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nuttx/libs/libc/modlib/modlib_bind.c
Tiago Medicci Serrano a5c92582a4 Rename CamelCase symbols to lowercase
2023-07-25 08:51:17 -07:00

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/****************************************************************************
* libs/libc/modlib/modlib_bind.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/elf.h>
#include <nuttx/lib/modlib.h>
#include "libc.h"
#include "modlib/modlib.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define I_REL 0 /* Index into relxxx[] arrays for relocations */
#define I_PLT 1 /* ... for PLTs */
#define N_RELS 2 /* Number of relxxx[] indexes */
/****************************************************************************
* Private Types
****************************************************************************/
/* REVISIT: This naming breaks the NuttX coding standard, but is consistent
* with legacy naming of other ELF types.
*/
typedef struct
{
dq_entry_t entry;
Elf_Sym sym;
int idx;
} Elf_SymCache;
struct
{
int stroff; /* offset to string table */
int symoff; /* offset to symbol table */
int lsymtab; /* size of symbol table */
int relentsz; /* size of relocation entry */
int reloff[2]; /* offset to the relocation section */
int relsz[2]; /* size of relocation table */
} reldata;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: modlib_readrels
*
* Description:
* Read the (ELF_Rel structure * buffer count) into memory.
*
****************************************************************************/
static inline int modlib_readrels(FAR struct mod_loadinfo_s *loadinfo,
FAR const Elf_Shdr *relsec,
int index, FAR Elf_Rel *rels,
int count)
{
off_t offset;
int size;
/* Verify that the symbol table index lies within symbol table */
if (index < 0 || index > (relsec->sh_size / sizeof(Elf_Rel)))
{
berr("ERROR: Bad relocation symbol index: %d\n", index);
return -EINVAL;
}
/* Get the file offset to the symbol table entry */
offset = sizeof(Elf_Rel) * index;
size = sizeof(Elf_Rel) * count;
if (offset + size > relsec->sh_size)
{
size = relsec->sh_size - offset;
}
/* And, finally, read the symbol table entry into memory */
return modlib_read(loadinfo, (FAR uint8_t *)rels, size,
relsec->sh_offset + offset);
}
/****************************************************************************
* Name: modlib_readrelas
*
* Description:
* Read the (ELF_Rela structure * buffer count) into memory.
*
****************************************************************************/
static inline int modlib_readrelas(FAR struct mod_loadinfo_s *loadinfo,
FAR const Elf_Shdr *relsec,
int index, FAR Elf_Rela *relas,
int count)
{
off_t offset;
int size;
/* Verify that the symbol table index lies within symbol table */
if (index < 0 || index > (relsec->sh_size / sizeof(Elf_Rela)))
{
berr("ERROR: Bad relocation symbol index: %d\n", index);
return -EINVAL;
}
/* Get the file offset to the symbol table entry */
offset = sizeof(Elf_Rela) * index;
size = sizeof(Elf_Rela) * count;
if (offset + size > relsec->sh_size)
{
size = relsec->sh_size - offset;
}
/* And, finally, read the symbol table entry into memory */
return modlib_read(loadinfo, (FAR uint8_t *)relas, size,
relsec->sh_offset + offset);
}
/****************************************************************************
* Name: modlib_relocate and modlib_relocateadd
*
* Description:
* Perform all relocations associated with a section.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static int modlib_relocate(FAR struct module_s *modp,
FAR struct mod_loadinfo_s *loadinfo, int relidx)
{
FAR Elf_Shdr *relsec = &loadinfo->shdr[relidx];
FAR Elf_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
FAR Elf_Rel *rels;
FAR Elf_Rel *rel;
FAR Elf_SymCache *cache;
FAR Elf_Sym *sym;
FAR dq_entry_t *e;
dq_queue_t q;
uintptr_t addr;
int symidx;
int ret;
int i;
int j;
rels = lib_malloc(CONFIG_MODLIB_RELOCATION_BUFFERCOUNT * sizeof(Elf_Rel));
if (!rels)
{
berr("Failed to allocate memory for elf relocation rels\n");
return -ENOMEM;
}
dq_init(&q);
/* Examine each relocation in the section. 'relsec' is the section
* containing the relations. 'dstsec' is the section containing the data
* to be relocated.
*/
ret = OK;
for (i = j = 0; i < relsec->sh_size / sizeof(Elf_Rel); i++)
{
/* Read the relocation entry into memory */
rel = &rels[i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT];
if (!(i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT))
{
ret = modlib_readrels(loadinfo, relsec, i, rels,
CONFIG_MODLIB_RELOCATION_BUFFERCOUNT);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: "
"Failed to read relocation entry: %d\n",
relidx, i, ret);
break;
}
}
/* Get the symbol table index for the relocation. This is contained
* in a bit-field within the r_info element.
*/
symidx = ELF_R_SYM(rel->r_info);
/* First try the cache */
sym = NULL;
for (e = dq_peek(&q); e; e = dq_next(e))
{
cache = (FAR Elf_SymCache *)e;
if (cache->idx == symidx)
{
dq_rem(&cache->entry, &q);
dq_addfirst(&cache->entry, &q);
sym = &cache->sym;
break;
}
}
/* If the symbol was not found in the cache, we will need to read the
* symbol from the file.
*/
if (sym == NULL)
{
if (j < CONFIG_MODLIB_SYMBOL_CACHECOUNT)
{
cache = lib_malloc(sizeof(Elf_SymCache));
if (!cache)
{
berr("Failed to allocate memory for elf symbols\n");
ret = -ENOMEM;
break;
}
j++;
}
else
{
cache = (FAR Elf_SymCache *)dq_remlast(&q);
}
sym = &cache->sym;
/* Read the symbol table entry into memory */
ret = modlib_readsym(loadinfo, symidx, sym,
&loadinfo->shdr[loadinfo->symtabidx]);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: "
"Failed to read symbol[%d]: %d\n",
relidx, i, symidx, ret);
lib_free(cache);
break;
}
/* Get the value of the symbol (in sym.st_value) */
ret = modlib_symvalue(modp, loadinfo, sym,
loadinfo->shdr[loadinfo->strtabidx].sh_offset);
if (ret < 0)
{
/* The special error -ESRCH is returned only in one condition:
* The symbol has no name.
*
* There are a few relocations for a few architectures that do
* no depend upon a named symbol. We don't know if that is the
* case here, but we will use a NULL symbol pointer to indicate
* that case to up_relocate(). That function can then do what
* is best.
*/
if (ret == -ESRCH)
{
berr("ERROR: Section %d reloc %d: "
"Undefined symbol[%d] has no name: %d\n",
relidx, i, symidx, ret);
}
else
{
berr("ERROR: Section %d reloc %d: "
"Failed to get value of symbol[%d]: %d\n",
relidx, i, symidx, ret);
lib_free(cache);
break;
}
}
cache->idx = symidx;
dq_addfirst(&cache->entry, &q);
}
if (sym->st_shndx == SHN_UNDEF && sym->st_name == 0)
{
sym = NULL;
}
/* Calculate the relocation address. */
if (rel->r_offset + sizeof(uint32_t) > dstsec->sh_size)
{
berr("ERROR: Section %d reloc %d: "
"Relocation address out of range, "
"offset %" PRIuPTR " size %ju\n",
relidx, i, (uintptr_t)rel->r_offset,
(uintmax_t)dstsec->sh_size);
ret = -EINVAL;
break;
}
addr = dstsec->sh_addr + rel->r_offset;
/* Now perform the architecture-specific relocation */
ret = up_relocate(rel, sym, addr);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: Relocation failed: %d\n",
relidx, i, ret);
break;
}
}
lib_free(rels);
while ((e = dq_peek(&q)))
{
dq_rem(e, &q);
lib_free(e);
}
return ret;
}
static int modlib_relocateadd(FAR struct module_s *modp,
FAR struct mod_loadinfo_s *loadinfo,
int relidx)
{
FAR Elf_Shdr *relsec = &loadinfo->shdr[relidx];
FAR Elf_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
FAR Elf_Rela *relas;
FAR Elf_Rela *rela;
FAR Elf_SymCache *cache;
FAR Elf_Sym *sym;
FAR dq_entry_t *e;
dq_queue_t q;
uintptr_t addr;
int symidx;
int ret;
int i;
int j;
relas = lib_malloc(CONFIG_MODLIB_RELOCATION_BUFFERCOUNT *
sizeof(Elf_Rela));
if (!relas)
{
berr("Failed to allocate memory for elf relocation relas\n");
return -ENOMEM;
}
dq_init(&q);
/* Examine each relocation in the section. 'relsec' is the section
* containing the relations. 'dstsec' is the section containing the data
* to be relocated.
*/
ret = OK;
for (i = j = 0; i < relsec->sh_size / sizeof(Elf_Rela); i++)
{
/* Read the relocation entry into memory */
rela = &relas[i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT];
if (!(i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT))
{
ret = modlib_readrelas(loadinfo, relsec, i, relas,
CONFIG_MODLIB_RELOCATION_BUFFERCOUNT);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: "
"Failed to read relocation entry: %d\n",
relidx, i, ret);
break;
}
}
/* Get the symbol table index for the relocation. This is contained
* in a bit-field within the r_info element.
*/
symidx = ELF_R_SYM(rela->r_info);
/* First try the cache */
sym = NULL;
for (e = dq_peek(&q); e; e = dq_next(e))
{
cache = (FAR Elf_SymCache *)e;
if (cache->idx == symidx)
{
dq_rem(&cache->entry, &q);
dq_addfirst(&cache->entry, &q);
sym = &cache->sym;
break;
}
}
/* If the symbol was not found in the cache, we will need to read the
* symbol from the file.
*/
if (sym == NULL)
{
if (j < CONFIG_MODLIB_SYMBOL_CACHECOUNT)
{
cache = lib_malloc(sizeof(Elf_SymCache));
if (!cache)
{
berr("Failed to allocate memory for elf symbols\n");
ret = -ENOMEM;
break;
}
j++;
}
else
{
cache = (FAR Elf_SymCache *)dq_remlast(&q);
}
sym = &cache->sym;
/* Read the symbol table entry into memory */
ret = modlib_readsym(loadinfo, symidx, sym,
&loadinfo->shdr[loadinfo->symtabidx]);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: "
"Failed to read symbol[%d]: %d\n",
relidx, i, symidx, ret);
lib_free(cache);
break;
}
/* Get the value of the symbol (in sym.st_value) */
ret = modlib_symvalue(modp, loadinfo, sym,
loadinfo->shdr[loadinfo->strtabidx].sh_offset);
if (ret < 0)
{
/* The special error -ESRCH is returned only in one condition:
* The symbol has no name.
*
* There are a few relocations for a few architectures that do
* no depend upon a named symbol. We don't know if that is the
* case here, but we will use a NULL symbol pointer to indicate
* that case to up_relocate(). That function can then do what
* is best.
*/
if (ret == -ESRCH)
{
berr("ERROR: Section %d reloc %d: "
"Undefined symbol[%d] has no name: %d\n",
relidx, i, symidx, ret);
}
else
{
berr("ERROR: Section %d reloc %d: "
"Failed to get value of symbol[%d]: %d\n",
relidx, i, symidx, ret);
lib_free(cache);
break;
}
}
cache->idx = symidx;
dq_addfirst(&cache->entry, &q);
}
if (sym->st_shndx == SHN_UNDEF && sym->st_name == 0)
{
sym = NULL;
}
/* Calculate the relocation address. */
if (rela->r_offset + sizeof(uint32_t) > dstsec->sh_size)
{
berr("ERROR: Section %d reloc %d: "
"Relocation address out of range, "
"offset %" PRIuPTR " size %ju\n",
relidx, i, (uintptr_t)rela->r_offset,
(uintmax_t)dstsec->sh_size);
ret = -EINVAL;
break;
}
addr = dstsec->sh_addr + rela->r_offset;
/* Now perform the architecture-specific relocation */
ret = up_relocateadd(rela, sym, addr);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: Relocation failed: %d\n",
relidx, i, ret);
break;
}
}
lib_free(relas);
while ((e = dq_peek(&q)))
{
dq_rem(e, &q);
lib_free(e);
}
return ret;
}
/****************************************************************************
* Name: modlib_relocatedyn
*
* Description:
* Perform all relocations associated with a dynamic section.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static int modlib_relocatedyn(FAR struct module_s *modp,
FAR struct mod_loadinfo_s *loadinfo,
int relidx)
{
FAR Elf_Shdr *shdr = &loadinfo->shdr[relidx];
FAR Elf_Shdr *symhdr;
FAR Elf_Dyn *dyn = NULL;
FAR Elf_Rel *rels = NULL;
FAR Elf_Rel *rel;
FAR Elf_Sym *sym = NULL;
uintptr_t addr;
int ret;
int i;
int idx_rel;
int idx_sym;
dyn = lib_malloc(shdr->sh_size);
ret = modlib_read(loadinfo, (FAR uint8_t *) dyn, shdr->sh_size,
shdr->sh_offset);
if (ret < 0)
{
berr("Failed to read dynamic section header");
return ret;
}
rels = lib_malloc(CONFIG_MODLIB_RELOCATION_BUFFERCOUNT * sizeof(Elf_Rel));
if (!rels)
{
berr("Failed to allocate memory for elf relocation rels\n");
lib_free(dyn);
return -ENOMEM;
}
memset((void *) &reldata, 0, sizeof(reldata));
for (i = 0; dyn[i].d_tag != DT_NULL; i++)
{
switch (dyn[i].d_tag)
{
case DT_REL :
reldata.reloff[I_REL] = dyn[i].d_un.d_val;
break;
case DT_RELSZ :
reldata.relsz[I_REL] = dyn[i].d_un.d_val;
break;
case DT_RELENT :
reldata.relentsz = dyn[i].d_un.d_val;
break;
case DT_SYMTAB :
reldata.symoff = dyn[i].d_un.d_val;
break;
case DT_STRTAB :
reldata.stroff = dyn[i].d_un.d_val;
break;
case DT_JMPREL :
reldata.reloff[I_PLT] = dyn[i].d_un.d_val;
break;
case DT_PLTRELSZ :
reldata.relsz[I_PLT] = dyn[i].d_un.d_val;
break;
}
}
symhdr = &loadinfo->shdr[loadinfo->dsymtabidx];
sym = lib_malloc(symhdr->sh_size);
if (!sym)
{
berr("Error obtaining storage for dynamic symbol table");
lib_free(rels);
lib_free(dyn);
return -ENOMEM;
}
ret = modlib_read(loadinfo, (uint8_t *) sym, symhdr->sh_size,
symhdr->sh_offset);
if (ret < 0)
{
berr("Error reading dynamic symbol table - %d", ret);
lib_free(sym);
lib_free(rels);
lib_free(dyn);
return ret;
}
reldata.lsymtab = reldata.stroff - reldata.symoff;
for (idx_rel = 0; idx_rel < N_RELS; idx_rel++)
{
if (reldata.reloff[idx_rel] == 0)
{
continue;
}
/* Examine each relocation in the .rel.* section. */
ret = OK;
for (i = 0; i < reldata.relsz[idx_rel] / reldata.relentsz; i++)
{
/* Process each relocation entry */
rel = &rels[i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT];
if (!(i % CONFIG_MODLIB_RELOCATION_BUFFERCOUNT))
{
size_t relsize = (sizeof(Elf_Rel) *
CONFIG_MODLIB_RELOCATION_BUFFERCOUNT);
if (reldata.relsz[idx_rel] < relsize)
{
relsize = reldata.relsz[idx_rel];
}
ret = modlib_read(loadinfo, (FAR uint8_t *) rels,
relsize,
reldata.reloff[idx_rel] +
i * sizeof(Elf_Rel));
if (ret < 0)
{
berr("ERROR: Section %d reloc %d:"
"Failed to read relocation entry: %d\n",
relidx, i, ret);
break;
}
}
/* Calculate the relocation address. */
if (rel->r_offset < 0)
{
berr("ERROR: Section %d reloc %d:"
"Relocation address out of range, offset %u\n",
relidx, i, (int) rel->r_offset);
ret = -EINVAL;
lib_free(sym);
lib_free(rels);
lib_free(dyn);
return ret;
}
/* Now perform the architecture-specific relocation */
if ((idx_sym = ELF_R_SYM(rel->r_info)) != 0)
{
if (sym[idx_sym].st_shndx == SHN_UNDEF) /* We have an external reference */
{
void *ep;
ep = modlib_findglobal(modp, loadinfo, symhdr,
&sym[idx_sym]);
if ((ep == NULL) && (ELF_ST_BIND(sym[idx_sym].st_info)
!= STB_WEAK))
{
berr("ERROR: Unable to resolve addr of ext ref %s\n",
loadinfo->iobuffer);
ret = -EINVAL;
lib_free(sym);
lib_free(rels);
lib_free(dyn);
return ret;
}
addr = rel->r_offset + loadinfo->textalloc;
*(uintptr_t *)addr = (uintptr_t)ep;
}
}
else
{
Elf_Sym dynsym;
addr = rel->r_offset - loadinfo->datasec + loadinfo->datastart;
if ((*(uint32_t *) addr) < loadinfo->datasec)
dynsym.st_value = *(uint32_t *) addr + loadinfo->textalloc;
else
dynsym.st_value = *(uint32_t *) addr -
loadinfo->datasec + loadinfo->datastart;
ret = up_relocate(rel, &dynsym, addr);
}
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: Relocation failed: %d\n",
relidx, i, ret);
lib_free(sym);
lib_free(rels);
lib_free(dyn);
return ret;
}
}
}
/* Iterate through the dynamic symbol table looking for global symbols to
* put in our own symbol table for use with dlgetsym()
*/
/* Relocate the entries in the table */
for (i = 0; i < (symhdr->sh_size / sizeof(Elf_Sym)); i++)
{
Elf_Shdr *s = &loadinfo->shdr[sym[i].st_shndx];
if (sym[i].st_shndx != SHN_UNDEF)
{
if (s->sh_addr < loadinfo->datasec)
sym[i].st_value = sym[i].st_value + loadinfo->textalloc;
else
sym[i].st_value = sym[i].st_value -
loadinfo->datasec + loadinfo->datastart;
}
}
ret = modlib_insertsymtab(modp, loadinfo, symhdr, sym);
lib_free(sym);
lib_free(rels);
lib_free(dyn);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: modlib_bind
*
* Description:
* Bind the imported symbol names in the loaded module described by
* 'loadinfo' using the exported symbol values provided by
* modlib_setsymtab().
*
* Input Parameters:
* modp - Module state information
* loadinfo - Load state information
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int modlib_bind(FAR struct module_s *modp,
FAR struct mod_loadinfo_s *loadinfo)
{
int ret;
int i;
/* Find the symbol and string tables */
ret = modlib_findsymtab(loadinfo);
if (ret < 0)
{
return ret;
}
/* Process relocations in every allocated section */
for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
{
/* Get the index to the relocation section */
int infosec = loadinfo->shdr[i].sh_info;
if (infosec >= loadinfo->ehdr.e_shnum)
{
continue;
}
if (loadinfo->ehdr.e_type == ET_DYN)
{
switch (loadinfo->shdr[i].sh_type)
{
case SHT_DYNAMIC :
ret = modlib_relocatedyn(modp, loadinfo, i);
break;
case SHT_DYNSYM :
loadinfo->dsymtabidx = i;
break;
case SHT_INIT_ARRAY :
loadinfo->initarr = loadinfo->shdr[i].sh_addr -
loadinfo->datasec +
loadinfo->datastart;
loadinfo->ninit = loadinfo->shdr[i].sh_size /
sizeof(uintptr_t);
break;
case SHT_FINI_ARRAY :
loadinfo->finiarr = loadinfo->shdr[i].sh_addr -
loadinfo->datasec +
loadinfo->datastart;
loadinfo->nfini = loadinfo->shdr[i].sh_size /
sizeof(uintptr_t);
break;
case SHT_PREINIT_ARRAY :
loadinfo->preiarr = loadinfo->shdr[i].sh_addr -
loadinfo->datasec +
loadinfo->datastart;
loadinfo->nprei = loadinfo->shdr[i].sh_size /
sizeof(uintptr_t);
break;
}
}
else
{
/* Make sure that the section is allocated. We can't relocate
* sections that were not loaded into memory.
*/
if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0)
{
continue;
}
/* Process the relocations by type */
switch (loadinfo->shdr[i].sh_type)
{
case SHT_REL :
ret = modlib_relocate(modp, loadinfo, i);
break;
case SHT_RELA :
ret = modlib_relocateadd(modp, loadinfo, i);
break;
}
}
if (ret < 0)
{
break;
}
}
/* Ensure that the I and D caches are coherent before starting the newly
* loaded module by cleaning the D cache (i.e., flushing the D cache
* contents to memory and invalidating the I cache).
*/
up_coherent_dcache(loadinfo->textalloc, loadinfo->textsize);
up_coherent_dcache(loadinfo->datastart, loadinfo->datasize);
return ret;
}
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