perf symbols: Simplify symbol machinery setup

And also express its configuration toggles via a struct.

Now all one has to do is to call symbol__init(NULL) if the
defaults are OK, or pass a struct symbol_conf pointer with the
desired configuration.

If a tool uses kernel_maps__find_symbol() to look at the kernel
and modules mappings for a symbol but didn't call symbol__init()
first, that will generate a one time warning too, alerting the
subcommand developer that symbol__init() must be called.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1259071517-3242-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

6 files changed, 51 insertions, 29 deletions

diff --git a/tools/perf/util/data_map.c b/tools/perf/util/data_map.c
index f318d19b2562..b238462b8983 100644
--- a/tools/perf/util/data_map.c
+++ b/tools/perf/util/data_map.c
@@ -101,8 +101,6 @@ out:
 
 int mmap_dispatch_perf_file(struct perf_header **pheader,
                             const char *input_name,
-                            const char *vmlinux_name,
-                            bool try_vmlinux_path,
                             int force,
                             int full_paths,
                             int *cwdlen,
@@ -172,12 +170,6 @@ int mmap_dispatch_perf_file(struct perf_header **pheader,
             curr_handler->sample_type_check(sample_type) < 0)
                 goto out_delete;
 
-        err = -ENOMEM;
-        if (kernel_maps__init(vmlinux_name, try_vmlinux_path, true) < 0) {
-                pr_err("failed to setup the kernel maps to resolve symbols\n");
-                goto out_delete;
-        }
-
         if (!full_paths) {
                 if (getcwd(__cwd, sizeof(__cwd)) == NULL) {
                         pr_err("failed to get the current directory\n");
diff --git a/tools/perf/util/data_map.h b/tools/perf/util/data_map.h
index 3f0d21b3819e..ae036ecd7625 100644
--- a/tools/perf/util/data_map.h
+++ b/tools/perf/util/data_map.h
@@ -23,8 +23,6 @@ struct perf_file_handler {
 void register_perf_file_handler(struct perf_file_handler *handler);
 int mmap_dispatch_perf_file(struct perf_header **pheader,
                             const char *input_name,
-                            const char *vmlinux_name,
-                            bool try_vmlinux_path,
                             int force,
                             int full_paths,
                             int *cwdlen,
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 1332f8ec04aa..271a1600e6f7 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -253,12 +253,6 @@ static int perf_header__adds_write(struct perf_header *self, int fd)
 
                 buildid_sec = &feat_sec[idx++];
 
-                /*
-                 * Read the kernel buildid nad the list of loaded modules with
-                 * its build_ids:
-                 */
-                kernel_maps__init(NULL, false, true);
-
                 /* Write build-ids */
                 buildid_sec->offset = lseek(fd, 0, SEEK_CUR);
                 err = dsos__write_buildid_table(fd);
diff --git a/tools/perf/util/include/asm/bug.h b/tools/perf/util/include/asm/bug.h
new file mode 100644
index 000000000000..7fcc6810adc2
--- /dev/null
+++ b/tools/perf/util/include/asm/bug.h
@@ -0,0 +1,22 @@
+#ifndef _PERF_ASM_GENERIC_BUG_H
+#define _PERF_ASM_GENERIC_BUG_H
+
+#define __WARN_printf(arg...)   do { fprintf(stderr, arg); } while (0)
+
+#define WARN(condition, format...) ({           \
+        int __ret_warn_on = !!(condition);      \
+        if (unlikely(__ret_warn_on))            \
+                __WARN_printf(format);          \
+        unlikely(__ret_warn_on);                \
+})
+
+#define WARN_ONCE(condition, format...) ({      \
+        static int __warned;                    \
+        int __ret_warn_once = !!(condition);    \
+                                                \
+        if (unlikely(__ret_warn_once))          \
+                if (WARN(!__warned, format))    \
+                        __warned = 1;           \
+        unlikely(__ret_warn_once);              \
+})
+#endif
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 44d81d5ae8cf..c4ca974b36e3 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -6,6 +6,7 @@
 
 #include "debug.h"
 
+#include <asm/bug.h>
 #include <libelf.h>
 #include <gelf.h>
 #include <elf.h>
@@ -37,6 +38,11 @@ unsigned int symbol__priv_size;
 static int vmlinux_path__nr_entries;
 static char **vmlinux_path;
 
+static struct symbol_conf symbol_conf__defaults = {
+        .use_modules      = true,
+        .try_vmlinux_path = true,
+};
+
 static struct rb_root kernel_maps;
 
 static void dso__fixup_sym_end(struct dso *self)
@@ -1166,7 +1172,9 @@ struct symbol *kernel_maps__find_symbol(u64 ip, struct map **mapp,
         if (map) {
                 ip = map->map_ip(map, ip);
                 return map__find_symbol(map, ip, filter);
-        }
+        } else
+                WARN_ONCE(RB_EMPTY_ROOT(&kernel_maps),
+                          "Empty kernel_maps, was symbol__init() called?\n");
 
         return NULL;
 }
@@ -1485,9 +1493,9 @@ size_t dsos__fprintf_buildid(FILE *fp)
         return ret;
 }
 
-static int kernel_maps__create_kernel_map(const char *vmlinux_name)
+static int kernel_maps__create_kernel_map(const struct symbol_conf *conf)
 {
-        struct dso *kernel = dso__new(vmlinux_name ?: "[kernel.kallsyms]");
+        struct dso *kernel = dso__new(conf->vmlinux_name ?: "[kernel.kallsyms]");
 
         if (kernel == NULL)
                 return -1;
@@ -1577,18 +1585,21 @@ out_fail:
         return -1;
 }
 
-int kernel_maps__init(const char *vmlinux_name, bool try_vmlinux_path,
-                      bool use_modules)
+static int kernel_maps__init(const struct symbol_conf *conf)
 {
-        if (try_vmlinux_path && vmlinux_path__init() < 0)
+        const struct symbol_conf *pconf = conf ?: &symbol_conf__defaults;
+
+        symbol__priv_size = pconf->priv_size;
+
+        if (pconf->try_vmlinux_path && vmlinux_path__init() < 0)
                 return -1;
 
-        if (kernel_maps__create_kernel_map(vmlinux_name) < 0) {
+        if (kernel_maps__create_kernel_map(pconf) < 0) {
                 vmlinux_path__exit();
                 return -1;
         }
 
-        if (use_modules && kernel_maps__create_module_maps() < 0)
+        if (pconf->use_modules && kernel_maps__create_module_maps() < 0)
                 pr_debug("Failed to load list of modules in use, "
                          "continuing...\n");
         /*
@@ -1598,8 +1609,8 @@ int kernel_maps__init(const char *vmlinux_name, bool try_vmlinux_path,
         return 0;
 }
 
-void symbol__init(unsigned int priv_size)
+int symbol__init(struct symbol_conf *conf)
 {
         elf_version(EV_CURRENT);
-        symbol__priv_size = priv_size;
+        return kernel_maps__init(conf);
 }
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 8c4d026e067a..5538691494af 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -49,6 +49,13 @@ struct symbol {
         char            name[0];
 };
 
+struct symbol_conf {
+        unsigned short  priv_size;
+        bool            try_vmlinux_path,
+                        use_modules;
+        const char      *vmlinux_name;
+};
+
 extern unsigned int symbol__priv_size;
 
 static inline void *symbol__priv(struct symbol *self)
@@ -93,11 +100,9 @@ int sysfs__read_build_id(const char *filename, void *bf, size_t size);
 bool dsos__read_build_ids(void);
 int build_id__sprintf(u8 *self, int len, char *bf);
 
-int kernel_maps__init(const char *vmlinux_name, bool try_vmlinux_path,
-                      bool use_modules);
 size_t kernel_maps__fprintf(FILE *fp);
 
-void symbol__init(unsigned int priv_size);
+int symbol__init(struct symbol_conf *conf);
 
 extern struct list_head dsos;
 extern struct map *kernel_map;