linux/kernel/trace/trace_syscalls.c
Tom Zanussi f306cc82a9 tracing: Update event filters for multibuffer
The trace event filters are still tied to event calls rather than
event files, which means you don't get what you'd expect when using
filters in the multibuffer case:

Before:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 2048
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

Setting the filter in tracing/instances/test1/events shouldn't affect
the same event in tracing/events as it does above.

After:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

We'd like to just move the filter directly from ftrace_event_call to
ftrace_event_file, but there are a couple cases that don't yet have
multibuffer support and therefore have to continue using the current
event_call-based filters.  For those cases, a new USE_CALL_FILTER bit
is added to the event_call flags, whose main purpose is to keep the
old behavior for those cases until they can be updated with
multibuffer support; at that point, the USE_CALL_FILTER flag (and the
new associated call_filter_check_discard() function) can go away.

The multibuffer support also made filter_current_check_discard()
redundant, so this change removes that function as well and replaces
it with filter_check_discard() (or call_filter_check_discard() as
appropriate).

Link: http://lkml.kernel.org/r/f16e9ce4270c62f46b2e966119225e1c3cca7e60.1382620672.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-11-05 16:50:20 -05:00

753 lines
18 KiB
C

#include <trace/syscall.h>
#include <trace/events/syscalls.h>
#include <linux/syscalls.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h> /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
#include <linux/ftrace.h>
#include <linux/perf_event.h>
#include <asm/syscall.h>
#include "trace_output.h"
#include "trace.h"
static DEFINE_MUTEX(syscall_trace_lock);
static int syscall_enter_register(struct ftrace_event_call *event,
enum trace_reg type, void *data);
static int syscall_exit_register(struct ftrace_event_call *event,
enum trace_reg type, void *data);
static struct list_head *
syscall_get_enter_fields(struct ftrace_event_call *call)
{
struct syscall_metadata *entry = call->data;
return &entry->enter_fields;
}
extern struct syscall_metadata *__start_syscalls_metadata[];
extern struct syscall_metadata *__stop_syscalls_metadata[];
static struct syscall_metadata **syscalls_metadata;
#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
{
/*
* Only compare after the "sys" prefix. Archs that use
* syscall wrappers may have syscalls symbols aliases prefixed
* with ".SyS" or ".sys" instead of "sys", leading to an unwanted
* mismatch.
*/
return !strcmp(sym + 3, name + 3);
}
#endif
#ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
/*
* Some architectures that allow for 32bit applications
* to run on a 64bit kernel, do not map the syscalls for
* the 32bit tasks the same as they do for 64bit tasks.
*
* *cough*x86*cough*
*
* In such a case, instead of reporting the wrong syscalls,
* simply ignore them.
*
* For an arch to ignore the compat syscalls it needs to
* define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
* define the function arch_trace_is_compat_syscall() to let
* the tracing system know that it should ignore it.
*/
static int
trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
{
if (unlikely(arch_trace_is_compat_syscall(regs)))
return -1;
return syscall_get_nr(task, regs);
}
#else
static inline int
trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
{
return syscall_get_nr(task, regs);
}
#endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)
{
struct syscall_metadata **start;
struct syscall_metadata **stop;
char str[KSYM_SYMBOL_LEN];
start = __start_syscalls_metadata;
stop = __stop_syscalls_metadata;
kallsyms_lookup(syscall, NULL, NULL, NULL, str);
if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
return NULL;
for ( ; start < stop; start++) {
if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
return *start;
}
return NULL;
}
static struct syscall_metadata *syscall_nr_to_meta(int nr)
{
if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
return NULL;
return syscalls_metadata[nr];
}
static enum print_line_t
print_syscall_enter(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *ent = iter->ent;
struct syscall_trace_enter *trace;
struct syscall_metadata *entry;
int i, ret, syscall;
trace = (typeof(trace))ent;
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry)
goto end;
if (entry->enter_event->event.type != ent->type) {
WARN_ON_ONCE(1);
goto end;
}
ret = trace_seq_printf(s, "%s(", entry->name);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
for (i = 0; i < entry->nb_args; i++) {
/* parameter types */
if (trace_flags & TRACE_ITER_VERBOSE) {
ret = trace_seq_printf(s, "%s ", entry->types[i]);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
/* parameter values */
ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
trace->args[i],
i == entry->nb_args - 1 ? "" : ", ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = trace_seq_putc(s, ')');
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
end:
ret = trace_seq_putc(s, '\n');
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
static enum print_line_t
print_syscall_exit(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *ent = iter->ent;
struct syscall_trace_exit *trace;
int syscall;
struct syscall_metadata *entry;
int ret;
trace = (typeof(trace))ent;
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry) {
trace_seq_putc(s, '\n');
return TRACE_TYPE_HANDLED;
}
if (entry->exit_event->event.type != ent->type) {
WARN_ON_ONCE(1);
return TRACE_TYPE_UNHANDLED;
}
ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
trace->ret);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
extern char *__bad_type_size(void);
#define SYSCALL_FIELD(type, name) \
sizeof(type) != sizeof(trace.name) ? \
__bad_type_size() : \
#type, #name, offsetof(typeof(trace), name), \
sizeof(trace.name), is_signed_type(type)
static int __init
__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
{
int i;
int pos = 0;
/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < entry->nb_args; i++) {
pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
entry->args[i], sizeof(unsigned long),
i == entry->nb_args - 1 ? "" : ", ");
}
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < entry->nb_args; i++) {
pos += snprintf(buf + pos, LEN_OR_ZERO,
", ((unsigned long)(REC->%s))", entry->args[i]);
}
#undef LEN_OR_ZERO
/* return the length of print_fmt */
return pos;
}
static int __init set_syscall_print_fmt(struct ftrace_event_call *call)
{
char *print_fmt;
int len;
struct syscall_metadata *entry = call->data;
if (entry->enter_event != call) {
call->print_fmt = "\"0x%lx\", REC->ret";
return 0;
}
/* First: called with 0 length to calculate the needed length */
len = __set_enter_print_fmt(entry, NULL, 0);
print_fmt = kmalloc(len + 1, GFP_KERNEL);
if (!print_fmt)
return -ENOMEM;
/* Second: actually write the @print_fmt */
__set_enter_print_fmt(entry, print_fmt, len + 1);
call->print_fmt = print_fmt;
return 0;
}
static void __init free_syscall_print_fmt(struct ftrace_event_call *call)
{
struct syscall_metadata *entry = call->data;
if (entry->enter_event == call)
kfree(call->print_fmt);
}
static int __init syscall_enter_define_fields(struct ftrace_event_call *call)
{
struct syscall_trace_enter trace;
struct syscall_metadata *meta = call->data;
int ret;
int i;
int offset = offsetof(typeof(trace), args);
ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
if (ret)
return ret;
for (i = 0; i < meta->nb_args; i++) {
ret = trace_define_field(call, meta->types[i],
meta->args[i], offset,
sizeof(unsigned long), 0,
FILTER_OTHER);
offset += sizeof(unsigned long);
}
return ret;
}
static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
{
struct syscall_trace_exit trace;
int ret;
ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
if (ret)
return ret;
ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
FILTER_OTHER);
return ret;
}
static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
{
struct trace_array *tr = data;
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
unsigned long irq_flags;
int pc;
int syscall_nr;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, tr->enabled_enter_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
local_save_flags(irq_flags);
pc = preempt_count();
buffer = tr->trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->enter_event->event.type, size, irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
if (!call_filter_check_discard(sys_data->enter_event, entry,
buffer, event))
trace_current_buffer_unlock_commit(buffer, event,
irq_flags, pc);
}
static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
{
struct trace_array *tr = data;
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
unsigned long irq_flags;
int pc;
int syscall_nr;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, tr->enabled_exit_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
local_save_flags(irq_flags);
pc = preempt_count();
buffer = tr->trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->exit_event->event.type, sizeof(*entry),
irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);
if (!call_filter_check_discard(sys_data->exit_event, entry,
buffer, event))
trace_current_buffer_unlock_commit(buffer, event,
irq_flags, pc);
}
static int reg_event_syscall_enter(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!tr->sys_refcount_enter)
ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
if (!ret) {
set_bit(num, tr->enabled_enter_syscalls);
tr->sys_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void unreg_event_syscall_enter(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_enter--;
clear_bit(num, tr->enabled_enter_syscalls);
if (!tr->sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, tr);
mutex_unlock(&syscall_trace_lock);
}
static int reg_event_syscall_exit(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!tr->sys_refcount_exit)
ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
if (!ret) {
set_bit(num, tr->enabled_exit_syscalls);
tr->sys_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void unreg_event_syscall_exit(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_exit--;
clear_bit(num, tr->enabled_exit_syscalls);
if (!tr->sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, tr);
mutex_unlock(&syscall_trace_lock);
}
static int __init init_syscall_trace(struct ftrace_event_call *call)
{
int id;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (num < 0 || num >= NR_syscalls) {
pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
((struct syscall_metadata *)call->data)->name);
return -ENOSYS;
}
if (set_syscall_print_fmt(call) < 0)
return -ENOMEM;
id = trace_event_raw_init(call);
if (id < 0) {
free_syscall_print_fmt(call);
return id;
}
return id;
}
struct trace_event_functions enter_syscall_print_funcs = {
.trace = print_syscall_enter,
};
struct trace_event_functions exit_syscall_print_funcs = {
.trace = print_syscall_exit,
};
struct ftrace_event_class __refdata event_class_syscall_enter = {
.system = "syscalls",
.reg = syscall_enter_register,
.define_fields = syscall_enter_define_fields,
.get_fields = syscall_get_enter_fields,
.raw_init = init_syscall_trace,
};
struct ftrace_event_class __refdata event_class_syscall_exit = {
.system = "syscalls",
.reg = syscall_exit_register,
.define_fields = syscall_exit_define_fields,
.fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
.raw_init = init_syscall_trace,
};
unsigned long __init __weak arch_syscall_addr(int nr)
{
return (unsigned long)sys_call_table[nr];
}
static int __init init_ftrace_syscalls(void)
{
struct syscall_metadata *meta;
unsigned long addr;
int i;
syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
GFP_KERNEL);
if (!syscalls_metadata) {
WARN_ON(1);
return -ENOMEM;
}
for (i = 0; i < NR_syscalls; i++) {
addr = arch_syscall_addr(i);
meta = find_syscall_meta(addr);
if (!meta)
continue;
meta->syscall_nr = i;
syscalls_metadata[i] = meta;
}
return 0;
}
early_initcall(init_ftrace_syscalls);
#ifdef CONFIG_PERF_EVENTS
static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
static int sys_perf_refcount_enter;
static int sys_perf_refcount_exit;
static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
{
struct syscall_metadata *sys_data;
struct syscall_trace_enter *rec;
struct hlist_head *head;
int syscall_nr;
int rctx;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
head = this_cpu_ptr(sys_data->enter_event->perf_events);
if (hlist_empty(head))
return;
/* get the size after alignment with the u32 buffer size field */
size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
size = ALIGN(size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
sys_data->enter_event->event.type, regs, &rctx);
if (!rec)
return;
rec->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args,
(unsigned long *)&rec->args);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
}
static int perf_sysenter_enable(struct ftrace_event_call *call)
{
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
if (!sys_perf_refcount_enter)
ret = register_trace_sys_enter(perf_syscall_enter, NULL);
if (ret) {
pr_info("event trace: Could not activate"
"syscall entry trace point");
} else {
set_bit(num, enabled_perf_enter_syscalls);
sys_perf_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void perf_sysenter_disable(struct ftrace_event_call *call)
{
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
sys_perf_refcount_enter--;
clear_bit(num, enabled_perf_enter_syscalls);
if (!sys_perf_refcount_enter)
unregister_trace_sys_enter(perf_syscall_enter, NULL);
mutex_unlock(&syscall_trace_lock);
}
static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
{
struct syscall_metadata *sys_data;
struct syscall_trace_exit *rec;
struct hlist_head *head;
int syscall_nr;
int rctx;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
head = this_cpu_ptr(sys_data->exit_event->perf_events);
if (hlist_empty(head))
return;
/* We can probably do that at build time */
size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
sys_data->exit_event->event.type, regs, &rctx);
if (!rec)
return;
rec->nr = syscall_nr;
rec->ret = syscall_get_return_value(current, regs);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
}
static int perf_sysexit_enable(struct ftrace_event_call *call)
{
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
if (!sys_perf_refcount_exit)
ret = register_trace_sys_exit(perf_syscall_exit, NULL);
if (ret) {
pr_info("event trace: Could not activate"
"syscall exit trace point");
} else {
set_bit(num, enabled_perf_exit_syscalls);
sys_perf_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void perf_sysexit_disable(struct ftrace_event_call *call)
{
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
sys_perf_refcount_exit--;
clear_bit(num, enabled_perf_exit_syscalls);
if (!sys_perf_refcount_exit)
unregister_trace_sys_exit(perf_syscall_exit, NULL);
mutex_unlock(&syscall_trace_lock);
}
#endif /* CONFIG_PERF_EVENTS */
static int syscall_enter_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return reg_event_syscall_enter(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_enter(file, event);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return perf_sysenter_enable(event);
case TRACE_REG_PERF_UNREGISTER:
perf_sysenter_disable(event);
return 0;
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}
static int syscall_exit_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return reg_event_syscall_exit(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_exit(file, event);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return perf_sysexit_enable(event);
case TRACE_REG_PERF_UNREGISTER:
perf_sysexit_disable(event);
return 0;
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}