diff options
| -rw-r--r-- | kernel/trace/Kconfig | 9 | ||||
| -rw-r--r-- | kernel/trace/Makefile | 1 | ||||
| -rw-r--r-- | kernel/trace/trace_stack.c | 254 |
3 files changed, 264 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 14d9505178c..2a22e46390d 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -106,6 +106,15 @@ config CONTEXT_SWITCH_TRACER This tracer gets called from the context switch and records all switching of tasks. +config STACK_TRACER + bool "Trace max stack" + depends on HAVE_FTRACE + select FTRACE + select STACKTRACE + help + This tracer records the max stack of the kernel, and displays + it in debugfs/tracing/stack_trace + config DYNAMIC_FTRACE bool "enable/disable ftrace tracepoints dynamically" depends on FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 71d17de1728..58ec61c44bd 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -19,6 +19,7 @@ obj-$(CONFIG_FTRACE) += trace_functions.o obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o +obj-$(CONFIG_STACK_TRACER) += trace_stack.o obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o libftrace-y := ftrace.o diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c new file mode 100644 index 00000000000..4d1e522e3fe --- /dev/null +++ b/kernel/trace/trace_stack.c @@ -0,0 +1,254 @@ +/* + * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> + * + */ +#include <linux/stacktrace.h> +#include <linux/kallsyms.h> +#include <linux/seq_file.h> +#include <linux/spinlock.h> +#include <linux/uaccess.h> +#include <linux/debugfs.h> +#include <linux/ftrace.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/fs.h> +#include "trace.h" + +#define STACK_TRACE_ENTRIES 500 + +static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES] = + { [0 ... (STACK_TRACE_ENTRIES-1)] = ULONG_MAX }; +static struct stack_trace max_stack_trace = { + .max_entries = STACK_TRACE_ENTRIES, + .entries = stack_dump_trace, +}; + +static unsigned long max_stack_size; +static raw_spinlock_t max_stack_lock = + (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + +static int stack_trace_disabled __read_mostly; +static DEFINE_PER_CPU(int, trace_active); + +static inline void check_stack(void) +{ + unsigned long this_size; + unsigned long flags; + + this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1); + this_size = THREAD_SIZE - this_size; + + if (this_size <= max_stack_size) + return; + + raw_local_irq_save(flags); + __raw_spin_lock(&max_stack_lock); + + /* a race could have already updated it */ + if (this_size <= max_stack_size) + goto out; + + max_stack_size = this_size; + + max_stack_trace.nr_entries = 0; + max_stack_trace.skip = 1; + + save_stack_trace(&max_stack_trace); + + out: + __raw_spin_unlock(&max_stack_lock); + raw_local_irq_restore(flags); +} + +static void +stack_trace_call(unsigned long ip, unsigned long parent_ip) +{ + int cpu, resched; + + if (unlikely(!ftrace_enabled || stack_trace_disabled)) + return; + + resched = need_resched(); + preempt_disable_notrace(); + + cpu = raw_smp_processor_id(); + /* no atomic needed, we only modify this variable by this cpu */ + if (per_cpu(trace_active, cpu)++ != 0) + goto out; + + check_stack(); + + out: + per_cpu(trace_active, cpu)--; + /* prevent recursion in schedule */ + if (resched) + preempt_enable_no_resched_notrace(); + else + preempt_enable_notrace(); +} + +static struct ftrace_ops trace_ops __read_mostly = +{ + .func = stack_trace_call, +}; + +static ssize_t +stack_max_size_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *ppos) +{ + unsigned long *ptr = filp->private_data; + char buf[64]; + int r; + + r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); + if (r > sizeof(buf)) + r = sizeof(buf); + return simple_read_from_buffer(ubuf, count, ppos, buf, r); +} + +static ssize_t +stack_max_size_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *ppos) +{ + long *ptr = filp->private_data; + unsigned long val, flags; + char buf[64]; + int ret; + + if (count >= sizeof(buf)) + return -EINVAL; + + if (copy_from_user(&buf, ubuf, count)) + return -EFAULT; + + buf[count] = 0; + + ret = strict_strtoul(buf, 10, &val); + if (ret < 0) + return ret; + + raw_local_irq_save(flags); + __raw_spin_lock(&max_stack_lock); + *ptr = val; + __raw_spin_unlock(&max_stack_lock); + raw_local_irq_restore(flags); + + return count; +} + +static struct file_operations stack_max_size_fops = { + .open = tracing_open_generic, + .read = stack_max_size_read, + .write = stack_max_size_write, +}; + +static void * +t_next(struct seq_file *m, void *v, loff_t *pos) +{ + unsigned long *t = m->private; + + (*pos)++; + + if (!t || *t == ULONG_MAX) + return NULL; + + t++; + m->private = t; + + return t; +} + +static void *t_start(struct seq_file *m, loff_t *pos) +{ + unsigned long *t = m->private; + loff_t l = 0; + + local_irq_disable(); + __raw_spin_lock(&max_stack_lock); + + for (; t && l < *pos; t = t_next(m, t, &l)) + ; + + return t; +} + +static void t_stop(struct seq_file *m, void *p) +{ + __raw_spin_unlock(&max_stack_lock); + local_irq_enable(); +} + +static int trace_lookup_stack(struct seq_file *m, unsigned long addr) +{ +#ifdef CONFIG_KALLSYMS + char str[KSYM_SYMBOL_LEN]; + + sprint_symbol(str, addr); + + return seq_printf(m, "[<%p>] %s\n", (void*)addr, str); +#else + return seq_printf(m, "%p\n", (void*)addr); +#endif +} + +static int t_show(struct seq_file *m, void *v) +{ + unsigned long *t = v; + + if (!t || *t == ULONG_MAX) + return 0; + + trace_lookup_stack(m, *t); + + return 0; +} + +static struct seq_operations stack_trace_seq_ops = { + .start = t_start, + .next = t_next, + .stop = t_stop, + .show = t_show, +}; + +static int stack_trace_open(struct inode *inode, struct file *file) +{ + int ret; + + ret = seq_open(file, &stack_trace_seq_ops); + if (!ret) { + struct seq_file *m = file->private_data; + m->private = stack_dump_trace; + } + + return ret; +} + +static struct file_operations stack_trace_fops = { + .open = stack_trace_open, + .read = seq_read, + .llseek = seq_lseek, +}; + +static __init int stack_trace_init(void) +{ + struct dentry *d_tracer; + struct dentry *entry; + + d_tracer = tracing_init_dentry(); + + entry = debugfs_create_file("stack_max_size", 0644, d_tracer, + &max_stack_size, &stack_max_size_fops); + if (!entry) + pr_warning("Could not create debugfs 'stack_max_size' entry\n"); + + entry = debugfs_create_file("stack_trace", 0444, d_tracer, + NULL, &stack_trace_fops); + if (!entry) + pr_warning("Could not create debugfs 'stack_trace' entry\n"); + + register_ftrace_function(&trace_ops); + + return 0; +} + +device_initcall(stack_trace_init); |