Vyacheslav Egorov
3e0ae6da5f
We are no longer using Dart VM in a setting where this matters as a security measure and it just complicates portability for no benefit. There is an indication that it is causing problems when running Linux build of Dart VM under Docker on Mac OS X. Fixes https://github.com/dart-lang/sdk/issues/54446 TEST=ci Cq-Include-Trybots: luci.dart.try:vm-fuchsia-release-arm64-try,vm-fuchsia-release-x64-try Change-Id: I11bdaa8faebaca1df6fd59097049bdaea9cb8e12 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/344581 Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Slava Egorov <vegorov@google.com>
92 lines
3.4 KiB
C++
92 lines
3.4 KiB
C++
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#include "vm/virtual_memory.h"
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#include "platform/assert.h"
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#include "platform/utils.h"
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#if defined(DART_HOST_OS_MACOS)
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#include <mach/mach.h>
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#endif
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namespace dart {
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bool VirtualMemory::InSamePage(uword address0, uword address1) {
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return (Utils::RoundDown(address0, PageSize()) ==
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Utils::RoundDown(address1, PageSize()));
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}
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void VirtualMemory::Truncate(intptr_t new_size) {
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ASSERT(Utils::IsAligned(new_size, PageSize()));
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ASSERT(new_size <= size());
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if (reserved_.size() ==
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region_.size()) { // Don't create holes in reservation.
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if (FreeSubSegment(reinterpret_cast<void*>(start() + new_size),
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size() - new_size)) {
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reserved_.set_size(new_size);
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}
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}
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region_.Subregion(region_, 0, new_size);
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}
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VirtualMemory* VirtualMemory::ForImagePage(void* pointer, uword size) {
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// Memory for precompilated instructions was allocated by the embedder, so
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// create a VirtualMemory without allocating.
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MemoryRegion region(pointer, size);
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MemoryRegion reserved(nullptr, 0); // null reservation indicates VM should
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// not attempt to free this memory.
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VirtualMemory* memory = new VirtualMemory(region, reserved);
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ASSERT(!memory->vm_owns_region());
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return memory;
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}
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#if !defined(DART_TARGET_OS_FUCHSIA)
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// TODO(52579): Reenable on Fuchsia.
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bool VirtualMemory::DuplicateRX(VirtualMemory* target) {
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const intptr_t aligned_size = Utils::RoundUp(size(), PageSize());
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ASSERT_LESS_OR_EQUAL(aligned_size, target->size());
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#if defined(DART_HOST_OS_MACOS) && defined(DART_PRECOMPILED_RUNTIME)
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// Mac is special cased because iOS doesn't allow allocating new executable
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// memory, so the default approach would fail. We are allowed to make new
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// mappings of existing executable memory using vm_remap though, which is
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// effectively the same for non-writable memory.
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const mach_port_t task = mach_task_self();
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const vm_address_t source_address = reinterpret_cast<vm_address_t>(address());
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const vm_size_t mem_size = aligned_size;
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const vm_prot_t read_execute = VM_PROT_READ | VM_PROT_EXECUTE;
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vm_prot_t current_protection = read_execute;
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vm_prot_t max_protection = read_execute;
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vm_address_t target_address =
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reinterpret_cast<vm_address_t>(target->address());
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kern_return_t status = vm_remap(
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task, &target_address, mem_size,
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/*mask=*/0,
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/*flags=*/VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE, task, source_address,
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/*copy=*/true, ¤t_protection, &max_protection,
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/*inheritance=*/VM_INHERIT_NONE);
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if (status != KERN_SUCCESS) {
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return false;
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}
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ASSERT(reinterpret_cast<void*>(target_address) == target->address());
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ASSERT_EQUAL(current_protection & read_execute, read_execute);
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ASSERT_EQUAL(max_protection & read_execute, read_execute);
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return true;
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#else // defined(DART_HOST_OS_MACOS)
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// TODO(52497): Use dual mapping on platforms where it's supported.
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// Check that target doesn't overlap with this.
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ASSERT(target->start() >= end() || target->end() <= start());
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memcpy(target->address(), address(), size()); // NOLINT
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Protect(target->address(), aligned_size, kReadExecute);
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return true;
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#endif // defined(DART_HOST_OS_MACOS)
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}
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#endif // !defined(DART_TARGET_OS_FUCHSIA)
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} // namespace dart
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