diff options
Diffstat (limited to 'gcc-4.9/libbacktrace/elf.c')
| -rw-r--r-- | gcc-4.9/libbacktrace/elf.c | 976 |
1 files changed, 976 insertions, 0 deletions
diff --git a/gcc-4.9/libbacktrace/elf.c b/gcc-4.9/libbacktrace/elf.c new file mode 100644 index 000000000..e63aaf5db --- /dev/null +++ b/gcc-4.9/libbacktrace/elf.c @@ -0,0 +1,976 @@ +/* elf.c -- Get debug data from an ELF file for backtraces. + Copyright (C) 2012-2014 Free Software Foundation, Inc. + Written by Ian Lance Taylor, Google. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + + (1) Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + (2) Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in + the documentation and/or other materials provided with the + distribution. + + (3) The name of the author may not be used to + endorse or promote products derived from this software without + specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, +INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING +IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +POSSIBILITY OF SUCH DAMAGE. */ + +#include "config.h" + +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> + +#ifdef HAVE_DL_ITERATE_PHDR +#include <link.h> +#endif + +#include "backtrace.h" +#include "internal.h" + +#ifndef HAVE_DL_ITERATE_PHDR + +/* Dummy version of dl_iterate_phdr for systems that don't have it. */ + +#define dl_phdr_info x_dl_phdr_info +#define dl_iterate_phdr x_dl_iterate_phdr + +struct dl_phdr_info +{ + uintptr_t dlpi_addr; + const char *dlpi_name; +}; + +static int +dl_iterate_phdr (int (*callback) (struct dl_phdr_info *, + size_t, void *) ATTRIBUTE_UNUSED, + void *data ATTRIBUTE_UNUSED) +{ + return 0; +} + +#endif /* ! defined (HAVE_DL_ITERATE_PHDR) */ + +/* The configure script must tell us whether we are 32-bit or 64-bit + ELF. We could make this code test and support either possibility, + but there is no point. This code only works for the currently + running executable, which means that we know the ELF mode at + configure mode. */ + +#if BACKTRACE_ELF_SIZE != 32 && BACKTRACE_ELF_SIZE != 64 +#error "Unknown BACKTRACE_ELF_SIZE" +#endif + +/* <link.h> might #include <elf.h> which might define our constants + with slightly different values. Undefine them to be safe. */ + +#undef EI_NIDENT +#undef EI_MAG0 +#undef EI_MAG1 +#undef EI_MAG2 +#undef EI_MAG3 +#undef EI_CLASS +#undef EI_DATA +#undef EI_VERSION +#undef ELF_MAG0 +#undef ELF_MAG1 +#undef ELF_MAG2 +#undef ELF_MAG3 +#undef ELFCLASS32 +#undef ELFCLASS64 +#undef ELFDATA2LSB +#undef ELFDATA2MSB +#undef EV_CURRENT +#undef ET_DYN +#undef SHN_LORESERVE +#undef SHN_XINDEX +#undef SHN_UNDEF +#undef SHT_SYMTAB +#undef SHT_STRTAB +#undef SHT_DYNSYM +#undef STT_OBJECT +#undef STT_FUNC + +/* Basic types. */ + +typedef uint16_t b_elf_half; /* Elf_Half. */ +typedef uint32_t b_elf_word; /* Elf_Word. */ +typedef int32_t b_elf_sword; /* Elf_Sword. */ + +#if BACKTRACE_ELF_SIZE == 32 + +typedef uint32_t b_elf_addr; /* Elf_Addr. */ +typedef uint32_t b_elf_off; /* Elf_Off. */ + +typedef uint32_t b_elf_wxword; /* 32-bit Elf_Word, 64-bit ELF_Xword. */ + +#else + +typedef uint64_t b_elf_addr; /* Elf_Addr. */ +typedef uint64_t b_elf_off; /* Elf_Off. */ +typedef uint64_t b_elf_xword; /* Elf_Xword. */ +typedef int64_t b_elf_sxword; /* Elf_Sxword. */ + +typedef uint64_t b_elf_wxword; /* 32-bit Elf_Word, 64-bit ELF_Xword. */ + +#endif + +/* Data structures and associated constants. */ + +#define EI_NIDENT 16 + +typedef struct { + unsigned char e_ident[EI_NIDENT]; /* ELF "magic number" */ + b_elf_half e_type; /* Identifies object file type */ + b_elf_half e_machine; /* Specifies required architecture */ + b_elf_word e_version; /* Identifies object file version */ + b_elf_addr e_entry; /* Entry point virtual address */ + b_elf_off e_phoff; /* Program header table file offset */ + b_elf_off e_shoff; /* Section header table file offset */ + b_elf_word e_flags; /* Processor-specific flags */ + b_elf_half e_ehsize; /* ELF header size in bytes */ + b_elf_half e_phentsize; /* Program header table entry size */ + b_elf_half e_phnum; /* Program header table entry count */ + b_elf_half e_shentsize; /* Section header table entry size */ + b_elf_half e_shnum; /* Section header table entry count */ + b_elf_half e_shstrndx; /* Section header string table index */ +} b_elf_ehdr; /* Elf_Ehdr. */ + +#define EI_MAG0 0 +#define EI_MAG1 1 +#define EI_MAG2 2 +#define EI_MAG3 3 +#define EI_CLASS 4 +#define EI_DATA 5 +#define EI_VERSION 6 + +#define ELFMAG0 0x7f +#define ELFMAG1 'E' +#define ELFMAG2 'L' +#define ELFMAG3 'F' + +#define ELFCLASS32 1 +#define ELFCLASS64 2 + +#define ELFDATA2LSB 1 +#define ELFDATA2MSB 2 + +#define EV_CURRENT 1 + +#define ET_DYN 3 + +typedef struct { + b_elf_word sh_name; /* Section name, index in string tbl */ + b_elf_word sh_type; /* Type of section */ + b_elf_wxword sh_flags; /* Miscellaneous section attributes */ + b_elf_addr sh_addr; /* Section virtual addr at execution */ + b_elf_off sh_offset; /* Section file offset */ + b_elf_wxword sh_size; /* Size of section in bytes */ + b_elf_word sh_link; /* Index of another section */ + b_elf_word sh_info; /* Additional section information */ + b_elf_wxword sh_addralign; /* Section alignment */ + b_elf_wxword sh_entsize; /* Entry size if section holds table */ +} b_elf_shdr; /* Elf_Shdr. */ + +#define SHN_UNDEF 0x0000 /* Undefined section */ +#define SHN_LORESERVE 0xFF00 /* Begin range of reserved indices */ +#define SHN_XINDEX 0xFFFF /* Section index is held elsewhere */ + +#define SHT_SYMTAB 2 +#define SHT_STRTAB 3 +#define SHT_DYNSYM 11 + +#if BACKTRACE_ELF_SIZE == 32 + +typedef struct +{ + b_elf_word st_name; /* Symbol name, index in string tbl */ + b_elf_addr st_value; /* Symbol value */ + b_elf_word st_size; /* Symbol size */ + unsigned char st_info; /* Symbol binding and type */ + unsigned char st_other; /* Visibility and other data */ + b_elf_half st_shndx; /* Symbol section index */ +} b_elf_sym; /* Elf_Sym. */ + +#else /* BACKTRACE_ELF_SIZE != 32 */ + +typedef struct +{ + b_elf_word st_name; /* Symbol name, index in string tbl */ + unsigned char st_info; /* Symbol binding and type */ + unsigned char st_other; /* Visibility and other data */ + b_elf_half st_shndx; /* Symbol section index */ + b_elf_addr st_value; /* Symbol value */ + b_elf_xword st_size; /* Symbol size */ +} b_elf_sym; /* Elf_Sym. */ + +#endif /* BACKTRACE_ELF_SIZE != 32 */ + +#define STT_OBJECT 1 +#define STT_FUNC 2 + +/* An index of ELF sections we care about. */ + +enum debug_section +{ + DEBUG_INFO, + DEBUG_LINE, + DEBUG_ABBREV, + DEBUG_RANGES, + DEBUG_STR, + DEBUG_MAX +}; + +/* Names of sections, indexed by enum elf_section. */ + +static const char * const debug_section_names[DEBUG_MAX] = +{ + ".debug_info", + ".debug_line", + ".debug_abbrev", + ".debug_ranges", + ".debug_str" +}; + +/* Information we gather for the sections we care about. */ + +struct debug_section_info +{ + /* Section file offset. */ + off_t offset; + /* Section size. */ + size_t size; + /* Section contents, after read from file. */ + const unsigned char *data; +}; + +/* Information we keep for an ELF symbol. */ + +struct elf_symbol +{ + /* The name of the symbol. */ + const char *name; + /* The address of the symbol. */ + uintptr_t address; + /* The size of the symbol. */ + size_t size; +}; + +/* Information to pass to elf_syminfo. */ + +struct elf_syminfo_data +{ + /* Symbols for the next module. */ + struct elf_syminfo_data *next; + /* The ELF symbols, sorted by address. */ + struct elf_symbol *symbols; + /* The number of symbols. */ + size_t count; +}; + +/* A dummy callback function used when we can't find any debug info. */ + +static int +elf_nodebug (struct backtrace_state *state ATTRIBUTE_UNUSED, + uintptr_t pc ATTRIBUTE_UNUSED, + backtrace_full_callback callback ATTRIBUTE_UNUSED, + backtrace_error_callback error_callback, void *data) +{ + error_callback (data, "no debug info in ELF executable", -1); + return 0; +} + +/* A dummy callback function used when we can't find a symbol + table. */ + +static void +elf_nosyms (struct backtrace_state *state ATTRIBUTE_UNUSED, + uintptr_t addr ATTRIBUTE_UNUSED, + backtrace_syminfo_callback callback ATTRIBUTE_UNUSED, + backtrace_error_callback error_callback, void *data) +{ + error_callback (data, "no symbol table in ELF executable", -1); +} + +/* Compare struct elf_symbol for qsort. */ + +static int +elf_symbol_compare (const void *v1, const void *v2) +{ + const struct elf_symbol *e1 = (const struct elf_symbol *) v1; + const struct elf_symbol *e2 = (const struct elf_symbol *) v2; + + if (e1->address < e2->address) + return -1; + else if (e1->address > e2->address) + return 1; + else + return 0; +} + +/* Compare an ADDR against an elf_symbol for bsearch. We allocate one + extra entry in the array so that this can look safely at the next + entry. */ + +static int +elf_symbol_search (const void *vkey, const void *ventry) +{ + const uintptr_t *key = (const uintptr_t *) vkey; + const struct elf_symbol *entry = (const struct elf_symbol *) ventry; + uintptr_t addr; + + addr = *key; + if (addr < entry->address) + return -1; + else if (addr >= entry->address + entry->size) + return 1; + else + return 0; +} + +/* Initialize the symbol table info for elf_syminfo. */ + +static int +elf_initialize_syminfo (struct backtrace_state *state, + uintptr_t base_address, + const unsigned char *symtab_data, size_t symtab_size, + const unsigned char *strtab, size_t strtab_size, + backtrace_error_callback error_callback, + void *data, struct elf_syminfo_data *sdata) +{ + size_t sym_count; + const b_elf_sym *sym; + size_t elf_symbol_count; + size_t elf_symbol_size; + struct elf_symbol *elf_symbols; + size_t i; + unsigned int j; + + sym_count = symtab_size / sizeof (b_elf_sym); + + /* We only care about function symbols. Count them. */ + sym = (const b_elf_sym *) symtab_data; + elf_symbol_count = 0; + for (i = 0; i < sym_count; ++i, ++sym) + { + int info; + + info = sym->st_info & 0xf; + if ((info == STT_FUNC || info == STT_OBJECT) + && sym->st_shndx != SHN_UNDEF) + ++elf_symbol_count; + } + + elf_symbol_size = elf_symbol_count * sizeof (struct elf_symbol); + elf_symbols = ((struct elf_symbol *) + backtrace_alloc (state, elf_symbol_size, error_callback, + data)); + if (elf_symbols == NULL) + return 0; + + sym = (const b_elf_sym *) symtab_data; + j = 0; + for (i = 0; i < sym_count; ++i, ++sym) + { + int info; + + info = sym->st_info & 0xf; + if (info != STT_FUNC && info != STT_OBJECT) + continue; + if (sym->st_shndx == SHN_UNDEF) + continue; + if (sym->st_name >= strtab_size) + { + error_callback (data, "symbol string index out of range", 0); + backtrace_free (state, elf_symbols, elf_symbol_size, error_callback, + data); + return 0; + } + elf_symbols[j].name = (const char *) strtab + sym->st_name; + elf_symbols[j].address = sym->st_value + base_address; + elf_symbols[j].size = sym->st_size; + ++j; + } + + backtrace_qsort (elf_symbols, elf_symbol_count, sizeof (struct elf_symbol), + elf_symbol_compare); + + sdata->next = NULL; + sdata->symbols = elf_symbols; + sdata->count = elf_symbol_count; + + return 1; +} + +/* Add EDATA to the list in STATE. */ + +static void +elf_add_syminfo_data (struct backtrace_state *state, + struct elf_syminfo_data *edata) +{ + if (!state->threaded) + { + struct elf_syminfo_data **pp; + + for (pp = (struct elf_syminfo_data **) (void *) &state->syminfo_data; + *pp != NULL; + pp = &(*pp)->next) + ; + *pp = edata; + } + else + { + while (1) + { + struct elf_syminfo_data **pp; + + pp = (struct elf_syminfo_data **) (void *) &state->syminfo_data; + + while (1) + { + struct elf_syminfo_data *p; + + p = backtrace_atomic_load_pointer (pp); + + if (p == NULL) + break; + + pp = &p->next; + } + + if (__sync_bool_compare_and_swap (pp, NULL, edata)) + break; + } + } +} + +/* Return the symbol name and value for an ADDR. */ + +static void +elf_syminfo (struct backtrace_state *state, uintptr_t addr, + backtrace_syminfo_callback callback, + backtrace_error_callback error_callback ATTRIBUTE_UNUSED, + void *data) +{ + struct elf_syminfo_data *edata; + struct elf_symbol *sym = NULL; + + if (!state->threaded) + { + for (edata = (struct elf_syminfo_data *) state->syminfo_data; + edata != NULL; + edata = edata->next) + { + sym = ((struct elf_symbol *) + bsearch (&addr, edata->symbols, edata->count, + sizeof (struct elf_symbol), elf_symbol_search)); + if (sym != NULL) + break; + } + } + else + { + struct elf_syminfo_data **pp; + + pp = (struct elf_syminfo_data **) (void *) &state->syminfo_data; + while (1) + { + edata = backtrace_atomic_load_pointer (pp); + if (edata == NULL) + break; + + sym = ((struct elf_symbol *) + bsearch (&addr, edata->symbols, edata->count, + sizeof (struct elf_symbol), elf_symbol_search)); + if (sym != NULL) + break; + + pp = &edata->next; + } + } + + if (sym == NULL) + callback (data, addr, NULL, 0, 0); + else + callback (data, addr, sym->name, sym->address, sym->size); +} + +/* Add the backtrace data for one ELF file. Returns 1 on success, + 0 on failure (in both cases descriptor is closed) or -1 if exe + is non-zero and the ELF file is ET_DYN, which tells the caller that + elf_add will need to be called on the descriptor again after + base_address is determined. */ + +static int +elf_add (struct backtrace_state *state, int descriptor, uintptr_t base_address, + backtrace_error_callback error_callback, void *data, + fileline *fileline_fn, int *found_sym, int *found_dwarf, int exe) +{ + struct backtrace_view ehdr_view; + b_elf_ehdr ehdr; + off_t shoff; + unsigned int shnum; + unsigned int shstrndx; + struct backtrace_view shdrs_view; + int shdrs_view_valid; + const b_elf_shdr *shdrs; + const b_elf_shdr *shstrhdr; + size_t shstr_size; + off_t shstr_off; + struct backtrace_view names_view; + int names_view_valid; + const char *names; + unsigned int symtab_shndx; + unsigned int dynsym_shndx; + unsigned int i; + struct debug_section_info sections[DEBUG_MAX]; + struct backtrace_view symtab_view; + int symtab_view_valid; + struct backtrace_view strtab_view; + int strtab_view_valid; + off_t min_offset; + off_t max_offset; + struct backtrace_view debug_view; + int debug_view_valid; + + *found_sym = 0; + *found_dwarf = 0; + + shdrs_view_valid = 0; + names_view_valid = 0; + symtab_view_valid = 0; + strtab_view_valid = 0; + debug_view_valid = 0; + + if (!backtrace_get_view (state, descriptor, 0, sizeof ehdr, error_callback, + data, &ehdr_view)) + goto fail; + + memcpy (&ehdr, ehdr_view.data, sizeof ehdr); + + backtrace_release_view (state, &ehdr_view, error_callback, data); + + if (ehdr.e_ident[EI_MAG0] != ELFMAG0 + || ehdr.e_ident[EI_MAG1] != ELFMAG1 + || ehdr.e_ident[EI_MAG2] != ELFMAG2 + || ehdr.e_ident[EI_MAG3] != ELFMAG3) + { + error_callback (data, "executable file is not ELF", 0); + goto fail; + } + if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) + { + error_callback (data, "executable file is unrecognized ELF version", 0); + goto fail; + } + +#if BACKTRACE_ELF_SIZE == 32 +#define BACKTRACE_ELFCLASS ELFCLASS32 +#else +#define BACKTRACE_ELFCLASS ELFCLASS64 +#endif + + if (ehdr.e_ident[EI_CLASS] != BACKTRACE_ELFCLASS) + { + error_callback (data, "executable file is unexpected ELF class", 0); + goto fail; + } + + if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB + && ehdr.e_ident[EI_DATA] != ELFDATA2MSB) + { + error_callback (data, "executable file has unknown endianness", 0); + goto fail; + } + + /* If the executable is ET_DYN, it is either a PIE, or we are running + directly a shared library with .interp. We need to wait for + dl_iterate_phdr in that case to determine the actual base_address. */ + if (exe && ehdr.e_type == ET_DYN) + return -1; + + shoff = ehdr.e_shoff; + shnum = ehdr.e_shnum; + shstrndx = ehdr.e_shstrndx; + + if ((shnum == 0 || shstrndx == SHN_XINDEX) + && shoff != 0) + { + struct backtrace_view shdr_view; + const b_elf_shdr *shdr; + + if (!backtrace_get_view (state, descriptor, shoff, sizeof shdr, + error_callback, data, &shdr_view)) + goto fail; + + shdr = (const b_elf_shdr *) shdr_view.data; + + if (shnum == 0) + shnum = shdr->sh_size; + + if (shstrndx == SHN_XINDEX) + { + shstrndx = shdr->sh_link; + + /* Versions of the GNU binutils between 2.12 and 2.18 did + not handle objects with more than SHN_LORESERVE sections + correctly. All large section indexes were offset by + 0x100. There is more information at + http://sourceware.org/bugzilla/show_bug.cgi?id-5900 . + Fortunately these object files are easy to detect, as the + GNU binutils always put the section header string table + near the end of the list of sections. Thus if the + section header string table index is larger than the + number of sections, then we know we have to subtract + 0x100 to get the real section index. */ + if (shstrndx >= shnum && shstrndx >= SHN_LORESERVE + 0x100) + shstrndx -= 0x100; + } + + backtrace_release_view (state, &shdr_view, error_callback, data); + } + + /* To translate PC to file/line when using DWARF, we need to find + the .debug_info and .debug_line sections. */ + + /* Read the section headers, skipping the first one. */ + + if (!backtrace_get_view (state, descriptor, shoff + sizeof (b_elf_shdr), + (shnum - 1) * sizeof (b_elf_shdr), + error_callback, data, &shdrs_view)) + goto fail; + shdrs_view_valid = 1; + shdrs = (const b_elf_shdr *) shdrs_view.data; + + /* Read the section names. */ + + shstrhdr = &shdrs[shstrndx - 1]; + shstr_size = shstrhdr->sh_size; + shstr_off = shstrhdr->sh_offset; + + if (!backtrace_get_view (state, descriptor, shstr_off, shstr_size, + error_callback, data, &names_view)) + goto fail; + names_view_valid = 1; + names = (const char *) names_view.data; + + symtab_shndx = 0; + dynsym_shndx = 0; + + memset (sections, 0, sizeof sections); + + /* Look for the symbol table. */ + for (i = 1; i < shnum; ++i) + { + const b_elf_shdr *shdr; + unsigned int sh_name; + const char *name; + int j; + + shdr = &shdrs[i - 1]; + + if (shdr->sh_type == SHT_SYMTAB) + symtab_shndx = i; + else if (shdr->sh_type == SHT_DYNSYM) + dynsym_shndx = i; + + sh_name = shdr->sh_name; + if (sh_name >= shstr_size) + { + error_callback (data, "ELF section name out of range", 0); + goto fail; + } + + name = names + sh_name; + + for (j = 0; j < (int) DEBUG_MAX; ++j) + { + if (strcmp (name, debug_section_names[j]) == 0) + { + sections[j].offset = shdr->sh_offset; + sections[j].size = shdr->sh_size; + break; + } + } + } + + if (symtab_shndx == 0) + symtab_shndx = dynsym_shndx; + if (symtab_shndx != 0) + { + const b_elf_shdr *symtab_shdr; + unsigned int strtab_shndx; + const b_elf_shdr *strtab_shdr; + struct elf_syminfo_data *sdata; + + symtab_shdr = &shdrs[symtab_shndx - 1]; + strtab_shndx = symtab_shdr->sh_link; + if (strtab_shndx >= shnum) + { + error_callback (data, + "ELF symbol table strtab link out of range", 0); + goto fail; + } + strtab_shdr = &shdrs[strtab_shndx - 1]; + + if (!backtrace_get_view (state, descriptor, symtab_shdr->sh_offset, + symtab_shdr->sh_size, error_callback, data, + &symtab_view)) + goto fail; + symtab_view_valid = 1; + + if (!backtrace_get_view (state, descriptor, strtab_shdr->sh_offset, + strtab_shdr->sh_size, error_callback, data, + &strtab_view)) + goto fail; + strtab_view_valid = 1; + + sdata = ((struct elf_syminfo_data *) + backtrace_alloc (state, sizeof *sdata, error_callback, data)); + if (sdata == NULL) + goto fail; + + if (!elf_initialize_syminfo (state, base_address, + symtab_view.data, symtab_shdr->sh_size, + strtab_view.data, strtab_shdr->sh_size, + error_callback, data, sdata)) + { + backtrace_free (state, sdata, sizeof *sdata, error_callback, data); + goto fail; + } + + /* We no longer need the symbol table, but we hold on to the + string table permanently. */ + backtrace_release_view (state, &symtab_view, error_callback, data); + + *found_sym = 1; + + elf_add_syminfo_data (state, sdata); + } + + /* FIXME: Need to handle compressed debug sections. */ + + backtrace_release_view (state, &shdrs_view, error_callback, data); + shdrs_view_valid = 0; + backtrace_release_view (state, &names_view, error_callback, data); + names_view_valid = 0; + + /* Read all the debug sections in a single view, since they are + probably adjacent in the file. We never release this view. */ + + min_offset = 0; + max_offset = 0; + for (i = 0; i < (int) DEBUG_MAX; ++i) + { + off_t end; + + if (sections[i].size == 0) + continue; + if (min_offset == 0 || sections[i].offset < min_offset) + min_offset = sections[i].offset; + end = sections[i].offset + sections[i].size; + if (end > max_offset) + max_offset = end; + } + if (min_offset == 0 || max_offset == 0) + { + if (!backtrace_close (descriptor, error_callback, data)) + goto fail; + *fileline_fn = elf_nodebug; + return 1; + } + + if (!backtrace_get_view (state, descriptor, min_offset, + max_offset - min_offset, + error_callback, data, &debug_view)) + goto fail; + debug_view_valid = 1; + + /* We've read all we need from the executable. */ + if (!backtrace_close (descriptor, error_callback, data)) + goto fail; + descriptor = -1; + + for (i = 0; i < (int) DEBUG_MAX; ++i) + { + if (sections[i].size == 0) + sections[i].data = NULL; + else + sections[i].data = ((const unsigned char *) debug_view.data + + (sections[i].offset - min_offset)); + } + + if (!backtrace_dwarf_add (state, base_address, + sections[DEBUG_INFO].data, + sections[DEBUG_INFO].size, + sections[DEBUG_LINE].data, + sections[DEBUG_LINE].size, + sections[DEBUG_ABBREV].data, + sections[DEBUG_ABBREV].size, + sections[DEBUG_RANGES].data, + sections[DEBUG_RANGES].size, + sections[DEBUG_STR].data, + sections[DEBUG_STR].size, + ehdr.e_ident[EI_DATA] == ELFDATA2MSB, + error_callback, data, fileline_fn)) + goto fail; + + *found_dwarf = 1; + + return 1; + + fail: + if (shdrs_view_valid) + backtrace_release_view (state, &shdrs_view, error_callback, data); + if (names_view_valid) + backtrace_release_view (state, &names_view, error_callback, data); + if (symtab_view_valid) + backtrace_release_view (state, &symtab_view, error_callback, data); + if (strtab_view_valid) + backtrace_release_view (state, &strtab_view, error_callback, data); + if (debug_view_valid) + backtrace_release_view (state, &debug_view, error_callback, data); + if (descriptor != -1) + backtrace_close (descriptor, error_callback, data); + return 0; +} + +/* Data passed to phdr_callback. */ + +struct phdr_data +{ + struct backtrace_state *state; + backtrace_error_callback error_callback; + void *data; + fileline *fileline_fn; + int *found_sym; + int *found_dwarf; + int exe_descriptor; +}; + +/* Callback passed to dl_iterate_phdr. Load debug info from shared + libraries. */ + +static int +phdr_callback (struct dl_phdr_info *info, size_t size ATTRIBUTE_UNUSED, + void *pdata) +{ + struct phdr_data *pd = (struct phdr_data *) pdata; + int descriptor; + int does_not_exist; + fileline elf_fileline_fn; + int found_dwarf; + + /* There is not much we can do if we don't have the module name, + unless executable is ET_DYN, where we expect the very first + phdr_callback to be for the PIE. */ + if (info->dlpi_name == NULL || info->dlpi_name[0] == '\0') + { + if (pd->exe_descriptor == -1) + return 0; + descriptor = pd->exe_descriptor; + pd->exe_descriptor = -1; + } + else + { + if (pd->exe_descriptor != -1) + { + backtrace_close (pd->exe_descriptor, pd->error_callback, pd->data); + pd->exe_descriptor = -1; + } + + descriptor = backtrace_open (info->dlpi_name, pd->error_callback, + pd->data, &does_not_exist); + if (descriptor < 0) + return 0; + } + + if (elf_add (pd->state, descriptor, info->dlpi_addr, pd->error_callback, + pd->data, &elf_fileline_fn, pd->found_sym, &found_dwarf, 0)) + { + if (found_dwarf) + { + *pd->found_dwarf = 1; + *pd->fileline_fn = elf_fileline_fn; + } + } + + return 0; +} + +/* Initialize the backtrace data we need from an ELF executable. At + the ELF level, all we need to do is find the debug info + sections. */ + +int +backtrace_initialize (struct backtrace_state *state, int descriptor, + backtrace_error_callback error_callback, + void *data, fileline *fileline_fn) +{ + int ret; + int found_sym; + int found_dwarf; + fileline elf_fileline_fn; + struct phdr_data pd; + + ret = elf_add (state, descriptor, 0, error_callback, data, &elf_fileline_fn, + &found_sym, &found_dwarf, 1); + if (!ret) + return 0; + + pd.state = state; + pd.error_callback = error_callback; + pd.data = data; + pd.fileline_fn = &elf_fileline_fn; + pd.found_sym = &found_sym; + pd.found_dwarf = &found_dwarf; + pd.exe_descriptor = ret < 0 ? descriptor : -1; + + dl_iterate_phdr (phdr_callback, (void *) &pd); + + if (!state->threaded) + { + if (found_sym) + state->syminfo_fn = elf_syminfo; + else if (state->syminfo_fn == NULL) + state->syminfo_fn = elf_nosyms; + } + else + { + if (found_sym) + backtrace_atomic_store_pointer (&state->syminfo_fn, elf_syminfo); + else + __sync_bool_compare_and_swap (&state->syminfo_fn, NULL, elf_nosyms); + } + + if (!state->threaded) + { + if (state->fileline_fn == NULL || state->fileline_fn == elf_nodebug) + *fileline_fn = elf_fileline_fn; + } + else + { + fileline current_fn; + + current_fn = backtrace_atomic_load_pointer (&state->fileline_fn); + if (current_fn == NULL || current_fn == elf_nodebug) + *fileline_fn = elf_fileline_fn; + } + + return 1; +} |