// SPDX-License-Identifier: GPL-2.0
|
/*
|
* Infrastructure to took into function calls and returns.
|
* Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
|
* Mostly borrowed from function tracer which
|
* is Copyright (c) Steven Rostedt <srostedt@redhat.com>
|
*
|
* Highly modified by Steven Rostedt (VMware).
|
*/
|
#include <linux/suspend.h>
|
#include <linux/ftrace.h>
|
#include <linux/slab.h>
|
|
#include <trace/events/sched.h>
|
|
#include "ftrace_internal.h"
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
#define ASSIGN_OPS_HASH(opsname, val) \
|
.func_hash = val, \
|
.local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
|
#else
|
#define ASSIGN_OPS_HASH(opsname, val)
|
#endif
|
|
static bool kill_ftrace_graph;
|
int ftrace_graph_active;
|
|
/* Both enabled by default (can be cleared by function_graph tracer flags */
|
static bool fgraph_sleep_time = true;
|
|
/**
|
* ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
|
*
|
* ftrace_graph_stop() is called when a severe error is detected in
|
* the function graph tracing. This function is called by the critical
|
* paths of function graph to keep those paths from doing any more harm.
|
*/
|
bool ftrace_graph_is_dead(void)
|
{
|
return kill_ftrace_graph;
|
}
|
|
/**
|
* ftrace_graph_stop - set to permanently disable function graph tracincg
|
*
|
* In case of an error int function graph tracing, this is called
|
* to try to keep function graph tracing from causing any more harm.
|
* Usually this is pretty severe and this is called to try to at least
|
* get a warning out to the user.
|
*/
|
void ftrace_graph_stop(void)
|
{
|
kill_ftrace_graph = true;
|
}
|
|
/* Add a function return address to the trace stack on thread info.*/
|
static int
|
ftrace_push_return_trace(unsigned long ret, unsigned long func,
|
unsigned long frame_pointer, unsigned long *retp)
|
{
|
unsigned long long calltime;
|
int index;
|
|
if (unlikely(ftrace_graph_is_dead()))
|
return -EBUSY;
|
|
if (!current->ret_stack)
|
return -EBUSY;
|
|
/*
|
* We must make sure the ret_stack is tested before we read
|
* anything else.
|
*/
|
smp_rmb();
|
|
/* The return trace stack is full */
|
if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
|
atomic_inc(¤t->trace_overrun);
|
return -EBUSY;
|
}
|
|
calltime = trace_clock_local();
|
|
index = ++current->curr_ret_stack;
|
barrier();
|
current->ret_stack[index].ret = ret;
|
current->ret_stack[index].func = func;
|
current->ret_stack[index].calltime = calltime;
|
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
|
current->ret_stack[index].fp = frame_pointer;
|
#endif
|
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
|
current->ret_stack[index].retp = retp;
|
#endif
|
return 0;
|
}
|
|
/*
|
* Not all archs define MCOUNT_INSN_SIZE which is used to look for direct
|
* functions. But those archs currently don't support direct functions
|
* anyway, and ftrace_find_rec_direct() is just a stub for them.
|
* Define MCOUNT_INSN_SIZE to keep those archs compiling.
|
*/
|
#ifndef MCOUNT_INSN_SIZE
|
/* Make sure this only works without direct calls */
|
# ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
|
# error MCOUNT_INSN_SIZE not defined with direct calls enabled
|
# endif
|
# define MCOUNT_INSN_SIZE 0
|
#endif
|
|
int function_graph_enter(unsigned long ret, unsigned long func,
|
unsigned long frame_pointer, unsigned long *retp)
|
{
|
struct ftrace_graph_ent trace;
|
|
/*
|
* Skip graph tracing if the return location is served by direct trampoline,
|
* since call sequence and return addresses is unpredicatable anymore.
|
* Ex: BPF trampoline may call original function and may skip frame
|
* depending on type of BPF programs attached.
|
*/
|
if (ftrace_direct_func_count &&
|
ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE))
|
return -EBUSY;
|
trace.func = func;
|
trace.depth = ++current->curr_ret_depth;
|
|
if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
|
goto out;
|
|
/* Only trace if the calling function expects to */
|
if (!ftrace_graph_entry(&trace))
|
goto out_ret;
|
|
return 0;
|
out_ret:
|
current->curr_ret_stack--;
|
out:
|
current->curr_ret_depth--;
|
return -EBUSY;
|
}
|
|
/* Retrieve a function return address to the trace stack on thread info.*/
|
static void
|
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
|
unsigned long frame_pointer)
|
{
|
int index;
|
|
index = current->curr_ret_stack;
|
|
if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
|
ftrace_graph_stop();
|
WARN_ON(1);
|
/* Might as well panic, otherwise we have no where to go */
|
*ret = (unsigned long)panic;
|
return;
|
}
|
|
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
|
/*
|
* The arch may choose to record the frame pointer used
|
* and check it here to make sure that it is what we expect it
|
* to be. If gcc does not set the place holder of the return
|
* address in the frame pointer, and does a copy instead, then
|
* the function graph trace will fail. This test detects this
|
* case.
|
*
|
* Currently, x86_32 with optimize for size (-Os) makes the latest
|
* gcc do the above.
|
*
|
* Note, -mfentry does not use frame pointers, and this test
|
* is not needed if CC_USING_FENTRY is set.
|
*/
|
if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
|
ftrace_graph_stop();
|
WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
|
" from func %ps return to %lx\n",
|
current->ret_stack[index].fp,
|
frame_pointer,
|
(void *)current->ret_stack[index].func,
|
current->ret_stack[index].ret);
|
*ret = (unsigned long)panic;
|
return;
|
}
|
#endif
|
|
*ret = current->ret_stack[index].ret;
|
trace->func = current->ret_stack[index].func;
|
trace->calltime = current->ret_stack[index].calltime;
|
trace->overrun = atomic_read(¤t->trace_overrun);
|
trace->depth = current->curr_ret_depth--;
|
/*
|
* We still want to trace interrupts coming in if
|
* max_depth is set to 1. Make sure the decrement is
|
* seen before ftrace_graph_return.
|
*/
|
barrier();
|
}
|
|
/*
|
* Hibernation protection.
|
* The state of the current task is too much unstable during
|
* suspend/restore to disk. We want to protect against that.
|
*/
|
static int
|
ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
|
void *unused)
|
{
|
switch (state) {
|
case PM_HIBERNATION_PREPARE:
|
pause_graph_tracing();
|
break;
|
|
case PM_POST_HIBERNATION:
|
unpause_graph_tracing();
|
break;
|
}
|
return NOTIFY_DONE;
|
}
|
|
static struct notifier_block ftrace_suspend_notifier = {
|
.notifier_call = ftrace_suspend_notifier_call,
|
};
|
|
/*
|
* Send the trace to the ring-buffer.
|
* @return the original return address.
|
*/
|
unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
|
{
|
struct ftrace_graph_ret trace;
|
unsigned long ret;
|
|
ftrace_pop_return_trace(&trace, &ret, frame_pointer);
|
trace.rettime = trace_clock_local();
|
ftrace_graph_return(&trace);
|
/*
|
* The ftrace_graph_return() may still access the current
|
* ret_stack structure, we need to make sure the update of
|
* curr_ret_stack is after that.
|
*/
|
barrier();
|
current->curr_ret_stack--;
|
|
if (unlikely(!ret)) {
|
ftrace_graph_stop();
|
WARN_ON(1);
|
/* Might as well panic. What else to do? */
|
ret = (unsigned long)panic;
|
}
|
|
return ret;
|
}
|
|
/**
|
* ftrace_graph_get_ret_stack - return the entry of the shadow stack
|
* @task: The task to read the shadow stack from
|
* @idx: Index down the shadow stack
|
*
|
* Return the ret_struct on the shadow stack of the @task at the
|
* call graph at @idx starting with zero. If @idx is zero, it
|
* will return the last saved ret_stack entry. If it is greater than
|
* zero, it will return the corresponding ret_stack for the depth
|
* of saved return addresses.
|
*/
|
struct ftrace_ret_stack *
|
ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
|
{
|
idx = task->curr_ret_stack - idx;
|
|
if (idx >= 0 && idx <= task->curr_ret_stack)
|
return &task->ret_stack[idx];
|
|
return NULL;
|
}
|
|
/**
|
* ftrace_graph_ret_addr - convert a potentially modified stack return address
|
* to its original value
|
*
|
* This function can be called by stack unwinding code to convert a found stack
|
* return address ('ret') to its original value, in case the function graph
|
* tracer has modified it to be 'return_to_handler'. If the address hasn't
|
* been modified, the unchanged value of 'ret' is returned.
|
*
|
* 'idx' is a state variable which should be initialized by the caller to zero
|
* before the first call.
|
*
|
* 'retp' is a pointer to the return address on the stack. It's ignored if
|
* the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
|
*/
|
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
|
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
|
unsigned long ret, unsigned long *retp)
|
{
|
int index = task->curr_ret_stack;
|
int i;
|
|
if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
|
return ret;
|
|
if (index < 0)
|
return ret;
|
|
for (i = 0; i <= index; i++)
|
if (task->ret_stack[i].retp == retp)
|
return task->ret_stack[i].ret;
|
|
return ret;
|
}
|
#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
|
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
|
unsigned long ret, unsigned long *retp)
|
{
|
int task_idx;
|
|
if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
|
return ret;
|
|
task_idx = task->curr_ret_stack;
|
|
if (!task->ret_stack || task_idx < *idx)
|
return ret;
|
|
task_idx -= *idx;
|
(*idx)++;
|
|
return task->ret_stack[task_idx].ret;
|
}
|
#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
|
|
static struct ftrace_ops graph_ops = {
|
.func = ftrace_stub,
|
.flags = FTRACE_OPS_FL_RECURSION_SAFE |
|
FTRACE_OPS_FL_INITIALIZED |
|
FTRACE_OPS_FL_PID |
|
FTRACE_OPS_FL_STUB,
|
#ifdef FTRACE_GRAPH_TRAMP_ADDR
|
.trampoline = FTRACE_GRAPH_TRAMP_ADDR,
|
/* trampoline_size is only needed for dynamically allocated tramps */
|
#endif
|
ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
|
};
|
|
void ftrace_graph_sleep_time_control(bool enable)
|
{
|
fgraph_sleep_time = enable;
|
}
|
|
int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
|
{
|
return 0;
|
}
|
|
/*
|
* Simply points to ftrace_stub, but with the proper protocol.
|
* Defined by the linker script in linux/vmlinux.lds.h
|
*/
|
extern void ftrace_stub_graph(struct ftrace_graph_ret *);
|
|
/* The callbacks that hook a function */
|
trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
|
trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
|
static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
|
|
/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
|
static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
|
{
|
int i;
|
int ret = 0;
|
int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
|
struct task_struct *g, *t;
|
|
for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
|
ret_stack_list[i] =
|
kmalloc_array(FTRACE_RETFUNC_DEPTH,
|
sizeof(struct ftrace_ret_stack),
|
GFP_KERNEL);
|
if (!ret_stack_list[i]) {
|
start = 0;
|
end = i;
|
ret = -ENOMEM;
|
goto free;
|
}
|
}
|
|
rcu_read_lock();
|
for_each_process_thread(g, t) {
|
if (start == end) {
|
ret = -EAGAIN;
|
goto unlock;
|
}
|
|
if (t->ret_stack == NULL) {
|
atomic_set(&t->trace_overrun, 0);
|
t->curr_ret_stack = -1;
|
t->curr_ret_depth = -1;
|
/* Make sure the tasks see the -1 first: */
|
smp_wmb();
|
t->ret_stack = ret_stack_list[start++];
|
}
|
}
|
|
unlock:
|
rcu_read_unlock();
|
free:
|
for (i = start; i < end; i++)
|
kfree(ret_stack_list[i]);
|
return ret;
|
}
|
|
static void
|
ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
|
struct task_struct *prev, struct task_struct *next)
|
{
|
unsigned long long timestamp;
|
int index;
|
|
/*
|
* Does the user want to count the time a function was asleep.
|
* If so, do not update the time stamps.
|
*/
|
if (fgraph_sleep_time)
|
return;
|
|
timestamp = trace_clock_local();
|
|
prev->ftrace_timestamp = timestamp;
|
|
/* only process tasks that we timestamped */
|
if (!next->ftrace_timestamp)
|
return;
|
|
/*
|
* Update all the counters in next to make up for the
|
* time next was sleeping.
|
*/
|
timestamp -= next->ftrace_timestamp;
|
|
for (index = next->curr_ret_stack; index >= 0; index--)
|
next->ret_stack[index].calltime += timestamp;
|
}
|
|
static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace)
|
{
|
if (!ftrace_ops_test(&global_ops, trace->func, NULL))
|
return 0;
|
return __ftrace_graph_entry(trace);
|
}
|
|
/*
|
* The function graph tracer should only trace the functions defined
|
* by set_ftrace_filter and set_ftrace_notrace. If another function
|
* tracer ops is registered, the graph tracer requires testing the
|
* function against the global ops, and not just trace any function
|
* that any ftrace_ops registered.
|
*/
|
void update_function_graph_func(void)
|
{
|
struct ftrace_ops *op;
|
bool do_test = false;
|
|
/*
|
* The graph and global ops share the same set of functions
|
* to test. If any other ops is on the list, then
|
* the graph tracing needs to test if its the function
|
* it should call.
|
*/
|
do_for_each_ftrace_op(op, ftrace_ops_list) {
|
if (op != &global_ops && op != &graph_ops &&
|
op != &ftrace_list_end) {
|
do_test = true;
|
/* in double loop, break out with goto */
|
goto out;
|
}
|
} while_for_each_ftrace_op(op);
|
out:
|
if (do_test)
|
ftrace_graph_entry = ftrace_graph_entry_test;
|
else
|
ftrace_graph_entry = __ftrace_graph_entry;
|
}
|
|
static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
|
|
static void
|
graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
|
{
|
atomic_set(&t->trace_overrun, 0);
|
t->ftrace_timestamp = 0;
|
/* make curr_ret_stack visible before we add the ret_stack */
|
smp_wmb();
|
t->ret_stack = ret_stack;
|
}
|
|
/*
|
* Allocate a return stack for the idle task. May be the first
|
* time through, or it may be done by CPU hotplug online.
|
*/
|
void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
|
{
|
t->curr_ret_stack = -1;
|
t->curr_ret_depth = -1;
|
/*
|
* The idle task has no parent, it either has its own
|
* stack or no stack at all.
|
*/
|
if (t->ret_stack)
|
WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
|
|
if (ftrace_graph_active) {
|
struct ftrace_ret_stack *ret_stack;
|
|
ret_stack = per_cpu(idle_ret_stack, cpu);
|
if (!ret_stack) {
|
ret_stack =
|
kmalloc_array(FTRACE_RETFUNC_DEPTH,
|
sizeof(struct ftrace_ret_stack),
|
GFP_KERNEL);
|
if (!ret_stack)
|
return;
|
per_cpu(idle_ret_stack, cpu) = ret_stack;
|
}
|
graph_init_task(t, ret_stack);
|
}
|
}
|
|
/* Allocate a return stack for newly created task */
|
void ftrace_graph_init_task(struct task_struct *t)
|
{
|
/* Make sure we do not use the parent ret_stack */
|
t->ret_stack = NULL;
|
t->curr_ret_stack = -1;
|
t->curr_ret_depth = -1;
|
|
if (ftrace_graph_active) {
|
struct ftrace_ret_stack *ret_stack;
|
|
ret_stack = kmalloc_array(FTRACE_RETFUNC_DEPTH,
|
sizeof(struct ftrace_ret_stack),
|
GFP_KERNEL);
|
if (!ret_stack)
|
return;
|
graph_init_task(t, ret_stack);
|
}
|
}
|
|
void ftrace_graph_exit_task(struct task_struct *t)
|
{
|
struct ftrace_ret_stack *ret_stack = t->ret_stack;
|
|
t->ret_stack = NULL;
|
/* NULL must become visible to IRQs before we free it: */
|
barrier();
|
|
kfree(ret_stack);
|
}
|
|
/* Allocate a return stack for each task */
|
static int start_graph_tracing(void)
|
{
|
struct ftrace_ret_stack **ret_stack_list;
|
int ret, cpu;
|
|
ret_stack_list = kmalloc_array(FTRACE_RETSTACK_ALLOC_SIZE,
|
sizeof(struct ftrace_ret_stack *),
|
GFP_KERNEL);
|
|
if (!ret_stack_list)
|
return -ENOMEM;
|
|
/* The cpu_boot init_task->ret_stack will never be freed */
|
for_each_online_cpu(cpu) {
|
if (!idle_task(cpu)->ret_stack)
|
ftrace_graph_init_idle_task(idle_task(cpu), cpu);
|
}
|
|
do {
|
ret = alloc_retstack_tasklist(ret_stack_list);
|
} while (ret == -EAGAIN);
|
|
if (!ret) {
|
ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
|
if (ret)
|
pr_info("ftrace_graph: Couldn't activate tracepoint"
|
" probe to kernel_sched_switch\n");
|
}
|
|
kfree(ret_stack_list);
|
return ret;
|
}
|
|
int register_ftrace_graph(struct fgraph_ops *gops)
|
{
|
int ret = 0;
|
|
mutex_lock(&ftrace_lock);
|
|
/* we currently allow only one tracer registered at a time */
|
if (ftrace_graph_active) {
|
ret = -EBUSY;
|
goto out;
|
}
|
|
register_pm_notifier(&ftrace_suspend_notifier);
|
|
ftrace_graph_active++;
|
ret = start_graph_tracing();
|
if (ret) {
|
ftrace_graph_active--;
|
goto out;
|
}
|
|
ftrace_graph_return = gops->retfunc;
|
|
/*
|
* Update the indirect function to the entryfunc, and the
|
* function that gets called to the entry_test first. Then
|
* call the update fgraph entry function to determine if
|
* the entryfunc should be called directly or not.
|
*/
|
__ftrace_graph_entry = gops->entryfunc;
|
ftrace_graph_entry = ftrace_graph_entry_test;
|
update_function_graph_func();
|
|
ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
|
out:
|
mutex_unlock(&ftrace_lock);
|
return ret;
|
}
|
|
void unregister_ftrace_graph(struct fgraph_ops *gops)
|
{
|
mutex_lock(&ftrace_lock);
|
|
if (unlikely(!ftrace_graph_active))
|
goto out;
|
|
ftrace_graph_active--;
|
ftrace_graph_return = ftrace_stub_graph;
|
ftrace_graph_entry = ftrace_graph_entry_stub;
|
__ftrace_graph_entry = ftrace_graph_entry_stub;
|
ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
|
unregister_pm_notifier(&ftrace_suspend_notifier);
|
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
|
|
out:
|
mutex_unlock(&ftrace_lock);
|
}
|
