--- /dev/null
+/*
+ * ring buffer based function tracer
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ * Copyright (C) 2004-2006 Ingo Molnar
+ * Copyright (C) 2004 Nadia Yvette Chambers
+ */
+#include <linux/ring_buffer.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+static void tracing_start_function_trace(struct trace_array *tr);
+static void tracing_stop_function_trace(struct trace_array *tr);
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs);
+static void
+function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs);
+static struct tracer_flags func_flags;
+
+/* Our option */
+enum {
+ TRACE_FUNC_OPT_STACK = 0x1,
+};
+
+static int allocate_ftrace_ops(struct trace_array *tr)
+{
+ struct ftrace_ops *ops;
+
+ ops = kzalloc(sizeof(*ops), GFP_KERNEL);
+ if (!ops)
+ return -ENOMEM;
+
+ /* Currently only the non stack verision is supported */
+ ops->func = function_trace_call;
+ ops->flags = FTRACE_OPS_FL_RECURSION_SAFE;
+
+ tr->ops = ops;
+ ops->private = tr;
+ return 0;
+}
+
+
+int ftrace_create_function_files(struct trace_array *tr,
+ struct dentry *parent)
+{
+ int ret;
+
+ /*
+ * The top level array uses the "global_ops", and the files are
+ * created on boot up.
+ */
+ if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+ return 0;
+
+ ret = allocate_ftrace_ops(tr);
+ if (ret)
+ return ret;
+
+ ftrace_create_filter_files(tr->ops, parent);
+
+ return 0;
+}
+
+void ftrace_destroy_function_files(struct trace_array *tr)
+{
+ ftrace_destroy_filter_files(tr->ops);
+ kfree(tr->ops);
+ tr->ops = NULL;
+}
+
+static int function_trace_init(struct trace_array *tr)
+{
+ ftrace_func_t func;
+
+ /*
+ * Instance trace_arrays get their ops allocated
+ * at instance creation. Unless it failed
+ * the allocation.
+ */
+ if (!tr->ops)
+ return -ENOMEM;
+
+ /* Currently only the global instance can do stack tracing */
+ if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
+ func_flags.val & TRACE_FUNC_OPT_STACK)
+ func = function_stack_trace_call;
+ else
+ func = function_trace_call;
+
+ ftrace_init_array_ops(tr, func);
+
+ tr->trace_buffer.cpu = get_cpu();
+ put_cpu();
+
+ tracing_start_cmdline_record();
+ tracing_start_function_trace(tr);
+ return 0;
+}
+
+static void function_trace_reset(struct trace_array *tr)
+{
+ tracing_stop_function_trace(tr);
+ tracing_stop_cmdline_record();
+ ftrace_reset_array_ops(tr);
+}
+
+static void function_trace_start(struct trace_array *tr)
+{
+ tracing_reset_online_cpus(&tr->trace_buffer);
+}
+
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs)
+{
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ int bit;
+ int cpu;
+ int pc;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ pc = preempt_count();
+ preempt_disable_notrace();
+
+ bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
+ if (bit < 0)
+ goto out;
+
+ cpu = smp_processor_id();
+ data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+ if (!atomic_read(&data->disabled)) {
+ local_save_flags(flags);
+ trace_function(tr, ip, parent_ip, flags, pc);
+ }
+ trace_clear_recursion(bit);
+
+ out:
+ preempt_enable_notrace();
+}
+
+static void
+function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs)
+{
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int cpu;
+ int pc;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ /*
+ * Need to use raw, since this must be called before the
+ * recursive protection is performed.
+ */
+ local_irq_save(flags);
+ cpu = raw_smp_processor_id();
+ data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1)) {
+ pc = preempt_count();
+ trace_function(tr, ip, parent_ip, flags, pc);
+ /*
+ * skip over 5 funcs:
+ * __ftrace_trace_stack,
+ * __trace_stack,
+ * function_stack_trace_call
+ * ftrace_list_func
+ * ftrace_call
+ */
+ __trace_stack(tr, flags, 5, pc);
+ }
+
+ atomic_dec(&data->disabled);
+ local_irq_restore(flags);
+}
+
+static struct tracer_opt func_opts[] = {
+#ifdef CONFIG_STACKTRACE
+ { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
+#endif
+ { } /* Always set a last empty entry */
+};
+
+static struct tracer_flags func_flags = {
+ .val = 0, /* By default: all flags disabled */
+ .opts = func_opts
+};
+
+static void tracing_start_function_trace(struct trace_array *tr)
+{
+ tr->function_enabled = 0;
+ register_ftrace_function(tr->ops);
+ tr->function_enabled = 1;
+}
+
+static void tracing_stop_function_trace(struct trace_array *tr)
+{
+ tr->function_enabled = 0;
+ unregister_ftrace_function(tr->ops);
+}
+
+static int
+func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
+{
+ switch (bit) {
+ case TRACE_FUNC_OPT_STACK:
+ /* do nothing if already set */
+ if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
+ break;
+
+ unregister_ftrace_function(tr->ops);
+
+ if (set) {
+ tr->ops->func = function_stack_trace_call;
+ register_ftrace_function(tr->ops);
+ } else {
+ tr->ops->func = function_trace_call;
+ register_ftrace_function(tr->ops);
+ }
+
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static struct tracer function_trace __tracer_data =
+{
+ .name = "function",
+ .init = function_trace_init,
+ .reset = function_trace_reset,
+ .start = function_trace_start,
+ .flags = &func_flags,
+ .set_flag = func_set_flag,
+ .allow_instances = true,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_function,
+#endif
+};
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static void update_traceon_count(void **data, bool on)
+{
+ long *count = (long *)data;
+ long old_count = *count;
+
+ /*
+ * Tracing gets disabled (or enabled) once per count.
+ * This function can be called at the same time on multiple CPUs.
+ * It is fine if both disable (or enable) tracing, as disabling
+ * (or enabling) the second time doesn't do anything as the
+ * state of the tracer is already disabled (or enabled).
+ * What needs to be synchronized in this case is that the count
+ * only gets decremented once, even if the tracer is disabled
+ * (or enabled) twice, as the second one is really a nop.
+ *
+ * The memory barriers guarantee that we only decrement the
+ * counter once. First the count is read to a local variable
+ * and a read barrier is used to make sure that it is loaded
+ * before checking if the tracer is in the state we want.
+ * If the tracer is not in the state we want, then the count
+ * is guaranteed to be the old count.
+ *
+ * Next the tracer is set to the state we want (disabled or enabled)
+ * then a write memory barrier is used to make sure that
+ * the new state is visible before changing the counter by
+ * one minus the old counter. This guarantees that another CPU
+ * executing this code will see the new state before seeing
+ * the new counter value, and would not do anything if the new
+ * counter is seen.
+ *
+ * Note, there is no synchronization between this and a user
+ * setting the tracing_on file. But we currently don't care
+ * about that.
+ */
+ if (!old_count)
+ return;
+
+ /* Make sure we see count before checking tracing state */
+ smp_rmb();
+
+ if (on == !!tracing_is_on())
+ return;
+
+ if (on)
+ tracing_on();
+ else
+ tracing_off();
+
+ /* unlimited? */
+ if (old_count == -1)
+ return;
+
+ /* Make sure tracing state is visible before updating count */
+ smp_wmb();
+
+ *count = old_count - 1;
+}
+
+static void
+ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ update_traceon_count(data, 1);
+}
+
+static void
+ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ update_traceon_count(data, 0);
+}
+
+static void
+ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ if (tracing_is_on())
+ return;
+
+ tracing_on();
+}
+
+static void
+ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ if (!tracing_is_on())
+ return;
+
+ tracing_off();
+}
+
+/*
+ * Skip 4:
+ * ftrace_stacktrace()
+ * function_trace_probe_call()
+ * ftrace_ops_list_func()
+ * ftrace_call()
+ */
+#define STACK_SKIP 4
+
+static void
+ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ trace_dump_stack(STACK_SKIP);
+}
+
+static void
+ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ long *count = (long *)data;
+ long old_count;
+ long new_count;
+
+ /*
+ * Stack traces should only execute the number of times the
+ * user specified in the counter.
+ */
+ do {
+
+ if (!tracing_is_on())
+ return;
+
+ old_count = *count;
+
+ if (!old_count)
+ return;
+
+ /* unlimited? */
+ if (old_count == -1) {
+ trace_dump_stack(STACK_SKIP);
+ return;
+ }
+
+ new_count = old_count - 1;
+ new_count = cmpxchg(count, old_count, new_count);
+ if (new_count == old_count)
+ trace_dump_stack(STACK_SKIP);
+
+ } while (new_count != old_count);
+}
+
+static int update_count(void **data)
+{
+ unsigned long *count = (long *)data;
+
+ if (!*count)
+ return 0;
+
+ if (*count != -1)
+ (*count)--;
+
+ return 1;
+}
+
+static void
+ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ if (update_count(data))
+ ftrace_dump(DUMP_ALL);
+}
+
+/* Only dump the current CPU buffer. */
+static void
+ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ if (update_count(data))
+ ftrace_dump(DUMP_ORIG);
+}
+
+static int
+ftrace_probe_print(const char *name, struct seq_file *m,
+ unsigned long ip, void *data)
+{
+ long count = (long)data;
+
+ seq_printf(m, "%ps:%s", (void *)ip, name);
+
+ if (count == -1)
+ seq_puts(m, ":unlimited\n");
+ else
+ seq_printf(m, ":count=%ld\n", count);
+
+ return 0;
+}
+
+static int
+ftrace_traceon_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("traceon", m, ip, data);
+}
+
+static int
+ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("traceoff", m, ip, data);
+}
+
+static int
+ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("stacktrace", m, ip, data);
+}
+
+static int
+ftrace_dump_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("dump", m, ip, data);
+}
+
+static int
+ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("cpudump", m, ip, data);
+}
+
+static struct ftrace_probe_ops traceon_count_probe_ops = {
+ .func = ftrace_traceon_count,
+ .print = ftrace_traceon_print,
+};
+
+static struct ftrace_probe_ops traceoff_count_probe_ops = {
+ .func = ftrace_traceoff_count,
+ .print = ftrace_traceoff_print,
+};
+
+static struct ftrace_probe_ops stacktrace_count_probe_ops = {
+ .func = ftrace_stacktrace_count,
+ .print = ftrace_stacktrace_print,
+};
+
+static struct ftrace_probe_ops dump_probe_ops = {
+ .func = ftrace_dump_probe,
+ .print = ftrace_dump_print,
+};
+
+static struct ftrace_probe_ops cpudump_probe_ops = {
+ .func = ftrace_cpudump_probe,
+ .print = ftrace_cpudump_print,
+};
+
+static struct ftrace_probe_ops traceon_probe_ops = {
+ .func = ftrace_traceon,
+ .print = ftrace_traceon_print,
+};
+
+static struct ftrace_probe_ops traceoff_probe_ops = {
+ .func = ftrace_traceoff,
+ .print = ftrace_traceoff_print,
+};
+
+static struct ftrace_probe_ops stacktrace_probe_ops = {
+ .func = ftrace_stacktrace,
+ .print = ftrace_stacktrace_print,
+};
+
+static int
+ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
+ struct ftrace_hash *hash, char *glob,
+ char *cmd, char *param, int enable)
+{
+ void *count = (void *)-1;
+ char *number;
+ int ret;
+
+ /* hash funcs only work with set_ftrace_filter */
+ if (!enable)
+ return -EINVAL;
+
+ if (glob[0] == '!') {
+ unregister_ftrace_function_probe_func(glob+1, ops);
+ return 0;
+ }
+
+ if (!param)
+ goto out_reg;
+
+ number = strsep(¶m, ":");
+
+ if (!strlen(number))
+ goto out_reg;
+
+ /*
+ * We use the callback data field (which is a pointer)
+ * as our counter.
+ */
+ ret = kstrtoul(number, 0, (unsigned long *)&count);
+ if (ret)
+ return ret;
+
+ out_reg:
+ ret = register_ftrace_function_probe(glob, ops, count);
+
+ return ret < 0 ? ret : 0;
+}
+
+static int
+ftrace_trace_onoff_callback(struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ /* we register both traceon and traceoff to this callback */
+ if (strcmp(cmd, "traceon") == 0)
+ ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
+ else
+ ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
+
+ return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+ param, enable);
+}
+
+static int
+ftrace_stacktrace_callback(struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
+
+ return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+ param, enable);
+}
+
+static int
+ftrace_dump_callback(struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ ops = &dump_probe_ops;
+
+ /* Only dump once. */
+ return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+ "1", enable);
+}
+
+static int
+ftrace_cpudump_callback(struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ ops = &cpudump_probe_ops;
+
+ /* Only dump once. */
+ return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+ "1", enable);
+}
+
+static struct ftrace_func_command ftrace_traceon_cmd = {
+ .name = "traceon",
+ .func = ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_traceoff_cmd = {
+ .name = "traceoff",
+ .func = ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_stacktrace_cmd = {
+ .name = "stacktrace",
+ .func = ftrace_stacktrace_callback,
+};
+
+static struct ftrace_func_command ftrace_dump_cmd = {
+ .name = "dump",
+ .func = ftrace_dump_callback,
+};
+
+static struct ftrace_func_command ftrace_cpudump_cmd = {
+ .name = "cpudump",
+ .func = ftrace_cpudump_callback,
+};
+
+static int __init init_func_cmd_traceon(void)
+{
+ int ret;
+
+ ret = register_ftrace_command(&ftrace_traceoff_cmd);
+ if (ret)
+ return ret;
+
+ ret = register_ftrace_command(&ftrace_traceon_cmd);
+ if (ret)
+ goto out_free_traceoff;
+
+ ret = register_ftrace_command(&ftrace_stacktrace_cmd);
+ if (ret)
+ goto out_free_traceon;
+
+ ret = register_ftrace_command(&ftrace_dump_cmd);
+ if (ret)
+ goto out_free_stacktrace;
+
+ ret = register_ftrace_command(&ftrace_cpudump_cmd);
+ if (ret)
+ goto out_free_dump;
+
+ return 0;
+
+ out_free_dump:
+ unregister_ftrace_command(&ftrace_dump_cmd);
+ out_free_stacktrace:
+ unregister_ftrace_command(&ftrace_stacktrace_cmd);
+ out_free_traceon:
+ unregister_ftrace_command(&ftrace_traceon_cmd);
+ out_free_traceoff:
+ unregister_ftrace_command(&ftrace_traceoff_cmd);
+
+ return ret;
+}
+#else
+static inline int init_func_cmd_traceon(void)
+{
+ return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+static __init int init_function_trace(void)
+{
+ init_func_cmd_traceon();
+ return register_tracer(&function_trace);
+}
+core_initcall(init_function_trace);
Code Review / kvmfornfv.git / blobdiff