1 files changed, 250 insertions, 0 deletions

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
new file mode 100644
index 000000000000..a2a3af29c943
--- /dev/null
+++ b/kernel/trace/trace_syscalls.c
@@ -0,0 +1,250 @@
+#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);
+
+/* 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);