Merge branch 'perfcounters-rename-for-linus' of git://git.kernel.org/pub/scm/linux...

[pandora-kernel.git] / kernel / trace / trace_syscalls.c

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 233f348..9fbce6c 100644 (file)
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -384,10 +384,13 @@ static int sys_prof_refcount_exit;
 
 static void prof_syscall_enter(struct pt_regs *regs, long id)
 {
-       struct syscall_trace_enter *rec;
        struct syscall_metadata *sys_data;
+       struct syscall_trace_enter *rec;
+       unsigned long flags;
+       char *raw_data;
        int syscall_nr;
        int size;
+       int cpu;
 
        syscall_nr = syscall_get_nr(current, regs);
        if (!test_bit(syscall_nr, enabled_prof_enter_syscalls))
@@ -402,20 +405,38 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
        size = ALIGN(size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
 
-       do {
-               char raw_data[size];
+       if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+                     "profile buffer not large enough"))
+               return;
+
+       /* Protect the per cpu buffer, begin the rcu read side */
+       local_irq_save(flags);
 
-               /* zero the dead bytes from align to not leak stack to user */
-               *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+       cpu = smp_processor_id();
+
+       if (in_nmi())
+               raw_data = rcu_dereference(trace_profile_buf_nmi);
+       else
+               raw_data = rcu_dereference(trace_profile_buf);
+
+       if (!raw_data)
+               goto end;
 
-               rec = (struct syscall_trace_enter *) raw_data;
-               tracing_generic_entry_update(&rec->ent, 0, 0);
-               rec->ent.type = sys_data->enter_id;
-               rec->nr = syscall_nr;
-               syscall_get_arguments(current, regs, 0, sys_data->nb_args,
-                                      (unsigned long *)&rec->args);
-               perf_tp_event(sys_data->enter_id, 0, 1, rec, size);
-       } while(0);
+       raw_data = per_cpu_ptr(raw_data, cpu);
+
+       /* zero the dead bytes from align to not leak stack to user */
+       *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+
+       rec = (struct syscall_trace_enter *) raw_data;
+       tracing_generic_entry_update(&rec->ent, 0, 0);
+       rec->ent.type = sys_data->enter_id;
+       rec->nr = syscall_nr;
+       syscall_get_arguments(current, regs, 0, sys_data->nb_args,
+                              (unsigned long *)&rec->args);
+       perf_tp_event(sys_data->enter_id, 0, 1, rec, size);
+
+end:
+       local_irq_restore(flags);
 }
 
 int reg_prof_syscall_enter(char *name)
@@ -460,8 +481,12 @@ void unreg_prof_syscall_enter(char *name)
 static void prof_syscall_exit(struct pt_regs *regs, long ret)
 {
        struct syscall_metadata *sys_data;
-       struct syscall_trace_exit rec;
+       struct syscall_trace_exit *rec;
+       unsigned long flags;
        int syscall_nr;
+       char *raw_data;
+       int size;
+       int cpu;
 
        syscall_nr = syscall_get_nr(current, regs);
        if (!test_bit(syscall_nr, enabled_prof_exit_syscalls))
@@ -471,12 +496,46 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
        if (!sys_data)
                return;
 
-       tracing_generic_entry_update(&rec.ent, 0, 0);
-       rec.ent.type = sys_data->exit_id;
-       rec.nr = syscall_nr;
-       rec.ret = syscall_get_return_value(current, regs);
+       /* We can probably do that at build time */
+       size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
+       size -= sizeof(u32);
 
-       perf_tp_event(sys_data->exit_id, 0, 1, &rec, sizeof(rec));
+       /*
+        * Impossible, but be paranoid with the future
+        * How to put this check outside runtime?
+        */
+       if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+               "exit event has grown above profile buffer size"))
+               return;
+
+       /* Protect the per cpu buffer, begin the rcu read side */
+       local_irq_save(flags);
+       cpu = smp_processor_id();
+
+       if (in_nmi())
+               raw_data = rcu_dereference(trace_profile_buf_nmi);
+       else
+               raw_data = rcu_dereference(trace_profile_buf);
+
+       if (!raw_data)
+               goto end;
+
+       raw_data = per_cpu_ptr(raw_data, cpu);
+
+       /* zero the dead bytes from align to not leak stack to user */
+       *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+
+       rec = (struct syscall_trace_exit *)raw_data;
+
+       tracing_generic_entry_update(&rec->ent, 0, 0);
+       rec->ent.type = sys_data->exit_id;
+       rec->nr = syscall_nr;
+       rec->ret = syscall_get_return_value(current, regs);
+
+       perf_tp_event(sys_data->exit_id, 0, 1, rec, size);
+
+end:
+       local_irq_restore(flags);
 }
 
 int reg_prof_syscall_exit(char *name)