+/*
+ * Copyright (C) 2015 Antoine Busque <abusque@efficios.com>
+ * Copyright (C) 2017 Francis Deslauriers <francis.deslauriers@efficios.com>
+ * Copyright (C) 2017 Erica Bugden <erica.bugden@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ */
+
+#include <algorithm>
+#include <common/compat/endian.h>
+#include <common/error.h>
+#include <common/lttng-elf.h>
+#include <common/macros.h>
+#include <common/readwrite.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <elf.h>
+
+#define BUF_LEN 4096
+#define TEXT_SECTION_NAME ".text"
+#define SYMBOL_TAB_SECTION_NAME ".symtab"
+#define STRING_TAB_SECTION_NAME ".strtab"
+#define DYNAMIC_SYMBOL_TAB_SECTION_NAME ".dynsym"
+#define DYNAMIC_STRING_TAB_SECTION_NAME ".dynstr"
+#define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt"
+#define NOTE_STAPSDT_NAME "stapsdt"
+#define NOTE_STAPSDT_TYPE 3
+#define MAX_SECTION_DATA_SIZE 512 * 1024 * 1024
+
+#if BYTE_ORDER == LITTLE_ENDIAN
+#define NATIVE_ELF_ENDIANNESS ELFDATA2LSB
+#else
+#define NATIVE_ELF_ENDIANNESS ELFDATA2MSB
+#endif
+
+#define next_4bytes_boundary(x) (typeof(x)) ((((uint64_t)x) + 3) & ~0x03)
+
+#define bswap(x) \
+ do { \
+ switch (sizeof(x)) { \
+ case 8: \
+ x = be64toh((uint64_t)x); \
+ break; \
+ case 4: \
+ x = be32toh((uint32_t)x); \
+ break; \
+ case 2: \
+ x = be16toh((uint16_t)x); \
+ break; \
+ case 1: \
+ break; \
+ default: \
+ abort(); \
+ } \
+ } while (0)
+
+#define bswap_shdr(shdr) \
+ do { \
+ bswap((shdr).sh_name); \
+ bswap((shdr).sh_type); \
+ bswap((shdr).sh_flags); \
+ bswap((shdr).sh_addr); \
+ bswap((shdr).sh_offset); \
+ bswap((shdr).sh_size); \
+ bswap((shdr).sh_link); \
+ bswap((shdr).sh_info); \
+ bswap((shdr).sh_addralign); \
+ bswap((shdr).sh_entsize); \
+ } while (0)
+
+#define bswap_ehdr(ehdr) \
+ do { \
+ bswap((ehdr).e_type); \
+ bswap((ehdr).e_machine); \
+ bswap((ehdr).e_version); \
+ bswap((ehdr).e_entry); \
+ bswap((ehdr).e_phoff); \
+ bswap((ehdr).e_shoff); \
+ bswap((ehdr).e_flags); \
+ bswap((ehdr).e_ehsize); \
+ bswap((ehdr).e_phentsize); \
+ bswap((ehdr).e_phnum); \
+ bswap((ehdr).e_shentsize); \
+ bswap((ehdr).e_shnum); \
+ bswap((ehdr).e_shstrndx); \
+ } while (0)
+
+#define copy_shdr(src_shdr, dst_shdr) \
+ do { \
+ (dst_shdr).sh_name = (src_shdr).sh_name; \
+ (dst_shdr).sh_type = (src_shdr).sh_type; \
+ (dst_shdr).sh_flags = (src_shdr).sh_flags; \
+ (dst_shdr).sh_addr = (src_shdr).sh_addr; \
+ (dst_shdr).sh_offset = (src_shdr).sh_offset; \
+ (dst_shdr).sh_size = (src_shdr).sh_size; \
+ (dst_shdr).sh_link = (src_shdr).sh_link; \
+ (dst_shdr).sh_info = (src_shdr).sh_info; \
+ (dst_shdr).sh_addralign = (src_shdr).sh_addralign; \
+ (dst_shdr).sh_entsize = (src_shdr).sh_entsize; \
+ } while (0)
+
+#define copy_ehdr(src_ehdr, dst_ehdr) \
+ do { \
+ (dst_ehdr).e_type = (src_ehdr).e_type; \
+ (dst_ehdr).e_machine = (src_ehdr).e_machine; \
+ (dst_ehdr).e_version = (src_ehdr).e_version; \
+ (dst_ehdr).e_entry = (src_ehdr).e_entry; \
+ (dst_ehdr).e_phoff = (src_ehdr).e_phoff; \
+ (dst_ehdr).e_shoff = (src_ehdr).e_shoff; \
+ (dst_ehdr).e_flags = (src_ehdr).e_flags; \
+ (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize; \
+ (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize; \
+ (dst_ehdr).e_phnum = (src_ehdr).e_phnum; \
+ (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize; \
+ (dst_ehdr).e_shnum = (src_ehdr).e_shnum; \
+ (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx; \
+ } while (0)
+
+#define copy_sym(src_sym, dst_sym) \
+ do { \
+ dst_sym.st_name = src_sym.st_name; \
+ dst_sym.st_info = src_sym.st_info; \
+ dst_sym.st_other = src_sym.st_other; \
+ dst_sym.st_shndx = src_sym.st_shndx; \
+ dst_sym.st_value = src_sym.st_value; \
+ dst_sym.st_size = src_sym.st_size; \
+ } while (0)
+
+#ifndef ELFCLASSNUM
+#define ELFCLASSNUM 3
+#endif
+
+#ifndef ELFDATANUM
+#define ELFDATANUM 3
+#endif
+
+#ifndef EV_NUM
+#define EV_NUM 2
+#endif
+
+struct lttng_elf_ehdr {
+ uint16_t e_type;
+ uint16_t e_machine;
+ uint32_t e_version;
+ uint64_t e_entry;
+ uint64_t e_phoff;
+ uint64_t e_shoff;
+ uint32_t e_flags;
+ uint16_t e_ehsize;
+ uint16_t e_phentsize;
+ uint16_t e_phnum;
+ uint16_t e_shentsize;
+ uint16_t e_shnum;
+ uint16_t e_shstrndx;
+};
+
+struct lttng_elf_shdr {
+ uint32_t sh_name;
+ uint32_t sh_type;
+ uint64_t sh_flags;
+ uint64_t sh_addr;
+ uint64_t sh_offset;
+ uint64_t sh_size;
+ uint32_t sh_link;
+ uint32_t sh_info;
+ uint64_t sh_addralign;
+ uint64_t sh_entsize;
+};
+
+/*
+ * This struct can hold both 32bit and 64bit symbol description. It's used with
+ * the copy_sym() macro. Using this abstraction, we can use the same code for
+ * both bitness.
+ */
+struct lttng_elf_sym {
+ uint32_t st_name;
+ uint8_t st_info;
+ uint8_t st_other;
+ uint16_t st_shndx;
+ uint64_t st_value;
+ uint64_t st_size;
+};
+
+struct lttng_elf {
+ int fd;
+ size_t file_size;
+ uint8_t bitness;
+ uint8_t endianness;
+ /* Offset in bytes to start of section names string table. */
+ off_t section_names_offset;
+ /* Size in bytes of section names string table. */
+ size_t section_names_size;
+ struct lttng_elf_ehdr *ehdr;
+};
+
+static inline
+int is_elf_32_bit(struct lttng_elf *elf)
+{
+ return elf->bitness == ELFCLASS32;
+}
+
+static inline
+int is_elf_native_endian(struct lttng_elf *elf)
+{
+ return elf->endianness == NATIVE_ELF_ENDIANNESS;
+}
+
+static
+int populate_section_header(struct lttng_elf * elf, struct lttng_elf_shdr *shdr,
+ uint32_t index)
+{
+ int ret = 0;
+ off_t offset;
+
+ /* Compute the offset of the section in the file */
+ offset = (off_t) elf->ehdr->e_shoff
+ + (off_t) index * elf->ehdr->e_shentsize;
+
+ if (lseek(elf->fd, offset, SEEK_SET) < 0) {
+ PERROR("Error seeking to the beginning of ELF section header");
+ ret = -1;
+ goto error;
+ }
+
+ if (is_elf_32_bit(elf)) {
+ Elf32_Shdr elf_shdr;
+
+ if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) {
+ PERROR("Error reading ELF section header");
+ ret = -1;
+ goto error;
+ }
+ if (!is_elf_native_endian(elf)) {
+ bswap_shdr(elf_shdr);
+ }
+ copy_shdr(elf_shdr, *shdr);
+ } else {
+ Elf64_Shdr elf_shdr;
+
+ if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) {
+ PERROR("Error reading ELF section header");
+ ret = -1;
+ goto error;
+ }
+ if (!is_elf_native_endian(elf)) {
+ bswap_shdr(elf_shdr);
+ }
+ copy_shdr(elf_shdr, *shdr);
+ }
+
+error:
+ return ret;
+}
+
+static
+int populate_elf_header(struct lttng_elf *elf)
+{
+ int ret = 0;
+
+ /*
+ * Move the read pointer back to the beginning to read the full header
+ * and copy it in our structure.
+ */
+ if (lseek(elf->fd, 0, SEEK_SET) < 0) {
+ PERROR("Error seeking to the beginning of the file");
+ ret = -1;
+ goto error;
+ }
+
+ /*
+ * Use macros to set fields in the ELF header struct for both 32bit and
+ * 64bit.
+ */
+ if (is_elf_32_bit(elf)) {
+ Elf32_Ehdr elf_ehdr;
+
+ if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) {
+ ret = -1;
+ goto error;
+ }
+ if (!is_elf_native_endian(elf)) {
+ bswap_ehdr(elf_ehdr);
+ }
+ copy_ehdr(elf_ehdr, *(elf->ehdr));
+ } else {
+ Elf64_Ehdr elf_ehdr;
+
+ if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) {
+ ret = -1;
+ goto error;
+ }
+ if (!is_elf_native_endian(elf)) {
+ bswap_ehdr(elf_ehdr);
+ }
+ copy_ehdr(elf_ehdr, *(elf->ehdr));
+ }
+error:
+ return ret;
+}
+
+/*
+ * Retrieve the nth (where n is the `index` argument) shdr (section
+ * header) from the given elf instance.
+ *
+ * 0 is returned on succes, -1 on failure.
+ */
+static
+int lttng_elf_get_section_hdr(struct lttng_elf *elf,
+ uint16_t index, struct lttng_elf_shdr *out_header)
+{
+ int ret = 0;
+
+ if (!elf) {
+ ret = -1;
+ goto error;
+ }
+
+ if (index >= elf->ehdr->e_shnum) {
+ ret = -1;
+ goto error;
+ }
+
+ ret = populate_section_header(elf, out_header, index);
+ if (ret) {
+ DBG("Error populating section header.");
+ goto error;
+ }
+
+error:
+ return ret;
+}
+
+/*
+ * Lookup a section's name from a given offset (usually from an shdr's
+ * sh_name value) in bytes relative to the beginning of the section
+ * names string table.
+ *
+ * If no name is found, NULL is returned.
+ */
+static
+char *lttng_elf_get_section_name(struct lttng_elf *elf, off_t offset)
+{
+ char *name = NULL;
+ size_t name_length = 0, to_read; /* name_length does not include \0 */
+
+ if (!elf) {
+ goto error;
+ }
+
+ if (offset >= elf->section_names_size) {
+ goto error;
+ }
+
+ if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) {
+ PERROR("Error seeking to the beginning of ELF string table section");
+ goto error;
+ }
+
+ to_read = elf->section_names_size - offset;
+
+ /* Find first \0 after or at current location, remember name_length. */
+ for (;;) {
+ char buf[BUF_LEN];
+ ssize_t read_len;
+ size_t i;
+
+ if (!to_read) {
+ goto error;
+ }
+ read_len = lttng_read(elf->fd, buf, std::min<size_t>(BUF_LEN, to_read));
+ if (read_len <= 0) {
+ PERROR("Error reading ELF string table section");
+ goto error;
+ }
+ for (i = 0; i < read_len; i++) {
+ if (buf[i] == '\0') {
+ name_length += i;
+ goto end;
+ }
+ }
+ name_length += read_len;
+ to_read -= read_len;
+ }
+end:
+ /*
+ * We found the length of the section name, now seek back to the
+ * beginning of the name and copy it in the newly allocated buffer.
+ */
+ name = (char *)zmalloc(sizeof(char) * (name_length + 1)); /* + 1 for \0 */
+ if (!name) {
+ PERROR("Error allocating ELF section name buffer");
+ goto error;
+ }
+ if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) {
+ PERROR("Error seeking to the offset of the ELF section name");
+ goto error;
+ }
+ if (lttng_read(elf->fd, name, name_length + 1) < name_length + 1) {
+ PERROR("Error reading the ELF section name");
+ goto error;
+ }
+
+ return name;
+
+error:
+ free(name);
+ return NULL;
+}
+
+static
+int lttng_elf_validate_and_populate(struct lttng_elf *elf)
+{
+ uint8_t version;
+ uint8_t e_ident[EI_NIDENT];
+ uint8_t *magic_number = NULL;
+ int ret = 0;
+
+ if (elf->fd == -1) {
+ DBG("fd error");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * First read the magic number, endianness and version to later populate
+ * the ELF header with the correct endianness and bitness.
+ * (see elf.h)
+ */
+
+ if (lseek(elf->fd, 0, SEEK_SET) < 0) {
+ PERROR("Error seeking the beginning of ELF file");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+ ret = lttng_read(elf->fd, e_ident, EI_NIDENT);
+ if (ret < EI_NIDENT) {
+ DBG("Error reading the ELF identification fields");
+ if (ret == -1) {
+ PERROR("Error reading the ELF identification fields");
+ }
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * Copy fields used to check that the target file is in fact a valid ELF
+ * file.
+ */
+ elf->bitness = e_ident[EI_CLASS];
+ elf->endianness = e_ident[EI_DATA];
+ version = e_ident[EI_VERSION];
+ magic_number = &e_ident[EI_MAG0];
+
+ /*
+ * Check the magic number.
+ */
+ if (memcmp(magic_number, ELFMAG, SELFMAG) != 0) {
+ DBG("Error check ELF magic number.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * Check the bitness is either ELFCLASS32 or ELFCLASS64.
+ */
+ if (elf->bitness <= ELFCLASSNONE || elf->bitness >= ELFCLASSNUM) {
+ DBG("ELF class error.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * Check the endianness is either ELFDATA2LSB or ELFDATA2MSB.
+ */
+ if (elf->endianness <= ELFDATANONE || elf->endianness >= ELFDATANUM) {
+ DBG("ELF endianness error.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * Check the version is ELF_CURRENT.
+ */
+ if (version <= EV_NONE || version >= EV_NUM) {
+ DBG("Wrong ELF version.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ elf->ehdr = (lttng_elf_ehdr *) zmalloc(sizeof(struct lttng_elf_ehdr));
+ if (!elf->ehdr) {
+ PERROR("Error allocation buffer for ELF header");
+ ret = LTTNG_ERR_NOMEM;
+ goto end;
+ }
+
+ /*
+ * Copy the content of the elf header.
+ */
+ ret = populate_elf_header(elf);
+ if (ret) {
+ DBG("Error reading ELF header,");
+ goto free_elf_error;
+ }
+
+ goto end;
+
+free_elf_error:
+ free(elf->ehdr);
+ elf->ehdr = NULL;
+end:
+ return ret;
+}
+
+/*
+ * Create an instance of lttng_elf for the ELF file located at
+ * `path`.
+ *
+ * Return a pointer to the instance on success, NULL on failure.
+ */
+static
+struct lttng_elf *lttng_elf_create(int fd)
+{
+ struct lttng_elf_shdr section_names_shdr;
+ struct lttng_elf *elf = NULL;
+ int ret;
+ struct stat stat_buf;
+
+ if (fd < 0) {
+ goto error;
+ }
+
+ ret = fstat(fd, &stat_buf);
+ if (ret) {
+ PERROR("Failed to determine size of elf file");
+ goto error;
+ }
+ if (!S_ISREG(stat_buf.st_mode)) {
+ ERR("Refusing to initialize lttng_elf from non-regular file");
+ goto error;
+ }
+
+ elf = (lttng_elf *) zmalloc(sizeof(struct lttng_elf));
+ if (!elf) {
+ PERROR("Error allocating struct lttng_elf");
+ goto error;
+ }
+ elf->file_size = (size_t) stat_buf.st_size;
+
+ elf->fd = dup(fd);
+ if (elf->fd < 0) {
+ PERROR("Error duplicating file descriptor to binary");
+ goto error;
+ }
+
+ ret = lttng_elf_validate_and_populate(elf);
+ if (ret) {
+ goto error;
+ }
+
+ ret = lttng_elf_get_section_hdr(
+ elf, elf->ehdr->e_shstrndx, §ion_names_shdr);
+ if (ret) {
+ goto error;
+ }
+
+ elf->section_names_offset = section_names_shdr.sh_offset;
+ elf->section_names_size = section_names_shdr.sh_size;
+ return elf;
+
+error:
+ if (elf) {
+ if (elf->ehdr) {
+ free(elf->ehdr);
+ }
+ if (elf->fd >= 0) {
+ if (close(elf->fd)) {
+ PERROR("Error closing file descriptor in error path");
+ abort();
+ }
+ }
+ free(elf);
+ }
+ return NULL;
+}
+
+/*
+ * Destroy the given lttng_elf instance.
+ */
+static
+void lttng_elf_destroy(struct lttng_elf *elf)
+{
+ if (!elf) {
+ return;
+ }
+
+ free(elf->ehdr);
+ if (close(elf->fd)) {
+ PERROR("Error closing file description in error path");
+ abort();
+ }
+ free(elf);
+}
+
+static
+int lttng_elf_get_section_hdr_by_name(struct lttng_elf *elf,
+ const char *section_name, struct lttng_elf_shdr *section_hdr)
+{
+ int i;
+ char *curr_section_name;
+
+ for (i = 0; i < elf->ehdr->e_shnum; ++i) {
+ bool name_equal;
+ int ret = lttng_elf_get_section_hdr(elf, i, section_hdr);
+
+ if (ret) {
+ break;
+ }
+ curr_section_name = lttng_elf_get_section_name(elf,
+ section_hdr->sh_name);
+ if (!curr_section_name) {
+ continue;
+ }
+ name_equal = strcmp(curr_section_name, section_name) == 0;
+ free(curr_section_name);
+ if (name_equal) {
+ return 0;
+ }
+ }
+ return LTTNG_ERR_ELF_PARSING;
+}
+
+static
+char *lttng_elf_get_section_data(struct lttng_elf *elf,
+ struct lttng_elf_shdr *shdr)
+{
+ int ret;
+ off_t section_offset;
+ char *data;
+ size_t max_alloc_size;
+
+ if (!elf || !shdr) {
+ goto error;
+ }
+
+ max_alloc_size = std::min<size_t>(MAX_SECTION_DATA_SIZE, elf->file_size);
+
+ section_offset = shdr->sh_offset;
+ if (lseek(elf->fd, section_offset, SEEK_SET) < 0) {
+ PERROR("Error seeking to section offset");
+ goto error;
+ }
+
+ if (shdr->sh_size > max_alloc_size) {
+ ERR("ELF section size exceeds maximal allowed size of %zu bytes",
+ max_alloc_size);
+ goto error;
+ }
+ data = (char *) zmalloc(shdr->sh_size);
+ if (!data) {
+ PERROR("Error allocating buffer for ELF section data");
+ goto error;
+ }
+ ret = lttng_read(elf->fd, data, shdr->sh_size);
+ if (ret == -1) {
+ PERROR("Error reading ELF section data");
+ goto free_error;
+ }
+
+ return data;
+
+free_error:
+ free(data);
+error:
+ return NULL;
+}
+
+/*
+ * Convert the virtual address in a binary's mapping to the offset of
+ * the corresponding instruction in the binary file.
+ * This function assumes the address is in the text section.
+ *
+ * Returns the offset on success or non-zero in case of failure.
+ */
+static
+int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle,
+ size_t addr, uint64_t *offset)
+{
+ int ret = 0;
+ off_t text_section_offset;
+ off_t text_section_addr_beg;
+ off_t text_section_addr_end;
+ off_t offset_in_section;
+ struct lttng_elf_shdr text_section_hdr;
+
+ if (!elf_handle) {
+ DBG("Invalid ELF handle.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto error;
+ }
+
+ /* Get a pointer to the .text section header. */
+ ret = lttng_elf_get_section_hdr_by_name(elf_handle,
+ TEXT_SECTION_NAME, &text_section_hdr);
+ if (ret) {
+ DBG("Text section not found in binary.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto error;
+ }
+
+ text_section_offset = text_section_hdr.sh_offset;
+ text_section_addr_beg = text_section_hdr.sh_addr;
+ text_section_addr_end =
+ text_section_addr_beg + text_section_hdr.sh_size;
+
+ /*
+ * Verify that the address is within the .text section boundaries.
+ */
+ if (addr < text_section_addr_beg || addr > text_section_addr_end) {
+ DBG("Address found is outside of the .text section addr=0x%zx, "
+ ".text section=[0x%jd - 0x%jd].", addr, (intmax_t)text_section_addr_beg,
+ (intmax_t)text_section_addr_end);
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto error;
+ }
+
+ offset_in_section = addr - text_section_addr_beg;
+
+ /*
+ * Add the target offset in the text section to the offset of this text
+ * section from the beginning of the binary file.
+ */
+ *offset = text_section_offset + offset_in_section;
+
+error:
+ return ret;
+}
+
+/*
+ * Compute the offset of a symbol from the begining of the ELF binary.
+ *
+ * On success, returns 0 offset parameter is set to the computed value
+ * On failure, returns -1.
+ */
+int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
+{
+ int ret = 0;
+ int sym_found = 0;
+ int sym_count = 0;
+ int sym_idx = 0;
+ uint64_t addr = 0;
+ char *curr_sym_str = NULL;
+ char *symbol_table_data = NULL;
+ char *string_table_data = NULL;
+ const char *string_table_name = NULL;
+ struct lttng_elf_shdr symtab_hdr;
+ struct lttng_elf_shdr strtab_hdr;
+ struct lttng_elf *elf = NULL;
+
+ if (!symbol || !offset ) {
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ elf = lttng_elf_create(fd);
+ if (!elf) {
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto end;
+ }
+
+ /*
+ * The .symtab section might not exist on stripped binaries.
+ * Try to get the symbol table section header first. If it's absent,
+ * try to get the dynamic symbol table. All symbols in the dynamic
+ * symbol tab are in the (normal) symbol table if it exists.
+ */
+ ret = lttng_elf_get_section_hdr_by_name(elf, SYMBOL_TAB_SECTION_NAME,
+ &symtab_hdr);
+ if (ret) {
+ DBG("Cannot get ELF Symbol Table section. Trying to get ELF Dynamic Symbol Table section.");
+ /* Get the dynamic symbol table section header. */
+ ret = lttng_elf_get_section_hdr_by_name(elf, DYNAMIC_SYMBOL_TAB_SECTION_NAME,
+ &symtab_hdr);
+ if (ret) {
+ DBG("Cannot get ELF Symbol Table nor Dynamic Symbol Table sections.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto destroy_elf;
+ }
+ string_table_name = DYNAMIC_STRING_TAB_SECTION_NAME;
+ } else {
+ string_table_name = STRING_TAB_SECTION_NAME;
+ }
+
+ /* Get the data associated with the symbol table section. */
+ symbol_table_data = lttng_elf_get_section_data(elf, &symtab_hdr);
+ if (symbol_table_data == NULL) {
+ DBG("Cannot get ELF Symbol Table data.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto destroy_elf;
+ }
+
+ /* Get the string table section header. */
+ ret = lttng_elf_get_section_hdr_by_name(elf, string_table_name,
+ &strtab_hdr);
+ if (ret) {
+ DBG("Cannot get ELF string table section.");
+ goto free_symbol_table_data;
+ }
+
+ /* Get the data associated with the string table section. */
+ string_table_data = lttng_elf_get_section_data(elf, &strtab_hdr);
+ if (string_table_data == NULL) {
+ DBG("Cannot get ELF string table section data.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto free_symbol_table_data;
+ }
+
+ /* Get the number of symbol in the table for the iteration. */
+ sym_count = symtab_hdr.sh_size / symtab_hdr.sh_entsize;
+
+ /* Loop over all symbol. */
+ for (sym_idx = 0; sym_idx < sym_count; sym_idx++) {
+ struct lttng_elf_sym curr_sym;
+
+ /* Get the symbol at the current index. */
+ if (is_elf_32_bit(elf)) {
+ Elf32_Sym tmp = ((Elf32_Sym *) symbol_table_data)[sym_idx];
+ copy_sym(tmp, curr_sym);
+ } else {
+ Elf64_Sym tmp = ((Elf64_Sym *) symbol_table_data)[sym_idx];
+ copy_sym(tmp, curr_sym);
+ }
+
+ /*
+ * If the st_name field is zero, there is no string name for
+ * this symbol; skip to the next symbol.
+ */
+ if (curr_sym.st_name == 0) {
+ continue;
+ }
+
+ /*
+ * Use the st_name field in the lttng_elf_sym struct to get offset of
+ * the symbol's name from the beginning of the string table.
+ */
+ curr_sym_str = string_table_data + curr_sym.st_name;
+
+ /*
+ * If the current symbol is not a function; skip to the next symbol.
+ */
+ /* Both 32bit and 64bit use the same 1 byte field for type. (See elf.h) */
+ if (ELF32_ST_TYPE(curr_sym.st_info) != STT_FUNC) {
+ continue;
+ }
+
+ /*
+ * Compare with the search symbol. If there is a match set the address
+ * output parameter and return success.
+ */
+ if (strcmp(symbol, curr_sym_str) == 0 ) {
+ sym_found = 1;
+ addr = curr_sym.st_value;
+ break;
+ }
+ }
+
+ if (!sym_found) {
+ DBG("Symbol not found.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto free_string_table_data;
+ }
+
+ /*
+ * Use the virtual address of the symbol to compute the offset of this
+ * symbol from the beginning of the executable file.
+ */
+ ret = lttng_elf_convert_addr_in_text_to_offset(elf, addr, offset);
+ if (ret) {
+ DBG("Cannot convert addr to offset.");
+ goto free_string_table_data;
+ }
+
+
+free_string_table_data:
+ free(string_table_data);
+free_symbol_table_data:
+ free(symbol_table_data);
+destroy_elf:
+ lttng_elf_destroy(elf);
+end:
+ return ret;
+}
+
+/*
+ * Compute the offsets of SDT probes from the begining of the ELF binary.
+ *
+ * On success, returns 0 and the nb_probes parameter is set to the number of
+ * offsets found and the offsets parameter points to an array of offsets where
+ * the SDT probes are.
+ * On failure, returns -1.
+ */
+int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name,
+ const char *probe_name, uint64_t **offsets, uint32_t *nb_probes)
+{
+ int ret = 0, nb_match = 0;
+ struct lttng_elf_shdr stap_note_section_hdr;
+ struct lttng_elf *elf = NULL;
+ char *stap_note_section_data = NULL;
+ char *curr_note_section_begin, *curr_data_ptr, *curr_probe, *curr_provider;
+ char *next_note_ptr;
+ uint32_t name_size, desc_size, note_type;
+ uint64_t curr_probe_location, curr_probe_offset, curr_semaphore_location;
+ uint64_t *probe_locs = NULL, *new_probe_locs = NULL;
+
+ if (!provider_name || !probe_name || !nb_probes || !offsets) {
+ DBG("Invalid arguments.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto error;
+ }
+
+ elf = lttng_elf_create(fd);
+ if (!elf) {
+ DBG("Error allocation ELF.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto error;
+ }
+
+ /* Get the stap note section header. */
+ ret = lttng_elf_get_section_hdr_by_name(elf, NOTE_STAPSDT_SECTION_NAME,
+ &stap_note_section_hdr);
+ if (ret) {
+ DBG("Cannot get ELF stap note section.");
+ goto destroy_elf_error;
+ }
+
+ /* Get the data associated with the stap note section. */
+ stap_note_section_data =
+ lttng_elf_get_section_data(elf, &stap_note_section_hdr);
+ if (stap_note_section_data == NULL) {
+ DBG("Cannot get ELF stap note section data.");
+ ret = LTTNG_ERR_ELF_PARSING;
+ goto destroy_elf_error;
+ }
+
+ next_note_ptr = stap_note_section_data;
+ curr_note_section_begin = stap_note_section_data;
+
+ *offsets = NULL;
+ while (1) {
+ curr_data_ptr = next_note_ptr;
+ /* Check if we have reached the end of the note section. */
+ if (curr_data_ptr >=
+ curr_note_section_begin +
+ stap_note_section_hdr.sh_size) {
+ *nb_probes = nb_match;
+ *offsets = probe_locs;
+ ret = 0;
+ break;
+ }
+ /* Get name size field. */
+ name_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr);
+ curr_data_ptr += sizeof(uint32_t);
+
+ /* Sanity check; a zero name_size is reserved. */
+ if (name_size == 0) {
+ DBG("Invalid name size field in SDT probe descriptions"
+ "section.");
+ ret = -1;
+ goto realloc_error;
+ }
+
+ /* Get description size field. */
+ desc_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr);
+ curr_data_ptr += sizeof(uint32_t);
+
+ /* Get type field. */
+ note_type = *(uint32_t *) curr_data_ptr;
+ curr_data_ptr += sizeof(uint32_t);
+
+ /*
+ * Move the pointer to the next note to be ready for the next
+ * iteration. The current note is made of 3 unsigned 32bit
+ * integers (name size, descriptor size and note type), the
+ * name and the descriptor. To move to the next note, we move
+ * the pointer according to those values.
+ */
+ next_note_ptr = next_note_ptr +
+ (3 * sizeof(uint32_t)) + desc_size + name_size;
+
+ /*
+ * Move ptr to the end of the name string (we don't need it)
+ * and go to the next 4 byte alignement.
+ */
+ if (note_type != NOTE_STAPSDT_TYPE ||
+ strncmp(curr_data_ptr, NOTE_STAPSDT_NAME, name_size) != 0) {
+ continue;
+ }
+
+ curr_data_ptr += name_size;
+
+ /* Get probe location. */
+ curr_probe_location = *(uint64_t *) curr_data_ptr;
+ curr_data_ptr += sizeof(uint64_t);
+
+ /* Pass over the base. Not needed. */
+ curr_data_ptr += sizeof(uint64_t);
+
+ /* Get semaphore location. */
+ curr_semaphore_location = *(uint64_t *) curr_data_ptr;
+ curr_data_ptr += sizeof(uint64_t);
+ /* Get provider name. */
+ curr_provider = curr_data_ptr;
+ curr_data_ptr += strlen(curr_provider) + 1;
+
+ /* Get probe name. */
+ curr_probe = curr_data_ptr;
+
+ /* Check if the provider and probe name match */
+ if (strcmp(provider_name, curr_provider) == 0 &&
+ strcmp(probe_name, curr_probe) == 0) {
+ int new_size;
+
+ /*
+ * We currently don't support SDT probes with semaphores. Return
+ * success as we found a matching probe but it's guarded by a
+ * semaphore.
+ */
+ if (curr_semaphore_location != 0) {
+ ret = LTTNG_ERR_SDT_PROBE_SEMAPHORE;
+ goto realloc_error;
+ }
+
+ new_size = (++nb_match) * sizeof(uint64_t);
+
+ /*
+ * Found a match with not semaphore, we need to copy the
+ * probe_location to the output parameter.
+ */
+ new_probe_locs = (uint64_t *) realloc(probe_locs, new_size);
+ if (!new_probe_locs) {
+ /* Error allocating a larger buffer */
+ DBG("Allocation error in SDT.");
+ ret = LTTNG_ERR_NOMEM;
+ goto realloc_error;
+ }
+ probe_locs = new_probe_locs;
+ new_probe_locs = NULL;
+
+ /*
+ * Use the virtual address of the probe to compute the offset of
+ * this probe from the beginning of the executable file.
+ */
+ ret = lttng_elf_convert_addr_in_text_to_offset(elf,
+ curr_probe_location, &curr_probe_offset);
+ if (ret) {
+ DBG("Conversion error in SDT.");
+ goto realloc_error;
+ }
+
+ probe_locs[nb_match - 1] = curr_probe_offset;
+ }
+ }
+
+end:
+ free(stap_note_section_data);
+destroy_elf_error:
+ lttng_elf_destroy(elf);
+error:
+ return ret;
+realloc_error:
+ free(probe_locs);
+ goto end;
+}
projects / lttng-tools.git / blobdiff