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-rw-r--r--mozglue/linker/CustomElf.cpp674
1 files changed, 674 insertions, 0 deletions
diff --git a/mozglue/linker/CustomElf.cpp b/mozglue/linker/CustomElf.cpp
new file mode 100644
index 0000000000..fa7dffa395
--- /dev/null
+++ b/mozglue/linker/CustomElf.cpp
@@ -0,0 +1,674 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <cstring>
+#include <sys/mman.h>
+#include <vector>
+#include <dlfcn.h>
+#include <signal.h>
+#include <string.h>
+#include "CustomElf.h"
+#include "BaseElf.h"
+#include "Mappable.h"
+#include "Logging.h"
+#include "mozilla/IntegerPrintfMacros.h"
+
+using namespace Elf;
+
+/* TODO: Fill ElfLoader::Singleton.lastError on errors. */
+
+const Ehdr* Ehdr::validate(const void* buf) {
+ if (!buf || buf == MAP_FAILED) return nullptr;
+
+ const Ehdr* ehdr = reinterpret_cast<const Ehdr*>(buf);
+
+ /* Only support ELF executables or libraries for the host system */
+ if (memcmp(ELFMAG, &ehdr->e_ident, SELFMAG) ||
+ ehdr->e_ident[EI_CLASS] != ELFCLASS ||
+ ehdr->e_ident[EI_DATA] != ELFDATA || ehdr->e_ident[EI_VERSION] != 1 ||
+ (ehdr->e_ident[EI_OSABI] != ELFOSABI &&
+ ehdr->e_ident[EI_OSABI] != ELFOSABI_NONE) ||
+#ifdef EI_ABIVERSION
+ ehdr->e_ident[EI_ABIVERSION] != ELFABIVERSION ||
+#endif
+ (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) ||
+ ehdr->e_machine != ELFMACHINE || ehdr->e_version != 1 ||
+ ehdr->e_phentsize != sizeof(Phdr))
+ return nullptr;
+
+ return ehdr;
+}
+
+namespace {
+
+void debug_phdr(const char* type, const Phdr* phdr) {
+ DEBUG_LOG("%s @0x%08" PRIxPTR
+ " ("
+ "filesz: 0x%08" PRIxPTR
+ ", "
+ "memsz: 0x%08" PRIxPTR
+ ", "
+ "offset: 0x%08" PRIxPTR
+ ", "
+ "flags: %c%c%c)",
+ type, uintptr_t(phdr->p_vaddr), uintptr_t(phdr->p_filesz),
+ uintptr_t(phdr->p_memsz), uintptr_t(phdr->p_offset),
+ phdr->p_flags & PF_R ? 'r' : '-', phdr->p_flags & PF_W ? 'w' : '-',
+ phdr->p_flags & PF_X ? 'x' : '-');
+}
+
+static int p_flags_to_mprot(Word flags) {
+ return ((flags & PF_X) ? PROT_EXEC : 0) | ((flags & PF_W) ? PROT_WRITE : 0) |
+ ((flags & PF_R) ? PROT_READ : 0);
+}
+
+} /* anonymous namespace */
+
+/**
+ * RAII wrapper for a mapping of the first page off a Mappable object.
+ * This calls Mappable::munmap instead of system munmap.
+ */
+class Mappable1stPagePtr : public GenericMappedPtr<Mappable1stPagePtr> {
+ public:
+ explicit Mappable1stPagePtr(Mappable* mappable)
+ : GenericMappedPtr<Mappable1stPagePtr>(
+ mappable->mmap(nullptr, PageSize(), PROT_READ, MAP_PRIVATE, 0)),
+ mappable(mappable) {}
+
+ private:
+ friend class GenericMappedPtr<Mappable1stPagePtr>;
+ void munmap(void* buf, size_t length) { mappable->munmap(buf, length); }
+
+ RefPtr<Mappable> mappable;
+};
+
+already_AddRefed<LibHandle> CustomElf::Load(Mappable* mappable,
+ const char* path, int flags) {
+ DEBUG_LOG("CustomElf::Load(\"%s\", 0x%x) = ...", path, flags);
+ if (!mappable) return nullptr;
+ /* Keeping a RefPtr of the CustomElf is going to free the appropriate
+ * resources when returning nullptr */
+ RefPtr<CustomElf> elf = new CustomElf(mappable, path);
+ /* Map the first page of the Elf object to access Elf and program headers */
+ Mappable1stPagePtr ehdr_raw(mappable);
+ if (ehdr_raw == MAP_FAILED) return nullptr;
+
+ const Ehdr* ehdr = Ehdr::validate(ehdr_raw);
+ if (!ehdr) return nullptr;
+
+ /* Scan Elf Program Headers and gather some information about them */
+ std::vector<const Phdr*> pt_loads;
+ Addr min_vaddr = (Addr)-1; // We want to find the lowest and biggest
+ Addr max_vaddr = 0; // virtual address used by this Elf.
+ const Phdr* dyn = nullptr;
+
+ const Phdr* first_phdr = reinterpret_cast<const Phdr*>(
+ reinterpret_cast<const char*>(ehdr) + ehdr->e_phoff);
+ const Phdr* end_phdr = &first_phdr[ehdr->e_phnum];
+#ifdef __ARM_EABI__
+ const Phdr* arm_exidx_phdr = nullptr;
+#endif
+
+ for (const Phdr* phdr = first_phdr; phdr < end_phdr; phdr++) {
+ switch (phdr->p_type) {
+ case PT_LOAD:
+ debug_phdr("PT_LOAD", phdr);
+ pt_loads.push_back(phdr);
+ if (phdr->p_vaddr < min_vaddr) min_vaddr = phdr->p_vaddr;
+ if (max_vaddr < phdr->p_vaddr + phdr->p_memsz)
+ max_vaddr = phdr->p_vaddr + phdr->p_memsz;
+ break;
+ case PT_DYNAMIC:
+ debug_phdr("PT_DYNAMIC", phdr);
+ if (!dyn) {
+ dyn = phdr;
+ } else {
+ ERROR("%s: Multiple PT_DYNAMIC segments detected", elf->GetPath());
+ return nullptr;
+ }
+ break;
+ case PT_TLS:
+ debug_phdr("PT_TLS", phdr);
+ if (phdr->p_memsz) {
+ ERROR("%s: TLS is not supported", elf->GetPath());
+ return nullptr;
+ }
+ break;
+ case PT_GNU_STACK:
+ debug_phdr("PT_GNU_STACK", phdr);
+// Skip on Android until bug 706116 is fixed
+#ifndef ANDROID
+ if (phdr->p_flags & PF_X) {
+ ERROR("%s: Executable stack is not supported", elf->GetPath());
+ return nullptr;
+ }
+#endif
+ break;
+#ifdef __ARM_EABI__
+ case PT_ARM_EXIDX:
+ /* We cannot initialize arm_exidx here
+ because we don't have a base yet */
+ arm_exidx_phdr = phdr;
+ break;
+#endif
+ default:
+ DEBUG_LOG("%s: Program header type #%d not handled", elf->GetPath(),
+ phdr->p_type);
+ }
+ }
+
+ if (min_vaddr != 0) {
+ ERROR("%s: Unsupported minimal virtual address: 0x%08" PRIxPTR,
+ elf->GetPath(), uintptr_t(min_vaddr));
+ return nullptr;
+ }
+ if (!dyn) {
+ ERROR("%s: No PT_DYNAMIC segment found", elf->GetPath());
+ return nullptr;
+ }
+
+ /* Reserve enough memory to map the complete virtual address space for this
+ * library.
+ * As we are using the base address from here to mmap something else with
+ * MAP_FIXED | MAP_SHARED, we need to make sure these mmaps will work. For
+ * instance, on armv6, MAP_SHARED mappings require a 16k alignment, but mmap
+ * MAP_PRIVATE only returns a 4k aligned address. So we first get a base
+ * address with MAP_SHARED, which guarantees the kernel returns an address
+ * that we'll be able to use with MAP_FIXED, and then remap MAP_PRIVATE at
+ * the same address, because of some bad side effects of keeping it as
+ * MAP_SHARED. */
+ elf->base.Assign(MemoryRange::mmap(nullptr, max_vaddr, PROT_NONE,
+ MAP_SHARED | MAP_ANONYMOUS, -1, 0));
+ if ((elf->base == MAP_FAILED) ||
+ (mmap(elf->base, max_vaddr, PROT_NONE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0) != elf->base)) {
+ ERROR("%s: Failed to mmap", elf->GetPath());
+ return nullptr;
+ }
+
+ /* Load and initialize library */
+ for (std::vector<const Phdr*>::iterator it = pt_loads.begin();
+ it < pt_loads.end(); ++it)
+ if (!elf->LoadSegment(*it)) return nullptr;
+
+ /* We're not going to mmap anymore */
+ mappable->finalize();
+
+ elf->l_addr = elf->base;
+ elf->l_name = elf->GetPath();
+ elf->l_ld = elf->GetPtr<Dyn>(dyn->p_vaddr);
+ ElfLoader::Singleton.Register(elf);
+
+ if (!elf->InitDyn(dyn)) return nullptr;
+
+ if (elf->has_text_relocs) {
+ for (std::vector<const Phdr*>::iterator it = pt_loads.begin();
+ it < pt_loads.end(); ++it)
+ mprotect(PageAlignedPtr(elf->GetPtr((*it)->p_vaddr)),
+ PageAlignedEndPtr((*it)->p_memsz),
+ p_flags_to_mprot((*it)->p_flags) | PROT_WRITE);
+ }
+
+ if (!elf->Relocate() || !elf->RelocateJumps()) return nullptr;
+
+ if (elf->has_text_relocs) {
+ for (std::vector<const Phdr*>::iterator it = pt_loads.begin();
+ it < pt_loads.end(); ++it)
+ mprotect(PageAlignedPtr(elf->GetPtr((*it)->p_vaddr)),
+ PageAlignedEndPtr((*it)->p_memsz),
+ p_flags_to_mprot((*it)->p_flags));
+ }
+
+ if (!elf->CallInit()) return nullptr;
+
+#ifdef __ARM_EABI__
+ if (arm_exidx_phdr)
+ elf->arm_exidx.InitSize(elf->GetPtr(arm_exidx_phdr->p_vaddr),
+ arm_exidx_phdr->p_memsz);
+#endif
+
+ DEBUG_LOG("CustomElf::Load(\"%s\", 0x%x) = %p", path, flags,
+ static_cast<void*>(elf));
+ return elf.forget();
+}
+
+CustomElf::~CustomElf() {
+ DEBUG_LOG("CustomElf::~CustomElf(%p [\"%s\"])", reinterpret_cast<void*>(this),
+ GetPath());
+ CallFini();
+ /* Normally, __cxa_finalize is called by the .fini function. However,
+ * Android NDK before r6b doesn't do that. Our wrapped cxa_finalize only
+ * calls destructors once, so call it in all cases. */
+ ElfLoader::__wrap_cxa_finalize(this);
+ ElfLoader::Singleton.Forget(this);
+}
+
+void* CustomElf::GetSymbolPtrInDeps(const char* symbol) const {
+ /* Resolve dlopen and related functions to point to ours */
+ if (symbol[0] == 'd' && symbol[1] == 'l') {
+ if (strcmp(symbol + 2, "open") == 0) return FunctionPtr(__wrap_dlopen);
+ if (strcmp(symbol + 2, "error") == 0) return FunctionPtr(__wrap_dlerror);
+ if (strcmp(symbol + 2, "close") == 0) return FunctionPtr(__wrap_dlclose);
+ if (strcmp(symbol + 2, "sym") == 0) return FunctionPtr(__wrap_dlsym);
+ if (strcmp(symbol + 2, "addr") == 0) return FunctionPtr(__wrap_dladdr);
+ if (strcmp(symbol + 2, "_iterate_phdr") == 0)
+ return FunctionPtr(__wrap_dl_iterate_phdr);
+ } else if (symbol[0] == '_' && symbol[1] == '_') {
+ /* Resolve a few C++ ABI specific functions to point to ours */
+#ifdef __ARM_EABI__
+ if (strcmp(symbol + 2, "aeabi_atexit") == 0)
+ return FunctionPtr(&ElfLoader::__wrap_aeabi_atexit);
+#else
+ if (strcmp(symbol + 2, "cxa_atexit") == 0)
+ return FunctionPtr(&ElfLoader::__wrap_cxa_atexit);
+#endif
+ if (strcmp(symbol + 2, "cxa_finalize") == 0)
+ return FunctionPtr(&ElfLoader::__wrap_cxa_finalize);
+ if (strcmp(symbol + 2, "dso_handle") == 0)
+ return const_cast<CustomElf*>(this);
+#ifdef __ARM_EABI__
+ if (strcmp(symbol + 2, "gnu_Unwind_Find_exidx") == 0)
+ return FunctionPtr(__wrap___gnu_Unwind_Find_exidx);
+#endif
+ } else if (symbol[0] == 's' && symbol[1] == 'i') {
+ if (strcmp(symbol + 2, "gnal") == 0) return FunctionPtr(signal);
+ if (strcmp(symbol + 2, "gaction") == 0) return FunctionPtr(sigaction);
+ }
+
+ void* sym;
+
+ unsigned long hash = Hash(symbol);
+
+ /* self_elf should never be NULL, but better safe than sorry. */
+ if (ElfLoader::Singleton.self_elf) {
+ /* We consider the library containing this code a permanent LD_PRELOAD,
+ * so, check if the symbol exists here first. */
+ sym = static_cast<BaseElf*>(ElfLoader::Singleton.self_elf.get())
+ ->GetSymbolPtr(symbol, hash);
+ if (sym) return sym;
+ }
+
+ /* Then search the symbol in our dependencies. Since we already searched in
+ * libraries the system linker loaded, skip those (on glibc systems). We
+ * also assume the symbol is to be found in one of the dependent libraries
+ * directly, not in their own dependent libraries. Building libraries with
+ * --no-allow-shlib-undefined ensures such indirect symbol dependency don't
+ * happen. */
+ for (std::vector<RefPtr<LibHandle> >::const_iterator it =
+ dependencies.begin();
+ it < dependencies.end(); ++it) {
+ /* Skip if it's the library containing this code, since we've already
+ * looked at it above. */
+ if (*it == ElfLoader::Singleton.self_elf) continue;
+ if (BaseElf* be = (*it)->AsBaseElf()) {
+ sym = be->GetSymbolPtr(symbol, hash);
+ } else {
+ sym = (*it)->GetSymbolPtr(symbol);
+ }
+ if (sym) return sym;
+ }
+ return nullptr;
+}
+
+bool CustomElf::LoadSegment(const Phdr* pt_load) const {
+ if (pt_load->p_type != PT_LOAD) {
+ DEBUG_LOG("%s: Elf::LoadSegment only takes PT_LOAD program headers",
+ GetPath());
+ return false;
+ ;
+ }
+
+ int prot = p_flags_to_mprot(pt_load->p_flags);
+
+ /* Mmap at page boundary */
+ Addr align = PageSize();
+ Addr align_offset;
+ void *mapped, *where;
+ do {
+ align_offset = pt_load->p_vaddr - AlignedPtr(pt_load->p_vaddr, align);
+ where = GetPtr(pt_load->p_vaddr - align_offset);
+ DEBUG_LOG("%s: Loading segment @%p %c%c%c", GetPath(), where,
+ prot & PROT_READ ? 'r' : '-', prot & PROT_WRITE ? 'w' : '-',
+ prot & PROT_EXEC ? 'x' : '-');
+ mapped = mappable->mmap(where, pt_load->p_filesz + align_offset, prot,
+ MAP_PRIVATE | MAP_FIXED,
+ pt_load->p_offset - align_offset);
+ if ((mapped != MAP_FAILED) || (pt_load->p_vaddr == 0) ||
+ (pt_load->p_align == align))
+ break;
+ /* The virtual address space for the library is properly aligned at
+ * 16k on ARMv6 (see CustomElf::Load), and so is the first segment
+ * (p_vaddr == 0). But subsequent segments may not be 16k aligned
+ * and fail to mmap. In such case, try to mmap again at the p_align
+ * boundary instead of page boundary. */
+ DEBUG_LOG("%s: Failed to mmap, retrying", GetPath());
+ align = pt_load->p_align;
+ } while (1);
+
+ if (mapped != where) {
+ if (mapped == MAP_FAILED) {
+ ERROR("%s: Failed to mmap", GetPath());
+ } else {
+ ERROR("%s: Didn't map at the expected location (wanted: %p, got: %p)",
+ GetPath(), where, mapped);
+ }
+ return false;
+ }
+
+ /* When p_memsz is greater than p_filesz, we need to have nulled out memory
+ * after p_filesz and before p_memsz.
+ * Above the end of the last page, and up to p_memsz, we already have nulled
+ * out memory because we mapped anonymous memory on the whole library virtual
+ * address space. We just need to adjust this anonymous memory protection
+ * flags. */
+ if (pt_load->p_memsz > pt_load->p_filesz) {
+ Addr file_end = pt_load->p_vaddr + pt_load->p_filesz;
+ Addr mem_end = pt_load->p_vaddr + pt_load->p_memsz;
+ Addr next_page = PageAlignedEndPtr(file_end);
+ if (next_page > file_end) {
+ void* ptr = GetPtr(file_end);
+ memset(ptr, 0, next_page - file_end);
+ }
+ if (mem_end > next_page) {
+ if (mprotect(GetPtr(next_page), mem_end - next_page, prot) < 0) {
+ ERROR("%s: Failed to mprotect", GetPath());
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
+namespace {
+
+void debug_dyn(const char* type, const Dyn* dyn) {
+ DEBUG_LOG("%s 0x%08" PRIxPTR, type, uintptr_t(dyn->d_un.d_val));
+}
+
+} /* anonymous namespace */
+
+bool CustomElf::InitDyn(const Phdr* pt_dyn) {
+ /* Scan PT_DYNAMIC segment and gather some information */
+ const Dyn* first_dyn = GetPtr<Dyn>(pt_dyn->p_vaddr);
+ const Dyn* end_dyn = GetPtr<Dyn>(pt_dyn->p_vaddr + pt_dyn->p_filesz);
+ std::vector<Word> dt_needed;
+ size_t symnum = 0;
+ for (const Dyn* dyn = first_dyn; dyn < end_dyn && dyn->d_tag; dyn++) {
+ switch (dyn->d_tag) {
+ case DT_NEEDED:
+ debug_dyn("DT_NEEDED", dyn);
+ dt_needed.push_back(dyn->d_un.d_val);
+ break;
+ case DT_HASH: {
+ debug_dyn("DT_HASH", dyn);
+ const Word* hash_table_header = GetPtr<Word>(dyn->d_un.d_ptr);
+ symnum = hash_table_header[1];
+ buckets.Init(&hash_table_header[2], hash_table_header[0]);
+ chains.Init(&*buckets.end());
+ } break;
+ case DT_STRTAB:
+ debug_dyn("DT_STRTAB", dyn);
+ strtab.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case DT_SYMTAB:
+ debug_dyn("DT_SYMTAB", dyn);
+ symtab.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case DT_SYMENT:
+ debug_dyn("DT_SYMENT", dyn);
+ if (dyn->d_un.d_val != sizeof(Sym)) {
+ ERROR("%s: Unsupported DT_SYMENT", GetPath());
+ return false;
+ }
+ break;
+ case DT_TEXTREL:
+ if (strcmp("libflashplayer.so", GetName()) == 0) {
+ has_text_relocs = true;
+ } else {
+ ERROR("%s: Text relocations are not supported", GetPath());
+ return false;
+ }
+ break;
+ case DT_STRSZ: /* Ignored */
+ debug_dyn("DT_STRSZ", dyn);
+ break;
+ case UNSUPPORTED_RELOC():
+ case UNSUPPORTED_RELOC(SZ):
+ case UNSUPPORTED_RELOC(ENT):
+ ERROR("%s: Unsupported relocations", GetPath());
+ return false;
+ case RELOC():
+ debug_dyn(STR_RELOC(), dyn);
+ relocations.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case RELOC(SZ):
+ debug_dyn(STR_RELOC(SZ), dyn);
+ relocations.InitSize(dyn->d_un.d_val);
+ break;
+ case RELOC(ENT):
+ debug_dyn(STR_RELOC(ENT), dyn);
+ if (dyn->d_un.d_val != sizeof(Reloc)) {
+ ERROR("%s: Unsupported DT_RELENT", GetPath());
+ return false;
+ }
+ break;
+ case DT_JMPREL:
+ debug_dyn("DT_JMPREL", dyn);
+ jumprels.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case DT_PLTRELSZ:
+ debug_dyn("DT_PLTRELSZ", dyn);
+ jumprels.InitSize(dyn->d_un.d_val);
+ break;
+ case DT_PLTGOT:
+ debug_dyn("DT_PLTGOT", dyn);
+ break;
+ case DT_INIT:
+ debug_dyn("DT_INIT", dyn);
+ init = dyn->d_un.d_ptr;
+ break;
+ case DT_INIT_ARRAY:
+ debug_dyn("DT_INIT_ARRAY", dyn);
+ init_array.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case DT_INIT_ARRAYSZ:
+ debug_dyn("DT_INIT_ARRAYSZ", dyn);
+ init_array.InitSize(dyn->d_un.d_val);
+ break;
+ case DT_FINI:
+ debug_dyn("DT_FINI", dyn);
+ fini = dyn->d_un.d_ptr;
+ break;
+ case DT_FINI_ARRAY:
+ debug_dyn("DT_FINI_ARRAY", dyn);
+ fini_array.Init(GetPtr(dyn->d_un.d_ptr));
+ break;
+ case DT_FINI_ARRAYSZ:
+ debug_dyn("DT_FINI_ARRAYSZ", dyn);
+ fini_array.InitSize(dyn->d_un.d_val);
+ break;
+ case DT_PLTREL:
+ if (dyn->d_un.d_val != RELOC()) {
+ ERROR("%s: Error: DT_PLTREL is not " STR_RELOC(), GetPath());
+ return false;
+ }
+ break;
+ case DT_FLAGS: {
+ Addr flags = dyn->d_un.d_val;
+ /* Treat as a DT_TEXTREL tag */
+ if (flags & DF_TEXTREL) {
+ if (strcmp("libflashplayer.so", GetName()) == 0) {
+ has_text_relocs = true;
+ } else {
+ ERROR("%s: Text relocations are not supported", GetPath());
+ return false;
+ }
+ }
+ /* we can treat this like having a DT_SYMBOLIC tag */
+ flags &= ~DF_SYMBOLIC;
+ if (flags)
+ WARN("%s: unhandled flags #%" PRIxPTR " not handled", GetPath(),
+ uintptr_t(flags));
+ } break;
+ case DT_SONAME: /* Should match GetName(), but doesn't matter */
+ case DT_SYMBOLIC: /* Indicates internal symbols should be looked up in
+ * the library itself first instead of the executable,
+ * which is actually what this linker does by default */
+ case RELOC(COUNT): /* Indicates how many relocations are relative, which
+ * is usually used to skip relocations on prelinked
+ * libraries. They are not supported anyways. */
+ case UNSUPPORTED_RELOC(COUNT): /* This should error out, but it doesn't
+ * really matter. */
+ case DT_FLAGS_1: /* Additional linker-internal flags that we don't care
+ * about. See DF_1_* values in src/include/elf/common.h
+ * in binutils. */
+ case DT_VERSYM: /* DT_VER* entries are used for symbol versioning, which
+ */
+ case DT_VERDEF: /* this linker doesn't support yet. */
+ case DT_VERDEFNUM:
+ case DT_VERNEED:
+ case DT_VERNEEDNUM:
+ /* Ignored */
+ break;
+ default:
+ WARN("%s: dynamic header type #%" PRIxPTR " not handled", GetPath(),
+ uintptr_t(dyn->d_tag));
+ }
+ }
+
+ if (!buckets || !symnum) {
+ ERROR("%s: Missing or broken DT_HASH", GetPath());
+ return false;
+ }
+ if (!strtab) {
+ ERROR("%s: Missing DT_STRTAB", GetPath());
+ return false;
+ }
+ if (!symtab) {
+ ERROR("%s: Missing DT_SYMTAB", GetPath());
+ return false;
+ }
+
+ /* Load dependent libraries */
+ for (size_t i = 0; i < dt_needed.size(); i++) {
+ const char* name = strtab.GetStringAt(dt_needed[i]);
+ RefPtr<LibHandle> handle =
+ ElfLoader::Singleton.Load(name, RTLD_GLOBAL | RTLD_LAZY, this);
+ if (!handle) return false;
+ dependencies.push_back(handle);
+ }
+
+ return true;
+}
+
+bool CustomElf::Relocate() {
+ DEBUG_LOG("Relocate %s @%p", GetPath(), static_cast<void*>(base));
+ uint32_t symtab_index = (uint32_t)-1;
+ void* symptr = nullptr;
+ for (Array<Reloc>::iterator rel = relocations.begin();
+ rel < relocations.end(); ++rel) {
+ /* Location of the relocation */
+ void* ptr = GetPtr(rel->r_offset);
+
+ /* R_*_RELATIVE relocations apply directly at the given location */
+ if (ELF_R_TYPE(rel->r_info) == R_RELATIVE) {
+ *(void**)ptr = GetPtr(rel->GetAddend(base));
+ continue;
+ }
+ /* Other relocation types need a symbol resolution */
+ /* Avoid symbol resolution when it's the same symbol as last iteration */
+ if (symtab_index != ELF_R_SYM(rel->r_info)) {
+ symtab_index = ELF_R_SYM(rel->r_info);
+ const Sym sym = symtab[symtab_index];
+ if (sym.st_shndx != SHN_UNDEF) {
+ symptr = GetPtr(sym.st_value);
+ } else {
+ /* TODO: handle symbol resolving to nullptr vs. being undefined. */
+ symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));
+ }
+ }
+
+ if (symptr == nullptr)
+ WARN("%s: Relocation to NULL @0x%08" PRIxPTR, GetPath(),
+ uintptr_t(rel->r_offset));
+
+ /* Apply relocation */
+ switch (ELF_R_TYPE(rel->r_info)) {
+ case R_GLOB_DAT:
+ /* R_*_GLOB_DAT relocations simply use the symbol value */
+ *(void**)ptr = symptr;
+ break;
+ case R_ABS:
+ /* R_*_ABS* relocations add the relocation added to the symbol value */
+ *(const char**)ptr = (const char*)symptr + rel->GetAddend(base);
+ break;
+ default:
+ ERROR("%s: Unsupported relocation type: 0x%" PRIxPTR, GetPath(),
+ uintptr_t(ELF_R_TYPE(rel->r_info)));
+ return false;
+ }
+ }
+ return true;
+}
+
+bool CustomElf::RelocateJumps() {
+ /* TODO: Dynamic symbol resolution */
+ for (Array<Reloc>::iterator rel = jumprels.begin(); rel < jumprels.end();
+ ++rel) {
+ /* Location of the relocation */
+ void* ptr = GetPtr(rel->r_offset);
+
+ /* Only R_*_JMP_SLOT relocations are expected */
+ if (ELF_R_TYPE(rel->r_info) != R_JMP_SLOT) {
+ ERROR("%s: Jump relocation type mismatch", GetPath());
+ return false;
+ }
+
+ /* TODO: Avoid code duplication with the relocations above */
+ const Sym sym = symtab[ELF_R_SYM(rel->r_info)];
+ void* symptr;
+ if (sym.st_shndx != SHN_UNDEF)
+ symptr = GetPtr(sym.st_value);
+ else
+ symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));
+
+ if (symptr == nullptr) {
+ if (ELF_ST_BIND(sym.st_info) == STB_WEAK) {
+ WARN("%s: Relocation to NULL @0x%08" PRIxPTR " for symbol \"%s\"",
+ GetPath(), uintptr_t(rel->r_offset),
+ strtab.GetStringAt(sym.st_name));
+ } else {
+ ERROR("%s: Relocation to NULL @0x%08" PRIxPTR " for symbol \"%s\"",
+ GetPath(), uintptr_t(rel->r_offset),
+ strtab.GetStringAt(sym.st_name));
+ return false;
+ }
+ }
+ /* Apply relocation */
+ *(void**)ptr = symptr;
+ }
+ return true;
+}
+
+bool CustomElf::CallInit() {
+ if (init) CallFunction(init);
+
+ for (Array<void*>::iterator it = init_array.begin(); it < init_array.end();
+ ++it) {
+ /* Android x86 NDK wrongly puts 0xffffffff in INIT_ARRAY */
+ if (*it && *it != reinterpret_cast<void*>(-1)) CallFunction(*it);
+ }
+ initialized = true;
+ return true;
+}
+
+void CustomElf::CallFini() {
+ if (!initialized) return;
+ for (Array<void*>::reverse_iterator it = fini_array.rbegin();
+ it < fini_array.rend(); ++it) {
+ /* Android x86 NDK wrongly puts 0xffffffff in FINI_ARRAY */
+ if (*it && *it != reinterpret_cast<void*>(-1)) CallFunction(*it);
+ }
+ if (fini) CallFunction(fini);
+}