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tracing: Make syscall events suitable for multiple buffers
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Currently the syscall events record into the global buffer. But if
multiple buffers are in place, then we need to have syscall events
record in the proper buffers.

By adding descriptors to pass to the syscall event functions, the
syscall events can now record into the buffers that have been assigned
to them (one event may be applied to mulitple buffers).

This will allow tracing high volume syscalls along with seldom occurring
syscalls without losing the seldom syscall events.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt authored and Steven Rostedt committed Mar 15, 2013
1 parent a7603ff commit 12ab74e
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Showing 2 changed files with 57 additions and 34 deletions.
11 changes: 11 additions & 0 deletions kernel/trace/trace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,11 @@
#include <linux/trace_seq.h>
#include <linux/ftrace_event.h>

#ifdef CONFIG_FTRACE_SYSCALLS
#include <asm/unistd.h> /* For NR_SYSCALLS */
#include <asm/syscall.h> /* some archs define it here */
#endif

enum trace_type {
__TRACE_FIRST_TYPE = 0,

Expand Down Expand Up @@ -173,6 +178,12 @@ struct trace_array {
int cpu;
int buffer_disabled;
struct trace_cpu trace_cpu; /* place holder */
#ifdef CONFIG_FTRACE_SYSCALLS
int sys_refcount_enter;
int sys_refcount_exit;
DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
#endif
int stop_count;
int clock_id;
struct tracer *current_trace;
Expand Down
80 changes: 46 additions & 34 deletions kernel/trace/trace_syscalls.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,6 @@
#include "trace.h"

static DEFINE_MUTEX(syscall_trace_lock);
static int sys_refcount_enter;
static int sys_refcount_exit;
static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);

static int syscall_enter_register(struct ftrace_event_call *event,
enum trace_reg type, void *data);
Expand Down Expand Up @@ -303,8 +299,9 @@ static int syscall_exit_define_fields(struct ftrace_event_call *call)
return ret;
}

static void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
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;
Expand All @@ -315,7 +312,7 @@ static void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_enter_syscalls))
if (!test_bit(syscall_nr, tr->enabled_enter_syscalls))
return;

sys_data = syscall_nr_to_meta(syscall_nr);
Expand All @@ -324,7 +321,8 @@ static void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)

size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;

event = trace_current_buffer_lock_reserve(&buffer,
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->enter_event->event.type, size, 0, 0);
if (!event)
return;
Expand All @@ -338,8 +336,9 @@ static void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
trace_current_buffer_unlock_commit(buffer, event, 0, 0);
}

static void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
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;
Expand All @@ -349,14 +348,15 @@ static void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_exit_syscalls))
if (!test_bit(syscall_nr, tr->enabled_exit_syscalls))
return;

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

event = trace_current_buffer_lock_reserve(&buffer,
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
if (!event)
return;
Expand All @@ -370,71 +370,79 @@ static void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
trace_current_buffer_unlock_commit(buffer, event, 0, 0);
}

static int reg_event_syscall_enter(struct ftrace_event_call *call)
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 (!sys_refcount_enter)
ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
if (!tr->sys_refcount_enter)
ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
if (!ret) {
set_bit(num, enabled_enter_syscalls);
sys_refcount_enter++;
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_call *call)
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);
sys_refcount_enter--;
clear_bit(num, enabled_enter_syscalls);
if (!sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
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_call *call)
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 (!sys_refcount_exit)
ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
if (!tr->sys_refcount_exit)
ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
if (!ret) {
set_bit(num, enabled_exit_syscalls);
sys_refcount_exit++;
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_call *call)
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);
sys_refcount_exit--;
clear_bit(num, enabled_exit_syscalls);
if (!sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
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);
}

Expand Down Expand Up @@ -685,11 +693,13 @@ static void perf_sysexit_disable(struct ftrace_event_call *call)
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(event);
return reg_event_syscall_enter(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_enter(event);
unreg_event_syscall_enter(file, event);
return 0;

#ifdef CONFIG_PERF_EVENTS
Expand All @@ -711,11 +721,13 @@ static int syscall_enter_register(struct ftrace_event_call *event,
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(event);
return reg_event_syscall_exit(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_exit(event);
unreg_event_syscall_exit(file, event);
return 0;

#ifdef CONFIG_PERF_EVENTS
Expand Down

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