perf tools: Support 'srccode' output

When looking at PT or brstackinsn traces with 'perf script' it can be
very useful to see the source code. This adds a simple facility to print
them with 'perf script', if the information is available through dwarf

  % perf record ...
  % perf script -F insn,ip,sym,srccode
  ...

            4004c6 main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004c6 main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004b3 main
  6                       v++;

  % perf record -b ...
  % perf script -F insn,ip,sym,srccode,brstackinsn

  ...
         main+22:
          0000000000400543        insn: e8 ca ff ff ff            # PRED
  |18                     f1();
          f1:
          0000000000400512        insn: 55
  |10       {
          0000000000400513        insn: 48 89 e5
          0000000000400516        insn: b8 00 00 00 00
  |11             f2();
          000000000040051b        insn: e8 d6 ff ff ff            # PRED
          f2:
          00000000004004f6        insn: 55
  |5        {
          00000000004004f7        insn: 48 89 e5
          00000000004004fa        insn: 8b 05 2c 0b 20 00
  |6              c = a / b;
          0000000000400500        insn: 8b 0d 2a 0b 20 00
          0000000000400506        insn: 99
          0000000000400507        insn: f7 f9
          0000000000400509        insn: 89 05 29 0b 20 00
          000000000040050f        insn: 90
  |7        }
          0000000000400510        insn: 5d
          0000000000400511        insn: c3                        # PRED
          f1+14:
          0000000000400520        insn: b8 00 00 00 00
  |12             f2();
          0000000000400525        insn: e8 cc ff ff ff            # PRED
          f2:
          00000000004004f6        insn: 55
  |5        {
          00000000004004f7        insn: 48 89 e5
          00000000004004fa        insn: 8b 05 2c 0b 20 00
  |6              c = a / b;

Not supported for callchains currently, would need some layout changes
there.

Committer notes:

Fixed the build on Alpine Linux (3.4 .. 3.8) by addressing this
warning:

  In file included from util/srccode.c:19:0:
  /usr/include/sys/fcntl.h:1:2: error: #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h> [-Werror=cpp]
   #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h>
    ^~~~~~~
  cc1: all warnings being treated as errors

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20181204001848.24769-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 186 insertions, 0 deletions

diff --git a/tools/perf/util/srccode.c b/tools/perf/util/srccode.c
new file mode 100644
index 000000000000..fcc8630f6dff
--- /dev/null
+++ b/tools/perf/util/srccode.c
@@ -0,0 +1,186 @@
+/*
+ * Manage printing of source lines
+ * Copyright (c) 2017, Intel Corporation.
+ * Author: Andi Kleen
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include "linux/list.h"
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include <string.h>
+#include "srccode.h"
+#include "debug.h"
+#include "util.h"
+
+#define MAXSRCCACHE (32*1024*1024)
+#define MAXSRCFILES     64
+#define SRC_HTAB_SZ	64
+
+struct srcfile {
+	struct hlist_node hash_nd;
+	struct list_head nd;
+	char *fn;
+	char **lines;
+	char *map;
+	unsigned numlines;
+	size_t maplen;
+};
+
+static struct hlist_head srcfile_htab[SRC_HTAB_SZ];
+static LIST_HEAD(srcfile_list);
+static long map_total_sz;
+static int num_srcfiles;
+
+static unsigned shash(unsigned char *s)
+{
+	unsigned h = 0;
+	while (*s)
+		h = 65599 * h + *s++;
+	return h ^ (h >> 16);
+}
+
+static int countlines(char *map, int maplen)
+{
+	int numl;
+	char *end = map + maplen;
+	char *p = map;
+
+	if (maplen == 0)
+		return 0;
+	numl = 0;
+	while (p < end && (p = memchr(p, '\n', end - p)) != NULL) {
+		numl++;
+		p++;
+	}
+	if (p < end)
+		numl++;
+	return numl;
+}
+
+static void fill_lines(char **lines, int maxline, char *map, int maplen)
+{
+	int l;
+	char *end = map + maplen;
+	char *p = map;
+
+	if (maplen == 0 || maxline == 0)
+		return;
+	l = 0;
+	lines[l++] = map;
+	while (p < end && (p = memchr(p, '\n', end - p)) != NULL) {
+		if (l >= maxline)
+			return;
+		lines[l++] = ++p;
+	}
+	if (p < end)
+		lines[l] = p;
+}
+
+static void free_srcfile(struct srcfile *sf)
+{
+	list_del(&sf->nd);
+	hlist_del(&sf->hash_nd);
+	map_total_sz -= sf->maplen;
+	munmap(sf->map, sf->maplen);
+	free(sf->lines);
+	free(sf->fn);
+	free(sf);
+	num_srcfiles--;
+}
+
+static struct srcfile *find_srcfile(char *fn)
+{
+	struct stat st;
+	struct srcfile *h;
+	int fd;
+	unsigned long sz;
+	unsigned hval = shash((unsigned char *)fn) % SRC_HTAB_SZ;
+
+	hlist_for_each_entry (h, &srcfile_htab[hval], hash_nd) {
+		if (!strcmp(fn, h->fn)) {
+			/* Move to front */
+			list_del(&h->nd);
+			list_add(&h->nd, &srcfile_list);
+			return h;
+		}
+	}
+
+	/* Only prune if there is more than one entry */
+	while ((num_srcfiles > MAXSRCFILES || map_total_sz > MAXSRCCACHE) &&
+	       srcfile_list.next != &srcfile_list) {
+		assert(!list_empty(&srcfile_list));
+		h = list_entry(srcfile_list.prev, struct srcfile, nd);
+		free_srcfile(h);
+	}
+
+	fd = open(fn, O_RDONLY);
+	if (fd < 0 || fstat(fd, &st) < 0) {
+		pr_debug("cannot open source file %s\n", fn);
+		return NULL;
+	}
+
+	h = malloc(sizeof(struct srcfile));
+	if (!h)
+		return NULL;
+
+	h->fn = strdup(fn);
+	if (!h->fn)
+		goto out_h;
+
+	h->maplen = st.st_size;
+	sz = (h->maplen + page_size - 1) & ~(page_size - 1);
+	h->map = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
+	close(fd);
+	if (h->map == (char *)-1) {
+		pr_debug("cannot mmap source file %s\n", fn);
+		goto out_fn;
+	}
+	h->numlines = countlines(h->map, h->maplen);
+	h->lines = calloc(h->numlines, sizeof(char *));
+	if (!h->lines)
+		goto out_map;
+	fill_lines(h->lines, h->numlines, h->map, h->maplen);
+	list_add(&h->nd, &srcfile_list);
+	hlist_add_head(&h->hash_nd, &srcfile_htab[hval]);
+	map_total_sz += h->maplen;
+	num_srcfiles++;
+	return h;
+
+out_map:
+	munmap(h->map, sz);
+out_fn:
+	free(h->fn);
+out_h:
+	free(h);
+	return NULL;
+}
+
+/* Result is not 0 terminated */
+char *find_sourceline(char *fn, unsigned line, int *lenp)
+{
+	char *l, *p;
+	struct srcfile *sf = find_srcfile(fn);
+	if (!sf)
+		return NULL;
+	line--;
+	if (line >= sf->numlines)
+		return NULL;
+	l = sf->lines[line];
+	if (!l)
+		return NULL;
+	p = memchr(l, '\n', sf->map + sf->maplen - l);
+	*lenp = p - l;
+	return l;
+}