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Merge "linker: rename load_offset to load_bias."

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This commit is contained in:
David 'Digit' Turner 2012-06-26 01:34:41 -07:00 committed by Android (Google) Code Review
commit 8941cfa17a
2 changed files with 43 additions and 18 deletions
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54
linker/linker.c
View File

@ -424,7 +424,7 @@ static unsigned elfhash(const char *_name)
}
static Elf32_Sym *
soinfo_do_lookup(soinfo *si, const char *name, unsigned *base, Elf32_Addr *offset)
soinfo_do_lookup(soinfo *si, const char *name, Elf32_Addr *offset)
{
unsigned elf_hash = elfhash(name);
Elf32_Sym *s;
@ -487,11 +487,10 @@ soinfo_do_lookup(soinfo *si, const char *name, unsigned *base, Elf32_Addr *offse
done:
if(s != NULL) {
TRACE_TYPE(LOOKUP, "%5d si %s sym %s s->st_value = 0x%08x, "
"found in %s, base = 0x%08x, load offset = 0x%08x\n",
"found in %s, base = 0x%08x, load bias = 0x%08x\n",
pid, si->name, name, s->st_value,
lsi->name, lsi->base, lsi->load_offset);
*base = lsi->base;
*offset = lsi->load_offset;
lsi->name, lsi->base, lsi->load_bias);
*offset = lsi->load_bias;
return s;
}
@ -812,13 +811,13 @@ soinfo_load_segments(soinfo* si, int fd, const Elf32_Phdr* phdr_table, int phdr_
* header table appear in ascending order, sorted on the
* p_vaddr member."
*/
si->load_offset = PAGE_START(phdr->p_vaddr);
si->load_bias = si->base - PAGE_START(phdr->p_vaddr);
break;
}
}
/* "base" might wrap around UINT32_MAX. */
base = (Elf32_Addr)(si->base - si->load_offset);
base = si->load_bias;
/* Now go through all the PT_LOAD segments and map them into memory
* at the appropriate locations. */
@ -1271,7 +1270,7 @@ static int soinfo_relocate(soinfo *si, Elf32_Rel *rel, unsigned count)
for (idx = 0; idx < count; ++idx) {
unsigned type = ELF32_R_TYPE(rel->r_info);
unsigned sym = ELF32_R_SYM(rel->r_info);
unsigned reloc = (unsigned)(rel->r_offset + si->base - si->load_offset);
unsigned reloc = (unsigned)(rel->r_offset + si->load_bias);
unsigned sym_addr = 0;
char *sym_name = NULL;
@ -1279,7 +1278,7 @@ static int soinfo_relocate(soinfo *si, Elf32_Rel *rel, unsigned count)
si->name, idx);
if(sym != 0) {
sym_name = (char *)(strtab + symtab[sym].st_name);
s = soinfo_do_lookup(si, sym_name, &base, &offset);
s = soinfo_do_lookup(si, sym_name, &offset);
if(s == NULL) {
/* We only allow an undefined symbol if this is a weak
reference.. */
@ -1346,7 +1345,7 @@ static int soinfo_relocate(soinfo *si, Elf32_Rel *rel, unsigned count)
return -1;
}
#endif
sym_addr = (unsigned)(s->st_value + base - offset);
sym_addr = (unsigned)(s->st_value + offset);
}
COUNT_RELOC(RELOC_SYMBOL);
} else {
@ -1652,7 +1651,7 @@ static int soinfo_link_image(soinfo *si, unsigned wr_offset)
{
unsigned *d;
/* "base" might wrap around UINT32_MAX. */
Elf32_Addr base = si->base - si->load_offset;
Elf32_Addr base = si->load_bias;
Elf32_Phdr *phdr = si->phdr;
int phnum = si->phnum;
@ -2128,13 +2127,14 @@ sanitize:
*/
int nn;
si->base = 0;
si->load_bias = 0;
for ( nn = 0; nn < si->phnum; nn++ ) {
if (si->phdr[nn].p_type == PT_PHDR) {
si->base = (Elf32_Addr) si->phdr - si->phdr[nn].p_vaddr;
si->load_bias = (Elf32_Addr)si->phdr - si->phdr[nn].p_vaddr;
si->base = (Elf32_Addr) si->phdr - si->phdr[nn].p_offset;
break;
}
}
si->load_offset = 0;
si->dynamic = (unsigned *)-1;
si->wrprotect_start = 0xffffffff;
si->wrprotect_end = 0;
@ -2233,6 +2233,32 @@ static unsigned find_linker_base(unsigned **elfdata) {
return 0; // should never happen
}
/* Compute the load-bias of an existing executable. This shall only
* be used to compute the load bias of an executable or shared library
* that was loaded by the kernel itself.
*
* Input:
* elf -> address of ELF header, assumed to be at the start of the file.
* Return:
* load bias, i.e. add the value of any p_vaddr in the file to get
* the corresponding address in memory.
*/
static Elf32_Addr
get_elf_exec_load_bias(const Elf32_Ehdr* elf)
{
Elf32_Addr offset = elf->e_phoff;
const Elf32_Phdr* phdr_table = (const Elf32_Phdr*)((char*)elf + offset);
const Elf32_Phdr* phdr_end = phdr_table + elf->e_phnum;
const Elf32_Phdr* phdr;
for (phdr = phdr_table; phdr < phdr_end; phdr++) {
if (phdr->p_type == PT_LOAD) {
return (Elf32_Addr)elf + phdr->p_offset - phdr->p_vaddr;
}
}
return 0;
}
/*
* This is the entry point for the linker, called from begin.S. This
* method is responsible for fixing the linker's own relocations, and
@ -2252,7 +2278,7 @@ unsigned __linker_init(unsigned **elfdata) {
memset(&linker_so, 0, sizeof(soinfo));
linker_so.base = linker_addr;
linker_so.load_offset = 0;
linker_so.load_bias = get_elf_exec_load_bias(elf_hdr);
linker_so.dynamic = (unsigned *) -1;
linker_so.phdr = phdr;
linker_so.phnum = elf_hdr->e_phnum;

7
linker/linker.h
View File

@ -164,10 +164,9 @@ struct soinfo
Elf32_Addr gnu_relro_start;
unsigned gnu_relro_len;
/* When you read a virtual address from the ELF file, add the load
* address (= "base" field) minus this value (= "load_offset") to get the
* real, corresponding address in the process' address space */
Elf32_Addr load_offset;
/* When you read a virtual address from the ELF file, add this
* value to get the corresponding address in the process' address space */
Elf32_Addr load_bias;
};