Revert of [wasm] Initial signal handler

src/trap-handler/handler-inside.cc

Index: src/trap-handler/handler-inside.cc
diff --git a/src/trap-handler/handler-inside.cc b/src/trap-handler/handler-inside.cc
deleted file mode 100644
index a51bd9427f0c9585e0f21cc4cc46a6736416750e..0000000000000000000000000000000000000000
--- a/src/trap-handler/handler-inside.cc
+++ /dev/null
@@ -1,170 +0,0 @@
-// Copyright 2017 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// PLEASE READ BEFORE CHANGING THIS FILE!
-//
-// This file implements the out of bounds signal handler for
-// WebAssembly. Signal handlers are notoriously difficult to get
-// right, and getting it wrong can lead to security
-// vulnerabilities. In order to minimize this risk, here are some
-// rules to follow.
-//
-// 1. Do not introduce any new external dependencies. This file needs
-//    to be self contained so it is easy to audit everything that a
-//    signal handler might do.
-//
-// 2. Any changes must be reviewed by someone from the crash reporting
-//    or security team. See OWNERS for suggested reviewers.
-//
-// For more information, see https://goo.gl/yMeyUY.
-//
-// This file contains most of the code that actually runs in a signal handler
-// context. Some additional code is used both inside and outside the signal
-// handler. This code can be found in handler-shared.cc.
-
-#include <signal.h>
-#include <stddef.h>
-#include <stdlib.h>
-
-#include "src/trap-handler/trap-handler-internal.h"
-#include "src/trap-handler/trap-handler.h"
-
-namespace v8 {
-namespace internal {
-namespace trap_handler {
-
-namespace {
-
-bool IsKernelGeneratedSignal(siginfo_t* info) {
-  return info->si_code > 0 && info->si_code != SI_USER &&
-         info->si_code != SI_QUEUE && info->si_code != SI_TIMER &&
-         info->si_code != SI_ASYNCIO && info->si_code != SI_MESGQ;
-}
-
-#if V8_TRAP_HANDLER_SUPPORTED
-class SigUnmaskStack {
- public:
-  explicit SigUnmaskStack(sigset_t sigs) {
-    // TODO(eholk): consider using linux-syscall-support for calling this
-    // syscall.
-    pthread_sigmask(SIG_UNBLOCK, &sigs, &old_mask_);
-  }
-
-  ~SigUnmaskStack() { pthread_sigmask(SIG_SETMASK, &old_mask_, nullptr); }
-
- private:
-  sigset_t old_mask_;
-
-  // We'd normally use DISALLOW_COPY_AND_ASSIGN, but we're avoiding a dependency
-  // on base/macros.h
-  SigUnmaskStack(const SigUnmaskStack&) = delete;
-  void operator=(const SigUnmaskStack&) = delete;
-};
-#endif
-}  // namespace
-
-#if V8_TRAP_HANDLER_SUPPORTED && V8_OS_LINUX
-bool TryHandleSignal(int signum, siginfo_t* info, ucontext_t* context) {
-  // Bail out early in case we got called for the wrong kind of signal.
-  if (signum != SIGSEGV) {
-    return false;
-  }
-
-  // Make sure the signal was generated by the kernel and not some other source.
-  if (!IsKernelGeneratedSignal(info)) {
-    return false;
-  }
-
-  // Ensure the faulting thread was actually running Wasm code.
-  if (!IsThreadInWasm()) {
-    return false;
-  }
-
-  // Clear g_thread_in_wasm_code, primarily to protect against nested faults.
-  g_thread_in_wasm_code = false;
-
-  // Begin signal mask scope. We need to be sure to restore the signal mask
-  // before we restore the g_thread_in_wasm_code flag.
-  {
-    // Unmask the signal so that if this signal handler crashes, the crash will
-    // be handled by the crash reporter.  Otherwise, the process might be killed
-    // with the crash going unreported.
-    sigset_t sigs;
-    // Fortunately, sigemptyset and sigaddset are async-signal-safe according to
-    // the POSIX standard.
-    sigemptyset(&sigs);
-    sigaddset(&sigs, SIGSEGV);
-    SigUnmaskStack unmask(sigs);
-
-    uintptr_t fault_addr = context->uc_mcontext.gregs[REG_RIP];
-
-    // TODO(eholk): broad code range check
-
-    // Taking locks in a signal handler is risky because a fault in the signal
-    // handler could lead to a deadlock when attempting to acquire the lock
-    // again. We guard against this case with g_thread_in_wasm_code. The lock
-    // may only be taken when not executing Wasm code (an assert in
-    // MetadataLock's constructor ensures this). This signal handler will bail
-    // out before trying to take the lock if g_thread_in_wasm_code is not set.
-    MetadataLock lock_holder;
-
-    for (size_t i = 0; i < gNumCodeObjects; ++i) {
-      const CodeProtectionInfo* data = gCodeObjects[i].code_info;
-      if (data == nullptr) {
-        continue;
-      }
-      const uintptr_t base = reinterpret_cast<uintptr_t>(data->base);
-
-      if (fault_addr >= base && fault_addr < base + data->size) {
-        // Hurray, we found the code object. Check for protected addresses.
-        const ptrdiff_t offset = fault_addr - base;
-
-        for (unsigned i = 0; i < data->num_protected_instructions; ++i) {
-          if (data->instructions[i].instr_offset == offset) {
-            // Hurray again, we found the actual instruction. Tell the caller to
-            // return to the landing pad.
-            context->uc_mcontext.gregs[REG_RIP] =
-                data->instructions[i].landing_offset + base;
-            return true;
-          }
-        }
-      }
-    }
-  }  // end signal mask scope
-
-  // If we get here, it's not a recoverable wasm fault, so we go to the next
-  // handler.
-  g_thread_in_wasm_code = true;
-  return false;
-}
-#endif  // V8_TRAP_HANDLER_SUPPORTED && V8_OS_LINUX
-
-#if V8_TRAP_HANDLER_SUPPORTED
-void HandleSignal(int signum, siginfo_t* info, void* context) {
-  ucontext_t* uc = reinterpret_cast<ucontext_t*>(context);
-
-  if (!TryHandleSignal(signum, info, uc)) {
-    // Since V8 didn't handle this signal, we want to re-raise the same signal.
-    // For kernel-generated SEGV signals, we do this by restoring the default
-    // SEGV handler and then returning. The fault will happen again and the
-    // usual SEGV handling will happen.
-    //
-    // We handle user-generated signals by calling raise() instead. This is for
-    // completeness. We should never actually see one of these, but just in
-    // case, we do the right thing.
-    struct sigaction action;
-    action.sa_handler = SIG_DFL;
-    sigemptyset(&action.sa_mask);
-    action.sa_flags = 0;
-    sigaction(signum, &action, nullptr);
-    if (!IsKernelGeneratedSignal(info)) {
-      raise(signum);
-    }
-  }
-  // TryHandleSignal modifies context to change where we return to.
-}
-#endif
-}  // namespace trap_handler
-}  // namespace internal
-}  // namespace v8