--- /dev/null
+/*
+ * 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/ftrace.h>
+#include <linux/module.h>
+#include <linux/sysctl.h>
+#include <linux/init.h>
+
+#include <asm/setup.h>
+
+#include "trace.h"
+
+#define STACK_TRACE_ENTRIES 500
+
+#ifdef CC_USING_FENTRY
+# define fentry 1
+#else
+# define fentry 0
+#endif
+
+static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
+ { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
+static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
+
+/*
+ * Reserve one entry for the passed in ip. This will allow
+ * us to remove most or all of the stack size overhead
+ * added by the stack tracer itself.
+ */
+static struct stack_trace max_stack_trace = {
+ .max_entries = STACK_TRACE_ENTRIES - 1,
+ .entries = &stack_dump_trace[1],
+};
+
+static unsigned long max_stack_size;
+static arch_spinlock_t max_stack_lock =
+ (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+
+static DEFINE_PER_CPU(int, trace_active);
+static DEFINE_MUTEX(stack_sysctl_mutex);
+
+int stack_tracer_enabled;
+static int last_stack_tracer_enabled;
+
+static inline void print_max_stack(void)
+{
+ long i;
+ int size;
+
+ pr_emerg(" Depth Size Location (%d entries)\n"
+ " ----- ---- --------\n",
+ max_stack_trace.nr_entries - 1);
+
+ for (i = 0; i < max_stack_trace.nr_entries; i++) {
+ if (stack_dump_trace[i] == ULONG_MAX)
+ break;
+ if (i+1 == max_stack_trace.nr_entries ||
+ stack_dump_trace[i+1] == ULONG_MAX)
+ size = stack_dump_index[i];
+ else
+ size = stack_dump_index[i] - stack_dump_index[i+1];
+
+ pr_emerg("%3ld) %8d %5d %pS\n", i, stack_dump_index[i],
+ size, (void *)stack_dump_trace[i]);
+ }
+}
+
+static inline void
+check_stack(unsigned long ip, unsigned long *stack)
+{
+ unsigned long this_size, flags; unsigned long *p, *top, *start;
+ static int tracer_frame;
+ int frame_size = ACCESS_ONCE(tracer_frame);
+ int i;
+
+ this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
+ this_size = THREAD_SIZE - this_size;
+ /* Remove the frame of the tracer */
+ this_size -= frame_size;
+
+ if (this_size <= max_stack_size)
+ return;
+
+ /* we do not handle interrupt stacks yet */
+ if (!object_is_on_stack(stack))
+ return;
+
+ local_irq_save(flags);
+ arch_spin_lock(&max_stack_lock);
+
+ /* In case another CPU set the tracer_frame on us */
+ if (unlikely(!frame_size))
+ this_size -= tracer_frame;
+
+ /* 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;
+
+ if (using_ftrace_ops_list_func())
+ max_stack_trace.skip = 4;
+ else
+ max_stack_trace.skip = 3;
+
+ save_stack_trace(&max_stack_trace);
+
+ /*
+ * Add the passed in ip from the function tracer.
+ * Searching for this on the stack will skip over
+ * most of the overhead from the stack tracer itself.
+ */
+ stack_dump_trace[0] = ip;
+ max_stack_trace.nr_entries++;
+
+ /*
+ * Now find where in the stack these are.
+ */
+ i = 0;
+ start = stack;
+ top = (unsigned long *)
+ (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
+
+ /*
+ * Loop through all the entries. One of the entries may
+ * for some reason be missed on the stack, so we may
+ * have to account for them. If they are all there, this
+ * loop will only happen once. This code only takes place
+ * on a new max, so it is far from a fast path.
+ */
+ while (i < max_stack_trace.nr_entries) {
+ int found = 0;
+
+ stack_dump_index[i] = this_size;
+ p = start;
+
+ for (; p < top && i < max_stack_trace.nr_entries; p++) {
+ if (*p == stack_dump_trace[i]) {
+ this_size = stack_dump_index[i++] =
+ (top - p) * sizeof(unsigned long);
+ found = 1;
+ /* Start the search from here */
+ start = p + 1;
+ /*
+ * We do not want to show the overhead
+ * of the stack tracer stack in the
+ * max stack. If we haven't figured
+ * out what that is, then figure it out
+ * now.
+ */
+ if (unlikely(!tracer_frame) && i == 1) {
+ tracer_frame = (p - stack) *
+ sizeof(unsigned long);
+ max_stack_size -= tracer_frame;
+ }
+ }
+ }
+
+ if (!found)
+ i++;
+ }
+
+ if (task_stack_end_corrupted(current)) {
+ print_max_stack();
+ BUG();
+ }
+
+ out:
+ arch_spin_unlock(&max_stack_lock);
+ local_irq_restore(flags);
+}
+
+static void
+stack_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs)
+{
+ unsigned long stack;
+ int cpu;
+
+ 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;
+
+ /*
+ * When fentry is used, the traced function does not get
+ * its stack frame set up, and we lose the parent.
+ * The ip is pretty useless because the function tracer
+ * was called before that function set up its stack frame.
+ * In this case, we use the parent ip.
+ *
+ * By adding the return address of either the parent ip
+ * or the current ip we can disregard most of the stack usage
+ * caused by the stack tracer itself.
+ *
+ * The function tracer always reports the address of where the
+ * mcount call was, but the stack will hold the return address.
+ */
+ if (fentry)
+ ip = parent_ip;
+ else
+ ip += MCOUNT_INSN_SIZE;
+
+ check_stack(ip, &stack);
+
+ out:
+ per_cpu(trace_active, cpu)--;
+ /* prevent recursion in schedule */
+ preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+ .func = stack_trace_call,
+ .flags = FTRACE_OPS_FL_RECURSION_SAFE,
+};
+
+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;
+ int ret;
+ int cpu;
+
+ ret = kstrtoul_from_user(ubuf, count, 10, &val);
+ if (ret)
+ return ret;
+
+ local_irq_save(flags);
+
+ /*
+ * In case we trace inside arch_spin_lock() or after (NMI),
+ * we will cause circular lock, so we also need to increase
+ * the percpu trace_active here.
+ */
+ cpu = smp_processor_id();
+ per_cpu(trace_active, cpu)++;
+
+ arch_spin_lock(&max_stack_lock);
+ *ptr = val;
+ arch_spin_unlock(&max_stack_lock);
+
+ per_cpu(trace_active, cpu)--;
+ local_irq_restore(flags);
+
+ return count;
+}
+
+static const struct file_operations stack_max_size_fops = {
+ .open = tracing_open_generic,
+ .read = stack_max_size_read,
+ .write = stack_max_size_write,
+ .llseek = default_llseek,
+};
+
+static void *
+__next(struct seq_file *m, loff_t *pos)
+{
+ long n = *pos - 1;
+
+ if (n >= max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX)
+ return NULL;
+
+ m->private = (void *)n;
+ return &m->private;
+}
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ (*pos)++;
+ return __next(m, pos);
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+ int cpu;
+
+ local_irq_disable();
+
+ cpu = smp_processor_id();
+ per_cpu(trace_active, cpu)++;
+
+ arch_spin_lock(&max_stack_lock);
+
+ if (*pos == 0)
+ return SEQ_START_TOKEN;
+
+ return __next(m, pos);
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+ int cpu;
+
+ arch_spin_unlock(&max_stack_lock);
+
+ cpu = smp_processor_id();
+ per_cpu(trace_active, cpu)--;
+
+ local_irq_enable();
+}
+
+static void trace_lookup_stack(struct seq_file *m, long i)
+{
+ unsigned long addr = stack_dump_trace[i];
+
+ seq_printf(m, "%pS\n", (void *)addr);
+}
+
+static void print_disabled(struct seq_file *m)
+{
+ seq_puts(m, "#\n"
+ "# Stack tracer disabled\n"
+ "#\n"
+ "# To enable the stack tracer, either add 'stacktrace' to the\n"
+ "# kernel command line\n"
+ "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
+ "#\n");
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+ long i;
+ int size;
+
+ if (v == SEQ_START_TOKEN) {
+ seq_printf(m, " Depth Size Location"
+ " (%d entries)\n"
+ " ----- ---- --------\n",
+ max_stack_trace.nr_entries - 1);
+
+ if (!stack_tracer_enabled && !max_stack_size)
+ print_disabled(m);
+
+ return 0;
+ }
+
+ i = *(long *)v;
+
+ if (i >= max_stack_trace.nr_entries ||
+ stack_dump_trace[i] == ULONG_MAX)
+ return 0;
+
+ if (i+1 == max_stack_trace.nr_entries ||
+ stack_dump_trace[i+1] == ULONG_MAX)
+ size = stack_dump_index[i];
+ else
+ size = stack_dump_index[i] - stack_dump_index[i+1];
+
+ seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size);
+
+ trace_lookup_stack(m, i);
+
+ return 0;
+}
+
+static const 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)
+{
+ return seq_open(file, &stack_trace_seq_ops);
+}
+
+static const struct file_operations stack_trace_fops = {
+ .open = stack_trace_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+static int
+stack_trace_filter_open(struct inode *inode, struct file *file)
+{
+ return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER,
+ inode, file);
+}
+
+static const struct file_operations stack_trace_filter_fops = {
+ .open = stack_trace_filter_open,
+ .read = seq_read,
+ .write = ftrace_filter_write,
+ .llseek = tracing_lseek,
+ .release = ftrace_regex_release,
+};
+
+int
+stack_trace_sysctl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+
+ mutex_lock(&stack_sysctl_mutex);
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+ if (ret || !write ||
+ (last_stack_tracer_enabled == !!stack_tracer_enabled))
+ goto out;
+
+ last_stack_tracer_enabled = !!stack_tracer_enabled;
+
+ if (stack_tracer_enabled)
+ register_ftrace_function(&trace_ops);
+ else
+ unregister_ftrace_function(&trace_ops);
+
+ out:
+ mutex_unlock(&stack_sysctl_mutex);
+ return ret;
+}
+
+static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
+
+static __init int enable_stacktrace(char *str)
+{
+ if (strncmp(str, "_filter=", 8) == 0)
+ strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);
+
+ stack_tracer_enabled = 1;
+ last_stack_tracer_enabled = 1;
+ return 1;
+}
+__setup("stacktrace", enable_stacktrace);
+
+static __init int stack_trace_init(void)
+{
+ struct dentry *d_tracer;
+
+ d_tracer = tracing_init_dentry();
+ if (IS_ERR(d_tracer))
+ return 0;
+
+ trace_create_file("stack_max_size", 0644, d_tracer,
+ &max_stack_size, &stack_max_size_fops);
+
+ trace_create_file("stack_trace", 0444, d_tracer,
+ NULL, &stack_trace_fops);
+
+ trace_create_file("stack_trace_filter", 0444, d_tracer,
+ NULL, &stack_trace_filter_fops);
+
+ if (stack_trace_filter_buf[0])
+ ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
+
+ if (stack_tracer_enabled)
+ register_ftrace_function(&trace_ops);
+
+ return 0;
+}
+
+device_initcall(stack_trace_init);
Code Review / kvmfornfv.git / blobdiff