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/* Recover relocatibility for addresses computed from debug information.
Copyright (C) 2005 Red Hat, Inc.
This program is Open Source software; you can redistribute it and/or
modify it under the terms of the Open Software License version 1.0 as
published by the Open Source Initiative.
You should have received a copy of the Open Software License along
with this program; if not, you may obtain a copy of the Open Software
License version 1.0 from http://www.opensource.org/licenses/osl.php or
by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
3001 King Ranch Road, Ukiah, CA 95482. */
#include "libdwflP.h"
struct dwfl_relocation
{
size_t count;
struct
{
Elf_Scn *scn;
const char *name;
GElf_Addr start, end;
} refs[0];
};
struct secref
{
struct secref *next;
Elf_Scn *scn;
const char *name;
GElf_Addr start, end;
};
static int
compare_secrefs (const void *a, const void *b)
{
struct secref *const *p1 = a;
struct secref *const *p2 = b;
return (*p1)->start - (*p2)->start;
}
static int
cache_sections (Dwfl_Module *mod)
{
size_t symshstrndx;
if (elf_getshstrndx (mod->symfile->elf, &symshstrndx) < 0)
{
__libdwfl_seterrno (DWFL_E_LIBELF);
return -1;
}
struct secref *refs = NULL;
size_t nrefs = 0;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (mod->symfile->elf, scn)) != NULL)
{
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
return -1;
if ((shdr->sh_flags & SHF_ALLOC) && shdr->sh_addr != 0)
{
const char *name = elf_strptr (mod->symfile->elf, symshstrndx,
shdr->sh_name);
if (name == NULL)
return -1;
struct secref *newref = alloca (sizeof *newref);
newref->scn = scn;
newref->name = name;
newref->start = shdr->sh_addr;
newref->end = shdr->sh_addr + shdr->sh_size;
newref->next = refs;
refs = newref;
++nrefs;
}
}
mod->reloc_info = malloc (offsetof (struct dwfl_relocation, refs[nrefs]));
if (mod->reloc_info == NULL)
{
__libdwfl_seterrno (DWFL_E_NOMEM);
return -1;
}
struct secref *sortrefs[nrefs];
for (size_t i = nrefs; i-- > 0; refs = refs->next)
sortrefs[i] = refs;
assert (refs == NULL);
qsort (sortrefs, nrefs, sizeof sortrefs[0], &compare_secrefs);
mod->reloc_info->count = nrefs;
for (size_t i = 0; i < nrefs; ++i)
{
mod->reloc_info->refs[i].name = sortrefs[i]->name;
mod->reloc_info->refs[i].scn = sortrefs[i]->scn;
mod->reloc_info->refs[i].start = sortrefs[i]->start;
mod->reloc_info->refs[i].end = sortrefs[i]->end;
}
return nrefs;
}
int
dwfl_module_relocations (Dwfl_Module *mod)
{
if (mod == NULL)
return -1;
if (mod->reloc_info != NULL)
return mod->reloc_info->count;
if (mod->dw == NULL)
{
Dwarf_Addr bias;
if (INTUSE(dwfl_module_getdwarf) (mod, &bias) == NULL)
return -1;
}
switch (mod->e_type)
{
case ET_REL:
return cache_sections (mod);
case ET_DYN:
return 1;
case ET_EXEC:
assert (mod->debug.bias == 0);
break;
}
return 0;
}
const char *
dwfl_module_relocation_info (Dwfl_Module *mod, unsigned int idx,
Elf32_Word *shndxp)
{
if (mod == NULL)
return NULL;
switch (mod->e_type)
{
case ET_REL:
break;
case ET_DYN:
if (idx != 0)
return NULL;
if (shndxp)
*shndxp = SHN_ABS;
return "";
default:
return NULL;
}
if (unlikely (mod->reloc_info == NULL) && cache_sections (mod) < 0)
return NULL;
struct dwfl_relocation *sections = mod->reloc_info;
if (idx >= sections->count)
return NULL;
if (shndxp)
*shndxp = elf_ndxscn (sections->refs[idx].scn);
return sections->refs[idx].name;
}
int
dwfl_module_relocate_address (Dwfl_Module *mod, Dwarf_Addr *addr)
{
if (mod == NULL)
return -1;
if (mod->dw == NULL)
{
Dwarf_Addr bias;
if (INTUSE(dwfl_module_getdwarf) (mod, &bias) == NULL)
return -1;
}
if (mod->e_type != ET_REL)
{
*addr -= mod->debug.bias;
return 0;
}
if (unlikely (mod->reloc_info == NULL) && cache_sections (mod) < 0)
return -1;
struct dwfl_relocation *sections = mod->reloc_info;
/* The sections are sorted by address, so we can use binary search. */
size_t l = 0, u = sections->count;
while (l < u)
{
size_t idx = (l + u) / 2;
if (*addr < sections->refs[idx].start)
u = idx;
else if (*addr > sections->refs[idx].end)
l = idx + 1;
else
{
/* Consider the limit of a section to be inside it, unless it's
inside the next one. A section limit address can appear in
line records. */
if (*addr == sections->refs[idx].end
&& idx < sections->count
&& *addr == sections->refs[idx + 1].start)
++idx;
*addr -= sections->refs[idx].start;
return idx;
}
}
__libdw_seterrno (DWARF_E_NO_MATCH);
return -1;
}
INTDEF (dwfl_module_relocate_address)
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