From 73c17d815000e425aea108226bcb57491a04f534 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 6 Oct 2017 10:46:01 -0300
Subject: perf mmap: Adopt push method from builtin-record.c

The previous prep patch was just to show exactly what changed in that
function, now its time to move that method and things only it uses to
the right place, mmap.[ch]

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-aaxywfgw3d44x6xlu8zm1avu@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/mmap.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

(limited to 'tools/perf/util/mmap.c')

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index dfc4a007f2c6..9fe5f9c7d577 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -8,6 +8,9 @@
  */
 
 #include <sys/mman.h>
+#include <inttypes.h>
+#include <asm/bug.h>
+#include "debug.h"
 #include "event.h"
 #include "mmap.h"
 #include "util.h" /* page_size */
@@ -250,3 +253,100 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
 
 	return 0;
 }
+
+static int backward_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
+{
+	struct perf_event_header *pheader;
+	u64 evt_head = head;
+	int size = mask + 1;
+
+	pr_debug2("backward_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
+	pheader = (struct perf_event_header *)(buf + (head & mask));
+	*start = head;
+	while (true) {
+		if (evt_head - head >= (unsigned int)size) {
+			pr_debug("Finished reading backward ring buffer: rewind\n");
+			if (evt_head - head > (unsigned int)size)
+				evt_head -= pheader->size;
+			*end = evt_head;
+			return 0;
+		}
+
+		pheader = (struct perf_event_header *)(buf + (evt_head & mask));
+
+		if (pheader->size == 0) {
+			pr_debug("Finished reading backward ring buffer: get start\n");
+			*end = evt_head;
+			return 0;
+		}
+
+		evt_head += pheader->size;
+		pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
+	}
+	WARN_ONCE(1, "Shouldn't get here\n");
+	return -1;
+}
+
+static int rb_find_range(void *data, int mask, u64 head, u64 old,
+			 u64 *start, u64 *end, bool backward)
+{
+	if (!backward) {
+		*start = old;
+		*end = head;
+		return 0;
+	}
+
+	return backward_rb_find_range(data, mask, head, start, end);
+}
+
+int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool backward,
+		    void *to, int push(void *to, void *buf, size_t size))
+{
+	u64 head = perf_mmap__read_head(md);
+	u64 old = md->prev;
+	u64 end = head, start = old;
+	unsigned char *data = md->base + page_size;
+	unsigned long size;
+	void *buf;
+	int rc = 0;
+
+	if (rb_find_range(data, md->mask, head, old, &start, &end, backward))
+		return -1;
+
+	if (start == end)
+		return 0;
+
+	size = end - start;
+	if (size > (unsigned long)(md->mask) + 1) {
+		WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
+
+		md->prev = head;
+		perf_mmap__consume(md, overwrite || backward);
+		return 0;
+	}
+
+	if ((start & md->mask) + size != (end & md->mask)) {
+		buf = &data[start & md->mask];
+		size = md->mask + 1 - (start & md->mask);
+		start += size;
+
+		if (push(to, buf, size) < 0) {
+			rc = -1;
+			goto out;
+		}
+	}
+
+	buf = &data[start & md->mask];
+	size = end - start;
+	start += size;
+
+	if (push(to, buf, size) < 0) {
+		rc = -1;
+		goto out;
+	}
+
+	md->prev = head;
+	perf_mmap__consume(md, overwrite || backward);
+out:
+	return rc;
+}
-- 
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