[PATCH v1 1/2] perf: add attr->mmap2 attribute to an event

[Stephane Eranian <eranian@google.com>]

Adds a new PERF_RECORD_MMAP2 record type.

Used to request mmap records with more information about
the mapping, including device major, minor and the inode
number for mappings associated with files or shared memory
segments. Works for code and data (with attr->mmap_data set).

Existing PERF_RECORD_MMAP record is unmodified by this patch.

Signed-off-by: Stephane Eranian <eranian@google.com>
---
 include/uapi/linux/perf_event.h |   22 ++++++++++++++++++++-
 kernel/events/core.c            |   41 +++++++++++++++++++++++++++++++++++----
 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d80d223..1eec8f5 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -275,8 +275,9 @@ struct perf_event_attr {
 
 				exclude_callchain_kernel : 1, /* exclude kernel callchains */
 				exclude_callchain_user   : 1, /* exclude user callchains */
+				mmap2          :  1, /* include mmap with inode data     */
 
-				__reserved_1   : 41;
+				__reserved_1   : 40;
 
 	union {
 		__u32		wakeup_events;	  /* wakeup every n events */
@@ -638,6 +639,25 @@ enum perf_event_type {
 	 */
 	PERF_RECORD_SAMPLE			= 9,
 
+	/*
+	 * The MMAP2 records are an augmented version of MMAP, they add
+	 * maj, min, ino numbers to be used to uniquely identify each mapping
+	 *
+	 * struct {
+	 *	struct perf_event_header	header;
+	 *
+	 *	u32				pid, tid;
+	 *	u64				addr;
+	 *	u64				len;
+	 *	u64				pgoff;
+	 *	u32				maj;
+	 *	u32				min;
+	 *	u64				ino;
+	 *	char				filename[];
+	 * };
+	 */
+	PERF_RECORD_MMAP2			= 10,
+
 	PERF_RECORD_MAX,			/* non-ABI */
 };
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e82e700..838a0bb 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4771,7 +4771,7 @@ perf_event_aux(perf_event_aux_output_cb output, void *data,
 /*
  * task tracking -- fork/exit
  *
- * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
+ * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap_data | attr.task
  */
 
 struct perf_task_event {
@@ -4791,8 +4791,9 @@ struct perf_task_event {
 
 static int perf_event_task_match(struct perf_event *event)
 {
-	return event->attr.comm || event->attr.mmap ||
-	       event->attr.mmap_data || event->attr.task;
+	return event->attr.comm  || event->attr.mmap ||
+	       event->attr.mmap2 || event->attr.mmap_data ||
+	       event->attr.task;
 }
 
 static void perf_event_task_output(struct perf_event *event,
@@ -4987,6 +4988,8 @@ struct perf_mmap_event {
 
 	const char		*file_name;
 	int			file_size;
+	int			maj, min;
+	u64			ino;
 
 	struct {
 		struct perf_event_header	header;
@@ -5007,7 +5010,7 @@ 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);
+	       (executable && (event->attr.mmap || event->attr.mmap2));
 }
 
 static void perf_event_mmap_output(struct perf_event *event,
@@ -5022,6 +5025,13 @@ static void perf_event_mmap_output(struct perf_event *event,
 	if (!perf_event_mmap_match(event, data))
 		return;
 
+	if (event->attr.mmap2) {
+		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);
+		mmap_event->event_id.header.size += sizeof(mmap_event->ino);
+	}
+
 	perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
 	ret = perf_output_begin(&handle, event,
 				mmap_event->event_id.header.size);
@@ -5032,6 +5042,13 @@ static void perf_event_mmap_output(struct perf_event *event,
 	mmap_event->event_id.tid = perf_event_tid(event, current);
 
 	perf_output_put(&handle, mmap_event->event_id);
+
+	if (event->attr.mmap2) {
+		perf_output_put(&handle, mmap_event->maj);
+		perf_output_put(&handle, mmap_event->min);
+		perf_output_put(&handle, mmap_event->ino);
+	}
+
 	__output_copy(&handle, mmap_event->file_name,
 				   mmap_event->file_size);
 
@@ -5046,6 +5063,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 {
 	struct vm_area_struct *vma = mmap_event->vma;
 	struct file *file = vma->vm_file;
+	int maj = 0, min = 0;
+	u64 ino = 0;
 	unsigned int size;
 	char tmp[16];
 	char *buf = NULL;
@@ -5054,6 +5073,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 	memset(tmp, 0, sizeof(tmp));
 
 	if (file) {
+		struct inode *inode;
+		dev_t dev;
 		/*
 		 * d_path works from the end of the rb backwards, so we
 		 * need to add enough zero bytes after the string to handle
@@ -5069,6 +5090,12 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 			name = strncpy(tmp, "//toolong", sizeof(tmp));
 			goto got_name;
 		}
+		inode = file_inode(vma->vm_file);
+		dev = inode->i_sb->s_dev;
+		ino = inode->i_ino;
+		maj = MAJOR(dev);
+		min = MINOR(dev);
+
 	} else {
 		if (arch_vma_name(mmap_event->vma)) {
 			name = strncpy(tmp, arch_vma_name(mmap_event->vma),
@@ -5099,6 +5126,9 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 
 	mmap_event->file_name = name;
 	mmap_event->file_size = size;
+	mmap_event->maj = maj;
+	mmap_event->min = min;
+	mmap_event->ino = ino;
 
 	if (!(vma->vm_flags & VM_EXEC))
 		mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA;
@@ -5135,6 +5165,9 @@ void perf_event_mmap(struct vm_area_struct *vma)
 			.len    = vma->vm_end - vma->vm_start,
 			.pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
 		},
+		/* .maj (attr_mmap2 only) */
+		/* .min (attr_mmap2 only) */
+		/* .ino (attr_mmap2 only) */
 	};
 
 	perf_event_mmap_event(&mmap_event);
-- 
1.7.9.5