perf probe: Cleanup debuginfo related code

Cleanup debuginfo related code to eliminate fragile code which
pointed by Ingo (Thanks!).
1) Invert logic of NO_DWARF_SUPPORT to DWARF_SUPPORT.
2) For removing assymetric/local variable ifdefs, introduce
  more helper functions.
3) Change options order to reduce the number of ifdefs.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1269274229-20442-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 200 insertions, 178 deletions

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 0abd25ee595f..c9918182715a 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -506,9 +506,8 @@ endif
 
 ifneq ($(shell sh -c "(echo '\#include <dwarf.h>'; echo '\#include <libdw.h>'; echo 'int main(void) { Dwarf *dbg; dbg = dwarf_begin(0, DWARF_C_READ); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/elfutils -ldw -lelf -o $(BITBUCKET) $(ALL_LDFLAGS) $(EXTLIBS) "$(QUIET_STDERR)" && echo y"), y)
         msg := $(warning No libdw.h found or old libdw.h found, disables dwarf support. Please install elfutils-devel/elfutils-dev);
-        BASIC_CFLAGS += -DNO_DWARF_SUPPORT
 else
-        BASIC_CFLAGS += -I/usr/include/elfutils
+        BASIC_CFLAGS += -I/usr/include/elfutils -DDWARF_SUPPORT
         EXTLIBS += -lelf -ldw
         LIB_OBJS += util/probe-finder.o
 endif
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index e0dafd9dfeb5..cf2ffa5a3842 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -109,7 +109,7 @@ static int opt_del_probe_event(const struct option *opt __used,
         return 0;
 }
 
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
 static int opt_show_lines(const struct option *opt __used,
                           const char *str, int unset __used)
 {
@@ -126,7 +126,7 @@ static const char * const probe_usage[] = {
         "perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
         "perf probe [<options>] --del '[GROUP:]EVENT' ...",
         "perf probe --list",
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
         "perf probe --line 'LINEDESC'",
 #endif
         NULL
@@ -135,20 +135,16 @@ static const char * const probe_usage[] = {
 static const struct option options[] = {
         OPT_BOOLEAN('v', "verbose", &verbose,
                     "be more verbose (show parsed arguments, etc)"),
-#ifndef NO_DWARF_SUPPORT
-        OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
-                   "file", "vmlinux pathname"),
-#endif
         OPT_BOOLEAN('l', "list", &params.list_events,
                     "list up current probe events"),
         OPT_CALLBACK('d', "del", NULL, "[GROUP:]EVENT", "delete a probe event.",
                 opt_del_probe_event),
         OPT_CALLBACK('a', "add", NULL,
-#ifdef NO_DWARF_SUPPORT
-                "[EVENT=]FUNC[+OFF|%return] [ARG ...]",
-#else
+#ifdef DWARF_SUPPORT
                 "[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT"
                 " [ARG ...]",
+#else
+                "[EVENT=]FUNC[+OFF|%return] [ARG ...]",
 #endif
                 "probe point definition, where\n"
                 "\t\tGROUP:\tGroup name (optional)\n"
@@ -156,23 +152,25 @@ static const struct option options[] = {
                 "\t\tFUNC:\tFunction name\n"
                 "\t\tOFF:\tOffset from function entry (in byte)\n"
                 "\t\t%return:\tPut the probe at function return\n"
-#ifdef NO_DWARF_SUPPORT
-                "\t\tARG:\tProbe argument (only \n"
-#else
+#ifdef DWARF_SUPPORT
                 "\t\tSRC:\tSource code path\n"
                 "\t\tRL:\tRelative line number from function entry.\n"
                 "\t\tAL:\tAbsolute line number in file.\n"
                 "\t\tPT:\tLazy expression of line code.\n"
                 "\t\tARG:\tProbe argument (local variable name or\n"
-#endif
                 "\t\t\tkprobe-tracer argument format.)\n",
+#else
+                "\t\tARG:\tProbe argument (kprobe-tracer argument format.)\n",
+#endif
                 opt_add_probe_event),
         OPT_BOOLEAN('f', "force", &params.force_add, "forcibly add events"
                     " with existing name"),
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
         OPT_CALLBACK('L', "line", NULL,
                      "FUNC[:RLN[+NUM|:RLN2]]|SRC:ALN[+NUM|:ALN2]",
                      "Show source code lines.", opt_show_lines),
+        OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
+                   "file", "vmlinux pathname"),
 #endif
         OPT__DRY_RUN(&probe_event_dry_run),
         OPT_END()
@@ -211,7 +209,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
                 return 0;
         }
 
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
         if (params.show_lines) {
                 if (params.nevents != 0 || params.dellist) {
                         pr_warning("  Error: Don't use --line with"
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c6603f3bb430..3fc0be741b8e 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -42,7 +42,8 @@
 #include "color.h"
 #include "symbol.h"
 #include "thread.h"
-#include "parse-events.h"  /* For debugfs_path */
+#include "trace-event.h"        /* For __unused */
+#include "parse-events.h"       /* For debugfs_path */
 #include "probe-event.h"
 #include "probe-finder.h"
 
@@ -70,10 +71,11 @@ static int e_snprintf(char *str, size_t size, const char *format, ...)
         return ret;
 }
 
+static char *synthesize_perf_probe_point(struct perf_probe_point *pp);
 static struct map_groups kmap_groups;
 static struct map *kmaps[MAP__NR_TYPES];
 
-/* Initialize symbol maps for vmlinux */
+/* Initialize symbol maps and path of vmlinux */
 static void init_vmlinux(void)
 {
         symbol_conf.sort_by_name = true;
@@ -89,7 +91,7 @@ static void init_vmlinux(void)
                 die("Failed to create kernel maps.");
 }
 
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
 static int open_vmlinux(void)
 {
         if (map__load(kmaps[MAP__FUNCTION], NULL) < 0) {
@@ -99,6 +101,176 @@ static int open_vmlinux(void)
         pr_debug("Try to open %s\n", kmaps[MAP__FUNCTION]->dso->long_name);
         return open(kmaps[MAP__FUNCTION]->dso->long_name, O_RDONLY);
 }
+
+static void convert_to_perf_probe_point(struct kprobe_trace_point *tp,
+                                        struct perf_probe_point *pp)
+{
+        struct symbol *sym;
+        int fd, ret = 0;
+
+        sym = map__find_symbol_by_name(kmaps[MAP__FUNCTION],
+                                       tp->symbol, NULL);
+        if (sym) {
+                fd = open_vmlinux();
+                ret = find_perf_probe_point(fd, sym->start + tp->offset, pp);
+                close(fd);
+        }
+        if (ret <= 0) {
+                pp->function = xstrdup(tp->symbol);
+                pp->offset = tp->offset;
+        }
+        pp->retprobe = tp->retprobe;
+}
+
+/* Try to find perf_probe_event with debuginfo */
+static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
+                                           struct kprobe_trace_event **tevs)
+{
+        bool need_dwarf = perf_probe_event_need_dwarf(pev);
+        int fd, ntevs;
+
+        fd = open_vmlinux();
+        if (fd < 0) {
+                if (need_dwarf)
+                        die("Could not open debuginfo file.");
+
+                pr_debug("Could not open vmlinux. Try to use symbols.\n");
+                return 0;
+        }
+
+        /* Searching trace events corresponding to probe event */
+        ntevs = find_kprobe_trace_events(fd, pev, tevs);
+        close(fd);
+
+        if (ntevs > 0)  /* Succeeded to find trace events */
+                return ntevs;
+
+        if (ntevs == 0) /* No error but failed to find probe point. */
+                die("Probe point '%s' not found. - probe not added.",
+                    synthesize_perf_probe_point(&pev->point));
+
+        /* Error path */
+        if (need_dwarf) {
+                if (ntevs == -ENOENT)
+                        pr_warning("No dwarf info found in the vmlinux - "
+                                "please rebuild with CONFIG_DEBUG_INFO=y.\n");
+                die("Could not analyze debuginfo.");
+        }
+        pr_debug("An error occurred in debuginfo analysis."
+                 " Try to use symbols.\n");
+        return 0;
+
+}
+
+#define LINEBUF_SIZE 256
+#define NR_ADDITIONAL_LINES 2
+
+static void show_one_line(FILE *fp, unsigned int l, bool skip, bool show_num)
+{
+        char buf[LINEBUF_SIZE];
+        const char *color = PERF_COLOR_BLUE;
+
+        if (fgets(buf, LINEBUF_SIZE, fp) == NULL)
+                goto error;
+        if (!skip) {
+                if (show_num)
+                        fprintf(stdout, "%7u  %s", l, buf);
+                else
+                        color_fprintf(stdout, color, "         %s", buf);
+        }
+
+        while (strlen(buf) == LINEBUF_SIZE - 1 &&
+               buf[LINEBUF_SIZE - 2] != '\n') {
+                if (fgets(buf, LINEBUF_SIZE, fp) == NULL)
+                        goto error;
+                if (!skip) {
+                        if (show_num)
+                                fprintf(stdout, "%s", buf);
+                        else
+                                color_fprintf(stdout, color, "%s", buf);
+                }
+        }
+        return;
+error:
+        if (feof(fp))
+                die("Source file is shorter than expected.");
+        else
+                die("File read error: %s", strerror(errno));
+}
+
+/*
+ * Show line-range always requires debuginfo to find source file and
+ * line number.
+ */
+void show_line_range(struct line_range *lr)
+{
+        unsigned int l = 1;
+        struct line_node *ln;
+        FILE *fp;
+        int fd, ret;
+
+        /* Search a line range */
+        init_vmlinux();
+        fd = open_vmlinux();
+        if (fd < 0)
+                die("Could not open debuginfo file.");
+        ret = find_line_range(fd, lr);
+        if (ret <= 0)
+                die("Source line is not found.\n");
+        close(fd);
+
+        setup_pager();
+
+        if (lr->function)
+                fprintf(stdout, "<%s:%d>\n", lr->function,
+                        lr->start - lr->offset);
+        else
+                fprintf(stdout, "<%s:%d>\n", lr->file, lr->start);
+
+        fp = fopen(lr->path, "r");
+        if (fp == NULL)
+                die("Failed to open %s: %s", lr->path, strerror(errno));
+        /* Skip to starting line number */
+        while (l < lr->start)
+                show_one_line(fp, l++, true, false);
+
+        list_for_each_entry(ln, &lr->line_list, list) {
+                while (ln->line > l)
+                        show_one_line(fp, (l++) - lr->offset, false, false);
+                show_one_line(fp, (l++) - lr->offset, false, true);
+        }
+
+        if (lr->end == INT_MAX)
+                lr->end = l + NR_ADDITIONAL_LINES;
+        while (l < lr->end && !feof(fp))
+                show_one_line(fp, (l++) - lr->offset, false, false);
+
+        fclose(fp);
+}
+
+#else   /* !DWARF_SUPPORT */
+
+static void convert_to_perf_probe_point(struct kprobe_trace_point *tp,
+                                        struct perf_probe_point *pp)
+{
+        pp->function = xstrdup(tp->symbol);
+        pp->offset = tp->offset;
+        pp->retprobe = tp->retprobe;
+}
+
+static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
+                                struct kprobe_trace_event **tevs __unused)
+{
+        if (perf_probe_event_need_dwarf(pev))
+                die("Debuginfo-analysis is not supported");
+        return 0;
+}
+
+void show_line_range(struct line_range *lr __unused)
+{
+        die("Debuginfo-analysis is not supported");
+}
+
 #endif
 
 void parse_line_range_desc(const char *arg, struct line_range *lr)
@@ -592,32 +764,14 @@ void convert_to_perf_probe_event(struct kprobe_trace_event *tev,
 {
         char buf[64];
         int i;
-#ifndef NO_DWARF_SUPPORT
-        struct symbol *sym;
-        int fd, ret = 0;
-
-        sym = map__find_symbol_by_name(kmaps[MAP__FUNCTION],
-                                       tev->point.symbol, NULL);
-        if (sym) {
-                fd = open_vmlinux();
-                ret = find_perf_probe_point(fd, sym->start + tev->point.offset,
-                                            &pev->point);
-                close(fd);
-        }
-        if (ret <= 0) {
-                pev->point.function = xstrdup(tev->point.symbol);
-                pev->point.offset = tev->point.offset;
-        }
-#else
-        /* Convert trace_point to probe_point */
-        pev->point.function = xstrdup(tev->point.symbol);
-        pev->point.offset = tev->point.offset;
-#endif
-        pev->point.retprobe = tev->point.retprobe;
 
+        /* Convert event/group name */
         pev->event = xstrdup(tev->event);
         pev->group = xstrdup(tev->group);
 
+        /* Convert trace_point to probe_point */
+        convert_to_perf_probe_point(&tev->point, &pev->point);
+
         /* Convert trace_arg to probe_arg */
         pev->nargs = tev->nargs;
         pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs);
@@ -944,52 +1098,13 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
                                           struct kprobe_trace_event **tevs)
 {
         struct symbol *sym;
-        bool need_dwarf;
-#ifndef NO_DWARF_SUPPORT
-        int fd;
-#endif
         int ntevs = 0, i;
         struct kprobe_trace_event *tev;
 
-        need_dwarf = perf_probe_event_need_dwarf(pev);
-
-        if (need_dwarf)
-#ifdef NO_DWARF_SUPPORT
-                die("Debuginfo-analysis is not supported");
-#else   /* !NO_DWARF_SUPPORT */
-                pr_debug("Some probes require debuginfo.\n");
-
-        fd = open_vmlinux();
-        if (fd < 0) {
-                if (need_dwarf)
-                        die("Could not open debuginfo file.");
-
-                pr_debug("Could not open vmlinux/module file."
-                         " Try to use symbols.\n");
-                goto end_dwarf;
-        }
-
-        /* Searching probe points */
-        ntevs = find_kprobe_trace_events(fd, pev, tevs);
-
-        if (ntevs > 0)  /* Found */
-                goto found;
-
-        if (ntevs == 0) /* No error but failed to find probe point. */
-                die("Probe point '%s' not found. - probe not added.",
-                    synthesize_perf_probe_point(&pev->point));
-
-        /* Error path */
-        if (need_dwarf) {
-                if (ntevs == -ENOENT)
-                        pr_warning("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO=y.\n");
-                die("Could not analyze debuginfo.");
-        }
-        pr_debug("An error occurred in debuginfo analysis."
-                 " Try to use symbols.\n");
-
-end_dwarf:
-#endif /* !NO_DWARF_SUPPORT */
+        /* Convert perf_probe_event with debuginfo */
+        ntevs = try_to_find_kprobe_trace_events(pev, tevs);
+        if (ntevs > 0)
+                return ntevs;
 
         /* Allocate trace event buffer */
         ntevs = 1;
@@ -1012,10 +1127,7 @@ end_dwarf:
         if (!sym)
                 die("Kernel symbol \'%s\' not found - probe not added.",
                     tev->point.symbol);
-#ifndef NO_DWARF_SUPPORT
-found:
-        close(fd);
-#endif
+
         return ntevs;
 }
 
@@ -1133,90 +1245,3 @@ void del_perf_probe_events(struct strlist *dellist)
         close(fd);
 }
 
-#define LINEBUF_SIZE 256
-#define NR_ADDITIONAL_LINES 2
-
-static void show_one_line(FILE *fp, unsigned int l, bool skip, bool show_num)
-{
-        char buf[LINEBUF_SIZE];
-        const char *color = PERF_COLOR_BLUE;
-
-        if (fgets(buf, LINEBUF_SIZE, fp) == NULL)
-                goto error;
-        if (!skip) {
-                if (show_num)
-                        fprintf(stdout, "%7u  %s", l, buf);
-                else
-                        color_fprintf(stdout, color, "         %s", buf);
-        }
-
-        while (strlen(buf) == LINEBUF_SIZE - 1 &&
-               buf[LINEBUF_SIZE - 2] != '\n') {
-                if (fgets(buf, LINEBUF_SIZE, fp) == NULL)
-                        goto error;
-                if (!skip) {
-                        if (show_num)
-                                fprintf(stdout, "%s", buf);
-                        else
-                                color_fprintf(stdout, color, "%s", buf);
-                }
-        }
-        return;
-error:
-        if (feof(fp))
-                die("Source file is shorter than expected.");
-        else
-                die("File read error: %s", strerror(errno));
-}
-
-void show_line_range(struct line_range *lr)
-{
-        unsigned int l = 1;
-        struct line_node *ln;
-        FILE *fp;
-#ifndef NO_DWARF_SUPPORT
-        int fd, ret;
-#endif
-
-        /* Search a line range */
-        init_vmlinux();
-#ifndef NO_DWARF_SUPPORT
-        fd = open_vmlinux();
-        if (fd < 0)
-                die("Could not open debuginfo file.");
-        ret = find_line_range(fd, lr);
-        if (ret <= 0)
-                die("Source line is not found.\n");
-        close(fd);
-#endif
-
-        setup_pager();
-
-        if (lr->function)
-                fprintf(stdout, "<%s:%d>\n", lr->function,
-                        lr->start - lr->offset);
-        else
-                fprintf(stdout, "<%s:%d>\n", lr->file, lr->start);
-
-        fp = fopen(lr->path, "r");
-        if (fp == NULL)
-                die("Failed to open %s: %s", lr->path, strerror(errno));
-        /* Skip to starting line number */
-        while (l < lr->start)
-                show_one_line(fp, l++, true, false);
-
-        list_for_each_entry(ln, &lr->line_list, list) {
-                while (ln->line > l)
-                        show_one_line(fp, (l++) - lr->offset, false, false);
-                show_one_line(fp, (l++) - lr->offset, false, true);
-        }
-
-        if (lr->end == INT_MAX)
-                lr->end = l + NR_ADDITIONAL_LINES;
-        while (l < lr->end && !feof(fp))
-                show_one_line(fp, (l++) - lr->offset, false, false);
-
-        fclose(fp);
-}
-
-
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 2f2307d4139f..3564f22954f1 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -15,7 +15,7 @@ static inline int is_c_varname(const char *name)
         return isalpha(name[0]) || name[0] == '_';
 }
 
-#ifndef NO_DWARF_SUPPORT
+#ifdef DWARF_SUPPORT
 /* Find kprobe_trace_events specified by perf_probe_event from debuginfo */
 extern int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
                                     struct kprobe_trace_event **tevs);
@@ -57,6 +57,6 @@ struct line_finder {
         int                     found;
 };
 
-#endif /* NO_DWARF_SUPPORT */
+#endif /* DWARF_SUPPORT */
 
 #endif /*_PROBE_FINDER_H */