diff options
| -rw-r--r-- | include/linux/ftrace.h | 4 | ||||
| -rw-r--r-- | kernel/trace/Kconfig | 19 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 313 |
3 files changed, 334 insertions, 2 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 015a3d2..0456c3a 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -153,6 +153,10 @@ struct dyn_ftrace { unsigned long flags; struct dyn_ftrace *newlist; }; +#ifdef CONFIG_FUNCTION_PROFILER + unsigned long counter; + struct hlist_node node; +#endif struct dyn_arch_ftrace arch; }; diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 8a4d729..95e9ad5 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -105,6 +105,7 @@ config FUNCTION_GRAPH_TRACER This is done by setting the current return address on the current task structure into a stack of calls. + config IRQSOFF_TRACER bool "Interrupts-off Latency Tracer" default n @@ -376,6 +377,24 @@ config DYNAMIC_FTRACE were made. If so, it runs stop_machine (stops all CPUS) and modifies the code to jump over the call to ftrace. +config FUNCTION_PROFILER + bool "Kernel function profiler" + depends on DYNAMIC_FTRACE + default n + help + This option enables the kernel function profiler. When the dynamic + function tracing is enabled, a counter is added into the function + records used by the dynamic function tracer. A file is created in + debugfs called function_profile_enabled which defaults to zero. + When a 1 is echoed into this file profiling begins, and when a + zero is entered, profiling stops. A file in the trace_stats + directory called functions, that show the list of functions that + have been hit and their counters. + + This takes up around 320K more memory. + + If in doubt, say N + config FTRACE_MCOUNT_RECORD def_bool y depends on DYNAMIC_FTRACE diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7b8722b..11f364c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -34,6 +34,7 @@ #include <asm/ftrace.h> #include "trace.h" +#include "trace_stat.h" #define FTRACE_WARN_ON(cond) \ do { \ @@ -261,7 +262,6 @@ struct ftrace_func_probe { struct rcu_head rcu; }; - enum { FTRACE_ENABLE_CALLS = (1 << 0), FTRACE_DISABLE_CALLS = (1 << 1), @@ -309,6 +309,307 @@ static struct dyn_ftrace *ftrace_free_records; } \ } +#ifdef CONFIG_FUNCTION_PROFILER +static struct hlist_head *ftrace_profile_hash; +static int ftrace_profile_bits; +static int ftrace_profile_enabled; +static DEFINE_MUTEX(ftrace_profile_lock); + +static void * +function_stat_next(void *v, int idx) +{ + struct dyn_ftrace *rec = v; + struct ftrace_page *pg; + + pg = (struct ftrace_page *)((unsigned long)rec & PAGE_MASK); + + again: + rec++; + if ((void *)rec >= (void *)&pg->records[pg->index]) { + pg = pg->next; + if (!pg) + return NULL; + rec = &pg->records[0]; + } + + if (rec->flags & FTRACE_FL_FREE || + rec->flags & FTRACE_FL_FAILED || + !(rec->flags & FTRACE_FL_CONVERTED) || + /* ignore non hit functions */ + !rec->counter) + goto again; + + return rec; +} + +static void *function_stat_start(struct tracer_stat *trace) +{ + return function_stat_next(&ftrace_pages_start->records[0], 0); +} + +static int function_stat_cmp(void *p1, void *p2) +{ + struct dyn_ftrace *a = p1; + struct dyn_ftrace *b = p2; + + if (a->counter < b->counter) + return -1; + if (a->counter > b->counter) + return 1; + else + return 0; +} + +static int function_stat_headers(struct seq_file *m) +{ + seq_printf(m, " Function Hit\n" + " -------- ---\n"); + return 0; +} + +static int function_stat_show(struct seq_file *m, void *v) +{ + struct dyn_ftrace *rec = v; + char str[KSYM_SYMBOL_LEN]; + + kallsyms_lookup(rec->ip, NULL, NULL, NULL, str); + + seq_printf(m, " %-30.30s %10lu\n", str, rec->counter); + return 0; +} + +static struct tracer_stat function_stats = { + .name = "functions", + .stat_start = function_stat_start, + .stat_next = function_stat_next, + .stat_cmp = function_stat_cmp, + .stat_headers = function_stat_headers, + .stat_show = function_stat_show +}; + +static void ftrace_profile_init(int nr_funcs) +{ + unsigned long addr; + int order; + int size; + + /* + * We are profiling all functions, lets make it 1/4th of the + * number of functions that are in core kernel. So we have to + * iterate 4 times. + */ + order = (sizeof(struct hlist_head) * nr_funcs) / 4; + order = get_order(order); + size = 1 << (PAGE_SHIFT + order); + + pr_info("Allocating %d KB for profiler hash\n", size >> 10); + + addr = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order); + if (!addr) { + pr_warning("Could not allocate function profiler hash\n"); + return; + } + + ftrace_profile_hash = (void *)addr; + + /* + * struct hlist_head should be a pointer of 4 or 8 bytes. + * And a simple bit manipulation can be done, but if for + * some reason struct hlist_head is not a mulitple of 2, + * then we play it safe, and simply count. This function + * is done once at boot up, so it is not that critical in + * performance. + */ + + size--; + size /= sizeof(struct hlist_head); + + for (; size; size >>= 1) + ftrace_profile_bits++; + + pr_info("Function profiler has %d hash buckets\n", + 1 << ftrace_profile_bits); + + return; +} + +static ssize_t +ftrace_profile_read(struct file *filp, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + char buf[64]; + int r; + + r = sprintf(buf, "%u\n", ftrace_profile_enabled); + return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); +} + +static void ftrace_profile_reset(void) +{ + struct dyn_ftrace *rec; + struct ftrace_page *pg; + + do_for_each_ftrace_rec(pg, rec) { + rec->counter = 0; + } while_for_each_ftrace_rec(); +} + +static struct dyn_ftrace *ftrace_find_profiled_func(unsigned long ip) +{ + struct dyn_ftrace *rec; + struct hlist_head *hhd; + struct hlist_node *n; + unsigned long flags; + unsigned long key; + + if (!ftrace_profile_hash) + return NULL; + + key = hash_long(ip, ftrace_profile_bits); + hhd = &ftrace_profile_hash[key]; + + if (hlist_empty(hhd)) + return NULL; + + local_irq_save(flags); + hlist_for_each_entry_rcu(rec, n, hhd, node) { + if (rec->ip == ip) + goto out; + } + rec = NULL; + out: + local_irq_restore(flags); + + return rec; +} + +static void +function_profile_call(unsigned long ip, unsigned long parent_ip) +{ + struct dyn_ftrace *rec; + unsigned long flags; + + if (!ftrace_profile_enabled) + return; + + local_irq_save(flags); + rec = ftrace_find_profiled_func(ip); + if (!rec) + goto out; + + rec->counter++; + out: + local_irq_restore(flags); +} + +static struct ftrace_ops ftrace_profile_ops __read_mostly = +{ + .func = function_profile_call, +}; + +static ssize_t +ftrace_profile_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + unsigned long val; + char buf[64]; + int ret; + + if (!ftrace_profile_hash) { + pr_info("Can not enable hash due to earlier problems\n"); + return -ENODEV; + } + + if (cnt >= sizeof(buf)) + return -EINVAL; + + if (copy_from_user(&buf, ubuf, cnt)) + return -EFAULT; + + buf[cnt] = 0; + + ret = strict_strtoul(buf, 10, &val); + if (ret < 0) + return ret; + + val = !!val; + + mutex_lock(&ftrace_profile_lock); + if (ftrace_profile_enabled ^ val) { + if (val) { + ftrace_profile_reset(); + register_ftrace_function(&ftrace_profile_ops); + ftrace_profile_enabled = 1; + } else { + ftrace_profile_enabled = 0; + unregister_ftrace_function(&ftrace_profile_ops); + } + } + mutex_unlock(&ftrace_profile_lock); + + filp->f_pos += cnt; + + return cnt; +} + +static const struct file_operations ftrace_profile_fops = { + .open = tracing_open_generic, + .read = ftrace_profile_read, + .write = ftrace_profile_write, +}; + +static void ftrace_profile_debugfs(struct dentry *d_tracer) +{ + struct dentry *entry; + int ret; + + ret = register_stat_tracer(&function_stats); + if (ret) { + pr_warning("Warning: could not register " + "function stats\n"); + return; + } + + entry = debugfs_create_file("function_profile_enabled", 0644, + d_tracer, NULL, &ftrace_profile_fops); + if (!entry) + pr_warning("Could not create debugfs " + "'function_profile_enabled' entry\n"); +} + +static void ftrace_add_profile(struct dyn_ftrace *rec) +{ + unsigned long key; + + if (!ftrace_profile_hash) + return; + + key = hash_long(rec->ip, ftrace_profile_bits); + hlist_add_head_rcu(&rec->node, &ftrace_profile_hash[key]); +} + +static void ftrace_profile_release(struct dyn_ftrace *rec) +{ + mutex_lock(&ftrace_profile_lock); + hlist_del(&rec->node); + mutex_unlock(&ftrace_profile_lock); +} + +#else /* CONFIG_FUNCTION_PROFILER */ +static void ftrace_profile_init(int nr_funcs) +{ +} +static void ftrace_add_profile(struct dyn_ftrace *rec) +{ +} +static void ftrace_profile_debugfs(struct dentry *d_tracer) +{ +} +static void ftrace_profile_release(struct dyn_ftrace *rec) +{ +} +#endif /* CONFIG_FUNCTION_PROFILER */ + #ifdef CONFIG_KPROBES static int frozen_record_count; @@ -359,8 +660,10 @@ void ftrace_release(void *start, unsigned long size) mutex_lock(&ftrace_lock); do_for_each_ftrace_rec(pg, rec) { if ((rec->ip >= s) && (rec->ip < e) && - !(rec->flags & FTRACE_FL_FREE)) + !(rec->flags & FTRACE_FL_FREE)) { ftrace_free_rec(rec); + ftrace_profile_release(rec); + } } while_for_each_ftrace_rec(); mutex_unlock(&ftrace_lock); } @@ -414,6 +717,8 @@ ftrace_record_ip(unsigned long ip) rec->newlist = ftrace_new_addrs; ftrace_new_addrs = rec; + ftrace_add_profile(rec); + return rec; } @@ -2157,6 +2462,8 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer) "'set_graph_function' entry\n"); #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + ftrace_profile_debugfs(d_tracer); + return 0; } @@ -2225,6 +2532,8 @@ void __init ftrace_init(void) if (ret) goto failed; + ftrace_profile_init(count); + last_ftrace_enabled = ftrace_enabled = 1; ret = ftrace_convert_nops(NULL, |
