diff options
| -rw-r--r-- | tools/perf/util/symbol-elf.c | 252 | ||||
| -rw-r--r-- | tools/perf/util/symbol.h | 22 |
2 files changed, 274 insertions, 0 deletions
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index b222552c7159..6f15b92cbf70 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -1789,6 +1789,258 @@ void kcore_extract__delete(struct kcore_extract *kce) unlink(kce->extract_filename); } +/** + * populate_sdt_note : Parse raw data and identify SDT note + * @elf: elf of the opened file + * @data: raw data of a section with description offset applied + * @len: note description size + * @type: type of the note + * @sdt_notes: List to add the SDT note + * + * Responsible for parsing the @data in section .note.stapsdt in @elf and + * if its an SDT note, it appends to @sdt_notes list. + */ +static int populate_sdt_note(Elf **elf, const char *data, size_t len, + struct list_head *sdt_notes) +{ + const char *provider, *name; + struct sdt_note *tmp = NULL; + GElf_Ehdr ehdr; + GElf_Addr base_off = 0; + GElf_Shdr shdr; + int ret = -EINVAL; + + union { + Elf64_Addr a64[NR_ADDR]; + Elf32_Addr a32[NR_ADDR]; + } buf; + + Elf_Data dst = { + .d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT, + .d_size = gelf_fsize((*elf), ELF_T_ADDR, NR_ADDR, EV_CURRENT), + .d_off = 0, .d_align = 0 + }; + Elf_Data src = { + .d_buf = (void *) data, .d_type = ELF_T_ADDR, + .d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0, + .d_align = 0 + }; + + tmp = (struct sdt_note *)calloc(1, sizeof(struct sdt_note)); + if (!tmp) { + ret = -ENOMEM; + goto out_err; + } + + INIT_LIST_HEAD(&tmp->note_list); + + if (len < dst.d_size + 3) + goto out_free_note; + + /* Translation from file representation to memory representation */ + if (gelf_xlatetom(*elf, &dst, &src, + elf_getident(*elf, NULL)[EI_DATA]) == NULL) { + pr_err("gelf_xlatetom : %s\n", elf_errmsg(-1)); + goto out_free_note; + } + + /* Populate the fields of sdt_note */ + provider = data + dst.d_size; + + name = (const char *)memchr(provider, '\0', data + len - provider); + if (name++ == NULL) + goto out_free_note; + + tmp->provider = strdup(provider); + if (!tmp->provider) { + ret = -ENOMEM; + goto out_free_note; + } + tmp->name = strdup(name); + if (!tmp->name) { + ret = -ENOMEM; + goto out_free_prov; + } + + if (gelf_getclass(*elf) == ELFCLASS32) { + memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr)); + tmp->bit32 = true; + } else { + memcpy(&tmp->addr, &buf, 3 * sizeof(Elf64_Addr)); + tmp->bit32 = false; + } + + if (!gelf_getehdr(*elf, &ehdr)) { + pr_debug("%s : cannot get elf header.\n", __func__); + ret = -EBADF; + goto out_free_name; + } + + /* Adjust the prelink effect : + * Find out the .stapsdt.base section. + * This scn will help us to handle prelinking (if present). + * Compare the retrieved file offset of the base section with the + * base address in the description of the SDT note. If its different, + * then accordingly, adjust the note location. + */ + if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL)) { + base_off = shdr.sh_offset; + if (base_off) { + if (tmp->bit32) + tmp->addr.a32[0] = tmp->addr.a32[0] + base_off - + tmp->addr.a32[1]; + else + tmp->addr.a64[0] = tmp->addr.a64[0] + base_off - + tmp->addr.a64[1]; + } + } + + list_add_tail(&tmp->note_list, sdt_notes); + return 0; + +out_free_name: + free(tmp->name); +out_free_prov: + free(tmp->provider); +out_free_note: + free(tmp); +out_err: + return ret; +} + +/** + * construct_sdt_notes_list : constructs a list of SDT notes + * @elf : elf to look into + * @sdt_notes : empty list_head + * + * Scans the sections in 'elf' for the section + * .note.stapsdt. It, then calls populate_sdt_note to find + * out the SDT events and populates the 'sdt_notes'. + */ +static int construct_sdt_notes_list(Elf *elf, struct list_head *sdt_notes) +{ + GElf_Ehdr ehdr; + Elf_Scn *scn = NULL; + Elf_Data *data; + GElf_Shdr shdr; + size_t shstrndx, next; + GElf_Nhdr nhdr; + size_t name_off, desc_off, offset; + int ret = 0; + + if (gelf_getehdr(elf, &ehdr) == NULL) { + ret = -EBADF; + goto out_ret; + } + if (elf_getshdrstrndx(elf, &shstrndx) != 0) { + ret = -EBADF; + goto out_ret; + } + + /* Look for the required section */ + scn = elf_section_by_name(elf, &ehdr, &shdr, SDT_NOTE_SCN, NULL); + if (!scn) { + ret = -ENOENT; + goto out_ret; + } + + if ((shdr.sh_type != SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC)) { + ret = -ENOENT; + goto out_ret; + } + + data = elf_getdata(scn, NULL); + + /* Get the SDT notes */ + for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off, + &desc_off)) > 0; offset = next) { + if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) && + !memcmp(data->d_buf + name_off, SDT_NOTE_NAME, + sizeof(SDT_NOTE_NAME))) { + /* Check the type of the note */ + if (nhdr.n_type != SDT_NOTE_TYPE) + goto out_ret; + + ret = populate_sdt_note(&elf, ((data->d_buf) + desc_off), + nhdr.n_descsz, sdt_notes); + if (ret < 0) + goto out_ret; + } + } + if (list_empty(sdt_notes)) + ret = -ENOENT; + +out_ret: + return ret; +} + +/** + * get_sdt_note_list : Wrapper to construct a list of sdt notes + * @head : empty list_head + * @target : file to find SDT notes from + * + * This opens the file, initializes + * the ELF and then calls construct_sdt_notes_list. + */ +int get_sdt_note_list(struct list_head *head, const char *target) +{ + Elf *elf; + int fd, ret; + + fd = open(target, O_RDONLY); + if (fd < 0) + return -EBADF; + + elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); + if (!elf) { + ret = -EBADF; + goto out_close; + } + ret = construct_sdt_notes_list(elf, head); + elf_end(elf); +out_close: + close(fd); + return ret; +} + +/** + * cleanup_sdt_note_list : free the sdt notes' list + * @sdt_notes: sdt notes' list + * + * Free up the SDT notes in @sdt_notes. + * Returns the number of SDT notes free'd. + */ +int cleanup_sdt_note_list(struct list_head *sdt_notes) +{ + struct sdt_note *tmp, *pos; + int nr_free = 0; + + list_for_each_entry_safe(pos, tmp, sdt_notes, note_list) { + list_del(&pos->note_list); + free(pos->name); + free(pos->provider); + free(pos); + nr_free++; + } + return nr_free; +} + +/** + * sdt_notes__get_count: Counts the number of sdt events + * @start: list_head to sdt_notes list + * + * Returns the number of SDT notes in a list + */ +int sdt_notes__get_count(struct list_head *start) +{ + struct sdt_note *sdt_ptr; + int count = 0; + + list_for_each_entry(sdt_ptr, start, note_list) + count++; + return count; +} + void symbol__elf_init(void) { elf_version(EV_CURRENT); diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h index b10d558a8803..699f7cbcfe72 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -342,4 +342,26 @@ void arch__sym_update(struct symbol *s, GElf_Sym *sym); int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb); +/* structure containing an SDT note's info */ +struct sdt_note { + char *name; /* name of the note*/ + char *provider; /* provider name */ + bool bit32; /* whether the location is 32 bits? */ + union { /* location, base and semaphore addrs */ + Elf64_Addr a64[3]; + Elf32_Addr a32[3]; + } addr; + struct list_head note_list; /* SDT notes' list */ +}; + +int get_sdt_note_list(struct list_head *head, const char *target); +int cleanup_sdt_note_list(struct list_head *sdt_notes); +int sdt_notes__get_count(struct list_head *start); + +#define SDT_BASE_SCN ".stapsdt.base" +#define SDT_NOTE_SCN ".note.stapsdt" +#define SDT_NOTE_TYPE 3 +#define SDT_NOTE_NAME "stapsdt" +#define NR_ADDR 3 + #endif /* __PERF_SYMBOL */ |