Re: [RFC] perf record: missing buildid for callstack modules
From: Peter Zijlstra
Date: Wed Jan 13 2016 - 07:40:51 EST
On Wed, Jan 13, 2016 at 11:21:07AM +0100, Ingo Molnar wrote:
>
> * Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> > > And this would (obviously) be a good time to see what else we'd like to
> > > stuff in there.
> >
> > Perhaps a version number? Else we'll be using those reserved bits again
> > when we decide to introduce MMAP4 ;-\
>
> No version numbers please. Cannot we have a size field and be done with it? The
> size is the 'version', if we only ever expand the record. (which is the typical
> case)
The current problem with that is that we use the 'remaining' size as
the length field for a string (with the PERF_RECORD_MMAP* records).
We could of course fix that no problem.
---
include/uapi/linux/perf_event.h | 27 ++++++++++++++++++++++++++-
kernel/events/core.c | 35 ++++++++++++++++++++++++-----------
2 files changed, 50 insertions(+), 12 deletions(-)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 1afe9623c1a7..b7b673387581 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -340,7 +340,8 @@ struct perf_event_attr {
comm_exec : 1, /* flag comm events that are due to an exec */
use_clockid : 1, /* use @clockid for time fields */
context_switch : 1, /* context switch data */
- __reserved_1 : 37;
+ mmap3 : 1, /* include mmap with mtime */
+ __reserved_1 : 36;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -856,6 +857,30 @@ enum perf_event_type {
*/
PERF_RECORD_SWITCH_CPU_WIDE = 15,
+ /*
+ * The MMAP3 records are an augmented version of MMAP2, they add
+ * mtime and filename_len, allowing for size based extensions.
+ *
+ * struct {
+ * struct perf_event_header header;
+ *
+ * u32 pid, tid;
+ * u64 addr;
+ * u64 len;
+ * u64 pgoff;
+ * u32 maj;
+ * u32 min;
+ * u64 ino;
+ * u64 ino_generation;
+ * u32 prot, flags;
+ * u64 mtime;
+ * u32 filename_len;
+ * char filename[2+];
+ * struct sample_id sample_id;
+ * }
+ */
+ PERF_RECORD_MMAP3 = 16,
+
PERF_RECORD_MAX, /* non-ABI */
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index bf8244190d0f..1cf15793f96c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5661,7 +5661,7 @@ perf_event_aux(perf_event_aux_output_cb output, void *data,
/*
* task tracking -- fork/exit
*
- * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap_data | attr.task
+ * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap3 | attr.mmap_data | attr.task
*/
struct perf_task_event {
@@ -5682,8 +5682,8 @@ struct perf_task_event {
static int perf_event_task_match(struct perf_event *event)
{
return event->attr.comm || event->attr.mmap ||
- event->attr.mmap2 || event->attr.mmap_data ||
- event->attr.task;
+ event->attr.mmap2 || event->attr.mmap3 ||
+ event->attr.mmap_data || event->attr.task;
}
static void perf_event_task_output(struct perf_event *event,
@@ -5867,11 +5867,12 @@ struct perf_mmap_event {
struct vm_area_struct *vma;
const char *file_name;
- int file_size;
+ u32 file_size;
int maj, min;
u64 ino;
u64 ino_generation;
u32 prot, flags;
+ u64 mtime;
struct {
struct perf_event_header header;
@@ -5892,11 +5893,10 @@ static int perf_event_mmap_match(struct perf_event *event,
int executable = vma->vm_flags & VM_EXEC;
return (!executable && event->attr.mmap_data) ||
- (executable && (event->attr.mmap || event->attr.mmap2));
+ (executable && (event->attr.mmap || event->attr.mmap2 || event->attr.mmap3));
}
-static void perf_event_mmap_output(struct perf_event *event,
- void *data)
+static void perf_event_mmap_output(struct perf_event *event, void *data)
{
struct perf_mmap_event *mmap_event = data;
struct perf_output_handle handle;
@@ -5907,7 +5907,7 @@ static void perf_event_mmap_output(struct perf_event *event,
if (!perf_event_mmap_match(event, data))
return;
- if (event->attr.mmap2) {
+ if (event->attr.mmap2 || event->attr.mmap3) {
mmap_event->event_id.header.type = PERF_RECORD_MMAP2;
mmap_event->event_id.header.size += sizeof(mmap_event->maj);
mmap_event->event_id.header.size += sizeof(mmap_event->min);
@@ -5916,6 +5916,11 @@ static void perf_event_mmap_output(struct perf_event *event,
mmap_event->event_id.header.size += sizeof(mmap_event->prot);
mmap_event->event_id.header.size += sizeof(mmap_event->flags);
}
+ if (event->attr.mmap3) {
+ mmap_event->event_id.header.type = PERF_RECORD_MMAP3;
+ mmap_event->event_id.header.size += sizeof(mmap_event->mtime);
+ mmap_event->event_id.header.size += sizeof(mmap_event->file_size);
+ }
perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
ret = perf_output_begin(&handle, event,
@@ -5928,7 +5933,7 @@ static void perf_event_mmap_output(struct perf_event *event,
perf_output_put(&handle, mmap_event->event_id);
- if (event->attr.mmap2) {
+ if (event->attr.mmap2 || event->attr.mmap3) {
perf_output_put(&handle, mmap_event->maj);
perf_output_put(&handle, mmap_event->min);
perf_output_put(&handle, mmap_event->ino);
@@ -5936,6 +5941,10 @@ static void perf_event_mmap_output(struct perf_event *event,
perf_output_put(&handle, mmap_event->prot);
perf_output_put(&handle, mmap_event->flags);
}
+ if (event->attr.mmap3) {
+ perf_output_put(&handle, mmap_event->mtime);
+ perf_output_put(&handle, mmap_event->file_size);
+ }
__output_copy(&handle, mmap_event->file_name,
mmap_event->file_size);
@@ -5954,8 +5963,9 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
int maj = 0, min = 0;
u64 ino = 0, gen = 0;
u32 prot = 0, flags = 0;
+ u64 mtime = 0;
unsigned int size;
- char tmp[16];
+ char tmp[18];
char *buf = NULL;
char *name;
@@ -5984,6 +5994,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
gen = inode->i_generation;
maj = MAJOR(dev);
min = MINOR(dev);
+ mtime = timespec_to_ns(&inode->i_mtime);
if (vma->vm_flags & VM_READ)
prot |= PROT_READ;
@@ -6043,7 +6054,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
* zero'd out to avoid leaking random bits to userspace.
*/
size = strlen(name)+1;
- while (!IS_ALIGNED(size, sizeof(u64)))
+ while (!IS_ALIGNED(2+size, sizeof(u64)))
name[size++] = '\0';
mmap_event->file_name = name;
@@ -6054,6 +6065,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
mmap_event->ino_generation = gen;
mmap_event->prot = prot;
mmap_event->flags = flags;
+ mmap_event->mtime = mtime;
if (!(vma->vm_flags & VM_EXEC))
mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA;
@@ -6096,6 +6108,7 @@ void perf_event_mmap(struct vm_area_struct *vma)
/* .ino_generation (attr_mmap2 only) */
/* .prot (attr_mmap2 only) */
/* .flags (attr_mmap2 only) */
+ /* .mtime (attr_mmap3 only) */
};
perf_event_mmap_event(&mmap_event);