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1cedca8ff4
Based on: c950e8a9 config: Fix spec file, add manpages and new GFDL license. With the following patches: configure: Add --disable-programs configure: Add --disable-shared configure: Fix -D_FORTIFY_SOURCE=2 check when CFLAGS contains -Wno-error libcpu: compile i386_lex.c with -Wno-implicit-fallthrough The plan is to stop relying on the distribution's version of elfutils and instead ship our own. This gives us freedom to assume that we're using the latest version and even ship our own patches (starting with a few build system improvements). More details are in scripts/update-elfutils.sh, which was used to generate this commit.
336 lines
11 KiB
C
336 lines
11 KiB
C
/* Find debugging and symbol information for a module in libdwfl.
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Copyright (C) 2005-2013 Red Hat, Inc.
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This file is part of elfutils.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "libdwflP.h"
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struct search_state
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{
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Dwfl_Module *mod;
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GElf_Addr addr;
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GElf_Sym *closest_sym;
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bool adjust_st_value;
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GElf_Word addr_shndx;
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Elf *addr_symelf;
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/* Keep track of the closest symbol we have seen so far.
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Here we store only symbols with nonzero st_size. */
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const char *closest_name;
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GElf_Addr closest_value;
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GElf_Word closest_shndx;
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Elf *closest_elf;
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/* Keep track of an eligible symbol with st_size == 0 as a fallback. */
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const char *sizeless_name;
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GElf_Sym sizeless_sym;
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GElf_Addr sizeless_value;
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GElf_Word sizeless_shndx;
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Elf *sizeless_elf;
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/* Keep track of the lowest address a relevant sizeless symbol could have. */
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GElf_Addr min_label;
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};
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/* Return true iff we consider ADDR to lie in the same section as SYM. */
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static inline bool
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same_section (struct search_state *state,
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GElf_Addr value, Elf *symelf, GElf_Word shndx)
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{
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/* For absolute symbols and the like, only match exactly. */
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if (shndx >= SHN_LORESERVE)
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return value == state->addr;
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/* If value might not be st_value, the shndx of the symbol might
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not match the section of the value. Explicitly look both up. */
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if (! state->adjust_st_value)
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{
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Dwarf_Addr v;
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if (state->addr_shndx == SHN_UNDEF)
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{
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v = state->addr;
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state->addr_shndx = __libdwfl_find_section_ndx (state->mod, &v);
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}
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v = value;
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return state->addr_shndx == __libdwfl_find_section_ndx (state->mod, &v);
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}
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/* Figure out what section ADDR lies in. */
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if (state->addr_shndx == SHN_UNDEF || state->addr_symelf != symelf)
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{
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GElf_Addr mod_addr = dwfl_deadjust_st_value (state->mod, symelf,
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state->addr);
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Elf_Scn *scn = NULL;
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state->addr_shndx = SHN_ABS;
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state->addr_symelf = symelf;
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while ((scn = elf_nextscn (symelf, scn)) != NULL)
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{
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GElf_Shdr shdr_mem;
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GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
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if (likely (shdr != NULL)
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&& mod_addr >= shdr->sh_addr
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&& mod_addr < shdr->sh_addr + shdr->sh_size)
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{
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state->addr_shndx = elf_ndxscn (scn);
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break;
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}
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}
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}
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return shndx == state->addr_shndx && state->addr_symelf == symelf;
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}
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/* Return GELF_ST_BIND as higher-is-better integer. */
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static inline int
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binding_value (const GElf_Sym *symp)
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{
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switch (GELF_ST_BIND (symp->st_info))
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{
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case STB_GLOBAL:
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return 3;
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case STB_WEAK:
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return 2;
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case STB_LOCAL:
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return 1;
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default:
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return 0;
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}
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}
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/* Try one symbol and associated value from the search table. */
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static inline void
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try_sym_value (struct search_state *state,
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GElf_Addr value, GElf_Sym *sym,
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const char *name, GElf_Word shndx,
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Elf *elf, bool resolved)
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{
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/* Even if we don't choose this symbol, its existence excludes
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any sizeless symbol (assembly label) that is below its upper
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bound. */
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if (value + sym->st_size > state->min_label)
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state->min_label = value + sym->st_size;
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if (sym->st_size == 0 || state->addr - value < sym->st_size)
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{
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/* This symbol is a better candidate than the current one
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if it's closer to ADDR or is global when it was local. */
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if (state->closest_name == NULL
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|| state->closest_value < value
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|| binding_value (state->closest_sym) < binding_value (sym))
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{
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if (sym->st_size != 0)
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{
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*state->closest_sym = *sym;
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state->closest_value = value;
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state->closest_shndx = shndx;
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state->closest_elf = elf;
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state->closest_name = name;
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}
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else if (state->closest_name == NULL
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&& value >= state->min_label
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&& same_section (state, value,
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resolved ? state->mod->main.elf : elf,
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shndx))
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{
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/* Handwritten assembly symbols sometimes have no
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st_size. If no symbol with proper size includes
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the address, we'll use the closest one that is in
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the same section as ADDR. */
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state->sizeless_sym = *sym;
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state->sizeless_value = value;
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state->sizeless_shndx = shndx;
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state->sizeless_elf = elf;
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state->sizeless_name = name;
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}
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}
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/* When the beginning of its range is no closer,
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the end of its range might be. Otherwise follow
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GELF_ST_BIND preference. If all are equal prefer
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the first symbol found. */
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else if (sym->st_size != 0
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&& state->closest_value == value
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&& ((state->closest_sym->st_size > sym->st_size
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&& (binding_value (state->closest_sym)
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<= binding_value (sym)))
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|| (state->closest_sym->st_size >= sym->st_size
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&& (binding_value (state->closest_sym)
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< binding_value (sym)))))
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{
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*state->closest_sym = *sym;
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state->closest_value = value;
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state->closest_shndx = shndx;
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state->closest_elf = elf;
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state->closest_name = name;
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}
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}
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}
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/* Look through the symbol table for a matching symbol. */
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static inline void
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search_table (struct search_state *state, int start, int end)
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{
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for (int i = start; i < end; ++i)
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{
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GElf_Sym sym;
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GElf_Addr value;
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GElf_Word shndx;
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Elf *elf;
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bool resolved;
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const char *name = __libdwfl_getsym (state->mod, i, &sym, &value,
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&shndx, &elf, NULL,
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&resolved,
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state->adjust_st_value);
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if (name != NULL && name[0] != '\0'
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&& sym.st_shndx != SHN_UNDEF
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&& value <= state->addr
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&& GELF_ST_TYPE (sym.st_info) != STT_SECTION
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&& GELF_ST_TYPE (sym.st_info) != STT_FILE
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&& GELF_ST_TYPE (sym.st_info) != STT_TLS)
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{
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try_sym_value (state, value, &sym, name, shndx, elf, resolved);
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/* If this is an addrinfo variant and the value could be
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resolved then also try matching the (adjusted) st_value. */
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if (resolved && state->mod->e_type != ET_REL)
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{
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GElf_Addr adjusted_st_value;
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adjusted_st_value = dwfl_adjusted_st_value (state->mod, elf,
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sym.st_value);
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if (value != adjusted_st_value
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&& adjusted_st_value <= state->addr)
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try_sym_value (state, adjusted_st_value, &sym, name, shndx,
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elf, false);
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}
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}
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}
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}
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/* Returns the name of the symbol "closest" to ADDR.
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Never returns symbols at addresses above ADDR.
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Wrapper for old dwfl_module_addrsym and new dwfl_module_addrinfo.
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adjust_st_value set to true returns adjusted SYM st_value, set to false
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it will not adjust SYM at all, but does match against resolved values. */
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static const char *
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__libdwfl_addrsym (Dwfl_Module *_mod, GElf_Addr _addr, GElf_Off *off,
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GElf_Sym *_closest_sym, GElf_Word *shndxp,
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Elf **elfp, Dwarf_Addr *biasp, bool _adjust_st_value)
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{
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int syments = INTUSE(dwfl_module_getsymtab) (_mod);
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if (syments < 0)
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return NULL;
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struct search_state state =
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{
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.addr = _addr,
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.mod = _mod,
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.closest_sym = _closest_sym,
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.adjust_st_value = _adjust_st_value,
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.addr_shndx = SHN_UNDEF,
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.addr_symelf = NULL,
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.closest_name = NULL,
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.closest_value = 0,
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.closest_shndx = SHN_UNDEF,
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.closest_elf = NULL,
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.sizeless_name = NULL,
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.sizeless_sym = { 0, 0, 0, 0, 0, SHN_UNDEF },
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.sizeless_value = 0,
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.sizeless_shndx = SHN_UNDEF,
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.sizeless_elf = NULL,
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.min_label = 0
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};
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/* First go through global symbols. mod->first_global and
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mod->aux_first_global are setup by dwfl_module_getsymtab to the
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index of the first global symbol in those symbol tables. Both
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are non-zero when the table exist, except when there is only a
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dynsym table loaded through phdrs, then first_global is zero and
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there will be no auxiliary table. All symbols with local binding
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come first in the symbol table, then all globals. The zeroth,
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null entry, in the auxiliary table is skipped if there is a main
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table. */
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int first_global = INTUSE (dwfl_module_getsymtab_first_global) (state.mod);
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if (first_global < 0)
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return NULL;
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search_table (&state, first_global == 0 ? 1 : first_global, syments);
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/* If we found nothing searching the global symbols, then try the locals.
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Unless we have a global sizeless symbol that matches exactly. */
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if (state.closest_name == NULL && first_global > 1
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&& (state.sizeless_name == NULL || state.sizeless_value != state.addr))
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search_table (&state, 1, first_global);
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/* If we found no proper sized symbol to use, fall back to the best
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candidate sizeless symbol we found, if any. */
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if (state.closest_name == NULL
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&& state.sizeless_name != NULL
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&& state.sizeless_value >= state.min_label)
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{
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*state.closest_sym = state.sizeless_sym;
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state.closest_value = state.sizeless_value;
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state.closest_shndx = state.sizeless_shndx;
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state.closest_elf = state.sizeless_elf;
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state.closest_name = state.sizeless_name;
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}
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*off = state.addr - state.closest_value;
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if (shndxp != NULL)
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*shndxp = state.closest_shndx;
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if (elfp != NULL)
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*elfp = state.closest_elf;
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if (biasp != NULL)
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*biasp = dwfl_adjusted_st_value (state.mod, state.closest_elf, 0);
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return state.closest_name;
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}
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const char *
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dwfl_module_addrsym (Dwfl_Module *mod, GElf_Addr addr,
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GElf_Sym *closest_sym, GElf_Word *shndxp)
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{
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GElf_Off off;
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return __libdwfl_addrsym (mod, addr, &off, closest_sym, shndxp,
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NULL, NULL, true);
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}
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INTDEF (dwfl_module_addrsym)
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const char
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*dwfl_module_addrinfo (Dwfl_Module *mod, GElf_Addr address,
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GElf_Off *offset, GElf_Sym *sym,
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GElf_Word *shndxp, Elf **elfp, Dwarf_Addr *bias)
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{
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return __libdwfl_addrsym (mod, address, offset, sym, shndxp, elfp, bias,
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false);
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}
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INTDEF (dwfl_module_addrinfo)
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