perf events: Separate the routines handling the PERF_SAMPLE_ identity fields

Those will be made available in sample like events like MMAP, EXEC, etc in a
followup patch. So precalculate the extra id header space and have a separate
routine to fill them up.

V2: Thomas noticed that the id header needs to be precalculated at
inherit_events too:

LKML-Reference: <alpine.LFD.2.00.1012031245220.2653@localhost6.localdomain6>

Tested-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ian Munsie <imunsie@au1.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1291318772-30880-2-git-send-email-acme@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 75 insertions, 54 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 7961b27aceea..a04799769566 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -133,6 +133,28 @@ static void unclone_ctx(struct perf_event_context *ctx)
         }
 }
 
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_tgid_nr_ns(p, event->ns);
+}
+
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_pid_nr_ns(p, event->ns);
+}
+
 /*
  * If we inherit events we want to return the parent event id
  * to userspace.
@@ -351,15 +373,30 @@ static void perf_event__header_size(struct perf_event *event)
         if (sample_type & PERF_SAMPLE_IP)
                 size += sizeof(data->ip);
 
+        if (sample_type & PERF_SAMPLE_ADDR)
+                size += sizeof(data->addr);
+
+        if (sample_type & PERF_SAMPLE_PERIOD)
+                size += sizeof(data->period);
+
+        if (sample_type & PERF_SAMPLE_READ)
+                size += event->read_size;
+
+        event->header_size = size;
+}
+
+static void perf_event__id_header_size(struct perf_event *event)
+{
+        struct perf_sample_data *data;
+        u64 sample_type = event->attr.sample_type;
+        u16 size = 0;
+
         if (sample_type & PERF_SAMPLE_TID)
                 size += sizeof(data->tid_entry);
 
         if (sample_type & PERF_SAMPLE_TIME)
                 size += sizeof(data->time);
 
-        if (sample_type & PERF_SAMPLE_ADDR)
-                size += sizeof(data->addr);
-
         if (sample_type & PERF_SAMPLE_ID)
                 size += sizeof(data->id);
 
@@ -369,13 +406,7 @@ static void perf_event__header_size(struct perf_event *event)
         if (sample_type & PERF_SAMPLE_CPU)
                 size += sizeof(data->cpu_entry);
 
-        if (sample_type & PERF_SAMPLE_PERIOD)
-                size += sizeof(data->period);
-
-        if (sample_type & PERF_SAMPLE_READ)
-                size += event->read_size;
-
-        event->header_size = size;
+        event->id_header_size = size;
 }
 
 static void perf_group_attach(struct perf_event *event)
@@ -3357,6 +3388,36 @@ __always_inline void perf_output_copy(struct perf_output_handle *handle,
         } while (len);
 }
 
+static void perf_event_header__init_id(struct perf_event_header *header,
+                                       struct perf_sample_data *data,
+                                       struct perf_event *event)
+{
+        u64 sample_type = event->attr.sample_type;
+
+        data->type = sample_type;
+        header->size += event->id_header_size;
+
+        if (sample_type & PERF_SAMPLE_TID) {
+                /* namespace issues */
+                data->tid_entry.pid = perf_event_pid(event, current);
+                data->tid_entry.tid = perf_event_tid(event, current);
+        }
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                data->time = perf_clock();
+
+        if (sample_type & PERF_SAMPLE_ID)
+                data->id = primary_event_id(event);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                data->stream_id = event->id;
+
+        if (sample_type & PERF_SAMPLE_CPU) {
+                data->cpu_entry.cpu      = raw_smp_processor_id();
+                data->cpu_entry.reserved = 0;
+        }
+}
+
 int perf_output_begin(struct perf_output_handle *handle,
                       struct perf_event *event, unsigned int size,
                       int nmi, int sample)
@@ -3459,28 +3520,6 @@ void perf_output_end(struct perf_output_handle *handle)
         rcu_read_unlock();
 }
 
-static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
-{
-        /*
-         * only top level events have the pid namespace they were created in
-         */
-        if (event->parent)
-                event = event->parent;
-
-        return task_tgid_nr_ns(p, event->ns);
-}
-
-static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
-{
-        /*
-         * only top level events have the pid namespace they were created in
-         */
-        if (event->parent)
-                event = event->parent;
-
-        return task_pid_nr_ns(p, event->ns);
-}
-
 static void perf_output_read_one(struct perf_output_handle *handle,
                                  struct perf_event *event,
                                  u64 enabled, u64 running)
@@ -3655,37 +3694,17 @@ void perf_prepare_sample(struct perf_event_header *header,
 {
         u64 sample_type = event->attr.sample_type;
 
-        data->type = sample_type;
-
         header->type = PERF_RECORD_SAMPLE;
         header->size = sizeof(*header) + event->header_size;
 
         header->misc = 0;
         header->misc |= perf_misc_flags(regs);
 
+        perf_event_header__init_id(header, data, event);
+
         if (sample_type & PERF_SAMPLE_IP)
                 data->ip = perf_instruction_pointer(regs);
 
-        if (sample_type & PERF_SAMPLE_TID) {
-                /* namespace issues */
-                data->tid_entry.pid = perf_event_pid(event, current);
-                data->tid_entry.tid = perf_event_tid(event, current);
-        }
-
-        if (sample_type & PERF_SAMPLE_TIME)
-                data->time = perf_clock();
-
-        if (sample_type & PERF_SAMPLE_ID)
-                data->id = primary_event_id(event);
-
-        if (sample_type & PERF_SAMPLE_STREAM_ID)
-                data->stream_id = event->id;
-
-        if (sample_type & PERF_SAMPLE_CPU) {
-                data->cpu_entry.cpu             = raw_smp_processor_id();
-                data->cpu_entry.reserved        = 0;
-        }
-
         if (sample_type & PERF_SAMPLE_CALLCHAIN) {
                 int size = 1;
 
@@ -5745,6 +5764,7 @@ SYSCALL_DEFINE5(perf_event_open,
          * Precalculate sample_data sizes
          */
         perf_event__header_size(event);
+        perf_event__id_header_size(event);
 
         /*
          * Drop the reference on the group_event after placing the
@@ -6102,6 +6122,7 @@ inherit_event(struct perf_event *parent_event,
          * Precalculate sample_data sizes
          */
         perf_event__header_size(child_event);
+        perf_event__id_header_size(child_event);
 
         /*
          * Link it up in the child's context: