diff options
Diffstat (limited to 'mozglue/linker/ElfLoader.cpp')
| -rw-r--r-- | mozglue/linker/ElfLoader.cpp | 164 |
1 files changed, 1 insertions, 163 deletions
diff --git a/mozglue/linker/ElfLoader.cpp b/mozglue/linker/ElfLoader.cpp index 76225d1e77..dd3d7daa8b 100644 --- a/mozglue/linker/ElfLoader.cpp +++ b/mozglue/linker/ElfLoader.cpp @@ -18,23 +18,6 @@ #include "Logging.h" #include <inttypes.h> -#if defined(ANDROID) -#include <sys/syscall.h> - -#include <android/api-level.h> -#if __ANDROID_API__ < 8 -/* Android API < 8 doesn't provide sigaltstack */ - -extern "C" { - -inline int sigaltstack(const stack_t *ss, stack_t *oss) { - return syscall(__NR_sigaltstack, ss, oss); -} - -} /* extern "C" */ -#endif /* __ANDROID_API__ */ -#endif /* ANDROID */ - #ifdef __ARM_EABI__ extern "C" MOZ_EXPORT const void * __gnu_Unwind_Find_exidx(void *pc, int *pcount) __attribute__((weak)); @@ -348,16 +331,6 @@ SystemElf::GetMappable() const const char *path = GetPath(); if (!path) return nullptr; -#ifdef ANDROID - /* On Android, if we don't have the full path, try in /system/lib */ - const char *name = LeafName(path); - std::string systemPath; - if (name == path) { - systemPath = "/system/lib/"; - systemPath += path; - path = systemPath.c_str(); - } -#endif return MappableFile::Create(path); } @@ -550,17 +523,9 @@ void ElfLoader::Init() { Dl_info info; - /* On Android < 4.1 can't reenter dl* functions. So when the library - * containing this code is dlopen()ed, it can't call dladdr from a - * static initializer. */ if (dladdr(_DYNAMIC, &info) != 0) { self_elf = LoadedElf::Create(info.dli_fname, info.dli_fbase); } -#if defined(ANDROID) - if (dladdr(FunctionPtr(syscall), &info) != 0) { - libc = LoadedElf::Create(info.dli_fname, info.dli_fbase); - } -#endif } ElfLoader::~ElfLoader() @@ -573,9 +538,6 @@ ElfLoader::~ElfLoader() /* Release self_elf and libc */ self_elf = nullptr; -#if defined(ANDROID) - libc = nullptr; -#endif /* Build up a list of all library handles with direct (external) references. * We actually skip system library handles because we want to keep at least @@ -962,88 +924,6 @@ ElfLoader::DebuggerHelper::Remove(ElfLoader::link_map *map) dbg->r_brk(); } -#if defined(ANDROID) -/* As some system libraries may be calling signal() or sigaction() to - * set a SIGSEGV handler, effectively breaking MappableSeekableZStream, - * or worse, restore our SIGSEGV handler with wrong flags (which using - * signal() will do), we want to hook into the system's sigaction() to - * replace it with our own wrapper instead, so that our handler is never - * replaced. We used to only do that with libraries this linker loads, - * but it turns out at least one system library does call signal() and - * breaks us (libsc-a3xx.so on the Samsung Galaxy S4). - * As libc's signal (bsd_signal/sysv_signal, really) calls sigaction - * under the hood, instead of calling the signal system call directly, - * we only need to hook sigaction. This is true for both bionic and - * glibc. - */ - -/* libc's sigaction */ -extern "C" int -sigaction(int signum, const struct sigaction *act, - struct sigaction *oldact); - -/* Simple reimplementation of sigaction. This is roughly equivalent - * to the assembly that comes in bionic, but not quite equivalent to - * glibc's implementation, so we only use this on Android. */ -int -sys_sigaction(int signum, const struct sigaction *act, - struct sigaction *oldact) -{ - return syscall(__NR_sigaction, signum, act, oldact); -} - -/* Replace the first instructions of the given function with a jump - * to the given new function. */ -template <typename T> -static bool -Divert(T func, T new_func) -{ - void *ptr = FunctionPtr(func); - uintptr_t addr = reinterpret_cast<uintptr_t>(ptr); - -#if defined(__i386__) - // A 32-bit jump is a 5 bytes instruction. - EnsureWritable w(ptr, 5); - *reinterpret_cast<unsigned char *>(addr) = 0xe9; // jmp - *reinterpret_cast<intptr_t *>(addr + 1) = - reinterpret_cast<uintptr_t>(new_func) - addr - 5; // target displacement - return true; -#elif defined(__arm__) - const unsigned char trampoline[] = { - // .thumb - 0x46, 0x04, // nop - 0x78, 0x47, // bx pc - 0x46, 0x04, // nop - // .arm - 0x04, 0xf0, 0x1f, 0xe5, // ldr pc, [pc, #-4] - // .word <new_func> - }; - const unsigned char *start; - if (addr & 0x01) { - /* Function is thumb, the actual address of the code is without the - * least significant bit. */ - addr--; - /* The arm part of the trampoline needs to be 32-bit aligned */ - if (addr & 0x02) - start = trampoline; - else - start = trampoline + 2; - } else { - /* Function is arm, we only need the arm part of the trampoline */ - start = trampoline + 6; - } - - size_t len = sizeof(trampoline) - (start - trampoline); - EnsureWritable w(reinterpret_cast<void *>(addr), len + sizeof(void *)); - memcpy(reinterpret_cast<void *>(addr), start, len); - *reinterpret_cast<void **>(addr + len) = FunctionPtr(new_func); - cacheflush(addr, addr + len + sizeof(void *), 0); - return true; -#else - return false; -#endif -} -#else #define sys_sigaction sigaction template <typename T> static bool @@ -1051,7 +931,7 @@ Divert(T func, T new_func) { return false; } -#endif + namespace { @@ -1144,48 +1024,6 @@ SEGVHandler::FinishInitialization() sigaction_func libc_sigaction; -#if defined(ANDROID) - /* Android > 4.4 comes with a sigaction wrapper in a LD_PRELOADed library - * (libsigchain) for ART. That wrapper kind of does the same trick as we - * do, so we need extra care in handling it. - * - Divert the libc's sigaction, assuming the LD_PRELOADed library uses - * it under the hood (which is more or less true according to the source - * of that library, since it's doing a lookup in RTLD_NEXT) - * - With the LD_PRELOADed library in place, all calls to sigaction from - * from system libraries will go to the LD_PRELOADed library. - * - The LD_PRELOADed library calls to sigaction go to our __wrap_sigaction. - * - The calls to sigaction from libraries faulty.lib loads are sent to - * the LD_PRELOADed library. - * In practice, for signal handling, this means: - * - The signal handler registered to the kernel is ours. - * - Our handler redispatches to the LD_PRELOADed library's if there's a - * segfault we don't handle. - * - The LD_PRELOADed library redispatches according to whatever system - * library or faulty.lib-loaded library set with sigaction. - * - * When there is no sigaction wrapper in place: - * - Divert the libc's sigaction. - * - Calls to sigaction from system library and faulty.lib-loaded libraries - * all go to the libc's sigaction, which end up in our __wrap_sigaction. - * - The signal handler registered to the kernel is ours. - * - Our handler redispatches according to whatever system library or - * faulty.lib-loaded library set with sigaction. - */ - void *libc = dlopen("libc.so", RTLD_GLOBAL | RTLD_LAZY); - if (libc) { - /* - * Lollipop bionic only has a small trampoline in sigaction, with the real - * work happening in __sigaction. Divert there instead of sigaction if it exists. - * Bug 1154803 - */ - libc_sigaction = reinterpret_cast<sigaction_func>(dlsym(libc, "__sigaction")); - - if (!libc_sigaction) { - libc_sigaction = - reinterpret_cast<sigaction_func>(dlsym(libc, "sigaction")); - } - } else -#endif { libc_sigaction = sigaction; } |