perf symbols: Add support for reading from /proc/kcore

In the absence of vmlinux, perf tools uses kallsyms for symbols.  If the
user has access, now also map to /proc/kcore.

The dso data_type is now set to either DSO_BINARY_TYPE__KCORE or
DSO_BINARY_TYPE__GUEST_KCORE as approprite.

This patch breaks the "vmlinux symtab matches kallsyms" test.  That is
fixed in a following patch.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1375875537-4509-8-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

9 files changed, 347 insertions, 3 deletions

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 1955804e82ff..e3c1ff8512c8 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -95,6 +95,11 @@ int dso__binary_type_file(struct dso *dso, enum dso_binary_type type,
                          dso->long_name);
                 break;
 
+        case DSO_BINARY_TYPE__KCORE:
+        case DSO_BINARY_TYPE__GUEST_KCORE:
+                snprintf(file, size, "%s", dso->long_name);
+                break;
+
         default:
         case DSO_BINARY_TYPE__KALLSYMS:
         case DSO_BINARY_TYPE__GUEST_KALLSYMS:
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 735a83751b19..b793053335d6 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -21,6 +21,8 @@ enum dso_binary_type {
         DSO_BINARY_TYPE__SYSTEM_PATH_DSO,
         DSO_BINARY_TYPE__GUEST_KMODULE,
         DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE,
+        DSO_BINARY_TYPE__KCORE,
+        DSO_BINARY_TYPE__GUEST_KCORE,
         DSO_BINARY_TYPE__NOT_FOUND,
 };
 
@@ -155,4 +157,10 @@ static inline bool dso__is_vmlinux(struct dso *dso)
                dso->data_type == DSO_BINARY_TYPE__GUEST_VMLINUX;
 }
 
+static inline bool dso__is_kcore(struct dso *dso)
+{
+        return dso->data_type == DSO_BINARY_TYPE__KCORE ||
+               dso->data_type == DSO_BINARY_TYPE__GUEST_KCORE;
+}
+
 #endif /* __PERF_DSO */
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index dc35dcffbd05..ef3b49cde04e 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -856,6 +856,18 @@ static void machine__set_kernel_mmap_len(struct machine *machine,
         }
 }
 
+static bool machine__uses_kcore(struct machine *machine)
+{
+        struct dso *dso;
+
+        list_for_each_entry(dso, &machine->kernel_dsos, node) {
+                if (dso__is_kcore(dso))
+                        return true;
+        }
+
+        return false;
+}
+
 static int machine__process_kernel_mmap_event(struct machine *machine,
                                               union perf_event *event)
 {
@@ -864,6 +876,10 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
         enum dso_kernel_type kernel_type;
         bool is_kernel_mmap;
 
+        /* If we have maps from kcore then we do not need or want any others */
+        if (machine__uses_kcore(machine))
+                return 0;
+
         machine__mmap_name(machine, kmmap_prefix, sizeof(kmmap_prefix));
         if (machine__is_host(machine))
                 kernel_type = DSO_TYPE_KERNEL;
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 4d599febfb0b..9e8304ca343e 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -555,3 +555,21 @@ struct map *maps__find(struct rb_root *maps, u64 ip)
 
         return NULL;
 }
+
+struct map *maps__first(struct rb_root *maps)
+{
+        struct rb_node *first = rb_first(maps);
+
+        if (first)
+                return rb_entry(first, struct map, rb_node);
+        return NULL;
+}
+
+struct map *maps__next(struct map *map)
+{
+        struct rb_node *next = rb_next(&map->rb_node);
+
+        if (next)
+                return rb_entry(next, struct map, rb_node);
+        return NULL;
+}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index a887f2c9dfbb..2cc93cbf0e17 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -112,6 +112,8 @@ size_t __map_groups__fprintf_maps(struct map_groups *mg,
 void maps__insert(struct rb_root *maps, struct map *map);
 void maps__remove(struct rb_root *maps, struct map *map);
 struct map *maps__find(struct rb_root *maps, u64 addr);
+struct map *maps__first(struct rb_root *maps);
+struct map *maps__next(struct map *map);
 void map_groups__init(struct map_groups *mg);
 void map_groups__exit(struct map_groups *mg);
 int map_groups__clone(struct map_groups *mg,
@@ -139,6 +141,17 @@ static inline struct map *map_groups__find(struct map_groups *mg,
         return maps__find(&mg->maps[type], addr);
 }
 
+static inline struct map *map_groups__first(struct map_groups *mg,
+                                            enum map_type type)
+{
+        return maps__first(&mg->maps[type]);
+}
+
+static inline struct map *map_groups__next(struct map *map)
+{
+        return maps__next(map);
+}
+
 struct symbol *map_groups__find_symbol(struct map_groups *mg,
                                        enum map_type type, u64 addr,
                                        struct map **mapp,
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 3eaa7b486e2e..a7b9ab557380 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -951,6 +951,57 @@ out_elf_end:
         return err;
 }
 
+static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
+{
+        GElf_Phdr phdr;
+        size_t i, phdrnum;
+        int err;
+        u64 sz;
+
+        if (elf_getphdrnum(elf, &phdrnum))
+                return -1;
+
+        for (i = 0; i < phdrnum; i++) {
+                if (gelf_getphdr(elf, i, &phdr) == NULL)
+                        return -1;
+                if (phdr.p_type != PT_LOAD)
+                        continue;
+                if (exe) {
+                        if (!(phdr.p_flags & PF_X))
+                                continue;
+                } else {
+                        if (!(phdr.p_flags & PF_R))
+                                continue;
+                }
+                sz = min(phdr.p_memsz, phdr.p_filesz);
+                if (!sz)
+                        continue;
+                err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
+                if (err)
+                        return err;
+        }
+        return 0;
+}
+
+int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
+                    bool *is_64_bit)
+{
+        int err;
+        Elf *elf;
+
+        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+        if (elf == NULL)
+                return -1;
+
+        if (is_64_bit)
+                *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
+
+        err = elf_read_maps(elf, exe, mapfn, data);
+
+        elf_end(elf);
+        return err;
+}
+
 void symbol__elf_init(void)
 {
         elf_version(EV_CURRENT);
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index a7390cde63bc..3a802c300fc5 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -301,6 +301,13 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
         return 0;
 }
 
+int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
+                    mapfn_t mapfn __maybe_unused, void *data __maybe_unused,
+                    bool *is_64_bit __maybe_unused)
+{
+        return -1;
+}
+
 void symbol__elf_init(void)
 {
 }
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b9056a8c1620..77f3b95bb46d 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -327,6 +327,16 @@ static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
         return NULL;
 }
 
+static struct symbol *symbols__first(struct rb_root *symbols)
+{
+        struct rb_node *n = rb_first(symbols);
+
+        if (n)
+                return rb_entry(n, struct symbol, rb_node);
+
+        return NULL;
+}
+
 struct symbol_name_rb_node {
         struct rb_node  rb_node;
         struct symbol   sym;
@@ -397,6 +407,11 @@ struct symbol *dso__find_symbol(struct dso *dso,
         return symbols__find(&dso->symbols[type], addr);
 }
 
+struct symbol *dso__first_symbol(struct dso *dso, enum map_type type)
+{
+        return symbols__first(&dso->symbols[type]);
+}
+
 struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,
                                         const char *name)
 {
@@ -533,6 +548,53 @@ static int dso__load_all_kallsyms(struct dso *dso, const char *filename,
         return kallsyms__parse(filename, &args, map__process_kallsym_symbol);
 }
 
+static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map,
+                                         symbol_filter_t filter)
+{
+        struct map_groups *kmaps = map__kmap(map)->kmaps;
+        struct map *curr_map;
+        struct symbol *pos;
+        int count = 0, moved = 0;
+        struct rb_root *root = &dso->symbols[map->type];
+        struct rb_node *next = rb_first(root);
+
+        while (next) {
+                char *module;
+
+                pos = rb_entry(next, struct symbol, rb_node);
+                next = rb_next(&pos->rb_node);
+
+                module = strchr(pos->name, '\t');
+                if (module)
+                        *module = '\0';
+
+                curr_map = map_groups__find(kmaps, map->type, pos->start);
+
+                if (!curr_map || (filter && filter(curr_map, pos))) {
+                        rb_erase(&pos->rb_node, root);
+                        symbol__delete(pos);
+                } else {
+                        pos->start -= curr_map->start - curr_map->pgoff;
+                        if (pos->end)
+                                pos->end -= curr_map->start - curr_map->pgoff;
+                        if (curr_map != map) {
+                                rb_erase(&pos->rb_node, root);
+                                symbols__insert(
+                                        &curr_map->dso->symbols[curr_map->type],
+                                        pos);
+                                ++moved;
+                        } else {
+                                ++count;
+                        }
+                }
+        }
+
+        /* Symbols have been adjusted */
+        dso->adjust_symbols = 1;
+
+        return count + moved;
+}
+
 /*
  * Split the symbols into maps, making sure there are no overlaps, i.e. the
  * kernel range is broken in several maps, named [kernel].N, as we don't have
@@ -674,6 +736,161 @@ bool symbol__restricted_filename(const char *filename,
         return restricted;
 }
 
+struct kcore_mapfn_data {
+        struct dso *dso;
+        enum map_type type;
+        struct list_head maps;
+};
+
+static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
+{
+        struct kcore_mapfn_data *md = data;
+        struct map *map;
+
+        map = map__new2(start, md->dso, md->type);
+        if (map == NULL)
+                return -ENOMEM;
+
+        map->end = map->start + len;
+        map->pgoff = pgoff;
+
+        list_add(&map->node, &md->maps);
+
+        return 0;
+}
+
+/*
+ * If kallsyms is referenced by name then we look for kcore in the same
+ * directory.
+ */
+static bool kcore_filename_from_kallsyms_filename(char *kcore_filename,
+                                                  const char *kallsyms_filename)
+{
+        char *name;
+
+        strcpy(kcore_filename, kallsyms_filename);
+        name = strrchr(kcore_filename, '/');
+        if (!name)
+                return false;
+
+        if (!strcmp(name, "/kallsyms")) {
+                strcpy(name, "/kcore");
+                return true;
+        }
+
+        return false;
+}
+
+static int dso__load_kcore(struct dso *dso, struct map *map,
+                           const char *kallsyms_filename)
+{
+        struct map_groups *kmaps = map__kmap(map)->kmaps;
+        struct machine *machine = kmaps->machine;
+        struct kcore_mapfn_data md;
+        struct map *old_map, *new_map, *replacement_map = NULL;
+        bool is_64_bit;
+        int err, fd;
+        char kcore_filename[PATH_MAX];
+        struct symbol *sym;
+
+        /* This function requires that the map is the kernel map */
+        if (map != machine->vmlinux_maps[map->type])
+                return -EINVAL;
+
+        if (!kcore_filename_from_kallsyms_filename(kcore_filename,
+                                                   kallsyms_filename))
+                return -EINVAL;
+
+        md.dso = dso;
+        md.type = map->type;
+        INIT_LIST_HEAD(&md.maps);
+
+        fd = open(kcore_filename, O_RDONLY);
+        if (fd < 0)
+                return -EINVAL;
+
+        /* Read new maps into temporary lists */
+        err = file__read_maps(fd, md.type == MAP__FUNCTION, kcore_mapfn, &md,
+                              &is_64_bit);
+        if (err)
+                goto out_err;
+
+        if (list_empty(&md.maps)) {
+                err = -EINVAL;
+                goto out_err;
+        }
+
+        /* Remove old maps */
+        old_map = map_groups__first(kmaps, map->type);
+        while (old_map) {
+                struct map *next = map_groups__next(old_map);
+
+                if (old_map != map)
+                        map_groups__remove(kmaps, old_map);
+                old_map = next;
+        }
+
+        /* Find the kernel map using the first symbol */
+        sym = dso__first_symbol(dso, map->type);
+        list_for_each_entry(new_map, &md.maps, node) {
+                if (sym && sym->start >= new_map->start &&
+                    sym->start < new_map->end) {
+                        replacement_map = new_map;
+                        break;
+                }
+        }
+
+        if (!replacement_map)
+                replacement_map = list_entry(md.maps.next, struct map, node);
+
+        /* Add new maps */
+        while (!list_empty(&md.maps)) {
+                new_map = list_entry(md.maps.next, struct map, node);
+                list_del(&new_map->node);
+                if (new_map == replacement_map) {
+                        map->start      = new_map->start;
+                        map->end        = new_map->end;
+                        map->pgoff      = new_map->pgoff;
+                        map->map_ip     = new_map->map_ip;
+                        map->unmap_ip   = new_map->unmap_ip;
+                        map__delete(new_map);
+                        /* Ensure maps are correctly ordered */
+                        map_groups__remove(kmaps, map);
+                        map_groups__insert(kmaps, map);
+                } else {
+                        map_groups__insert(kmaps, new_map);
+                }
+        }
+
+        /*
+         * Set the data type and long name so that kcore can be read via
+         * dso__data_read_addr().
+         */
+        if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
+                dso->data_type = DSO_BINARY_TYPE__GUEST_KCORE;
+        else
+                dso->data_type = DSO_BINARY_TYPE__KCORE;
+        dso__set_long_name(dso, strdup(kcore_filename));
+
+        close(fd);
+
+        if (map->type == MAP__FUNCTION)
+                pr_debug("Using %s for kernel object code\n", kcore_filename);
+        else
+                pr_debug("Using %s for kernel data\n", kcore_filename);
+
+        return 0;
+
+out_err:
+        while (!list_empty(&md.maps)) {
+                map = list_entry(md.maps.next, struct map, node);
+                list_del(&map->node);
+                map__delete(map);
+        }
+        close(fd);
+        return -EINVAL;
+}
+
 int dso__load_kallsyms(struct dso *dso, const char *filename,
                        struct map *map, symbol_filter_t filter)
 {
@@ -691,7 +908,10 @@ int dso__load_kallsyms(struct dso *dso, const char *filename,
         else
                 dso->symtab_type = DSO_BINARY_TYPE__KALLSYMS;
 
-        return dso__split_kallsyms(dso, map, filter);
+        if (!dso__load_kcore(dso, map, filename))
+                return dso__split_kallsyms_for_kcore(dso, map, filter);
+        else
+                return dso__split_kallsyms(dso, map, filter);
 }
 
 static int dso__load_perf_map(struct dso *dso, struct map *map,
@@ -1065,7 +1285,7 @@ do_kallsyms:
                 pr_debug("Using %s for symbols\n", kallsyms_filename);
         free(kallsyms_allocated_filename);
 
-        if (err > 0) {
+        if (err > 0 && !dso__is_kcore(dso)) {
                 dso__set_long_name(dso, strdup("[kernel.kallsyms]"));
                 map__fixup_start(map);
                 map__fixup_end(map);
@@ -1109,8 +1329,9 @@ static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map,
         }
 
         err = dso__load_kallsyms(dso, kallsyms_filename, map, filter);
-        if (err > 0) {
+        if (err > 0)
                 pr_debug("Using %s for symbols\n", kallsyms_filename);
+        if (err > 0 && !dso__is_kcore(dso)) {
                 machine__mmap_name(machine, path, sizeof(path));
                 dso__set_long_name(dso, strdup(path));
                 map__fixup_start(map);
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 5f720dc076da..fd5b70ea2981 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -215,6 +215,7 @@ struct symbol *dso__find_symbol(struct dso *dso, enum map_type type,
                                 u64 addr);
 struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,
                                         const char *name);
+struct symbol *dso__first_symbol(struct dso *dso, enum map_type type);
 
 int filename__read_build_id(const char *filename, void *bf, size_t size);
 int sysfs__read_build_id(const char *filename, void *bf, size_t size);
@@ -247,4 +248,8 @@ void symbols__fixup_duplicate(struct rb_root *symbols);
 void symbols__fixup_end(struct rb_root *symbols);
 void __map_groups__fixup_end(struct map_groups *mg, enum map_type type);
 
+typedef int (*mapfn_t)(u64 start, u64 len, u64 pgoff, void *data);
+int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
+                    bool *is_64_bit);
+
 #endif /* __PERF_SYMBOL */