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linux-user: Load symbols from the interpreter.

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First, adjust load_symbols to accept a load_bias parameter.  At the same
time, read the entire section header table in one go, use pread instead
f lseek+read for the symbol and string tables, and properly free
allocated structures on error exit paths.

Second, adjust load_elf_interp to compute load_bias.  This requires
finding out the built-in load addresses.  Which allows us to honor a
pre-linked interpreter image when possible, and eliminate the hard-coded
INTERP_MAP_SIZE value.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
This commit is contained in:
Richard Henderson 2010-07-27 10:25:33 -07:00 committed by Edgar E. Iglesias
parent 991f8f0c91
commit 682674b841
1 changed files with 101 additions and 88 deletions
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189
linux-user/elfload.c
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@ -829,9 +829,6 @@ struct exec
#define ZMAGIC 0413 #define ZMAGIC 0413
#define QMAGIC 0314 #define QMAGIC 0314
/* max code+data+bss space allocated to elf interpreter */
#define INTERP_MAP_SIZE (32 * 1024 * 1024)
/* max code+data+bss+brk space allocated to ET_DYN executables */ /* max code+data+bss+brk space allocated to ET_DYN executables */
#define ET_DYN_MAP_SIZE (128 * 1024 * 1024) #define ET_DYN_MAP_SIZE (128 * 1024 * 1024)
@ -920,6 +917,7 @@ static inline void bswap_sym(struct elf_sym *sym) { }
#ifdef USE_ELF_CORE_DUMP #ifdef USE_ELF_CORE_DUMP
static int elf_core_dump(int, const CPUState *); static int elf_core_dump(int, const CPUState *);
#endif /* USE_ELF_CORE_DUMP */ #endif /* USE_ELF_CORE_DUMP */
static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias);
/* /*
* 'copy_elf_strings()' copies argument/envelope strings from user * 'copy_elf_strings()' copies argument/envelope strings from user
@ -1146,15 +1144,11 @@ static abi_ulong load_elf_interp(struct elfhdr * interp_elf_ex,
char bprm_buf[BPRM_BUF_SIZE]) char bprm_buf[BPRM_BUF_SIZE])
{ {
struct elf_phdr *elf_phdata = NULL; struct elf_phdr *elf_phdata = NULL;
struct elf_phdr *eppnt; abi_ulong load_addr, load_bias, loaddr, hiaddr;
abi_ulong load_addr = 0;
int load_addr_set = 0;
int retval; int retval;
abi_ulong error; abi_ulong error;
int i; int i;
error = 0;
bswap_ehdr(interp_elf_ex); bswap_ehdr(interp_elf_ex);
/* First of all, some simple consistency checks */ /* First of all, some simple consistency checks */
if ((interp_elf_ex->e_type != ET_EXEC && if ((interp_elf_ex->e_type != ET_EXEC &&
@ -1163,7 +1157,6 @@ static abi_ulong load_elf_interp(struct elfhdr * interp_elf_ex,
return ~((abi_ulong)0UL); return ~((abi_ulong)0UL);
} }
/* Now read in all of the header information */ /* Now read in all of the header information */
if (sizeof(struct elf_phdr) * interp_elf_ex->e_phnum > TARGET_PAGE_SIZE) if (sizeof(struct elf_phdr) * interp_elf_ex->e_phnum > TARGET_PAGE_SIZE)
@ -1196,41 +1189,56 @@ static abi_ulong load_elf_interp(struct elfhdr * interp_elf_ex,
} }
bswap_phdr(elf_phdata, interp_elf_ex->e_phnum); bswap_phdr(elf_phdata, interp_elf_ex->e_phnum);
/* Find the maximum size of the image and allocate an appropriate
amount of memory to handle that. */
loaddr = -1, hiaddr = 0;
for (i = 0; i < interp_elf_ex->e_phnum; ++i) {
if (elf_phdata[i].p_type == PT_LOAD) {
abi_ulong a = elf_phdata[i].p_vaddr;
if (a < loaddr) {
loaddr = a;
}
a += elf_phdata[i].p_memsz;
if (a > hiaddr) {
hiaddr = a;
}
}
}
load_addr = loaddr;
if (interp_elf_ex->e_type == ET_DYN) { if (interp_elf_ex->e_type == ET_DYN) {
/* in order to avoid hardcoding the interpreter load /* The image indicates that it can be loaded anywhere. Find a
address in qemu, we allocate a big enough memory zone */ location that can hold the memory space required. If the
error = target_mmap(0, INTERP_MAP_SIZE, image is pre-linked, LOADDR will be non-zero. Since we do
PROT_NONE, MAP_PRIVATE | MAP_ANON, not supply MAP_FIXED here we'll use that address if and
-1, 0); only if it remains available. */
if (error == -1) { load_addr = target_mmap(loaddr, hiaddr - loaddr, PROT_NONE,
MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
-1, 0);
if (load_addr == -1) {
perror("mmap"); perror("mmap");
exit(-1); exit(-1);
} }
load_addr = error;
load_addr_set = 1;
} }
load_bias = load_addr - loaddr;
eppnt = elf_phdata; for (i = 0; i < interp_elf_ex->e_phnum; i++) {
for(i=0; i<interp_elf_ex->e_phnum; i++, eppnt++) struct elf_phdr *eppnt = elf_phdata + i;
if (eppnt->p_type == PT_LOAD) { if (eppnt->p_type == PT_LOAD) {
int elf_type = MAP_PRIVATE | MAP_DENYWRITE; abi_ulong vaddr, vaddr_po, vaddr_ps, vaddr_ef, vaddr_em;
int elf_prot = 0; int elf_prot = 0;
abi_ulong vaddr = 0;
if (eppnt->p_flags & PF_R) elf_prot = PROT_READ; if (eppnt->p_flags & PF_R) elf_prot = PROT_READ;
if (eppnt->p_flags & PF_W) elf_prot |= PROT_WRITE; if (eppnt->p_flags & PF_W) elf_prot |= PROT_WRITE;
if (eppnt->p_flags & PF_X) elf_prot |= PROT_EXEC; if (eppnt->p_flags & PF_X) elf_prot |= PROT_EXEC;
if (interp_elf_ex->e_type == ET_EXEC || load_addr_set) {
elf_type |= MAP_FIXED;
vaddr = eppnt->p_vaddr;
}
error = target_mmap(load_addr+TARGET_ELF_PAGESTART(vaddr),
eppnt->p_filesz + TARGET_ELF_PAGEOFFSET(eppnt->p_vaddr),
elf_prot,
elf_type,
interpreter_fd,
eppnt->p_offset - TARGET_ELF_PAGEOFFSET(eppnt->p_vaddr));
vaddr = load_bias + eppnt->p_vaddr;
vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr);
vaddr_ps = TARGET_ELF_PAGESTART(vaddr);
error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po,
elf_prot, MAP_PRIVATE | MAP_FIXED,
interpreter_fd, eppnt->p_offset - vaddr_po);
if (error == -1) { if (error == -1) {
/* Real error */ /* Real error */
close(interpreter_fd); close(interpreter_fd);
@ -1238,26 +1246,25 @@ static abi_ulong load_elf_interp(struct elfhdr * interp_elf_ex,
return ~((abi_ulong)0UL); return ~((abi_ulong)0UL);
} }
if (!load_addr_set && interp_elf_ex->e_type == ET_DYN) { vaddr_ef = vaddr + eppnt->p_filesz;
load_addr = error; vaddr_em = vaddr + eppnt->p_memsz;
load_addr_set = 1;
}
/* If the load segment requests extra zeros (e.g. bss), map it. */ /* If the load segment requests extra zeros (e.g. bss), map it. */
if (eppnt->p_filesz < eppnt->p_memsz) { if (vaddr_ef < vaddr_em) {
abi_ulong base = load_addr + eppnt->p_vaddr; zero_bss(vaddr_ef, vaddr_em, elf_prot);
zero_bss(base + eppnt->p_filesz,
base + eppnt->p_memsz, elf_prot);
} }
} }
}
/* Now use mmap to map the library into memory. */ if (qemu_log_enabled()) {
load_symbols(interp_elf_ex, interpreter_fd, load_bias);
}
close(interpreter_fd); close(interpreter_fd);
free(elf_phdata); free(elf_phdata);
*interp_load_addr = load_addr; *interp_load_addr = load_addr;
return ((abi_ulong) interp_elf_ex->e_entry) + load_addr; return ((abi_ulong) interp_elf_ex->e_entry) + load_bias;
} }
static int symfind(const void *s0, const void *s1) static int symfind(const void *s0, const void *s1)
@ -1306,82 +1313,87 @@ static int symcmp(const void *s0, const void *s1)
} }
/* Best attempt to load symbols from this ELF object. */ /* Best attempt to load symbols from this ELF object. */
static void load_symbols(struct elfhdr *hdr, int fd) static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias)
{ {
unsigned int i, nsyms; int i, shnum, nsyms, sym_idx = 0, str_idx = 0;
struct elf_shdr sechdr, symtab, strtab; struct elf_shdr *shdr;
char *strings; char *strings;
struct syminfo *s; struct syminfo *s;
struct elf_sym *syms; struct elf_sym *syms;
lseek(fd, hdr->e_shoff, SEEK_SET); shnum = hdr->e_shnum;
for (i = 0; i < hdr->e_shnum; i++) { i = shnum * sizeof(struct elf_shdr);
if (read(fd, &sechdr, sizeof(sechdr)) != sizeof(sechdr)) shdr = (struct elf_shdr *)alloca(i);
return; if (pread(fd, shdr, i, hdr->e_shoff) != i) {
bswap_shdr(&sechdr, 1); return;
if (sechdr.sh_type == SHT_SYMTAB) { }
symtab = sechdr;
lseek(fd, hdr->e_shoff bswap_shdr(shdr, shnum);
+ sizeof(sechdr) * sechdr.sh_link, SEEK_SET); for (i = 0; i < shnum; ++i) {
if (read(fd, &strtab, sizeof(strtab)) if (shdr[i].sh_type == SHT_SYMTAB) {
!= sizeof(strtab)) sym_idx = i;
return; str_idx = shdr[i].sh_link;
bswap_shdr(&strtab, 1);
goto found; goto found;
} }
} }
return; /* Shouldn't happen... */
/* There will be no symbol table if the file was stripped. */
return;
found: found:
/* Now know where the strtab and symtab are. Snarf them. */ /* Now know where the strtab and symtab are. Snarf them. */
s = malloc(sizeof(*s)); s = malloc(sizeof(*s));
syms = malloc(symtab.sh_size); if (!s) {
if (!syms)
return; return;
s->disas_strtab = strings = malloc(strtab.sh_size); }
if (!s->disas_strtab)
i = shdr[str_idx].sh_size;
s->disas_strtab = strings = malloc(i);
if (!strings || pread(fd, strings, i, shdr[str_idx].sh_offset) != i) {
free(s);
free(strings);
return; return;
}
lseek(fd, symtab.sh_offset, SEEK_SET); i = shdr[sym_idx].sh_size;
if (read(fd, syms, symtab.sh_size) != symtab.sh_size) syms = malloc(i);
if (!syms || pread(fd, syms, i, shdr[sym_idx].sh_offset) != i) {
free(s);
free(strings);
free(syms);
return; return;
}
nsyms = symtab.sh_size / sizeof(struct elf_sym); nsyms = i / sizeof(struct elf_sym);
for (i = 0; i < nsyms; ) {
i = 0;
while (i < nsyms) {
bswap_sym(syms + i); bswap_sym(syms + i);
// Throw away entries which we do not need. /* Throw away entries which we do not need. */
if (syms[i].st_shndx == SHN_UNDEF || if (syms[i].st_shndx == SHN_UNDEF
syms[i].st_shndx >= SHN_LORESERVE || || syms[i].st_shndx >= SHN_LORESERVE
ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) { || ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) {
nsyms--; if (i < --nsyms) {
if (i < nsyms) {
syms[i] = syms[nsyms]; syms[i] = syms[nsyms];
} }
continue; } else {
}
#if defined(TARGET_ARM) || defined (TARGET_MIPS) #if defined(TARGET_ARM) || defined (TARGET_MIPS)
/* The bottom address bit marks a Thumb or MIPS16 symbol. */ /* The bottom address bit marks a Thumb or MIPS16 symbol. */
syms[i].st_value &= ~(target_ulong)1; syms[i].st_value &= ~(target_ulong)1;
#endif #endif
i++; syms[i].st_value += load_bias;
i++;
}
} }
syms = realloc(syms, nsyms * sizeof(*syms));
syms = realloc(syms, nsyms * sizeof(*syms));
qsort(syms, nsyms, sizeof(*syms), symcmp); qsort(syms, nsyms, sizeof(*syms), symcmp);
lseek(fd, strtab.sh_offset, SEEK_SET);
if (read(fd, strings, strtab.sh_size) != strtab.sh_size)
return;
s->disas_num_syms = nsyms; s->disas_num_syms = nsyms;
#if ELF_CLASS == ELFCLASS32 #if ELF_CLASS == ELFCLASS32
s->disas_symtab.elf32 = syms; s->disas_symtab.elf32 = syms;
s->lookup_symbol = lookup_symbolxx;
#else #else
s->disas_symtab.elf64 = syms; s->disas_symtab.elf64 = syms;
s->lookup_symbol = lookup_symbolxx;
#endif #endif
s->lookup_symbol = lookup_symbolxx;
s->next = syminfos; s->next = syminfos;
syminfos = s; syminfos = s;
} }
@ -1788,8 +1800,9 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
free(elf_phdata); free(elf_phdata);
if (qemu_log_enabled()) if (qemu_log_enabled()) {
load_symbols(&elf_ex, bprm->fd); load_symbols(&elf_ex, bprm->fd, load_bias);
}
if (interpreter_type != INTERPRETER_AOUT) close(bprm->fd); if (interpreter_type != INTERPRETER_AOUT) close(bprm->fd);
info->personality = (ibcs2_interpreter ? PER_SVR4 : PER_LINUX); info->personality = (ibcs2_interpreter ? PER_SVR4 : PER_LINUX);