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qemu/linux-user/elfload.c
Richard Henderson 9affb4decd common-user: Move probe_guest_base from linux-user 
Prepare to share probe_guest_base with bsd-user.

Create a linux_probe_guest_base wrapper with the portions
of probe_guest_base that are linux specific: managing the
commpage for various targets.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2026-07-10 14:40:42 -07:00

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/* This is the Linux kernel elf-loading code, ported into user space */
#include "qemu/osdep.h"
#include <sys/param.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include "qemu.h"
#include "user/tswap-target.h"
#include "user/page-protection.h"
#include "exec/page-protection.h"
#include "exec/mmap-lock.h"
#include "exec/translation-block.h"
#include "exec/tswap.h"
#include "user-internals.h"
#include "signal-common.h"
#include "loader.h"
#include "user-mmap.h"
#include "disas/disas.h"
#include "qemu/bitops.h"
#include "qemu/path.h"
#include "qemu/queue.h"
#include "qemu/guest-random.h"
#include "qemu/units.h"
#include "qemu/lockable.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "target_elf.h"
#include "target_signal.h"
#include "tcg/debuginfo.h"
#ifdef TARGET_ARM
#include "target/arm/cpu-features.h"
#endif
#ifndef TARGET_ARCH_HAS_SIGTRAMP_PAGE
#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
#endif
#define ELF_OSABI ELFOSABI_SYSV
/* from personality.h */
/*
* Flags for bug emulation.
*
* These occupy the top three bytes.
*/
enum {
ADDR_NO_RANDOMIZE = 0x0040000, /* disable randomization of VA space */
FDPIC_FUNCPTRS = 0x0080000, /* userspace function ptrs point to
descriptors (signal handling) */
MMAP_PAGE_ZERO = 0x0100000,
ADDR_COMPAT_LAYOUT = 0x0200000,
READ_IMPLIES_EXEC = 0x0400000,
ADDR_LIMIT_32BIT = 0x0800000,
SHORT_INODE = 0x1000000,
WHOLE_SECONDS = 0x2000000,
STICKY_TIMEOUTS = 0x4000000,
ADDR_LIMIT_3GB = 0x8000000,
};
/*
* Personality types.
*
* These go in the low byte. Avoid using the top bit, it will
* conflict with error returns.
*/
enum {
PER_LINUX = 0x0000,
PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT,
PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS,
PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
PER_SVR3 = 0x0002 | STICKY_TIMEOUTS | SHORT_INODE,
PER_SCOSVR3 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE,
PER_OSR5 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS,
PER_WYSEV386 = 0x0004 | STICKY_TIMEOUTS | SHORT_INODE,
PER_ISCR4 = 0x0005 | STICKY_TIMEOUTS,
PER_BSD = 0x0006,
PER_SUNOS = 0x0006 | STICKY_TIMEOUTS,
PER_XENIX = 0x0007 | STICKY_TIMEOUTS | SHORT_INODE,
PER_LINUX32 = 0x0008,
PER_LINUX32_3GB = 0x0008 | ADDR_LIMIT_3GB,
PER_IRIX32 = 0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */
PER_IRIXN32 = 0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */
PER_IRIX64 = 0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */
PER_RISCOS = 0x000c,
PER_SOLARIS = 0x000d | STICKY_TIMEOUTS,
PER_UW7 = 0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
PER_OSF4 = 0x000f, /* OSF/1 v4 */
PER_HPUX = 0x0010,
PER_MASK = 0x00ff,
};
/*
* Return the base personality without flags.
*/
#define personality(pers) (pers & PER_MASK)
int info_is_fdpic(struct image_info *info)
{
return info->personality == PER_LINUX_FDPIC;
}
#if TARGET_BIG_ENDIAN
#define ELF_DATA ELFDATA2MSB
#else
#define ELF_DATA ELFDATA2LSB
#endif
#ifdef USE_UID16
typedef abi_ushort target_uid_t;
typedef abi_ushort target_gid_t;
#else
typedef abi_uint target_uid_t;
typedef abi_uint target_gid_t;
#endif
typedef abi_int target_pid_t;
#ifndef elf_check_machine
#define elf_check_machine(x) ((x) == ELF_MACHINE)
#endif
#ifndef elf_check_abi
#define elf_check_abi(x) (1)
#endif
#ifndef STACK_GROWS_DOWN
#define STACK_GROWS_DOWN 1
#endif
#ifndef STACK_ALIGNMENT
#define STACK_ALIGNMENT 16
#endif
#ifdef TARGET_ABI32
#undef ELF_CLASS
#define ELF_CLASS ELFCLASS32
#undef bswaptls
#define bswaptls(ptr) bswap32s(ptr)
#endif
#ifndef EXSTACK_DEFAULT
#define EXSTACK_DEFAULT false
#endif
/*
* Provide fallback definitions that the target may omit.
* One way or another, we'll get a link error if the setting of
* HAVE_* doesn't match the implementation.
*/
#ifndef HAVE_ELF_HWCAP
abi_ulong get_elf_hwcap(CPUState *cs) { return 0; }
#endif
#ifndef HAVE_ELF_HWCAP2
abi_ulong get_elf_hwcap2(CPUState *cs) { g_assert_not_reached(); }
#define HAVE_ELF_HWCAP2 0
#endif
#ifndef HAVE_ELF_PLATFORM
const char *get_elf_platform(CPUState *cs) { return NULL; }
#endif
#ifndef HAVE_ELF_BASE_PLATFORM
const char *get_elf_base_platform(CPUState *cs) { return NULL; }
#endif
#ifndef HAVE_ELF_GNU_PROPERTY
bool arch_parse_elf_property(uint32_t pr_type, uint32_t pr_datasz,
const uint32_t *data, struct image_info *info,
Error **errp)
{
g_assert_not_reached();
}
#define HAVE_ELF_GNU_PROPERTY 0
#endif
#include "elf.h"
#define DLINFO_ITEMS 16
static inline void memcpy_fromfs(void * to, const void * from, unsigned long n)
{
memcpy(to, from, n);
}
static void bswap_ehdr(struct elfhdr *ehdr)
{
if (!target_needs_bswap()) {
return;
}
bswap16s(&ehdr->e_type); /* Object file type */
bswap16s(&ehdr->e_machine); /* Architecture */
bswap32s(&ehdr->e_version); /* Object file version */
bswaptls(&ehdr->e_entry); /* Entry point virtual address */
bswaptls(&ehdr->e_phoff); /* Program header table file offset */
bswaptls(&ehdr->e_shoff); /* Section header table file offset */
bswap32s(&ehdr->e_flags); /* Processor-specific flags */
bswap16s(&ehdr->e_ehsize); /* ELF header size in bytes */
bswap16s(&ehdr->e_phentsize); /* Program header table entry size */
bswap16s(&ehdr->e_phnum); /* Program header table entry count */
bswap16s(&ehdr->e_shentsize); /* Section header table entry size */
bswap16s(&ehdr->e_shnum); /* Section header table entry count */
bswap16s(&ehdr->e_shstrndx); /* Section header string table index */
}
static void bswap_phdr(struct elf_phdr *phdr, int phnum)
{
if (!target_needs_bswap()) {
return;
}
for (int i = 0; i < phnum; ++i, ++phdr) {
bswap32s(&phdr->p_type); /* Segment type */
bswap32s(&phdr->p_flags); /* Segment flags */
bswaptls(&phdr->p_offset); /* Segment file offset */
bswaptls(&phdr->p_vaddr); /* Segment virtual address */
bswaptls(&phdr->p_paddr); /* Segment physical address */
bswaptls(&phdr->p_filesz); /* Segment size in file */
bswaptls(&phdr->p_memsz); /* Segment size in memory */
bswaptls(&phdr->p_align); /* Segment alignment */
}
}
static void bswap_shdr(struct elf_shdr *shdr, int shnum)
{
if (!target_needs_bswap()) {
return;
}
for (int i = 0; i < shnum; ++i, ++shdr) {
bswap32s(&shdr->sh_name);
bswap32s(&shdr->sh_type);
bswaptls(&shdr->sh_flags);
bswaptls(&shdr->sh_addr);
bswaptls(&shdr->sh_offset);
bswaptls(&shdr->sh_size);
bswap32s(&shdr->sh_link);
bswap32s(&shdr->sh_info);
bswaptls(&shdr->sh_addralign);
bswaptls(&shdr->sh_entsize);
}
}
static void bswap_sym(struct elf_sym *sym)
{
if (!target_needs_bswap()) {
return;
}
bswap32s(&sym->st_name);
bswaptls(&sym->st_value);
bswaptls(&sym->st_size);
bswap16s(&sym->st_shndx);
}
#ifdef TARGET_MIPS
static void bswap_mips_abiflags(Mips_elf_abiflags_v0 *abiflags)
{
if (!target_needs_bswap()) {
return;
}
bswap16s(&abiflags->version);
bswap32s(&abiflags->ases);
bswap32s(&abiflags->isa_ext);
bswap32s(&abiflags->flags1);
bswap32s(&abiflags->flags2);
}
#endif
#ifdef HAVE_ELF_CORE_DUMP
static int elf_core_dump(int, const CPUArchState *);
#endif /* HAVE_ELF_CORE_DUMP */
static void load_symbols(struct elfhdr *hdr, const ImageSource *src,
abi_ulong load_bias);
/* Verify the portions of EHDR within E_IDENT for the target.
This can be performed before bswapping the entire header. */
static bool elf_check_ident(struct elfhdr *ehdr)
{
return (ehdr->e_ident[EI_MAG0] == ELFMAG0
&& ehdr->e_ident[EI_MAG1] == ELFMAG1
&& ehdr->e_ident[EI_MAG2] == ELFMAG2
&& ehdr->e_ident[EI_MAG3] == ELFMAG3
&& ehdr->e_ident[EI_CLASS] == ELF_CLASS
&& ehdr->e_ident[EI_DATA] == ELF_DATA
&& ehdr->e_ident[EI_VERSION] == EV_CURRENT);
}
/* Verify the portions of EHDR outside of E_IDENT for the target.
This has to wait until after bswapping the header. */
static bool elf_check_ehdr(struct elfhdr *ehdr)
{
return (elf_check_machine(ehdr->e_machine)
&& elf_check_abi(ehdr->e_flags)
&& ehdr->e_ehsize == sizeof(struct elfhdr)
&& ehdr->e_phentsize == sizeof(struct elf_phdr)
&& (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN));
}
/*
* 'copy_elf_strings()' copies argument/envelope strings from user
* memory to free pages in kernel mem. These are in a format ready
* to be put directly into the top of new user memory.
*
*/
static abi_ulong copy_elf_strings(int argc, char **argv, char *scratch,
abi_ulong p, abi_ulong stack_limit)
{
char *tmp;
int len, i;
abi_ulong top = p;
if (!p) {
return 0; /* bullet-proofing */
}
if (STACK_GROWS_DOWN) {
int offset = ((p - 1) % TARGET_PAGE_SIZE) + 1;
for (i = argc - 1; i >= 0; --i) {
tmp = argv[i];
if (!tmp) {
fprintf(stderr, "VFS: argc is wrong");
exit(-1);
}
len = strlen(tmp) + 1;
tmp += len;
if (len > (p - stack_limit)) {
return 0;
}
while (len) {
int bytes_to_copy = (len > offset) ? offset : len;
tmp -= bytes_to_copy;
p -= bytes_to_copy;
offset -= bytes_to_copy;
len -= bytes_to_copy;
memcpy_fromfs(scratch + offset, tmp, bytes_to_copy);
if (offset == 0) {
memcpy_to_target(p, scratch, top - p);
top = p;
offset = TARGET_PAGE_SIZE;
}
}
}
if (p != top) {
memcpy_to_target(p, scratch + offset, top - p);
}
} else {
int remaining = TARGET_PAGE_SIZE - (p % TARGET_PAGE_SIZE);
for (i = 0; i < argc; ++i) {
tmp = argv[i];
if (!tmp) {
fprintf(stderr, "VFS: argc is wrong");
exit(-1);
}
len = strlen(tmp) + 1;
if (len > (stack_limit - p)) {
return 0;
}
while (len) {
int bytes_to_copy = (len > remaining) ? remaining : len;
memcpy_fromfs(scratch + (p - top), tmp, bytes_to_copy);
tmp += bytes_to_copy;
remaining -= bytes_to_copy;
p += bytes_to_copy;
len -= bytes_to_copy;
if (remaining == 0) {
memcpy_to_target(top, scratch, p - top);
top = p;
remaining = TARGET_PAGE_SIZE;
}
}
}
if (p != top) {
memcpy_to_target(top, scratch, p - top);
}
}
return p;
}
/* Older linux kernels provide up to MAX_ARG_PAGES (default: 32) of
* argument/environment space. Newer kernels (>2.6.33) allow more,
* dependent on stack size, but guarantee at least 32 pages for
* backwards compatibility.
*/
#define STACK_LOWER_LIMIT (32 * TARGET_PAGE_SIZE)
static abi_ulong setup_arg_pages(struct linux_binprm *bprm,
struct image_info *info)
{
abi_ulong size, error, guard;
int prot;
size = guest_stack_size;
if (size < STACK_LOWER_LIMIT) {
size = STACK_LOWER_LIMIT;
}
if (STACK_GROWS_DOWN) {
guard = TARGET_PAGE_SIZE;
if (guard < qemu_real_host_page_size()) {
guard = qemu_real_host_page_size();
}
} else {
/* no guard page for hppa target where stack grows upwards. */
guard = 0;
}
prot = PROT_READ | PROT_WRITE;
if (info->exec_stack) {
prot |= PROT_EXEC;
}
error = target_mmap(0, size + guard, prot,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (error == -1) {
perror("mmap stack");
exit(-1);
}
/* We reserve one extra page at the top of the stack as guard. */
if (STACK_GROWS_DOWN) {
target_mprotect(error, guard, PROT_NONE);
info->stack_limit = error + guard;
return info->stack_limit + size - sizeof(void *);
} else {
info->stack_limit = error + size;
return error;
}
}
/**
* zero_bss:
*
* Map and zero the bss. We need to explicitly zero any fractional pages
* after the data section (i.e. bss). Return false on mapping failure.
*/
static bool zero_bss(abi_ulong start_bss, abi_ulong end_bss,
int prot, Error **errp)
{
abi_ulong align_bss;
align_bss = TARGET_PAGE_ALIGN(start_bss);
end_bss = TARGET_PAGE_ALIGN(end_bss);
if (start_bss < align_bss) {
int flags = page_get_flags(start_bss);
if (!(flags & PAGE_RWX)) {
/*
* The whole address space of the executable was reserved
* at the start, therefore all pages will be VALID.
* But assuming there are no PROT_NONE PT_LOAD segments,
* a PROT_NONE page means no data all bss, and we can
* simply extend the new anon mapping back to the start
* of the page of bss.
*/
align_bss -= TARGET_PAGE_SIZE;
} else {
abi_ulong start_page_aligned = start_bss & TARGET_PAGE_MASK;
/*
* The logical OR between flags and PAGE_WRITE works because
* in include/exec/page-protection.h they are defined as PROT_*
* values, matching mprotect().
* Temporarily enable write access to zero the fractional bss.
* target_mprotect() handles TB invalidation if needed.
*/
if (!(flags & PAGE_WRITE)) {
if (target_mprotect(start_page_aligned,
TARGET_PAGE_SIZE,
prot | PAGE_WRITE) == -1) {
error_setg_errno(errp, errno,
"Error enabling write access for bss");
return false;
}
}
/* The page is already mapped and now guaranteed writable. */
memset(g2h_untagged(start_bss), 0, align_bss - start_bss);
if (!(flags & PAGE_WRITE)) {
if (target_mprotect(start_page_aligned,
TARGET_PAGE_SIZE, prot) == -1) {
error_setg_errno(errp, errno,
"Error restoring bss first permissions");
return false;
}
}
}
}
if (align_bss < end_bss &&
target_mmap(align_bss, end_bss - align_bss, prot,
MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0) == -1) {
error_setg_errno(errp, errno, "Error mapping bss");
return false;
}
return true;
}
#if defined(TARGET_ARM)
static int elf_is_fdpic(struct elfhdr *exec)
{
return exec->e_ident[EI_OSABI] == ELFOSABI_ARM_FDPIC;
}
#elif defined(TARGET_XTENSA)
static int elf_is_fdpic(struct elfhdr *exec)
{
return exec->e_ident[EI_OSABI] == ELFOSABI_XTENSA_FDPIC;
}
#else
/* Default implementation, always false. */
static int elf_is_fdpic(struct elfhdr *exec)
{
return 0;
}
#endif
static abi_ulong loader_build_fdpic_loadmap(struct image_info *info, abi_ulong sp)
{
uint16_t n;
struct elf32_fdpic_loadseg *loadsegs = info->loadsegs;
/* elf32_fdpic_loadseg */
n = info->nsegs;
while (n--) {
sp -= 12;
put_user_u32(loadsegs[n].addr, sp+0);
put_user_u32(loadsegs[n].p_vaddr, sp+4);
put_user_u32(loadsegs[n].p_memsz, sp+8);
}
/* elf32_fdpic_loadmap */
sp -= 4;
put_user_u16(0, sp+0); /* version */
put_user_u16(info->nsegs, sp+2); /* nsegs */
info->personality = PER_LINUX_FDPIC;
info->loadmap_addr = sp;
return sp;
}
static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
struct elfhdr *exec,
struct image_info *info,
struct image_info *interp_info,
struct image_info *vdso_info)
{
abi_ulong sp;
abi_ulong u_argc, u_argv, u_envp, u_auxv;
int size;
int i;
abi_ulong u_rand_bytes;
uint8_t k_rand_bytes[16];
abi_ulong u_platform, u_base_platform;
const char *k_platform, *k_base_platform;
const int n = sizeof(elf_addr_t);
sp = p;
/* Needs to be before we load the env/argc/... */
if (elf_is_fdpic(exec)) {
/* Need 4 byte alignment for these structs */
sp &= ~3;
sp = loader_build_fdpic_loadmap(info, sp);
info->other_info = interp_info;
if (interp_info) {
interp_info->other_info = info;
sp = loader_build_fdpic_loadmap(interp_info, sp);
info->interpreter_loadmap_addr = interp_info->loadmap_addr;
info->interpreter_pt_dynamic_addr = interp_info->pt_dynamic_addr;
} else {
info->interpreter_loadmap_addr = 0;
info->interpreter_pt_dynamic_addr = 0;
}
}
u_base_platform = 0;
k_base_platform = get_elf_base_platform(thread_cpu);
if (k_base_platform) {
size_t len = strlen(k_base_platform) + 1;
if (STACK_GROWS_DOWN) {
sp -= (len + n - 1) & ~(n - 1);
u_base_platform = sp;
/* FIXME - check return value of memcpy_to_target() for failure */
memcpy_to_target(sp, k_base_platform, len);
} else {
memcpy_to_target(sp, k_base_platform, len);
u_base_platform = sp;
sp += len + 1;
}
}
u_platform = 0;
k_platform = get_elf_platform(thread_cpu);
if (k_platform) {
size_t len = strlen(k_platform) + 1;
if (STACK_GROWS_DOWN) {
sp -= (len + n - 1) & ~(n - 1);
u_platform = sp;
/* FIXME - check return value of memcpy_to_target() for failure */
memcpy_to_target(sp, k_platform, len);
} else {
memcpy_to_target(sp, k_platform, len);
u_platform = sp;
sp += len + 1;
}
}
/* Provide 16 byte alignment for the PRNG, and basic alignment for
* the argv and envp pointers.
*/
if (STACK_GROWS_DOWN) {
sp = QEMU_ALIGN_DOWN(sp, 16);
} else {
sp = QEMU_ALIGN_UP(sp, 16);
}
/*
* Generate 16 random bytes for userspace PRNG seeding.
*/
qemu_guest_getrandom_nofail(k_rand_bytes, sizeof(k_rand_bytes));
if (STACK_GROWS_DOWN) {
sp -= 16;
u_rand_bytes = sp;
/* FIXME - check return value of memcpy_to_target() for failure */
memcpy_to_target(sp, k_rand_bytes, 16);
} else {
memcpy_to_target(sp, k_rand_bytes, 16);
u_rand_bytes = sp;
sp += 16;
}
size = (DLINFO_ITEMS + 1) * 2;
if (k_base_platform) {
size += 2;
}
if (k_platform) {
size += 2;
}
if (vdso_info) {
size += 2;
}
#ifdef DLINFO_ARCH_ITEMS
size += DLINFO_ARCH_ITEMS * 2;
#endif
if (HAVE_ELF_HWCAP2) {
size += 2;
}
info->auxv_len = size * n;
size += envc + argc + 2;
size += 1; /* argc itself */
size *= n;
/* Allocate space and finalize stack alignment for entry now. */
if (STACK_GROWS_DOWN) {
u_argc = QEMU_ALIGN_DOWN(sp - size, STACK_ALIGNMENT);
sp = u_argc;
} else {
u_argc = sp;
sp = QEMU_ALIGN_UP(sp + size, STACK_ALIGNMENT);
}
u_argv = u_argc + n;
u_envp = u_argv + (argc + 1) * n;
u_auxv = u_envp + (envc + 1) * n;
info->saved_auxv = u_auxv;
info->argc = argc;
info->envc = envc;
info->argv = u_argv;
info->envp = u_envp;
/* This is correct because Linux defines
* elf_addr_t as Elf32_Off / Elf64_Off
*/
#define NEW_AUX_ENT(id, val) do { \
put_user_ual(id, u_auxv); u_auxv += n; \
put_user_ual(val, u_auxv); u_auxv += n; \
} while(0)
#ifdef ARCH_DLINFO
/*
* ARCH_DLINFO must come first so platform specific code can enforce
* special alignment requirements on the AUXV if necessary (eg. PPC).
*/
ARCH_DLINFO;
#endif
/* There must be exactly DLINFO_ITEMS entries here, or the assert
* on info->auxv_len will trigger.
*/
NEW_AUX_ENT(AT_PHDR, (abi_ulong)(info->phdr_addr));
NEW_AUX_ENT(AT_PHENT, (abi_ulong)(sizeof (struct elf_phdr)));
NEW_AUX_ENT(AT_PHNUM, (abi_ulong)(exec->e_phnum));
NEW_AUX_ENT(AT_PAGESZ, (abi_ulong)(TARGET_PAGE_SIZE));
NEW_AUX_ENT(AT_BASE, (abi_ulong)(interp_info ? interp_info->load_addr : 0));
NEW_AUX_ENT(AT_FLAGS, (abi_ulong)0);
NEW_AUX_ENT(AT_ENTRY, info->entry);
NEW_AUX_ENT(AT_UID, (abi_ulong) getuid());
NEW_AUX_ENT(AT_EUID, (abi_ulong) geteuid());
NEW_AUX_ENT(AT_GID, (abi_ulong) getgid());
NEW_AUX_ENT(AT_EGID, (abi_ulong) getegid());
NEW_AUX_ENT(AT_HWCAP, get_elf_hwcap(thread_cpu));
NEW_AUX_ENT(AT_CLKTCK, (abi_ulong) sysconf(_SC_CLK_TCK));
NEW_AUX_ENT(AT_RANDOM, (abi_ulong) u_rand_bytes);
NEW_AUX_ENT(AT_SECURE, (abi_ulong) qemu_getauxval(AT_SECURE));
NEW_AUX_ENT(AT_EXECFN, info->file_string);
if (HAVE_ELF_HWCAP2) {
NEW_AUX_ENT(AT_HWCAP2, get_elf_hwcap2(thread_cpu));
}
if (u_base_platform) {
NEW_AUX_ENT(AT_BASE_PLATFORM, u_base_platform);
}
if (u_platform) {
NEW_AUX_ENT(AT_PLATFORM, u_platform);
}
if (vdso_info) {
NEW_AUX_ENT(AT_SYSINFO_EHDR, vdso_info->load_addr);
}
NEW_AUX_ENT (AT_NULL, 0);
#undef NEW_AUX_ENT
/* Check that our initial calculation of the auxv length matches how much
* we actually put into it.
*/
assert(info->auxv_len == u_auxv - info->saved_auxv);
put_user_ual(argc, u_argc);
p = info->arg_strings;
for (i = 0; i < argc; ++i) {
put_user_ual(p, u_argv);
u_argv += n;
p += target_strlen(p) + 1;
}
put_user_ual(0, u_argv);
p = info->env_strings;
for (i = 0; i < envc; ++i) {
put_user_ual(p, u_envp);
u_envp += n;
p += target_strlen(p) + 1;
}
put_user_ual(0, u_envp);
return sp;
}
void linux_probe_guest_base(const char *image_name,
const PGBRange *image_range)
{
#ifdef COMMPAGE
const PGBRange * const commpage_range = &(PGBRange){
COMMPAGE, COMMPAGE + TARGET_PAGE_SIZE - 1
};
#else
const PGBRange * const commpage_range = NULL;
#endif
probe_guest_base(image_name, image_range, commpage_range);
/* Reserve and initialize the commpage. */
#if defined(COMMPAGE) || defined(HAVE_GUEST_COMMPAGE)
if (!init_guest_commpage()) {
/* We have already probed for the commpage being free. */
g_assert_not_reached();
}
#endif
}
enum {
/* The string "GNU\0" as a magic number. */
GNU0_MAGIC = const_le32('G' | 'N' << 8 | 'U' << 16),
NOTE_DATA_SZ = 1 * KiB,
NOTE_NAME_SZ = 4,
ELF_GNU_PROPERTY_ALIGN = ELF_CLASS == ELFCLASS32 ? 4 : 8,
};
/*
* Process a single gnu_property entry.
* Return false for error.
*/
static bool parse_elf_property(const uint32_t *data, int *off, int datasz,
struct image_info *info, bool have_prev_type,
uint32_t *prev_type, Error **errp)
{
uint32_t pr_type, pr_datasz, step;
if (*off > datasz || !QEMU_IS_ALIGNED(*off, ELF_GNU_PROPERTY_ALIGN)) {
goto error_data;
}
datasz -= *off;
data += *off / sizeof(uint32_t);
if (datasz < 2 * sizeof(uint32_t)) {
goto error_data;
}
pr_type = data[0];
pr_datasz = data[1];
data += 2;
datasz -= 2 * sizeof(uint32_t);
step = ROUND_UP(pr_datasz, ELF_GNU_PROPERTY_ALIGN);
if (step > datasz) {
goto error_data;
}
/* Properties are supposed to be unique and sorted on pr_type. */
if (have_prev_type && pr_type <= *prev_type) {
if (pr_type == *prev_type) {
error_setg(errp, "Duplicate property in PT_GNU_PROPERTY");
} else {
error_setg(errp, "Unsorted property in PT_GNU_PROPERTY");
}
return false;
}
*prev_type = pr_type;
if (!arch_parse_elf_property(pr_type, pr_datasz, data, info, errp)) {
return false;
}
*off += 2 * sizeof(uint32_t) + step;
return true;
error_data:
error_setg(errp, "Ill-formed property in PT_GNU_PROPERTY");
return false;
}
/* Process NT_GNU_PROPERTY_TYPE_0. */
static bool parse_elf_properties(const ImageSource *src,
struct image_info *info,
const struct elf_phdr *phdr,
Error **errp)
{
union {
struct elf_note nhdr;
uint32_t data[NOTE_DATA_SZ / sizeof(uint32_t)];
} note;
int n, off, datasz;
bool have_prev_type;
uint32_t prev_type;
/* Unless the arch requires properties, ignore them. */
if (!HAVE_ELF_GNU_PROPERTY) {
return true;
}
/* If the properties are crazy large, that's too bad. */
n = phdr->p_filesz;
if (n > sizeof(note)) {
error_setg(errp, "PT_GNU_PROPERTY too large");
return false;
}
if (n < sizeof(note.nhdr)) {
error_setg(errp, "PT_GNU_PROPERTY too small");
return false;
}
if (!imgsrc_read(&note, phdr->p_offset, n, src, errp)) {
return false;
}
/*
* The contents of a valid PT_GNU_PROPERTY is a sequence of uint32_t.
* Swap most of them now, beyond the header and namesz.
*/
if (target_needs_bswap()) {
for (int i = 4; i < n / 4; i++) {
bswap32s(note.data + i);
}
}
/*
* Note that nhdr is 3 words, and that the "name" described by namesz
* immediately follows nhdr and is thus at the 4th word. Further, all
* of the inputs to the kernel's round_up are multiples of 4.
*/
if (tswap32(note.nhdr.n_type) != NT_GNU_PROPERTY_TYPE_0 ||
tswap32(note.nhdr.n_namesz) != NOTE_NAME_SZ ||
note.data[3] != GNU0_MAGIC) {
error_setg(errp, "Invalid note in PT_GNU_PROPERTY");
return false;
}
off = sizeof(note.nhdr) + NOTE_NAME_SZ;
datasz = tswap32(note.nhdr.n_descsz) + off;
if (datasz > n) {
error_setg(errp, "Invalid note size in PT_GNU_PROPERTY");
return false;
}
have_prev_type = false;
prev_type = 0;
while (1) {
if (off == datasz) {
return true; /* end, exit ok */
}
if (!parse_elf_property(note.data, &off, datasz, info,
have_prev_type, &prev_type, errp)) {
return false;
}
have_prev_type = true;
}
}
/**
* load_elf_image: Load an ELF image into the address space.
* @image_name: the filename of the image, to use in error messages.
* @src: the ImageSource from which to read.
* @info: info collected from the loaded image.
* @ehdr: the ELF header, not yet bswapped.
* @pinterp_name: record any PT_INTERP string found.
*
* On return: @info values will be filled in, as necessary or available.
*/
static void load_elf_image(const char *image_name, const ImageSource *src,
struct image_info *info, struct elfhdr *ehdr,
char **pinterp_name)
{
g_autofree struct elf_phdr *phdr = NULL;
PGBRange range = { -1, 0 };
abi_ulong load_addr, load_bias, error, align;
size_t reserve_size, align_size;
int i, prot_exec;
Error *err = NULL;
/*
* First of all, some simple consistency checks.
* Note that we rely on the bswapped ehdr staying in bprm_buf,
* for later use by load_elf_binary and create_elf_tables.
*/
if (!imgsrc_read(ehdr, 0, sizeof(*ehdr), src, &err)) {
goto exit_errmsg;
}
if (!elf_check_ident(ehdr)) {
error_setg(&err, "Invalid ELF image for this architecture");
goto exit_errmsg;
}
bswap_ehdr(ehdr);
if (!elf_check_ehdr(ehdr)) {
error_setg(&err, "Invalid ELF image for this architecture");
goto exit_errmsg;
}
phdr = imgsrc_read_alloc(ehdr->e_phoff,
ehdr->e_phnum * sizeof(struct elf_phdr),
src, &err);
if (phdr == NULL) {
goto exit_errmsg;
}
bswap_phdr(phdr, ehdr->e_phnum);
info->nsegs = 0;
info->pt_dynamic_addr = 0;
mmap_lock();
/*
* Find the maximum size of the image and allocate an appropriate
* amount of memory to handle that. Locate the interpreter, if any.
*/
align = 0;
info->exec_stack = EXSTACK_DEFAULT;
for (i = 0; i < ehdr->e_phnum; ++i) {
struct elf_phdr *eppnt = phdr + i;
if (eppnt->p_type == PT_LOAD) {
abi_ulong a = eppnt->p_vaddr & TARGET_PAGE_MASK;
if (a < range.lo) {
range.lo = a;
}
a = eppnt->p_vaddr + eppnt->p_memsz - 1;
if (a > range.hi) {
range.hi = a;
}
++info->nsegs;
align |= eppnt->p_align;
} else if (eppnt->p_type == PT_INTERP && pinterp_name) {
g_autofree char *interp_name = NULL;
if (*pinterp_name) {
error_setg(&err, "Multiple PT_INTERP entries");
goto exit_errmsg;
}
interp_name = imgsrc_read_alloc(eppnt->p_offset, eppnt->p_filesz,
src, &err);
if (interp_name == NULL) {
goto exit_errmsg;
}
if (interp_name[eppnt->p_filesz - 1] != 0) {
error_setg(&err, "Invalid PT_INTERP entry");
goto exit_errmsg;
}
*pinterp_name = g_steal_pointer(&interp_name);
} else if (eppnt->p_type == PT_GNU_PROPERTY) {
if (!parse_elf_properties(src, info, eppnt, &err)) {
goto exit_errmsg;
}
} else if (eppnt->p_type == PT_GNU_STACK) {
info->exec_stack = eppnt->p_flags & PF_X;
}
}
load_addr = range.lo;
align = pow2ceil(align);
if (pinterp_name != NULL) {
if (ehdr->e_type == ET_EXEC) {
/*
* Make sure that the low address does not conflict with
* MMAP_MIN_ADDR or the QEMU application itself.
*/
linux_probe_guest_base(image_name, &range);
} else {
/* The binary is dynamic; we still need to select guest_base. */
linux_probe_guest_base(image_name, NULL);
/*
* Avoid collision with the loader by providing a different
* default load address.
*/
load_addr += elf_et_dyn_base;
/*
* TODO: Better support for mmap alignment is desirable.
* Since we do not have complete control over the guest
* address space, we prefer the kernel to choose some address
* rather than force the use of LOAD_ADDR via MAP_FIXED.
*/
if (align) {
load_addr &= -align;
}
}
}
/*
* Reserve address space for all of this.
*
* In the case of ET_EXEC, we supply MAP_FIXED_NOREPLACE so that we get
* exactly the address range that is required. Without reserved_va,
* the guest address space is not isolated. We have attempted to avoid
* conflict with the host program itself via probe_guest_base, but using
* MAP_FIXED_NOREPLACE instead of MAP_FIXED provides an extra check.
*
* Otherwise this is ET_DYN, and we are searching for a location
* that can hold the memory space required. If the image is
* pre-linked, LOAD_ADDR will be non-zero, and the kernel should
* honor that address if it happens to be free.
*
* In both cases, we will overwrite pages in this range with mappings
* from the executable.
*/
reserve_size = range.hi - range.lo + 1;
align_size = reserve_size;
if (ehdr->e_type != ET_EXEC && align > qemu_real_host_page_size()) {
align_size += align - 1;
}
load_addr = target_mmap(load_addr, align_size, PROT_NONE,
MAP_PRIVATE | MAP_ANON | MAP_NORESERVE |
(ehdr->e_type == ET_EXEC ? MAP_FIXED_NOREPLACE : 0),
-1, 0);
if (load_addr == -1) {
goto exit_mmap;
}
if (align_size != reserve_size) {
abi_ulong align_addr = ROUND_UP(load_addr, align);
abi_ulong align_end = TARGET_PAGE_ALIGN(align_addr + reserve_size);
abi_ulong load_end = TARGET_PAGE_ALIGN(load_addr + align_size);
if (align_addr != load_addr) {
target_munmap(load_addr, align_addr - load_addr);
}
if (align_end != load_end) {
target_munmap(align_end, load_end - align_end);
}
load_addr = align_addr;
}
load_bias = load_addr - range.lo;
if (elf_is_fdpic(ehdr)) {
struct elf32_fdpic_loadseg *loadsegs = info->loadsegs =
g_malloc(sizeof(*loadsegs) * info->nsegs);
for (i = 0; i < ehdr->e_phnum; ++i) {
switch (phdr[i].p_type) {
case PT_DYNAMIC:
info->pt_dynamic_addr = phdr[i].p_vaddr + load_bias;
break;
case PT_LOAD:
loadsegs->addr = phdr[i].p_vaddr + load_bias;
loadsegs->p_vaddr = phdr[i].p_vaddr;
loadsegs->p_memsz = phdr[i].p_memsz;
++loadsegs;
break;
}
}
}
info->load_bias = load_bias;
info->code_offset = load_bias;
info->data_offset = load_bias;
info->load_addr = load_addr;
info->entry = ehdr->e_entry + load_bias;
/*
* Fallback for AT_PHDR if the program headers do not fall within
* any PT_LOAD segment (see the loop below, which overrides this with
* the correct in-memory address when a containing segment is found).
*/
info->phdr_addr = load_addr + ehdr->e_phoff;
info->start_code = -1;
info->end_code = 0;
info->start_data = -1;
info->end_data = 0;
/* Usual start for brk is after all sections of the main executable. */
info->brk = TARGET_PAGE_ALIGN(range.hi + load_bias);
info->elf_flags = ehdr->e_flags;
#ifdef TARGET_MIPS
info->use_k0_tls = (ehdr->e_flags & EF_MIPS_MACH) == EF_MIPS_MACH_OCTEON;
#endif
prot_exec = PROT_EXEC;
#ifdef TARGET_AARCH64
/*
* If the BTI feature is present, this indicates that the executable
* pages of the startup binary should be mapped with PROT_BTI, so that
* branch targets are enforced.
*
* The startup binary is either the interpreter or the static executable.
* The interpreter is responsible for all pages of a dynamic executable.
*
* Elf notes are backward compatible to older cpus.
* Do not enable BTI unless it is supported.
*/
if ((info->note_flags & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
&& (pinterp_name == NULL || *pinterp_name == 0)
&& cpu_isar_feature(aa64_bti, ARM_CPU(thread_cpu))) {
prot_exec |= TARGET_PROT_BTI;
}
#endif
for (i = 0; i < ehdr->e_phnum; i++) {
struct elf_phdr *eppnt = phdr + i;
if (eppnt->p_type == PT_LOAD) {
abi_ulong vaddr, vaddr_po, vaddr_ps, vaddr_ef, vaddr_em;
int elf_prot = 0;
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_X) {
elf_prot |= prot_exec;
}
vaddr = load_bias + eppnt->p_vaddr;
vaddr_po = vaddr & ~TARGET_PAGE_MASK;
vaddr_ps = vaddr & TARGET_PAGE_MASK;
vaddr_ef = vaddr + eppnt->p_filesz;
vaddr_em = vaddr + eppnt->p_memsz;
/*
* If this segment contains the program headers, record their
* in-memory address for AT_PHDR. This matches the kernel, which
* locates the headers via the containing PT_LOAD rather than
* assuming load_addr + e_phoff (false when the phdrs are not
* mapped 1:1 from file offset 0, e.g. relocated into their own
* segment by a binary patcher).
*/
if (eppnt->p_offset <= ehdr->e_phoff &&
ehdr->e_phoff < eppnt->p_offset + eppnt->p_filesz) {
info->phdr_addr = vaddr + (ehdr->e_phoff - eppnt->p_offset);
}
/*
* Some segments may be completely empty, with a non-zero p_memsz
* but no backing file segment.
*/
if (eppnt->p_filesz != 0) {
error = imgsrc_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po,
elf_prot, MAP_PRIVATE | MAP_FIXED,
src, eppnt->p_offset - vaddr_po);
if (error == -1) {
goto exit_mmap;
}
}
/* If the load segment requests extra zeros (e.g. bss), map it. */
if (vaddr_ef < vaddr_em &&
!zero_bss(vaddr_ef, vaddr_em, elf_prot, &err)) {
goto exit_errmsg;
}
/* Find the full program boundaries. */
if (elf_prot & PROT_EXEC) {
if (vaddr < info->start_code) {
info->start_code = vaddr;
}
if (vaddr_ef > info->end_code) {
info->end_code = vaddr_ef;
}
}
if (elf_prot & PROT_WRITE) {
if (vaddr < info->start_data) {
info->start_data = vaddr;
}
if (vaddr_ef > info->end_data) {
info->end_data = vaddr_ef;
}
}
#ifdef TARGET_MIPS
} else if (eppnt->p_type == PT_MIPS_ABIFLAGS) {
Mips_elf_abiflags_v0 abiflags;
if (!imgsrc_read(&abiflags, eppnt->p_offset, sizeof(abiflags),
src, &err)) {
goto exit_errmsg;
}
bswap_mips_abiflags(&abiflags);
info->fp_abi = abiflags.fp_abi;
#endif
}
}
if (info->end_data == 0) {
info->start_data = info->end_code;
info->end_data = info->end_code;
}
if (qemu_log_enabled()) {
load_symbols(ehdr, src, load_bias);
}
debuginfo_report_elf(image_name, src->fd, load_bias);
mmap_unlock();
close(src->fd);
return;
exit_mmap:
error_setg_errno(&err, errno, "Error mapping file");
goto exit_errmsg;
exit_errmsg:
error_reportf_err(err, "%s: ", image_name);
exit(-1);
}
static void load_elf_interp(const char *filename, struct image_info *info,
char bprm_buf[BPRM_BUF_SIZE])
{
struct elfhdr ehdr;
ImageSource src;
int fd, retval;
Error *err = NULL;
fd = open(path(filename), O_RDONLY);
if (fd < 0) {
error_setg_file_open(&err, errno, filename);
error_report_err(err);
exit(-1);
}
retval = read(fd, bprm_buf, BPRM_BUF_SIZE);
if (retval < 0) {
error_setg_errno(&err, errno, "Error reading file header");
error_reportf_err(err, "%s: ", filename);
exit(-1);
}
src.fd = fd;
src.cache = bprm_buf;
src.cache_size = retval;
load_elf_image(filename, &src, info, &ehdr, NULL);
}
#ifndef HAVE_VDSO_IMAGE_INFO
const VdsoImageInfo *get_vdso_image_info(uint32_t elf_flags)
{
#ifdef VDSO_HEADER
#include VDSO_HEADER
return &vdso_image_info;
#else
return NULL;
#endif
}
#endif /* HAVE_VDSO_IMAGE_INFO */
static void load_elf_vdso(struct image_info *info, const VdsoImageInfo *vdso)
{
ImageSource src;
struct elfhdr ehdr;
abi_ulong load_bias, load_addr;
src.fd = -1;
src.cache = vdso->image;
src.cache_size = vdso->image_size;
load_elf_image("<internal-vdso>", &src, info, &ehdr, NULL);
load_addr = info->load_addr;
load_bias = info->load_bias;
/*
* We need to relocate the VDSO image. The one built into the kernel
* is built for a fixed address. The one built for QEMU is not, since
* that requires close control of the guest address space.
* We pre-processed the image to locate all of the addresses that need
* to be updated.
*/
for (unsigned i = 0, n = vdso->reloc_count; i < n; i++) {
abi_ulong *addr = g2h_untagged(load_addr + vdso->relocs[i]);
*addr = tswapal(tswapal(*addr) + load_bias);
}
/* Install signal trampolines, if present. */
if (vdso->sigreturn_ofs) {
default_sigreturn = load_addr + vdso->sigreturn_ofs;
}
if (vdso->rt_sigreturn_ofs) {
default_rt_sigreturn = load_addr + vdso->rt_sigreturn_ofs;
}
if (vdso->sigreturn_region_start_ofs) {
vdso_sigreturn_region_start =
load_addr + vdso->sigreturn_region_start_ofs;
vdso_sigreturn_region_end = load_addr + vdso->sigreturn_region_end_ofs;
}
/* Remove write from VDSO segment. */
target_mprotect(info->start_data, info->end_data - info->start_data,
PROT_READ | PROT_EXEC);
}
static int symfind(const void *s0, const void *s1)
{
struct elf_sym *sym = (struct elf_sym *)s1;
__typeof(sym->st_value) addr = *(uint64_t *)s0;
int result = 0;
if (addr < sym->st_value) {
result = -1;
} else if (addr >= sym->st_value + sym->st_size) {
result = 1;
}
return result;
}
static const char *lookup_symbolxx(struct syminfo *s, uint64_t orig_addr)
{
#if ELF_CLASS == ELFCLASS32
struct elf_sym *syms = s->disas_symtab.elf32;
#else
struct elf_sym *syms = s->disas_symtab.elf64;
#endif
// binary search
struct elf_sym *sym;
sym = bsearch(&orig_addr, syms, s->disas_num_syms, sizeof(*syms), symfind);
if (sym != NULL) {
return s->disas_strtab + sym->st_name;
}
return "";
}
/* FIXME: This should use elf_ops.h.inc */
static int symcmp(const void *s0, const void *s1)
{
struct elf_sym *sym0 = (struct elf_sym *)s0;
struct elf_sym *sym1 = (struct elf_sym *)s1;
return (sym0->st_value < sym1->st_value)
? -1
: ((sym0->st_value > sym1->st_value) ? 1 : 0);
}
/* Best attempt to load symbols from this ELF object. */
static void load_symbols(struct elfhdr *hdr, const ImageSource *src,
abi_ulong load_bias)
{
int i, shnum, nsyms, sym_idx = 0, str_idx = 0;
g_autofree struct elf_shdr *shdr = NULL;
char *strings = NULL;
struct elf_sym *syms = NULL;
struct elf_sym *new_syms;
uint64_t segsz;
shnum = hdr->e_shnum;
shdr = imgsrc_read_alloc(hdr->e_shoff, shnum * sizeof(struct elf_shdr),
src, NULL);
if (shdr == NULL) {
return;
}
bswap_shdr(shdr, shnum);
for (i = 0; i < shnum; ++i) {
if (shdr[i].sh_type == SHT_SYMTAB) {
sym_idx = i;
str_idx = shdr[i].sh_link;
goto found;
}
}
/* There will be no symbol table if the file was stripped. */
return;
found:
/* Now know where the strtab and symtab are. Snarf them. */
segsz = shdr[str_idx].sh_size;
strings = g_try_malloc(segsz);
if (!strings) {
goto give_up;
}
if (!imgsrc_read(strings, shdr[str_idx].sh_offset, segsz, src, NULL)) {
goto give_up;
}
segsz = shdr[sym_idx].sh_size;
if (segsz / sizeof(struct elf_sym) > INT_MAX) {
/*
* Implausibly large symbol table: give up rather than ploughing
* on with the number of symbols calculation overflowing.
*/
goto give_up;
}
nsyms = segsz / sizeof(struct elf_sym);
syms = g_try_malloc(segsz);
if (!syms) {
goto give_up;
}
if (!imgsrc_read(syms, shdr[sym_idx].sh_offset, segsz, src, NULL)) {
goto give_up;
}
for (i = 0; i < nsyms; ) {
bswap_sym(syms + i);
/* Throw away entries which we do not need. */
if (syms[i].st_shndx == SHN_UNDEF
|| syms[i].st_shndx >= SHN_LORESERVE
|| ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) {
if (i < --nsyms) {
syms[i] = syms[nsyms];
}
} else {
#if defined(TARGET_ARM) || defined (TARGET_MIPS)
/* The bottom address bit marks a Thumb or MIPS16 symbol. */
syms[i].st_value &= ~(target_ulong)1;
#endif
syms[i].st_value += load_bias;
i++;
}
}
/* No "useful" symbol. */
if (nsyms == 0) {
goto give_up;
}
/*
* Attempt to free the storage associated with the local symbols
* that we threw away. Whether or not this has any effect on the
* memory allocation depends on the malloc implementation and how
* many symbols we managed to discard.
*/
new_syms = g_try_renew(struct elf_sym, syms, nsyms);
if (new_syms == NULL) {
goto give_up;
}
syms = new_syms;
qsort(syms, nsyms, sizeof(*syms), symcmp);
{
struct syminfo *s = g_new(struct syminfo, 1);
s->disas_strtab = strings;
s->disas_num_syms = nsyms;
#if ELF_CLASS == ELFCLASS32
s->disas_symtab.elf32 = syms;
#else
s->disas_symtab.elf64 = syms;
#endif
s->lookup_symbol = lookup_symbolxx;
s->next = syminfos;
syminfos = s;
}
return;
give_up:
g_free(strings);
g_free(syms);
}
uint32_t get_elf_eflags(int fd)
{
struct elfhdr ehdr;
off_t offset;
int ret;
/* Read ELF header */
offset = lseek(fd, 0, SEEK_SET);
if (offset == (off_t) -1) {
return 0;
}
ret = read(fd, &ehdr, sizeof(ehdr));
if (ret < sizeof(ehdr)) {
return 0;
}
offset = lseek(fd, offset, SEEK_SET);
if (offset == (off_t) -1) {
return 0;
}
/* Check ELF signature */
if (!elf_check_ident(&ehdr)) {
return 0;
}
/* check header */
bswap_ehdr(&ehdr);
if (!elf_check_ehdr(&ehdr)) {
return 0;
}
/* return architecture id */
return ehdr.e_flags;
}
int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
{
/*
* We need a copy of the elf header for passing to create_elf_tables.
* We will have overwritten the original when we re-use bprm->buf
* while loading the interpreter. Allocate the storage for this now
* and let elf_load_image do any swapping that may be required.
*/
struct elfhdr ehdr;
struct image_info interp_info, vdso_info;
char *elf_interpreter = NULL;
char *scratch;
memset(&interp_info, 0, sizeof(interp_info));
#ifdef TARGET_MIPS
interp_info.fp_abi = MIPS_ABI_FP_UNKNOWN;
#endif
load_elf_image(bprm->filename, &bprm->src, info, &ehdr, &elf_interpreter);
/* Do this so that we can load the interpreter, if need be. We will
change some of these later */
bprm->p = setup_arg_pages(bprm, info);
scratch = g_new0(char, TARGET_PAGE_SIZE);
if (STACK_GROWS_DOWN) {
bprm->p = copy_elf_strings(1, &bprm->filename, scratch,
bprm->p, info->stack_limit);
info->file_string = bprm->p;
bprm->p = copy_elf_strings(bprm->envc, bprm->envp, scratch,
bprm->p, info->stack_limit);
info->env_strings = bprm->p;
bprm->p = copy_elf_strings(bprm->argc, bprm->argv, scratch,
bprm->p, info->stack_limit);
info->arg_strings = bprm->p;
} else {
info->arg_strings = bprm->p;
bprm->p = copy_elf_strings(bprm->argc, bprm->argv, scratch,
bprm->p, info->stack_limit);
info->env_strings = bprm->p;
bprm->p = copy_elf_strings(bprm->envc, bprm->envp, scratch,
bprm->p, info->stack_limit);
info->file_string = bprm->p;
bprm->p = copy_elf_strings(1, &bprm->filename, scratch,
bprm->p, info->stack_limit);
}
g_free(scratch);
if (!bprm->p) {
fprintf(stderr, "%s: %s\n", bprm->filename, strerror(E2BIG));
exit(-1);
}
if (elf_interpreter) {
load_elf_interp(elf_interpreter, &interp_info, bprm->buf);
/*
* While unusual because of ELF_ET_DYN_BASE, if we are unlucky
* with the mappings the interpreter can be loaded above but
* near the main executable, which can leave very little room
* for the heap.
* If the current brk has less than 16MB, use the end of the
* interpreter.
*/
if (interp_info.brk > info->brk &&
interp_info.load_bias - info->brk < 16 * MiB) {
info->brk = interp_info.brk;
}
/* If the program interpreter is one of these two, then assume
an iBCS2 image. Otherwise assume a native linux image. */
if (strcmp(elf_interpreter, "/usr/lib/libc.so.1") == 0
|| strcmp(elf_interpreter, "/usr/lib/ld.so.1") == 0) {
info->personality = PER_SVR4;
/* Why this, you ask??? Well SVr4 maps page 0 as read-only,
and some applications "depend" upon this behavior. Since
we do not have the power to recompile these, we emulate
the SVr4 behavior. Sigh. */
target_mmap(0, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC,
MAP_FIXED_NOREPLACE | MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
}
#ifdef TARGET_MIPS
info->interp_fp_abi = interp_info.fp_abi;
#endif
}
/*
* Load a vdso if available, which will amongst other things contain the
* signal trampolines. Otherwise, allocate a separate page for them.
*/
const VdsoImageInfo *vdso = get_vdso_image_info(info->elf_flags);
if (vdso) {
load_elf_vdso(&vdso_info, vdso);
info->vdso = vdso_info.load_bias;
} else if (TARGET_ARCH_HAS_SIGTRAMP_PAGE) {
abi_long tramp_page = target_mmap(0, TARGET_PAGE_SIZE,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON, -1, 0);
if (tramp_page == -1) {
return -errno;
}
setup_sigtramp(tramp_page);
target_mprotect(tramp_page, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC);
vdso_sigreturn_region_start = tramp_page;
vdso_sigreturn_region_end = tramp_page + TARGET_PAGE_SIZE;
}
bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &ehdr, info,
elf_interpreter ? &interp_info : NULL,
vdso ? &vdso_info : NULL);
info->start_stack = bprm->p;
/* If we have an interpreter, set that as the program's entry point.
Copy the load_bias as well, to help PPC64 interpret the entry
point as a function descriptor. Do this after creating elf tables
so that we copy the original program entry point into the AUXV. */
if (elf_interpreter) {
info->load_bias = interp_info.load_bias;
info->entry = interp_info.entry;
g_free(elf_interpreter);
}
#ifdef HAVE_ELF_CORE_DUMP
bprm->core_dump = &elf_core_dump;
#endif
return 0;
}
#ifdef HAVE_ELF_CORE_DUMP
/*
* Definitions to generate Intel SVR4-like core files.
* These mostly have the same names as the SVR4 types with "target_elf_"
* tacked on the front to prevent clashes with linux definitions,
* and the typedef forms have been avoided. This is mostly like
* the SVR4 structure, but more Linuxy, with things that Linux does
* not support and which gdb doesn't really use excluded.
*
* Fields we don't dump (their contents is zero) in linux-user qemu
* are marked with XXX.
*
* Core dump code is copied from linux kernel (fs/binfmt_elf.c).
*
* Porting ELF coredump for target is (quite) simple process. First you
* define HAVE_ELF_CORE_DUMP in target ELF code (where init_thread() for
* the target resides):
*
* #define HAVE_ELF_CORE_DUMP
*
* Next you define type of register set used for dumping:
* typedef struct target_elf_gregset_t { ... } target_elf_gregset_t;
*
* Last step is to implement target specific function that copies registers
* from given cpu into just specified register set. Prototype is:
*
* void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUArchState *env);
*
* Parameters:
* regs - copy register values into here (allocated and zeroed by caller)
* env - copy registers from here
*
* Example for ARM target is provided in this file.
*/
struct target_elf_siginfo {
abi_int si_signo; /* signal number */
abi_int si_code; /* extra code */
abi_int si_errno; /* errno */
};
struct target_elf_prstatus {
struct target_elf_siginfo pr_info; /* Info associated with signal */
abi_short pr_cursig; /* Current signal */
abi_ulong pr_sigpend; /* XXX */
abi_ulong pr_sighold; /* XXX */
target_pid_t pr_pid;
target_pid_t pr_ppid;
target_pid_t pr_pgrp;
target_pid_t pr_sid;
struct target_timeval pr_utime; /* XXX User time */
struct target_timeval pr_stime; /* XXX System time */
struct target_timeval pr_cutime; /* XXX Cumulative user time */
struct target_timeval pr_cstime; /* XXX Cumulative system time */
target_elf_gregset_t pr_reg; /* GP registers */
abi_int pr_fpvalid; /* XXX */
};
#define ELF_PRARGSZ (80) /* Number of chars for args */
struct target_elf_prpsinfo {
char pr_state; /* numeric process state */
char pr_sname; /* char for pr_state */
char pr_zomb; /* zombie */
char pr_nice; /* nice val */
abi_ulong pr_flag; /* flags */
target_uid_t pr_uid;
target_gid_t pr_gid;
target_pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid;
/* Lots missing */
char pr_fname[16] QEMU_NONSTRING; /* filename of executable */
char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
};
static void bswap_prstatus(struct target_elf_prstatus *prstatus)
{
if (!target_needs_bswap()) {
return;
}
prstatus->pr_info.si_signo = tswap32(prstatus->pr_info.si_signo);
prstatus->pr_info.si_code = tswap32(prstatus->pr_info.si_code);
prstatus->pr_info.si_errno = tswap32(prstatus->pr_info.si_errno);
prstatus->pr_cursig = tswap16(prstatus->pr_cursig);
prstatus->pr_sigpend = tswapal(prstatus->pr_sigpend);
prstatus->pr_sighold = tswapal(prstatus->pr_sighold);
prstatus->pr_pid = tswap32(prstatus->pr_pid);
prstatus->pr_ppid = tswap32(prstatus->pr_ppid);
prstatus->pr_pgrp = tswap32(prstatus->pr_pgrp);
prstatus->pr_sid = tswap32(prstatus->pr_sid);
/* cpu times are not filled, so we skip them */
/* regs should be in correct format already */
prstatus->pr_fpvalid = tswap32(prstatus->pr_fpvalid);
}
static void bswap_psinfo(struct target_elf_prpsinfo *psinfo)
{
if (!target_needs_bswap()) {
return;
}
psinfo->pr_flag = tswapal(psinfo->pr_flag);
psinfo->pr_uid = tswap16(psinfo->pr_uid);
psinfo->pr_gid = tswap16(psinfo->pr_gid);
psinfo->pr_pid = tswap32(psinfo->pr_pid);
psinfo->pr_ppid = tswap32(psinfo->pr_ppid);
psinfo->pr_pgrp = tswap32(psinfo->pr_pgrp);
psinfo->pr_sid = tswap32(psinfo->pr_sid);
}
static void bswap_note(struct elf_note *en)
{
if (!target_needs_bswap()) {
return;
}
bswap32s(&en->n_namesz);
bswap32s(&en->n_descsz);
bswap32s(&en->n_type);
}
/*
* Calculate file (dump) size of given memory region.
*/
static size_t vma_dump_size(vaddr start, vaddr end, int flags)
{
/* The area must be readable and dumpable. */
if (!(flags & PAGE_READ) || (flags & PAGE_DONTDUMP)) {
return 0;
}
/*
* Usually we don't dump executable pages as they contain
* non-writable code that debugger can read directly from
* target library etc. If there is no elf header, we dump it.
*/
if (!(flags & PAGE_WRITE_ORG) &&
(flags & PAGE_EXEC) &&
memcmp(g2h_untagged(start), ELFMAG, SELFMAG) == 0) {
return 0;
}
return end - start;
}
static size_t size_note(const char *name, size_t datasz)
{
size_t namesz = strlen(name) + 1;
namesz = ROUND_UP(namesz, 4);
datasz = ROUND_UP(datasz, 4);
return sizeof(struct elf_note) + namesz + datasz;
}
static void *fill_note(void **pptr, int type, const char *name, size_t datasz)
{
void *ptr = *pptr;
struct elf_note *n = ptr;
size_t namesz = strlen(name) + 1;
n->n_namesz = namesz;
n->n_descsz = datasz;
n->n_type = type;
bswap_note(n);
ptr += sizeof(*n);
memcpy(ptr, name, namesz);
namesz = ROUND_UP(namesz, 4);
datasz = ROUND_UP(datasz, 4);
*pptr = ptr + namesz + datasz;
return ptr + namesz;
}
static void fill_elf_header(struct elfhdr *elf, int segs, uint16_t machine,
uint32_t flags)
{
memcpy(elf->e_ident, ELFMAG, SELFMAG);
elf->e_ident[EI_CLASS] = ELF_CLASS;
elf->e_ident[EI_DATA] = ELF_DATA;
elf->e_ident[EI_VERSION] = EV_CURRENT;
elf->e_ident[EI_OSABI] = ELF_OSABI;
elf->e_type = ET_CORE;
elf->e_machine = machine;
elf->e_version = EV_CURRENT;
elf->e_phoff = sizeof(struct elfhdr);
elf->e_flags = flags;
elf->e_ehsize = sizeof(struct elfhdr);
elf->e_phentsize = sizeof(struct elf_phdr);
elf->e_phnum = segs;
bswap_ehdr(elf);
}
static void fill_elf_note_phdr(struct elf_phdr *phdr, size_t sz, off_t offset)
{
phdr->p_type = PT_NOTE;
phdr->p_offset = offset;
phdr->p_filesz = sz;
bswap_phdr(phdr, 1);
}
static void fill_prstatus_note(void *data, CPUState *cpu, int signr)
{
/*
* Because note memory is only aligned to 4, and target_elf_prstatus
* may well have higher alignment requirements, fill locally and
* memcpy to the destination afterward.
*/
struct target_elf_prstatus prstatus = {
.pr_info.si_signo = signr,
.pr_cursig = signr,
.pr_pid = get_task_state(cpu)->ts_tid,
.pr_ppid = getppid(),
.pr_pgrp = getpgrp(),
.pr_sid = getsid(0),
};
elf_core_copy_regs(&prstatus.pr_reg, cpu_env(cpu));
bswap_prstatus(&prstatus);
memcpy(data, &prstatus, sizeof(prstatus));
}
static void fill_prpsinfo_note(void *data, const TaskState *ts)
{
/*
* Because note memory is only aligned to 4, and target_elf_prpsinfo
* may well have higher alignment requirements, fill locally and
* memcpy to the destination afterward.
*/
struct target_elf_prpsinfo psinfo = {
.pr_pid = getpid(),
.pr_ppid = getppid(),
.pr_pgrp = getpgrp(),
.pr_sid = getsid(0),
.pr_uid = getuid(),
.pr_gid = getgid(),
};
char *base_filename;
size_t len;
len = ts->info->env_strings - ts->info->arg_strings;
len = MIN(len, ELF_PRARGSZ);
memcpy(&psinfo.pr_psargs, g2h_untagged(ts->info->arg_strings), len);
for (size_t i = 0; i < len; i++) {
if (psinfo.pr_psargs[i] == 0) {
psinfo.pr_psargs[i] = ' ';
}
}
base_filename = g_path_get_basename(ts->bprm->filename);
/*
* Using strncpy here is fine: at max-length,
* this field is not NUL-terminated.
*/
strncpy(psinfo.pr_fname, base_filename, sizeof(psinfo.pr_fname));
g_free(base_filename);
bswap_psinfo(&psinfo);
memcpy(data, &psinfo, sizeof(psinfo));
}
static void fill_auxv_note(void *data, const TaskState *ts)
{
memcpy(data, g2h_untagged(ts->info->saved_auxv), ts->info->auxv_len);
}
/*
* Constructs name of coredump file. We have following convention
* for the name:
* qemu_<basename-of-target-binary>_<date>-<time>_<pid>.core
*
* Returns the filename
*/
static char *core_dump_filename(const TaskState *ts)
{
g_autoptr(GDateTime) now = g_date_time_new_now_local();
g_autofree char *nowstr = g_date_time_format(now, "%Y%m%d-%H%M%S");
g_autofree char *base_filename = g_path_get_basename(ts->bprm->filename);
return g_strdup_printf("qemu_%s_%s_%d.core",
base_filename, nowstr, (int)getpid());
}
static int dump_write(int fd, const void *ptr, size_t size)
{
const char *bufp = (const char *)ptr;
ssize_t bytes_written, bytes_left;
bytes_written = 0;
bytes_left = size;
/*
* In normal conditions, single write(2) should do but
* in case of socket etc. this mechanism is more portable.
*/
do {
bytes_written = write(fd, bufp, bytes_left);
if (bytes_written < 0) {
if (errno == EINTR)
continue;
return (-1);
} else if (bytes_written == 0) { /* eof */
return (-1);
}
bufp += bytes_written;
bytes_left -= bytes_written;
} while (bytes_left > 0);
return (0);
}
static int wmr_page_unprotect_regions(void *opaque, vaddr start,
vaddr end, int flags)
{
if ((flags & (PAGE_WRITE | PAGE_WRITE_ORG)) == PAGE_WRITE_ORG) {
size_t step = MAX(TARGET_PAGE_SIZE, qemu_real_host_page_size());
while (1) {
page_unprotect(NULL, start, 0);
if (end - start <= step) {
break;
}
start += step;
}
}
return 0;
}
typedef struct {
unsigned count;
size_t size;
} CountAndSizeRegions;
static int wmr_count_and_size_regions(void *opaque, vaddr start,
vaddr end, int flags)
{
CountAndSizeRegions *css = opaque;
css->count++;
css->size += vma_dump_size(start, end, flags);
return 0;
}
typedef struct {
struct elf_phdr *phdr;
off_t offset;
} FillRegionPhdr;
static int wmr_fill_region_phdr(void *opaque, vaddr start,
vaddr end, int flags)
{
FillRegionPhdr *d = opaque;
struct elf_phdr *phdr = d->phdr;
phdr->p_type = PT_LOAD;
phdr->p_vaddr = start;
phdr->p_paddr = 0;
phdr->p_filesz = vma_dump_size(start, end, flags);
phdr->p_offset = d->offset;
d->offset += phdr->p_filesz;
phdr->p_memsz = end - start;
phdr->p_flags = (flags & PAGE_READ ? PF_R : 0)
| (flags & PAGE_WRITE_ORG ? PF_W : 0)
| (flags & PAGE_EXEC ? PF_X : 0);
phdr->p_align = TARGET_PAGE_SIZE;
bswap_phdr(phdr, 1);
d->phdr = phdr + 1;
return 0;
}
static int wmr_write_region(void *opaque, vaddr start,
vaddr end, int flags)
{
int fd = *(int *)opaque;
size_t size = vma_dump_size(start, end, flags);
if (!size) {
return 0;
}
return dump_write(fd, g2h_untagged(start), size);
}
/*
* Write out ELF coredump.
*
* See documentation of ELF object file format in:
* http://www.caldera.com/developers/devspecs/gabi41.pdf
*
* Coredump format in linux is following:
*
* 0 +----------------------+ \
* | ELF header | ET_CORE |
* +----------------------+ |
* | ELF program headers | |--- headers
* | - NOTE section | |
* | - PT_LOAD sections | |
* +----------------------+ /
* | NOTEs: |
* | - NT_PRSTATUS |
* | - NT_PRSINFO |
* | - NT_AUXV |
* +----------------------+ <-- aligned to target page
* | Process memory dump |
* : :
* . .
* : :
* | |
* +----------------------+
*
* NT_PRSTATUS -> struct elf_prstatus (per thread)
* NT_PRSINFO -> struct elf_prpsinfo
* NT_AUXV is array of { type, value } pairs (see fill_auxv_note()).
*
* Format follows System V format as close as possible. Current
* version limitations are as follows:
* - no floating point registers are dumped
*
* Function returns 0 in case of success, negative errno otherwise.
*
* TODO: make this work also during runtime: it should be
* possible to force coredump from running process and then
* continue processing. For example qemu could set up SIGUSR2
* handler (provided that target process haven't registered
* handler for that) that does the dump when signal is received.
*/
#ifdef TARGET_SPARC
#include "sparc/cpu_loop.h"
#endif
static int elf_core_dump(int signr, const CPUArchState *env)
{
const CPUState *cpu = env_cpu_const(env);
const TaskState *ts = (const TaskState *)get_task_state((CPUState *)cpu);
struct rlimit dumpsize;
CountAndSizeRegions css;
off_t offset, note_offset, data_offset;
size_t note_size;
int cpus, ret;
int fd = -1;
CPUState *cpu_iter;
if (prctl(PR_GET_DUMPABLE) == 0) {
return 0;
}
if (getrlimit(RLIMIT_CORE, &dumpsize) < 0 || dumpsize.rlim_cur == 0) {
return 0;
}
cpu_list_lock();
mmap_lock();
#ifdef TARGET_SPARC
CPU_FOREACH(cpu_iter) {
flush_windows(cpu_env(cpu_iter));
}
#endif
/* By unprotecting, we merge vmas that might be split. */
walk_memory_regions(NULL, wmr_page_unprotect_regions);
/*
* Walk through target process memory mappings and
* set up structure containing this information.
*/
memset(&css, 0, sizeof(css));
walk_memory_regions(&css, wmr_count_and_size_regions);
cpus = 0;
CPU_FOREACH(cpu_iter) {
cpus++;
}
offset = sizeof(struct elfhdr);
offset += (css.count + 1) * sizeof(struct elf_phdr);
note_offset = offset;
offset += size_note("CORE", ts->info->auxv_len);
offset += size_note("CORE", sizeof(struct target_elf_prpsinfo));
offset += size_note("CORE", sizeof(struct target_elf_prstatus)) * cpus;
note_size = offset - note_offset;
data_offset = TARGET_PAGE_ALIGN(offset);
/* Do not dump if the corefile size exceeds the limit. */
if (dumpsize.rlim_cur != RLIM_INFINITY
&& dumpsize.rlim_cur < data_offset + css.size) {
errno = 0;
goto out;
}
{
g_autofree char *corefile = core_dump_filename(ts);
fd = open(corefile, O_WRONLY | O_CREAT | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
}
if (fd < 0) {
goto out;
}
/*
* There is a fair amount of alignment padding within the notes
* as well as preceeding the process memory. Allocate a zeroed
* block to hold it all. Write all of the headers directly into
* this buffer and then write it out as a block.
*/
{
g_autofree void *header = g_malloc0(data_offset);
FillRegionPhdr frp;
void *hptr, *dptr;
/* Create elf file header. */
hptr = header;
fill_elf_header(hptr, css.count + 1, ELF_MACHINE, 0);
hptr += sizeof(struct elfhdr);
/* Create elf program headers. */
fill_elf_note_phdr(hptr, note_size, note_offset);
hptr += sizeof(struct elf_phdr);
frp.phdr = hptr;
frp.offset = data_offset;
walk_memory_regions(&frp, wmr_fill_region_phdr);
hptr = frp.phdr;
/* Create the notes. */
dptr = fill_note(&hptr, NT_AUXV, "CORE", ts->info->auxv_len);
fill_auxv_note(dptr, ts);
dptr = fill_note(&hptr, NT_PRPSINFO, "CORE",
sizeof(struct target_elf_prpsinfo));
fill_prpsinfo_note(dptr, ts);
CPU_FOREACH(cpu_iter) {
dptr = fill_note(&hptr, NT_PRSTATUS, "CORE",
sizeof(struct target_elf_prstatus));
fill_prstatus_note(dptr, cpu_iter, cpu_iter == cpu ? signr : 0);
}
if (dump_write(fd, header, data_offset) < 0) {
goto out;
}
}
/*
* Finally write process memory into the corefile as well.
*/
if (walk_memory_regions(&fd, wmr_write_region) < 0) {
goto out;
}
errno = 0;
out:
ret = -errno;
mmap_unlock();
cpu_list_unlock();
if (fd >= 0) {
close(fd);
}
return ret;
}
#endif /* HAVE_ELF_CORE_DUMP */
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