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tracing: Add trace events for each syscall entry/exit

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Layer Frederic's syscall tracer on tracepoints. We create trace events
via hooking into the SYSCALL_DEFINE macros. This allows us to
individually toggle syscall entry and exit points on/off.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Jason Baron
2009-08-10 16:52:47 -04:00
committed by Frederic Weisbecker
parent 69fd4f0eb2
commit fb34a08c34
3 changed files with 166 additions and 110 deletions
Download Patch File Download Diff File Expand all files Collapse all files

197
kernel/trace/trace_syscalls.c
View File

@@ -1,15 +1,16 @@
#include <trace/syscall.h>
#include <linux/kernel.h>
#include <linux/ftrace.h>
#include <asm/syscall.h>
#include "trace_output.h"
#include "trace.h"
/* Keep a counter of the syscall tracing users */
static int refcount;
/* Prevent from races on thread flags toggling */
static DEFINE_MUTEX(syscall_trace_lock);
static int sys_refcount_enter;
static int sys_refcount_exit;
static DECLARE_BITMAP(enabled_enter_syscalls, FTRACE_SYSCALL_MAX);
static DECLARE_BITMAP(enabled_exit_syscalls, FTRACE_SYSCALL_MAX);
/* Option to display the parameters types */
enum {
@@ -95,53 +96,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags)
return TRACE_TYPE_HANDLED;
}
void start_ftrace_syscalls(void)
{
unsigned long flags;
struct task_struct *g, *t;
mutex_lock(&syscall_trace_lock);
/* Don't enable the flag on the tasks twice */
if (++refcount != 1)
goto unlock;
read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, t) {
set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
} while_each_thread(g, t);
read_unlock_irqrestore(&tasklist_lock, flags);
unlock:
mutex_unlock(&syscall_trace_lock);
}
void stop_ftrace_syscalls(void)
{
unsigned long flags;
struct task_struct *g, *t;
mutex_lock(&syscall_trace_lock);
/* There are perhaps still some users */
if (--refcount)
goto unlock;
read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, t) {
clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
} while_each_thread(g, t);
read_unlock_irqrestore(&tasklist_lock, flags);
unlock:
mutex_unlock(&syscall_trace_lock);
}
void ftrace_syscall_enter(struct pt_regs *regs)
void ftrace_syscall_enter(struct pt_regs *regs, long id)
{
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
@@ -150,6 +105,8 @@ void ftrace_syscall_enter(struct pt_regs *regs)
int syscall_nr;
syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_enter_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
@@ -170,7 +127,7 @@ void ftrace_syscall_enter(struct pt_regs *regs)
trace_wake_up();
}
void ftrace_syscall_exit(struct pt_regs *regs)
void ftrace_syscall_exit(struct pt_regs *regs, long ret)
{
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
@@ -178,6 +135,8 @@ void ftrace_syscall_exit(struct pt_regs *regs)
int syscall_nr;
syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_exit_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
@@ -196,54 +155,94 @@ void ftrace_syscall_exit(struct pt_regs *regs)
trace_wake_up();
}
static int init_syscall_tracer(struct trace_array *tr)
int reg_event_syscall_enter(void *ptr)
{
start_ftrace_syscalls();
int ret = 0;
int num;
char *name;
return 0;
}
static void reset_syscall_tracer(struct trace_array *tr)
{
stop_ftrace_syscalls();
tracing_reset_online_cpus(tr);
}
static struct trace_event syscall_enter_event = {
.type = TRACE_SYSCALL_ENTER,
.trace = print_syscall_enter,
};
static struct trace_event syscall_exit_event = {
.type = TRACE_SYSCALL_EXIT,
.trace = print_syscall_exit,
};
static struct tracer syscall_tracer __read_mostly = {
.name = "syscall",
.init = init_syscall_tracer,
.reset = reset_syscall_tracer,
.flags = &syscalls_flags,
};
__init int register_ftrace_syscalls(void)
{
int ret;
ret = register_ftrace_event(&syscall_enter_event);
if (!ret) {
printk(KERN_WARNING "event %d failed to register\n",
syscall_enter_event.type);
WARN_ON_ONCE(1);
name = (char *)ptr;
num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!sys_refcount_enter)
ret = register_trace_syscall_enter(ftrace_syscall_enter);
if (ret) {
pr_info("event trace: Could not activate"
"syscall entry trace point");
} else {
set_bit(num, enabled_enter_syscalls);
sys_refcount_enter++;
}
ret = register_ftrace_event(&syscall_exit_event);
if (!ret) {
printk(KERN_WARNING "event %d failed to register\n",
syscall_exit_event.type);
WARN_ON_ONCE(1);
}
return register_tracer(&syscall_tracer);
mutex_unlock(&syscall_trace_lock);
return ret;
}
device_initcall(register_ftrace_syscalls);
void unreg_event_syscall_enter(void *ptr)
{
int num;
char *name;
name = (char *)ptr;
num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return;
mutex_lock(&syscall_trace_lock);
sys_refcount_enter--;
clear_bit(num, enabled_enter_syscalls);
if (!sys_refcount_enter)
unregister_trace_syscall_enter(ftrace_syscall_enter);
mutex_unlock(&syscall_trace_lock);
}
int reg_event_syscall_exit(void *ptr)
{
int ret = 0;
int num;
char *name;
name = (char *)ptr;
num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!sys_refcount_exit)
ret = register_trace_syscall_exit(ftrace_syscall_exit);
if (ret) {
pr_info("event trace: Could not activate"
"syscall exit trace point");
} else {
set_bit(num, enabled_exit_syscalls);
sys_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
void unreg_event_syscall_exit(void *ptr)
{
int num;
char *name;
name = (char *)ptr;
num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return;
mutex_lock(&syscall_trace_lock);
sys_refcount_exit--;
clear_bit(num, enabled_exit_syscalls);
if (!sys_refcount_exit)
unregister_trace_syscall_exit(ftrace_syscall_exit);
mutex_unlock(&syscall_trace_lock);
}
struct trace_event event_syscall_enter = {
.trace = print_syscall_enter,
.type = TRACE_SYSCALL_ENTER
};
struct trace_event event_syscall_exit = {
.trace = print_syscall_exit,
.type = TRACE_SYSCALL_EXIT
};