diff options
Diffstat (limited to 'kernel/trace/trace_branch.c')
| -rw-r--r-- | kernel/trace/trace_branch.c | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c new file mode 100644 index 000000000..eff099123 --- /dev/null +++ b/kernel/trace/trace_branch.c @@ -0,0 +1,455 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * unlikely profiler + * + * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> + */ +#include <linux/kallsyms.h> +#include <linux/seq_file.h> +#include <linux/spinlock.h> +#include <linux/irqflags.h> +#include <linux/uaccess.h> +#include <linux/module.h> +#include <linux/ftrace.h> +#include <linux/hash.h> +#include <linux/fs.h> +#include <asm/local.h> + +#include "trace.h" +#include "trace_stat.h" +#include "trace_output.h" + +#ifdef CONFIG_BRANCH_TRACER + +static struct tracer branch_trace; +static int branch_tracing_enabled __read_mostly; +static DEFINE_MUTEX(branch_tracing_mutex); + +static struct trace_array *branch_tracer; + +static void +probe_likely_condition(struct ftrace_likely_data *f, int val, int expect) +{ + struct trace_event_call *call = &event_branch; + struct trace_array *tr = branch_tracer; + struct trace_buffer *buffer; + struct trace_array_cpu *data; + struct ring_buffer_event *event; + struct trace_branch *entry; + unsigned long flags; + int pc; + const char *p; + + if (current->trace_recursion & TRACE_BRANCH_BIT) + return; + + /* + * I would love to save just the ftrace_likely_data pointer, but + * this code can also be used by modules. Ugly things can happen + * if the module is unloaded, and then we go and read the + * pointer. This is slower, but much safer. + */ + + if (unlikely(!tr)) + return; + + raw_local_irq_save(flags); + current->trace_recursion |= TRACE_BRANCH_BIT; + data = this_cpu_ptr(tr->array_buffer.data); + if (atomic_read(&data->disabled)) + goto out; + + pc = preempt_count(); + buffer = tr->array_buffer.buffer; + event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH, + sizeof(*entry), flags, pc); + if (!event) + goto out; + + entry = ring_buffer_event_data(event); + + /* Strip off the path, only save the file */ + p = f->data.file + strlen(f->data.file); + while (p >= f->data.file && *p != '/') + p--; + p++; + + strncpy(entry->func, f->data.func, TRACE_FUNC_SIZE); + strncpy(entry->file, p, TRACE_FILE_SIZE); + entry->func[TRACE_FUNC_SIZE] = 0; + entry->file[TRACE_FILE_SIZE] = 0; + entry->constant = f->constant; + entry->line = f->data.line; + entry->correct = val == expect; + + if (!call_filter_check_discard(call, entry, buffer, event)) + trace_buffer_unlock_commit_nostack(buffer, event); + + out: + current->trace_recursion &= ~TRACE_BRANCH_BIT; + raw_local_irq_restore(flags); +} + +static inline +void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) +{ + if (!branch_tracing_enabled) + return; + + probe_likely_condition(f, val, expect); +} + +int enable_branch_tracing(struct trace_array *tr) +{ + mutex_lock(&branch_tracing_mutex); + branch_tracer = tr; + /* + * Must be seen before enabling. The reader is a condition + * where we do not need a matching rmb() + */ + smp_wmb(); + branch_tracing_enabled++; + mutex_unlock(&branch_tracing_mutex); + + return 0; +} + +void disable_branch_tracing(void) +{ + mutex_lock(&branch_tracing_mutex); + + if (!branch_tracing_enabled) + goto out_unlock; + + branch_tracing_enabled--; + + out_unlock: + mutex_unlock(&branch_tracing_mutex); +} + +static int branch_trace_init(struct trace_array *tr) +{ + return enable_branch_tracing(tr); +} + +static void branch_trace_reset(struct trace_array *tr) +{ + disable_branch_tracing(); +} + +static enum print_line_t trace_branch_print(struct trace_iterator *iter, + int flags, struct trace_event *event) +{ + struct trace_branch *field; + + trace_assign_type(field, iter->ent); + + trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", + field->correct ? " ok " : " MISS ", + field->func, + field->file, + field->line); + + return trace_handle_return(&iter->seq); +} + +static void branch_print_header(struct seq_file *s) +{ + seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" + " FUNC:FILE:LINE\n" + "# | | | | | " + " |\n"); +} + +static struct trace_event_functions trace_branch_funcs = { + .trace = trace_branch_print, +}; + +static struct trace_event trace_branch_event = { + .type = TRACE_BRANCH, + .funcs = &trace_branch_funcs, +}; + +static struct tracer branch_trace __read_mostly = +{ + .name = "branch", + .init = branch_trace_init, + .reset = branch_trace_reset, +#ifdef CONFIG_FTRACE_SELFTEST + .selftest = trace_selftest_startup_branch, +#endif /* CONFIG_FTRACE_SELFTEST */ + .print_header = branch_print_header, +}; + +__init static int init_branch_tracer(void) +{ + int ret; + + ret = register_trace_event(&trace_branch_event); + if (!ret) { + printk(KERN_WARNING "Warning: could not register " + "branch events\n"); + return 1; + } + return register_tracer(&branch_trace); +} +core_initcall(init_branch_tracer); + +#else +static inline +void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) +{ +} +#endif /* CONFIG_BRANCH_TRACER */ + +void ftrace_likely_update(struct ftrace_likely_data *f, int val, + int expect, int is_constant) +{ + unsigned long flags = user_access_save(); + + /* A constant is always correct */ + if (is_constant) { + f->constant++; + val = expect; + } + /* + * I would love to have a trace point here instead, but the + * trace point code is so inundated with unlikely and likely + * conditions that the recursive nightmare that exists is too + * much to try to get working. At least for now. + */ + trace_likely_condition(f, val, expect); + + /* FIXME: Make this atomic! */ + if (val == expect) + f->data.correct++; + else + f->data.incorrect++; + + user_access_restore(flags); +} +EXPORT_SYMBOL(ftrace_likely_update); + +extern unsigned long __start_annotated_branch_profile[]; +extern unsigned long __stop_annotated_branch_profile[]; + +static int annotated_branch_stat_headers(struct seq_file *m) +{ + seq_puts(m, " correct incorrect % " + " Function " + " File Line\n" + " ------- --------- - " + " -------- " + " ---- ----\n"); + return 0; +} + +static inline long get_incorrect_percent(const struct ftrace_branch_data *p) +{ + long percent; + + if (p->correct) { + percent = p->incorrect * 100; + percent /= p->correct + p->incorrect; + } else + percent = p->incorrect ? 100 : -1; + + return percent; +} + +static const char *branch_stat_process_file(struct ftrace_branch_data *p) +{ + const char *f; + + /* Only print the file, not the path */ + f = p->file + strlen(p->file); + while (f >= p->file && *f != '/') + f--; + return ++f; +} + +static void branch_stat_show(struct seq_file *m, + struct ftrace_branch_data *p, const char *f) +{ + long percent; + + /* + * The miss is overlayed on correct, and hit on incorrect. + */ + percent = get_incorrect_percent(p); + + if (percent < 0) + seq_puts(m, " X "); + else + seq_printf(m, "%3ld ", percent); + + seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); +} + +static int branch_stat_show_normal(struct seq_file *m, + struct ftrace_branch_data *p, const char *f) +{ + seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); + branch_stat_show(m, p, f); + return 0; +} + +static int annotate_branch_stat_show(struct seq_file *m, void *v) +{ + struct ftrace_likely_data *p = v; + const char *f; + int l; + + f = branch_stat_process_file(&p->data); + + if (!p->constant) + return branch_stat_show_normal(m, &p->data, f); + + l = snprintf(NULL, 0, "/%lu", p->constant); + l = l > 8 ? 0 : 8 - l; + + seq_printf(m, "%8lu/%lu %*lu ", + p->data.correct, p->constant, l, p->data.incorrect); + branch_stat_show(m, &p->data, f); + return 0; +} + +static void *annotated_branch_stat_start(struct tracer_stat *trace) +{ + return __start_annotated_branch_profile; +} + +static void * +annotated_branch_stat_next(void *v, int idx) +{ + struct ftrace_likely_data *p = v; + + ++p; + + if ((void *)p >= (void *)__stop_annotated_branch_profile) + return NULL; + + return p; +} + +static int annotated_branch_stat_cmp(const void *p1, const void *p2) +{ + const struct ftrace_branch_data *a = p1; + const struct ftrace_branch_data *b = p2; + + long percent_a, percent_b; + + percent_a = get_incorrect_percent(a); + percent_b = get_incorrect_percent(b); + + if (percent_a < percent_b) + return -1; + if (percent_a > percent_b) + return 1; + + if (a->incorrect < b->incorrect) + return -1; + if (a->incorrect > b->incorrect) + return 1; + + /* + * Since the above shows worse (incorrect) cases + * first, we continue that by showing best (correct) + * cases last. + */ + if (a->correct > b->correct) + return -1; + if (a->correct < b->correct) + return 1; + + return 0; +} + +static struct tracer_stat annotated_branch_stats = { + .name = "branch_annotated", + .stat_start = annotated_branch_stat_start, + .stat_next = annotated_branch_stat_next, + .stat_cmp = annotated_branch_stat_cmp, + .stat_headers = annotated_branch_stat_headers, + .stat_show = annotate_branch_stat_show +}; + +__init static int init_annotated_branch_stats(void) +{ + int ret; + + ret = register_stat_tracer(&annotated_branch_stats); + if (!ret) { + printk(KERN_WARNING "Warning: could not register " + "annotated branches stats\n"); + return 1; + } + return 0; +} +fs_initcall(init_annotated_branch_stats); + +#ifdef CONFIG_PROFILE_ALL_BRANCHES + +extern unsigned long __start_branch_profile[]; +extern unsigned long __stop_branch_profile[]; + +static int all_branch_stat_headers(struct seq_file *m) +{ + seq_puts(m, " miss hit % " + " Function " + " File Line\n" + " ------- --------- - " + " -------- " + " ---- ----\n"); + return 0; +} + +static void *all_branch_stat_start(struct tracer_stat *trace) +{ + return __start_branch_profile; +} + +static void * +all_branch_stat_next(void *v, int idx) +{ + struct ftrace_branch_data *p = v; + + ++p; + + if ((void *)p >= (void *)__stop_branch_profile) + return NULL; + + return p; +} + +static int all_branch_stat_show(struct seq_file *m, void *v) +{ + struct ftrace_branch_data *p = v; + const char *f; + + f = branch_stat_process_file(p); + return branch_stat_show_normal(m, p, f); +} + +static struct tracer_stat all_branch_stats = { + .name = "branch_all", + .stat_start = all_branch_stat_start, + .stat_next = all_branch_stat_next, + .stat_headers = all_branch_stat_headers, + .stat_show = all_branch_stat_show +}; + +__init static int all_annotated_branch_stats(void) +{ + int ret; + + ret = register_stat_tracer(&all_branch_stats); + if (!ret) { + printk(KERN_WARNING "Warning: could not register " + "all branches stats\n"); + return 1; + } + return 0; +} +fs_initcall(all_annotated_branch_stats); +#endif /* CONFIG_PROFILE_ALL_BRANCHES */ |