/*
   * builtin-ftrace.c
   *
   * Copyright (c) 2013  LG Electronics,  Namhyung Kim <namhyung@kernel.org>
   *
   * Released under the GPL v2.
   */
  
  #include "builtin.h"
  #include "perf.h"

  #include <errno.h>

  #include <unistd.h>
  #include <signal.h>

  #include <fcntl.h>

  #include <poll.h>

  
  #include "debug.h"
  #include <subcmd/parse-options.h>

  #include <api/fs/tracing_path.h>

  #include "evlist.h"
  #include "target.h"

  #include "cpumap.h"

  #include "thread_map.h"

  #include "util/config.h"

  
  
  #define DEFAULT_TRACER  "function_graph"
  
  struct perf_ftrace {
  	struct perf_evlist *evlist;
  	struct target target;
  	const char *tracer;
  };
  
  static bool done;
  
  static void sig_handler(int sig __maybe_unused)
  {
  	done = true;
  }
  
  /*
   * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
   * we asked by setting its exec_error to the function below,
   * ftrace__workload_exec_failed_signal.
   *
   * XXX We need to handle this more appropriately, emitting an error, etc.
   */
  static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
  						siginfo_t *info __maybe_unused,
  						void *ucontext __maybe_unused)
  {
  	/* workload_exec_errno = info->si_value.sival_int; */
  	done = true;
  }

  static int __write_tracing_file(const char *name, const char *val, bool append)

  {
  	char *file;
  	int fd, ret = -1;
  	ssize_t size = strlen(val);

  	int flags = O_WRONLY;

  
  	file = get_tracing_file(name);
  	if (!file) {
  		pr_debug("cannot get tracing file: %s
  ", name);
  		return -1;
  	}

  	if (append)
  		flags |= O_APPEND;
  	else
  		flags |= O_TRUNC;
  
  	fd = open(file, flags);

  	if (fd < 0) {
  		pr_debug("cannot open tracing file: %s
  ", name);
  		goto out;
  	}
  
  	if (write(fd, val, size) == size)
  		ret = 0;
  	else
  		pr_debug("write '%s' to tracing/%s failed
  ", val, name);
  
  	close(fd);
  out:
  	put_tracing_file(file);
  	return ret;
  }

  static int write_tracing_file(const char *name, const char *val)
  {
  	return __write_tracing_file(name, val, false);
  }
  
  static int append_tracing_file(const char *name, const char *val)
  {
  	return __write_tracing_file(name, val, true);
  }

  static int reset_tracing_cpu(void);

  static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
  {
  	if (write_tracing_file("tracing_on", "0") < 0)
  		return -1;
  
  	if (write_tracing_file("current_tracer", "nop") < 0)
  		return -1;
  
  	if (write_tracing_file("set_ftrace_pid", " ") < 0)
  		return -1;

  	if (reset_tracing_cpu() < 0)
  		return -1;

  	return 0;
  }

  static int set_tracing_pid(struct perf_ftrace *ftrace)
  {
  	int i;
  	char buf[16];
  
  	if (target__has_cpu(&ftrace->target))
  		return 0;
  
  	for (i = 0; i < thread_map__nr(ftrace->evlist->threads); i++) {
  		scnprintf(buf, sizeof(buf), "%d",
  			  ftrace->evlist->threads->map[i]);
  		if (append_tracing_file("set_ftrace_pid", buf) < 0)
  			return -1;
  	}
  	return 0;
  }

  static int set_tracing_cpumask(struct cpu_map *cpumap)
  {
  	char *cpumask;
  	size_t mask_size;
  	int ret;
  	int last_cpu;
  
  	last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
  	mask_size = (last_cpu + 3) / 4 + 1;
  	mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
  
  	cpumask = malloc(mask_size);
  	if (cpumask == NULL) {
  		pr_debug("failed to allocate cpu mask
  ");
  		return -1;
  	}
  
  	cpu_map__snprint_mask(cpumap, cpumask, mask_size);
  
  	ret = write_tracing_file("tracing_cpumask", cpumask);
  
  	free(cpumask);
  	return ret;
  }
  
  static int set_tracing_cpu(struct perf_ftrace *ftrace)
  {
  	struct cpu_map *cpumap = ftrace->evlist->cpus;
  
  	if (!target__has_cpu(&ftrace->target))
  		return 0;
  
  	return set_tracing_cpumask(cpumap);
  }
  
  static int reset_tracing_cpu(void)
  {
  	struct cpu_map *cpumap = cpu_map__new(NULL);
  	int ret;
  
  	ret = set_tracing_cpumask(cpumap);
  	cpu_map__put(cpumap);
  	return ret;
  }

  static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
  {
  	char *trace_file;
  	int trace_fd;

  	char buf[4096];
  	struct pollfd pollfd = {
  		.events = POLLIN,
  	};
  
  	if (geteuid() != 0) {
  		pr_err("ftrace only works for root!
  ");
  		return -1;
  	}

  	signal(SIGINT, sig_handler);
  	signal(SIGUSR1, sig_handler);
  	signal(SIGCHLD, sig_handler);

  	signal(SIGPIPE, sig_handler);

  	if (reset_tracing_files(ftrace) < 0)
  		goto out;

  
  	/* reset ftrace buffer */
  	if (write_tracing_file("trace", "0") < 0)
  		goto out;

  	if (argc && perf_evlist__prepare_workload(ftrace->evlist,
  				&ftrace->target, argv, false,
  				ftrace__workload_exec_failed_signal) < 0) {

  		goto out;
  	}

  	if (set_tracing_pid(ftrace) < 0) {
  		pr_err("failed to set ftrace pid
  ");
  		goto out_reset;

  	}

  	if (set_tracing_cpu(ftrace) < 0) {
  		pr_err("failed to set tracing cpumask
  ");
  		goto out_reset;
  	}

  	if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
  		pr_err("failed to set current_tracer to %s
  ", ftrace->tracer);
  		goto out_reset;

  	}
  
  	trace_file = get_tracing_file("trace_pipe");
  	if (!trace_file) {
  		pr_err("failed to open trace_pipe
  ");

  		goto out_reset;

  	}
  
  	trace_fd = open(trace_file, O_RDONLY);
  
  	put_tracing_file(trace_file);
  
  	if (trace_fd < 0) {
  		pr_err("failed to open trace_pipe
  ");

  		goto out_reset;

  	}
  
  	fcntl(trace_fd, F_SETFL, O_NONBLOCK);
  	pollfd.fd = trace_fd;
  
  	if (write_tracing_file("tracing_on", "1") < 0) {
  		pr_err("can't enable tracing
  ");
  		goto out_close_fd;
  	}

  	setup_pager();

  	perf_evlist__start_workload(ftrace->evlist);
  
  	while (!done) {
  		if (poll(&pollfd, 1, -1) < 0)
  			break;
  
  		if (pollfd.revents & POLLIN) {
  			int n = read(trace_fd, buf, sizeof(buf));
  			if (n < 0)
  				break;
  			if (fwrite(buf, n, 1, stdout) != 1)
  				break;
  		}
  	}
  
  	write_tracing_file("tracing_on", "0");
  
  	/* read remaining buffer contents */
  	while (true) {
  		int n = read(trace_fd, buf, sizeof(buf));
  		if (n <= 0)
  			break;
  		if (fwrite(buf, n, 1, stdout) != 1)
  			break;
  	}
  
  out_close_fd:
  	close(trace_fd);

  out_reset:

  	reset_tracing_files(ftrace);

  out:

  	return done ? 0 : -1;
  }

  static int perf_ftrace_config(const char *var, const char *value, void *cb)
  {
  	struct perf_ftrace *ftrace = cb;
  
  	if (prefixcmp(var, "ftrace."))
  		return 0;
  
  	if (strcmp(var, "ftrace.tracer"))
  		return -1;
  
  	if (!strcmp(value, "function_graph") ||
  	    !strcmp(value, "function")) {
  		ftrace->tracer = value;
  		return 0;
  	}
  
  	pr_err("Please select \"function_graph\" (default) or \"function\"
  ");
  	return -1;
  }

  int cmd_ftrace(int argc, const char **argv)

  {
  	int ret;
  	struct perf_ftrace ftrace = {

  		.tracer = DEFAULT_TRACER,

  		.target = { .uid = UINT_MAX, },
  	};
  	const char * const ftrace_usage[] = {

  		"perf ftrace [<options>] [<command>]",

  		"perf ftrace [<options>] -- <command> [<options>]",
  		NULL
  	};
  	const struct option ftrace_options[] = {
  	OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",

  		   "tracer to use: function_graph(default) or function"),

  	OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
  		   "trace on existing process id"),

  	OPT_INCR('v', "verbose", &verbose,
  		 "be more verbose"),

  	OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
  		    "system-wide collection from all CPUs"),
  	OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
  		    "list of cpus to monitor"),

  	OPT_END()
  	};

  	ret = perf_config(perf_ftrace_config, &ftrace);
  	if (ret < 0)
  		return -1;

  	argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
  			    PARSE_OPT_STOP_AT_NON_OPTION);

  	if (!argc && target__none(&ftrace.target))

  		usage_with_options(ftrace_usage, ftrace_options);

  	ret = target__validate(&ftrace.target);
  	if (ret) {
  		char errbuf[512];
  
  		target__strerror(&ftrace.target, ret, errbuf, 512);
  		pr_err("%s
  ", errbuf);
  		return -EINVAL;
  	}

  	ftrace.evlist = perf_evlist__new();
  	if (ftrace.evlist == NULL)
  		return -ENOMEM;
  
  	ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
  	if (ret < 0)
  		goto out_delete_evlist;

  	ret = __cmd_ftrace(&ftrace, argc, argv);
  
  out_delete_evlist:
  	perf_evlist__delete(ftrace.evlist);
  
  	return ret;
  }