linux/kernel/trace/trace_syscalls.c

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tracing/syscalls: use a dedicated file header Impact: fix build warnings and possibe compat misbehavior on IA64 Building a kernel on ia64 might trigger these ugly build warnings: CC arch/ia64/ia32/sys_ia32.o In file included from arch/ia64/ia32/sys_ia32.c:55: arch/ia64/ia32/ia32priv.h:290:1: warning: "elf_check_arch" redefined In file included from include/linux/elf.h:7, from include/linux/module.h:14, from include/linux/ftrace.h:8, from include/linux/syscalls.h:68, from arch/ia64/ia32/sys_ia32.c:18: arch/ia64/include/asm/elf.h:19:1: warning: this is the location of the previous definition [...] sys_ia32.c includes linux/syscalls.h which in turn includes linux/ftrace.h to import the syscalls tracing prototypes. But including ftrace.h can pull too much things for a low level file, especially on ia64 where the ia32 private headers conflict with higher level headers. Now we isolate the syscall tracing headers in their own lightweight file. Reported-by: Tony Luck <tony.luck@intel.com> Tested-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Jason Baron <jbaron@redhat.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Jiaying Zhang <jiayingz@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: Martin Bligh <mbligh@google.com> Cc: Michael Davidson <md@google.com> LKML-Reference: <20090408184058.GB6017@nowhere> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-08 18:40:59 +00:00
#include <trace/syscall.h>
#include <linux/kernel.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);
/* Option to display the parameters types */
enum {
TRACE_SYSCALLS_OPT_TYPES = 0x1,
};
static struct tracer_opt syscalls_opts[] = {
{ TRACER_OPT(syscall_arg_type, TRACE_SYSCALLS_OPT_TYPES) },
{ }
};
static struct tracer_flags syscalls_flags = {
.val = 0, /* By default: no parameters types */
.opts = syscalls_opts
};
enum print_line_t
print_syscall_enter(struct trace_iterator *iter, int flags)
{
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_assign_type(trace, ent);
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry)
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 (syscalls_flags.val & TRACE_SYSCALLS_OPT_TYPES) {
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;
}
end:
trace_seq_printf(s, "\n");
return TRACE_TYPE_HANDLED;
}
enum print_line_t
print_syscall_exit(struct trace_iterator *iter, int flags)
{
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_assign_type(trace, ent);
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry) {
trace_seq_printf(s, "\n");
return TRACE_TYPE_HANDLED;
}
ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
trace->ret);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
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;
arch_init_ftrace_syscalls();
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)
{
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
int size;
int syscall_nr;
syscall_nr = syscall_get_nr(current, regs);
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_ENTER, size,
0, 0);
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);
trace_current_buffer_unlock_commit(event, 0, 0);
trace_wake_up();
}
void ftrace_syscall_exit(struct pt_regs *regs)
{
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
int syscall_nr;
syscall_nr = syscall_get_nr(current, regs);
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_EXIT,
sizeof(*entry), 0, 0);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);
trace_current_buffer_unlock_commit(event, 0, 0);
trace_wake_up();
}
static int init_syscall_tracer(struct trace_array *tr)
{
start_ftrace_syscalls();
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);
}
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);
}
device_initcall(register_ftrace_syscalls);