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tracing: Add perf counter support for syscalls tracing
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The perf counter support is automated for usual trace events. But we
have to define specific callbacks for this to handle syscalls trace
events

Make 'perf stat -e syscalls:sys_enter_blah' work with syscall style
tracepoints.

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>
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Jason Baron authored and Frederic Weisbecker committed Aug 11, 2009
1 parent 64c12e0 commit f4b5ffc
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2 changes: 2 additions & 0 deletions include/linux/perf_counter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -734,6 +734,8 @@ extern int sysctl_perf_counter_mlock;
extern int sysctl_perf_counter_sample_rate;

extern void perf_counter_init(void);
extern void perf_tpcounter_event(int event_id, u64 addr, u64 count,
void *record, int entry_size);

#ifndef perf_misc_flags
#define perf_misc_flags(regs) (user_mode(regs) ? PERF_EVENT_MISC_USER : \
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52 changes: 51 additions & 1 deletion include/linux/syscalls.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,53 @@ struct perf_counter_attr;
#define __SC_TEST5(t5, a5, ...) __SC_TEST(t5); __SC_TEST4(__VA_ARGS__)
#define __SC_TEST6(t6, a6, ...) __SC_TEST(t6); __SC_TEST5(__VA_ARGS__)

#ifdef CONFIG_EVENT_PROFILE
#define TRACE_SYS_ENTER_PROFILE(sname) \
static int prof_sysenter_enable_##sname(struct ftrace_event_call *event_call) \
{ \
int ret = 0; \
if (!atomic_inc_return(&event_enter_##sname.profile_count)) \
ret = reg_prof_syscall_enter("sys"#sname); \
return ret; \
} \
\
static void prof_sysenter_disable_##sname(struct ftrace_event_call *event_call)\
{ \
if (atomic_add_negative(-1, &event_enter_##sname.profile_count)) \
unreg_prof_syscall_enter("sys"#sname); \
}

#define TRACE_SYS_EXIT_PROFILE(sname) \
static int prof_sysexit_enable_##sname(struct ftrace_event_call *event_call) \
{ \
int ret = 0; \
if (!atomic_inc_return(&event_exit_##sname.profile_count)) \
ret = reg_prof_syscall_exit("sys"#sname); \
return ret; \
} \
\
static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
{ \
if (atomic_add_negative(-1, &event_exit_##sname.profile_count)) \
unreg_prof_syscall_exit("sys"#sname); \
}

#define TRACE_SYS_ENTER_PROFILE_INIT(sname) \
.profile_count = ATOMIC_INIT(-1), \
.profile_enable = prof_sysenter_enable_##sname, \
.profile_disable = prof_sysenter_disable_##sname,

#define TRACE_SYS_EXIT_PROFILE_INIT(sname) \
.profile_count = ATOMIC_INIT(-1), \
.profile_enable = prof_sysexit_enable_##sname, \
.profile_disable = prof_sysexit_disable_##sname,
#else
#define TRACE_SYS_ENTER_PROFILE(sname)
#define TRACE_SYS_ENTER_PROFILE_INIT(sname)
#define TRACE_SYS_EXIT_PROFILE(sname)
#define TRACE_SYS_EXIT_PROFILE_INIT(sname)
#endif

#ifdef CONFIG_FTRACE_SYSCALLS
#define __SC_STR_ADECL1(t, a) #a
#define __SC_STR_ADECL2(t, a, ...) #a, __SC_STR_ADECL1(__VA_ARGS__)
Expand All @@ -113,7 +160,6 @@ struct perf_counter_attr;
#define __SC_STR_TDECL5(t, a, ...) #t, __SC_STR_TDECL4(__VA_ARGS__)
#define __SC_STR_TDECL6(t, a, ...) #t, __SC_STR_TDECL5(__VA_ARGS__)


#define SYSCALL_TRACE_ENTER_EVENT(sname) \
static struct ftrace_event_call event_enter_##sname; \
struct trace_event enter_syscall_print_##sname = { \
Expand All @@ -134,6 +180,7 @@ struct perf_counter_attr;
init_preds(&event_enter_##sname); \
return 0; \
} \
TRACE_SYS_ENTER_PROFILE(sname); \
static struct ftrace_event_call __used \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_events"))) \
Expand All @@ -145,6 +192,7 @@ struct perf_counter_attr;
.regfunc = reg_event_syscall_enter, \
.unregfunc = unreg_event_syscall_enter, \
.data = "sys"#sname, \
TRACE_SYS_ENTER_PROFILE_INIT(sname) \
}

#define SYSCALL_TRACE_EXIT_EVENT(sname) \
Expand All @@ -167,6 +215,7 @@ struct perf_counter_attr;
init_preds(&event_exit_##sname); \
return 0; \
} \
TRACE_SYS_EXIT_PROFILE(sname); \
static struct ftrace_event_call __used \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_events"))) \
Expand All @@ -178,6 +227,7 @@ struct perf_counter_attr;
.regfunc = reg_event_syscall_exit, \
.unregfunc = unreg_event_syscall_exit, \
.data = "sys"#sname, \
TRACE_SYS_EXIT_PROFILE_INIT(sname) \
}

#define SYSCALL_METADATA(sname, nb) \
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7 changes: 7 additions & 0 deletions include/trace/syscall.h
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,13 @@ extern int reg_event_syscall_exit(void *ptr);
extern void unreg_event_syscall_exit(void *ptr);
enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags);
enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags);
#endif
#ifdef CONFIG_EVENT_PROFILE
int reg_prof_syscall_enter(char *name);
void unreg_prof_syscall_enter(char *name);
int reg_prof_syscall_exit(char *name);
void unreg_prof_syscall_exit(char *name);

#endif

#endif /* _TRACE_SYSCALL_H */
121 changes: 121 additions & 0 deletions kernel/trace/trace_syscalls.c
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#include <trace/syscall.h>
#include <linux/kernel.h>
#include <linux/ftrace.h>
#include <linux/perf_counter.h>
#include <asm/syscall.h>

#include "trace_output.h"
Expand Down Expand Up @@ -252,3 +253,123 @@ struct trace_event event_syscall_enter = {
struct trace_event event_syscall_exit = {
.trace = print_syscall_exit,
};

#ifdef CONFIG_EVENT_PROFILE
static DECLARE_BITMAP(enabled_prof_enter_syscalls, FTRACE_SYSCALL_MAX);
static DECLARE_BITMAP(enabled_prof_exit_syscalls, FTRACE_SYSCALL_MAX);
static int sys_prof_refcount_enter;
static int sys_prof_refcount_exit;

static void prof_syscall_enter(struct pt_regs *regs, long id)
{
struct syscall_metadata *sys_data;
int syscall_nr;

syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_prof_enter_syscalls))
return;

sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;

perf_tpcounter_event(sys_data->enter_id, 0, 1, NULL, 0);
}

int reg_prof_syscall_enter(char *name)
{
int ret = 0;
int num;

num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return -ENOSYS;

mutex_lock(&syscall_trace_lock);
if (!sys_prof_refcount_enter)
ret = register_trace_syscall_enter(prof_syscall_enter);
if (ret) {
pr_info("event trace: Could not activate"
"syscall entry trace point");
} else {
set_bit(num, enabled_prof_enter_syscalls);
sys_prof_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}

void unreg_prof_syscall_enter(char *name)
{
int num;

num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return;

mutex_lock(&syscall_trace_lock);
sys_prof_refcount_enter--;
clear_bit(num, enabled_prof_enter_syscalls);
if (!sys_prof_refcount_enter)
unregister_trace_syscall_enter(prof_syscall_enter);
mutex_unlock(&syscall_trace_lock);
}

static void prof_syscall_exit(struct pt_regs *regs, long ret)
{
struct syscall_metadata *sys_data;
int syscall_nr;

syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_prof_exit_syscalls))
return;

sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;

perf_tpcounter_event(sys_data->exit_id, 0, 1, NULL, 0);
}

int reg_prof_syscall_exit(char *name)
{
int ret = 0;
int num;

num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return -ENOSYS;

mutex_lock(&syscall_trace_lock);
if (!sys_prof_refcount_exit)
ret = register_trace_syscall_exit(prof_syscall_exit);
if (ret) {
pr_info("event trace: Could not activate"
"syscall entry trace point");
} else {
set_bit(num, enabled_prof_exit_syscalls);
sys_prof_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}

void unreg_prof_syscall_exit(char *name)
{
int num;

num = syscall_name_to_nr(name);
if (num < 0 || num >= FTRACE_SYSCALL_MAX)
return;

mutex_lock(&syscall_trace_lock);
sys_prof_refcount_exit--;
clear_bit(num, enabled_prof_exit_syscalls);
if (!sys_prof_refcount_exit)
unregister_trace_syscall_exit(prof_syscall_exit);
mutex_unlock(&syscall_trace_lock);
}

#endif


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