linux-user: Load vdso image if available
The vdso image will be pre-processed into a C data array, with a simple list of relocations to perform, and identifying the location of signal trampolines. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@ -33,6 +33,19 @@
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#undef ELF_ARCH
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#undef ELF_ARCH
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#endif
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#endif
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#ifndef TARGET_ARCH_HAS_SIGTRAMP_PAGE
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#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
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#endif
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typedef struct {
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const uint8_t *image;
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const uint32_t *relocs;
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unsigned image_size;
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unsigned reloc_count;
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unsigned sigreturn_ofs;
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unsigned rt_sigreturn_ofs;
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} VdsoImageInfo;
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#define ELF_OSABI ELFOSABI_SYSV
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#define ELF_OSABI ELFOSABI_SYSV
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/* from personality.h */
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/* from personality.h */
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@ -2471,7 +2484,8 @@ static abi_ulong loader_build_fdpic_loadmap(struct image_info *info, abi_ulong s
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static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
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static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
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struct elfhdr *exec,
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struct elfhdr *exec,
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struct image_info *info,
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struct image_info *info,
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struct image_info *interp_info)
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struct image_info *interp_info,
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struct image_info *vdso_info)
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{
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{
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abi_ulong sp;
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abi_ulong sp;
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abi_ulong u_argc, u_argv, u_envp, u_auxv;
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abi_ulong u_argc, u_argv, u_envp, u_auxv;
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@ -2559,10 +2573,15 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
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}
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}
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size = (DLINFO_ITEMS + 1) * 2;
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size = (DLINFO_ITEMS + 1) * 2;
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if (k_base_platform)
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if (k_base_platform) {
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size += 2;
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size += 2;
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if (k_platform)
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}
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if (k_platform) {
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size += 2;
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size += 2;
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}
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if (vdso_info) {
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size += 2;
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}
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#ifdef DLINFO_ARCH_ITEMS
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#ifdef DLINFO_ARCH_ITEMS
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size += DLINFO_ARCH_ITEMS * 2;
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size += DLINFO_ARCH_ITEMS * 2;
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#endif
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#endif
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@ -2644,6 +2663,9 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
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if (u_platform) {
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if (u_platform) {
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NEW_AUX_ENT(AT_PLATFORM, u_platform);
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NEW_AUX_ENT(AT_PLATFORM, u_platform);
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}
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}
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if (vdso_info) {
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NEW_AUX_ENT(AT_SYSINFO_EHDR, vdso_info->load_addr);
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}
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NEW_AUX_ENT (AT_NULL, 0);
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NEW_AUX_ENT (AT_NULL, 0);
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#undef NEW_AUX_ENT
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#undef NEW_AUX_ENT
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@ -3521,6 +3543,52 @@ static void load_elf_interp(const char *filename, struct image_info *info,
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load_elf_image(filename, &src, info, &ehdr, NULL);
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load_elf_image(filename, &src, info, &ehdr, NULL);
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}
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}
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#ifdef VDSO_HEADER
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#include VDSO_HEADER
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#define vdso_image_info() &vdso_image_info
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#else
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#define vdso_image_info() NULL
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#endif
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static void load_elf_vdso(struct image_info *info, const VdsoImageInfo *vdso)
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{
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ImageSource src;
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struct elfhdr ehdr;
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abi_ulong load_bias, load_addr;
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src.fd = -1;
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src.cache = vdso->image;
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src.cache_size = vdso->image_size;
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load_elf_image("<internal-vdso>", &src, info, &ehdr, NULL);
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load_addr = info->load_addr;
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load_bias = info->load_bias;
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/*
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* We need to relocate the VDSO image. The one built into the kernel
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* is built for a fixed address. The one built for QEMU is not, since
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* that requires close control of the guest address space.
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* We pre-processed the image to locate all of the addresses that need
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* to be updated.
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*/
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for (unsigned i = 0, n = vdso->reloc_count; i < n; i++) {
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abi_ulong *addr = g2h_untagged(load_addr + vdso->relocs[i]);
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*addr = tswapal(tswapal(*addr) + load_bias);
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}
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/* Install signal trampolines, if present. */
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if (vdso->sigreturn_ofs) {
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default_sigreturn = load_addr + vdso->sigreturn_ofs;
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}
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if (vdso->rt_sigreturn_ofs) {
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default_rt_sigreturn = load_addr + vdso->rt_sigreturn_ofs;
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}
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/* Remove write from VDSO segment. */
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target_mprotect(info->start_data, info->end_data - info->start_data,
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PROT_READ | PROT_EXEC);
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}
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static int symfind(const void *s0, const void *s1)
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static int symfind(const void *s0, const void *s1)
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{
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{
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struct elf_sym *sym = (struct elf_sym *)s1;
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struct elf_sym *sym = (struct elf_sym *)s1;
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@ -3726,7 +3794,7 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
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* and let elf_load_image do any swapping that may be required.
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* and let elf_load_image do any swapping that may be required.
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*/
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*/
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struct elfhdr ehdr;
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struct elfhdr ehdr;
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struct image_info interp_info;
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struct image_info interp_info, vdso_info;
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char *elf_interpreter = NULL;
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char *elf_interpreter = NULL;
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char *scratch;
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char *scratch;
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@ -3807,10 +3875,13 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
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}
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}
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/*
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/*
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* TODO: load a vdso, which would also contain the signal trampolines.
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* Load a vdso if available, which will amongst other things contain the
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* Otherwise, allocate a private page to hold them.
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* signal trampolines. Otherwise, allocate a separate page for them.
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*/
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*/
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if (TARGET_ARCH_HAS_SIGTRAMP_PAGE) {
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const VdsoImageInfo *vdso = vdso_image_info();
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if (vdso) {
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load_elf_vdso(&vdso_info, vdso);
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} else if (TARGET_ARCH_HAS_SIGTRAMP_PAGE) {
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abi_long tramp_page = target_mmap(0, TARGET_PAGE_SIZE,
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abi_long tramp_page = target_mmap(0, TARGET_PAGE_SIZE,
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PROT_READ | PROT_WRITE,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANON, -1, 0);
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MAP_PRIVATE | MAP_ANON, -1, 0);
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@ -3822,8 +3893,9 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
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target_mprotect(tramp_page, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC);
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target_mprotect(tramp_page, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC);
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}
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}
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bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &ehdr,
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bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &ehdr, info,
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info, (elf_interpreter ? &interp_info : NULL));
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elf_interpreter ? &interp_info : NULL,
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vdso ? &vdso_info : NULL);
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info->start_stack = bprm->p;
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info->start_stack = bprm->p;
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/* If we have an interpreter, set that as the program's entry point.
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/* If we have an interpreter, set that as the program's entry point.
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