mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 16:07:39 +00:00
d19ad0775d
In preparation to have arguments of a function passed to callbacks attached to functions as default, change the default callback prototype to receive a struct ftrace_regs as the forth parameter instead of a pt_regs. For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they will now need to get the pt_regs via a ftrace_get_regs() helper call. If this is called by a callback that their ftrace_ops did not have a FL_SAVE_REGS flag set, it that helper function will return NULL. This will allow the ftrace_regs to hold enough just to get the parameters and stack pointer, but without the worry that callbacks may have a pt_regs that is not completely filled. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
582 lines
15 KiB
C
582 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
|
|
*
|
|
*/
|
|
#include <linux/sched/task_stack.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <linux/security.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
|
|
|
|
static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES];
|
|
static unsigned stack_trace_index[STACK_TRACE_ENTRIES];
|
|
|
|
static unsigned int stack_trace_nr_entries;
|
|
static unsigned long stack_trace_max_size;
|
|
static arch_spinlock_t stack_trace_max_lock =
|
|
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
|
|
|
|
DEFINE_PER_CPU(int, disable_stack_tracer);
|
|
static DEFINE_MUTEX(stack_sysctl_mutex);
|
|
|
|
int stack_tracer_enabled;
|
|
|
|
static void print_max_stack(void)
|
|
{
|
|
long i;
|
|
int size;
|
|
|
|
pr_emerg(" Depth Size Location (%d entries)\n"
|
|
" ----- ---- --------\n",
|
|
stack_trace_nr_entries);
|
|
|
|
for (i = 0; i < stack_trace_nr_entries; i++) {
|
|
if (i + 1 == stack_trace_nr_entries)
|
|
size = stack_trace_index[i];
|
|
else
|
|
size = stack_trace_index[i] - stack_trace_index[i+1];
|
|
|
|
pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i],
|
|
size, (void *)stack_dump_trace[i]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The stack tracer looks for a maximum stack at each call from a function. It
|
|
* registers a callback from ftrace, and in that callback it examines the stack
|
|
* size. It determines the stack size from the variable passed in, which is the
|
|
* address of a local variable in the stack_trace_call() callback function.
|
|
* The stack size is calculated by the address of the local variable to the top
|
|
* of the current stack. If that size is smaller than the currently saved max
|
|
* stack size, nothing more is done.
|
|
*
|
|
* If the size of the stack is greater than the maximum recorded size, then the
|
|
* following algorithm takes place.
|
|
*
|
|
* For architectures (like x86) that store the function's return address before
|
|
* saving the function's local variables, the stack will look something like
|
|
* this:
|
|
*
|
|
* [ top of stack ]
|
|
* 0: sys call entry frame
|
|
* 10: return addr to entry code
|
|
* 11: start of sys_foo frame
|
|
* 20: return addr to sys_foo
|
|
* 21: start of kernel_func_bar frame
|
|
* 30: return addr to kernel_func_bar
|
|
* 31: [ do trace stack here ]
|
|
*
|
|
* The save_stack_trace() is called returning all the functions it finds in the
|
|
* current stack. Which would be (from the bottom of the stack to the top):
|
|
*
|
|
* return addr to kernel_func_bar
|
|
* return addr to sys_foo
|
|
* return addr to entry code
|
|
*
|
|
* Now to figure out how much each of these functions' local variable size is,
|
|
* a search of the stack is made to find these values. When a match is made, it
|
|
* is added to the stack_dump_trace[] array. The offset into the stack is saved
|
|
* in the stack_trace_index[] array. The above example would show:
|
|
*
|
|
* stack_dump_trace[] | stack_trace_index[]
|
|
* ------------------ + -------------------
|
|
* return addr to kernel_func_bar | 30
|
|
* return addr to sys_foo | 20
|
|
* return addr to entry | 10
|
|
*
|
|
* The print_max_stack() function above, uses these values to print the size of
|
|
* each function's portion of the stack.
|
|
*
|
|
* for (i = 0; i < nr_entries; i++) {
|
|
* size = i == nr_entries - 1 ? stack_trace_index[i] :
|
|
* stack_trace_index[i] - stack_trace_index[i+1]
|
|
* print "%d %d %d %s\n", i, stack_trace_index[i], size, stack_dump_trace[i]);
|
|
* }
|
|
*
|
|
* The above shows
|
|
*
|
|
* depth size location
|
|
* ----- ---- --------
|
|
* 0 30 10 kernel_func_bar
|
|
* 1 20 10 sys_foo
|
|
* 2 10 10 entry code
|
|
*
|
|
* Now for architectures that might save the return address after the functions
|
|
* local variables (saving the link register before calling nested functions),
|
|
* this will cause the stack to look a little different:
|
|
*
|
|
* [ top of stack ]
|
|
* 0: sys call entry frame
|
|
* 10: start of sys_foo_frame
|
|
* 19: return addr to entry code << lr saved before calling kernel_func_bar
|
|
* 20: start of kernel_func_bar frame
|
|
* 29: return addr to sys_foo_frame << lr saved before calling next function
|
|
* 30: [ do trace stack here ]
|
|
*
|
|
* Although the functions returned by save_stack_trace() may be the same, the
|
|
* placement in the stack will be different. Using the same algorithm as above
|
|
* would yield:
|
|
*
|
|
* stack_dump_trace[] | stack_trace_index[]
|
|
* ------------------ + -------------------
|
|
* return addr to kernel_func_bar | 30
|
|
* return addr to sys_foo | 29
|
|
* return addr to entry | 19
|
|
*
|
|
* Where the mapping is off by one:
|
|
*
|
|
* kernel_func_bar stack frame size is 29 - 19 not 30 - 29!
|
|
*
|
|
* To fix this, if the architecture sets ARCH_RET_ADDR_AFTER_LOCAL_VARS the
|
|
* values in stack_trace_index[] are shifted by one to and the number of
|
|
* stack trace entries is decremented by one.
|
|
*
|
|
* stack_dump_trace[] | stack_trace_index[]
|
|
* ------------------ + -------------------
|
|
* return addr to kernel_func_bar | 29
|
|
* return addr to sys_foo | 19
|
|
*
|
|
* Although the entry function is not displayed, the first function (sys_foo)
|
|
* will still include the stack size of it.
|
|
*/
|
|
static 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 = READ_ONCE(tracer_frame);
|
|
int i, x;
|
|
|
|
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 <= stack_trace_max_size)
|
|
return;
|
|
|
|
/* we do not handle interrupt stacks yet */
|
|
if (!object_is_on_stack(stack))
|
|
return;
|
|
|
|
/* Can't do this from NMI context (can cause deadlocks) */
|
|
if (in_nmi())
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
arch_spin_lock(&stack_trace_max_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 <= stack_trace_max_size)
|
|
goto out;
|
|
|
|
stack_trace_max_size = this_size;
|
|
|
|
stack_trace_nr_entries = stack_trace_save(stack_dump_trace,
|
|
ARRAY_SIZE(stack_dump_trace) - 1,
|
|
0);
|
|
|
|
/* Skip over the overhead of the stack tracer itself */
|
|
for (i = 0; i < stack_trace_nr_entries; i++) {
|
|
if (stack_dump_trace[i] == ip)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Some archs may not have the passed in ip in the dump.
|
|
* If that happens, we need to show everything.
|
|
*/
|
|
if (i == stack_trace_nr_entries)
|
|
i = 0;
|
|
|
|
/*
|
|
* Now find where in the stack these are.
|
|
*/
|
|
x = 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 < stack_trace_nr_entries) {
|
|
int found = 0;
|
|
|
|
stack_trace_index[x] = this_size;
|
|
p = start;
|
|
|
|
for (; p < top && i < stack_trace_nr_entries; p++) {
|
|
/*
|
|
* The READ_ONCE_NOCHECK is used to let KASAN know that
|
|
* this is not a stack-out-of-bounds error.
|
|
*/
|
|
if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
|
|
stack_dump_trace[x] = stack_dump_trace[i++];
|
|
this_size = stack_trace_index[x++] =
|
|
(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)) {
|
|
tracer_frame = (p - stack) *
|
|
sizeof(unsigned long);
|
|
stack_trace_max_size -= tracer_frame;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!found)
|
|
i++;
|
|
}
|
|
|
|
#ifdef ARCH_FTRACE_SHIFT_STACK_TRACER
|
|
/*
|
|
* Some archs will store the link register before calling
|
|
* nested functions. This means the saved return address
|
|
* comes after the local storage, and we need to shift
|
|
* for that.
|
|
*/
|
|
if (x > 1) {
|
|
memmove(&stack_trace_index[0], &stack_trace_index[1],
|
|
sizeof(stack_trace_index[0]) * (x - 1));
|
|
x--;
|
|
}
|
|
#endif
|
|
|
|
stack_trace_nr_entries = x;
|
|
|
|
if (task_stack_end_corrupted(current)) {
|
|
print_max_stack();
|
|
BUG();
|
|
}
|
|
|
|
out:
|
|
arch_spin_unlock(&stack_trace_max_lock);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/* Some archs may not define MCOUNT_INSN_SIZE */
|
|
#ifndef MCOUNT_INSN_SIZE
|
|
# define MCOUNT_INSN_SIZE 0
|
|
#endif
|
|
|
|
static void
|
|
stack_trace_call(unsigned long ip, unsigned long parent_ip,
|
|
struct ftrace_ops *op, struct ftrace_regs *fregs)
|
|
{
|
|
unsigned long stack;
|
|
|
|
preempt_disable_notrace();
|
|
|
|
/* no atomic needed, we only modify this variable by this cpu */
|
|
__this_cpu_inc(disable_stack_tracer);
|
|
if (__this_cpu_read(disable_stack_tracer) != 1)
|
|
goto out;
|
|
|
|
/* If rcu is not watching, then save stack trace can fail */
|
|
if (!rcu_is_watching())
|
|
goto out;
|
|
|
|
ip += MCOUNT_INSN_SIZE;
|
|
|
|
check_stack(ip, &stack);
|
|
|
|
out:
|
|
__this_cpu_dec(disable_stack_tracer);
|
|
/* prevent recursion in schedule */
|
|
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;
|
|
int ret;
|
|
|
|
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 disable_stack_tracer here.
|
|
*/
|
|
__this_cpu_inc(disable_stack_tracer);
|
|
|
|
arch_spin_lock(&stack_trace_max_lock);
|
|
*ptr = val;
|
|
arch_spin_unlock(&stack_trace_max_lock);
|
|
|
|
__this_cpu_dec(disable_stack_tracer);
|
|
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 >= stack_trace_nr_entries)
|
|
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)
|
|
{
|
|
local_irq_disable();
|
|
|
|
__this_cpu_inc(disable_stack_tracer);
|
|
|
|
arch_spin_lock(&stack_trace_max_lock);
|
|
|
|
if (*pos == 0)
|
|
return SEQ_START_TOKEN;
|
|
|
|
return __next(m, pos);
|
|
}
|
|
|
|
static void t_stop(struct seq_file *m, void *p)
|
|
{
|
|
arch_spin_unlock(&stack_trace_max_lock);
|
|
|
|
__this_cpu_dec(disable_stack_tracer);
|
|
|
|
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",
|
|
stack_trace_nr_entries);
|
|
|
|
if (!stack_tracer_enabled && !stack_trace_max_size)
|
|
print_disabled(m);
|
|
|
|
return 0;
|
|
}
|
|
|
|
i = *(long *)v;
|
|
|
|
if (i >= stack_trace_nr_entries)
|
|
return 0;
|
|
|
|
if (i + 1 == stack_trace_nr_entries)
|
|
size = stack_trace_index[i];
|
|
else
|
|
size = stack_trace_index[i] - stack_trace_index[i+1];
|
|
|
|
seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_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)
|
|
{
|
|
int ret;
|
|
|
|
ret = security_locked_down(LOCKDOWN_TRACEFS);
|
|
if (ret)
|
|
return ret;
|
|
|
|
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,
|
|
};
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
|
|
static int
|
|
stack_trace_filter_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct ftrace_ops *ops = inode->i_private;
|
|
|
|
/* Checks for tracefs lockdown */
|
|
return ftrace_regex_open(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,
|
|
};
|
|
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
|
|
int
|
|
stack_trace_sysctl(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
int was_enabled;
|
|
int ret;
|
|
|
|
mutex_lock(&stack_sysctl_mutex);
|
|
was_enabled = !!stack_tracer_enabled;
|
|
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
|
|
if (ret || !write || (was_enabled == !!stack_tracer_enabled))
|
|
goto out;
|
|
|
|
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)
|
|
{
|
|
int len;
|
|
|
|
if ((len = str_has_prefix(str, "_filter=")))
|
|
strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE);
|
|
|
|
stack_tracer_enabled = 1;
|
|
return 1;
|
|
}
|
|
__setup("stacktrace", enable_stacktrace);
|
|
|
|
static __init int stack_trace_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = tracing_init_dentry();
|
|
if (ret)
|
|
return 0;
|
|
|
|
trace_create_file("stack_max_size", 0644, NULL,
|
|
&stack_trace_max_size, &stack_max_size_fops);
|
|
|
|
trace_create_file("stack_trace", 0444, NULL,
|
|
NULL, &stack_trace_fops);
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
trace_create_file("stack_trace_filter", 0644, NULL,
|
|
&trace_ops, &stack_trace_filter_fops);
|
|
#endif
|
|
|
|
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);
|