TEST_CODE_READING_NO_ACCESS;
 	else
 		err = TEST_CODE_READING_OK;
 out_err:
 	if (evlist) {
 		perf_evlist__delete(evlist);
 	} else {
 		cpu_map__delete(cpus);
 		thread_map__delete(threads);
 	}
 	machines__destroy_kernel_maps(&machines);
 	machine__delete_threads(machine);
 	machines__exit(&machines);

 	return err;
 }

 int test__code_reading(void)
 {
 	int ret;

 	ret = do_test_code_reading(false);
 	if (!ret)
 		ret = do_test_code_reading(true);

 	switch (ret) {
 	case TEST_CODE_READING_OK:
 		return 0;
 	case TEST_CODE_READING_NO_VMLINUX:
 		fprintf(stderr, " (no vmlinux)");
 		return 0;
 	case TEST_CODE_READING_NO_KCORE:
 		fprintf(stderr, " (no kcore)");
 		return 0;
 	case TEST_CODE_READING_NO_ACCESS:
 		fprintf(stderr, " (no access)");
 		return 0;
 	case TEST_CODE_READING_NO_KERNEL_OBJ:
 		fprintf(stderr, " (no kernel obj)");
 		return 0;
 	default:
 		return -1;
 	};
 }
	#include <linux/types.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <stdio.h>
	#include <ctype.h>
	#include <string.h>

	#include "parse-events.h"
	#include "evlist.h"
	#include "evsel.h"
	#include "thread_map.h"
	#include "cpumap.h"
	#include "machine.h"
	#include "event.h"
	#include "thread.h"

	#include "tests.h"

	#define BUFSZ 1024
	#define READLEN 128

	struct state {
	u64 done[1024];
	size_t done_cnt;
	};

	static unsigned int hex(char c)
	{
	if (c >= '0' && c <= '9')
	return c - '0';
	if (c >= 'a' && c <= 'f')
	return c - 'a' + 10;
	return c - 'A' + 10;
	}

	static void read_objdump_line(const char line, size_t line_len, void *buf,
	size_t *len)
	{
	const char *p;
	size_t i;

	/* Skip to a colon */
	p = strchr(line, ':');
	if (!p)
	return;
	i = p + 1 - line;

	/* Read bytes */
	while (*len) {
	char c1, c2;

	/* Skip spaces */
	for (; i < line_len; i++) {
	if (!isspace(line[i]))
	break;
	}
	/* Get 2 hex digits */
	if (i >= line_len \|\| !isxdigit(line[i]))
	break;
	c1 = line[i++];
	if (i >= line_len \|\| !isxdigit(line[i]))
	break;
	c2 = line[i++];
	/* Followed by a space */
	if (i < line_len && line[i] && !isspace(line[i]))
	break;
	/* Store byte */
	(unsigned char )*buf = (hex(c1) << 4) \| hex(c2);
	*buf += 1;
	*len -= 1;
	}
	}

	static int read_objdump_output(FILE f, void buf, size_t len)
	{
	char *line = NULL;
	size_t line_len;
	ssize_t ret;
	int err = 0;

	while (1) {
	ret = getline(&line, &line_len, f);
	if (feof(f))
	break;
	if (ret < 0) {
	pr_debug("getline failed\n");
	err = -1;
	break;
	}
	read_objdump_line(line, ret, buf, len);
	}

	free(line);

	return err;
	}

	static int read_via_objdump(const char filename, u64 addr, void buf,
	size_t len)
	{
	char cmd[PATH_MAX * 2];
	const char *fmt;
	FILE *f;
	int ret;

	fmt = "%s -d --start-address=0x%"PRIx64" --stop-address=0x%"PRIx64" %s";
	ret = snprintf(cmd, sizeof(cmd), fmt, "objdump", addr, addr + len,
	filename);
	if (ret <= 0 \|\| (size_t)ret >= sizeof(cmd))
	return -1;

	pr_debug("Objdump command is: %s\n", cmd);

	/* Ignore objdump errors */
	strcat(cmd, " 2>/dev/null");

	f = popen(cmd, "r");
	if (!f) {
	pr_debug("popen failed\n");
	return -1;
	}

	ret = read_objdump_output(f, &buf, &len);
	if (len) {
	pr_debug("objdump read too few bytes\n");
	if (!ret)
	ret = len;
	}

	pclose(f);

	return ret;
	}

	static int read_object_code(u64 addr, size_t len, u8 cpumode,
	struct thread thread, struct state state)
	{
	struct addr_location al;
	unsigned char buf1[BUFSZ];
	unsigned char buf2[BUFSZ];
	size_t ret_len;
	u64 objdump_addr;
	int ret;

	pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);

	thread__find_addr_map(thread, cpumode, MAP__FUNCTION, addr, &al);
	if (!al.map \|\| !al.map->dso) {
	pr_debug("thread__find_addr_map failed\n");
	return -1;
	}

	pr_debug("File is: %s\n", al.map->dso->long_name);

	if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
	!dso__is_kcore(al.map->dso)) {
	pr_debug("Unexpected kernel address - skipping\n");
	return 0;
	}

	pr_debug("On file address is: %#"PRIx64"\n", al.addr);

	if (len > BUFSZ)
	len = BUFSZ;

	/* Do not go off the map */
	if (addr + len > al.map->end)
	len = al.map->end - addr;

	/* Read the object code using perf */
	ret_len = dso__data_read_offset(al.map->dso, thread->mg->machine,
	al.addr, buf1, len);
	if (ret_len != len) {
	pr_debug("dso__data_read_offset failed\n");
	return -1;
	}

	/*
	* Converting addresses for use by objdump requires more information.
	* map__load() does that. See map__rip_2objdump() for details.
	*/
	if (map__load(al.map, NULL))
	return -1;

	/* objdump struggles with kcore - try each map only once */
	if (dso__is_kcore(al.map->dso)) {
	size_t d;

	for (d = 0; d < state->done_cnt; d++) {
	if (state->done[d] == al.map->start) {
	pr_debug("kcore map tested already");
	pr_debug(" - skipping\n");
	return 0;
	}
	}
	if (state->done_cnt >= ARRAY_SIZE(state->done)) {
	pr_debug("Too many kcore maps - skipping\n");
	return 0;
	}
	state->done[state->done_cnt++] = al.map->start;
	}

	/* Read the object code using objdump */
	objdump_addr = map__rip_2objdump(al.map, al.addr);
	ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
	if (ret > 0) {
	/*
	* The kernel maps are inaccurate - assume objdump is right in
	* that case.
	*/
	if (cpumode == PERF_RECORD_MISC_KERNEL \|\|
	cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
	len -= ret;
	if (len) {
	pr_debug("Reducing len to %zu\n", len);
	} else if (dso__is_kcore(al.map->dso)) {
	/*
	* objdump cannot handle very large segments
	* that may be found in kcore.
	*/
	pr_debug("objdump failed for kcore");
	pr_debug(" - skipping\n");
	return 0;
	} else {
	return -1;
	}
	}
	}
	if (ret < 0) {
	pr_debug("read_via_objdump failed\n");
	return -1;
	}

	/* The results should be identical */
	if (memcmp(buf1, buf2, len)) {
	pr_debug("Bytes read differ from those read by objdump\n");
	return -1;
	}
	pr_debug("Bytes read match those read by objdump\n");

	return 0;
	}

	static int process_sample_event(struct machine *machine,
	struct perf_evlist *evlist,
	union perf_event event, struct state state)
	{
	struct perf_sample sample;
	struct thread *thread;
	u8 cpumode;

	if (perf_evlist__parse_sample(evlist, event, &sample)) {
	pr_debug("perf_evlist__parse_sample failed\n");
	return -1;
	}

	thread = machine__findnew_thread(machine, sample.pid, sample.tid);
	if (!thread) {
	pr_debug("machine__findnew_thread failed\n");
	return -1;
	}

	cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

	return read_object_code(sample.ip, READLEN, cpumode, thread, state);
	}

	static int process_event(struct machine machine, struct perf_evlist evlist,
	union perf_event event, struct state state)
	{
	if (event->header.type == PERF_RECORD_SAMPLE)
	return process_sample_event(machine, evlist, event, state);

	if (event->header.type == PERF_RECORD_THROTTLE \|\|
	event->header.type == PERF_RECORD_UNTHROTTLE)
	return 0;

	if (event->header.type < PERF_RECORD_MAX) {
	int ret;

	ret = machine__process_event(machine, event, NULL);
	if (ret < 0)
	pr_debug("machine__process_event failed, event type %u\n",
	event->header.type);
	return ret;
	}

	return 0;
	}

	static int process_events(struct machine machine, struct perf_evlist evlist,
	struct state *state)
	{
	union perf_event *event;
	int i, ret;

	for (i = 0; i < evlist->nr_mmaps; i++) {
	while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
	ret = process_event(machine, evlist, event, state);
	perf_evlist__mmap_consume(evlist, i);
	if (ret < 0)
	return ret;
	}
	}
	return 0;
	}

	static int comp(const void a, const void b)
	{
	return (int )a - (int )b;
	}

	static void do_sort_something(void)
	{
	int buf[40960], i;

	for (i = 0; i < (int)ARRAY_SIZE(buf); i++)
	buf[i] = ARRAY_SIZE(buf) - i - 1;

	qsort(buf, ARRAY_SIZE(buf), sizeof(int), comp);

	for (i = 0; i < (int)ARRAY_SIZE(buf); i++) {
	if (buf[i] != i) {
	pr_debug("qsort failed\n");
	break;
	}
	}
	}

	static void sort_something(void)
	{
	int i;

	for (i = 0; i < 10; i++)
	do_sort_something();
	}

	static void syscall_something(void)
	{
	int pipefd[2];
	int i;

	for (i = 0; i < 1000; i++) {
	if (pipe(pipefd) < 0) {
	pr_debug("pipe failed\n");
	break;
	}
	close(pipefd[1]);
	close(pipefd[0]);
	}
	}

	static void fs_something(void)
	{
	const char *test_file_name = "temp-perf-code-reading-test-file--";
	FILE *f;
	int i;

	for (i = 0; i < 1000; i++) {
	f = fopen(test_file_name, "w+");
	if (f) {
	fclose(f);
	unlink(test_file_name);
	}
	}
	}

	static void do_something(void)
	{
	fs_something();

	sort_something();

	syscall_something();
	}

	enum {
	TEST_CODE_READING_OK,
	TEST_CODE_READING_NO_VMLINUX,
	TEST_CODE_READING_NO_KCORE,
	TEST_CODE_READING_NO_ACCESS,
	TEST_CODE_READING_NO_KERNEL_OBJ,
	};

	static int do_test_code_reading(bool try_kcore)
	{
	struct machines machines;
	struct machine *machine;
	struct thread *thread;
	struct record_opts opts = {
	.mmap_pages = UINT_MAX,
	.user_freq = UINT_MAX,
	.user_interval = ULLONG_MAX,
	.freq = 4000,
	.target = {
	.uses_mmap = true,
	},
	};
	struct state state = {
	.done_cnt = 0,
	};
	struct thread_map *threads = NULL;
	struct cpu_map *cpus = NULL;
	struct perf_evlist *evlist = NULL;
	struct perf_evsel *evsel = NULL;
	int err = -1, ret;
	pid_t pid;
	struct map *map;
	bool have_vmlinux, have_kcore, excl_kernel = false;

	pid = getpid();

	machines__init(&machines);
	machine = &machines.host;

	ret = machine__create_kernel_maps(machine);
	if (ret < 0) {
	pr_debug("machine__create_kernel_maps failed\n");
	goto out_err;
	}

	/* Force the use of kallsyms instead of vmlinux to try kcore */
	if (try_kcore)
	symbol_conf.kallsyms_name = "/proc/kallsyms";

	/* Load kernel map */
	map = machine->vmlinux_maps[MAP__FUNCTION];
	ret = map__load(map, NULL);
	if (ret < 0) {
	pr_debug("map__load failed\n");
	goto out_err;
	}
	have_vmlinux = dso__is_vmlinux(map->dso);
	have_kcore = dso__is_kcore(map->dso);

	/* 2nd time through we just try kcore */
	if (try_kcore && !have_kcore)
	return TEST_CODE_READING_NO_KCORE;

	/* No point getting kernel events if there is no kernel object */
	if (!have_vmlinux && !have_kcore)
	excl_kernel = true;

	threads = thread_map__new_by_tid(pid);
	if (!threads) {
	pr_debug("thread_map__new_by_tid failed\n");
	goto out_err;
	}

	ret = perf_event__synthesize_thread_map(NULL, threads,
	perf_event__process, machine, false);
	if (ret < 0) {
	pr_debug("perf_event__synthesize_thread_map failed\n");
	goto out_err;
	}

	thread = machine__findnew_thread(machine, pid, pid);
	if (!thread) {
	pr_debug("machine__findnew_thread failed\n");
	goto out_err;
	}

	cpus = cpu_map__new(NULL);
	if (!cpus) {
	pr_debug("cpu_map__new failed\n");
	goto out_err;
	}

	while (1) {
	const char *str;

	evlist = perf_evlist__new();
	if (!evlist) {
	pr_debug("perf_evlist__new failed\n");
	goto out_err;
	}

	perf_evlist__set_maps(evlist, cpus, threads);

	if (excl_kernel)
	str = "cycles:u";
	else
	str = "cycles";
	pr_debug("Parsing event '%s'\n", str);
	ret = parse_events(evlist, str);
	if (ret < 0) {
	pr_debug("parse_events failed\n");
	goto out_err;
	}

	perf_evlist__config(evlist, &opts);

	evsel = perf_evlist__first(evlist);

	evsel->attr.comm = 1;
	evsel->attr.disabled = 1;
	evsel->attr.enable_on_exec = 0;

	ret = perf_evlist__open(evlist);
	if (ret < 0) {
	if (!excl_kernel) {
	excl_kernel = true;
	perf_evlist__set_maps(evlist, NULL, NULL);
	perf_evlist__delete(evlist);
	evlist = NULL;
	continue;
	}
	pr_debug("perf_evlist__open failed\n");
	goto out_err;
	}
	break;
	}

	ret = perf_evlist__mmap(evlist, UINT_MAX, false);
	if (ret < 0) {
	pr_debug("perf_evlist__mmap failed\n");
	goto out_err;
	}

	perf_evlist__enable(evlist);

	do_something();

	perf_evlist__disable(evlist);

	ret = process_events(machine, evlist, &state);
	if (ret < 0)
	goto out_err;

	if (!have_vmlinux && !have_kcore && !try_kcore)
	err = TEST_CODE_READING_NO_KERNEL_OBJ;
	else if (!have_vmlinux && !try_kcore)
	err = TEST_CODE_READING_NO_VMLINUX;
	else if (excl_kernel)
	err = TEST_CODE_READING_NO_ACCESS;
	else
	err = TEST_CODE_READING_OK;
	out_err:
	if (evlist) {
	perf_evlist__delete(evlist);
	} else {
	cpu_map__delete(cpus);
	thread_map__delete(threads);
	}
	machines__destroy_kernel_maps(&machines);
	machine__delete_threads(machine);
	machines__exit(&machines);

	return err;
	}

	int test__code_reading(void)
	{
	int ret;

	ret = do_test_code_reading(false);
	if (!ret)
	ret = do_test_code_reading(true);

	switch (ret) {
	case TEST_CODE_READING_OK:
	return 0;
	case TEST_CODE_READING_NO_VMLINUX:
	fprintf(stderr, " (no vmlinux)");
	return 0;
	case TEST_CODE_READING_NO_KCORE:
	fprintf(stderr, " (no kcore)");
	return 0;
	case TEST_CODE_READING_NO_ACCESS:
	fprintf(stderr, " (no access)");
	return 0;
	case TEST_CODE_READING_NO_KERNEL_OBJ:
	fprintf(stderr, " (no kernel obj)");
	return 0;
	default:
	return -1;
	};
	}