Liam Appelbe
07f587504b
This reverts https://dart-review.googlesource.com/c/sdk/+/306674 Patchset 1 is a pure rollback of the rollback. Patchset 2 is https://dart-review.googlesource.com/c/sdk/+/306316 Patchset 4+ is the forward fix for the Fuchsia issues. The Fuchsia bug that we're fixing (or working around), is that VirtualMemory::DuplicateRX doesn't work on Fuchsia. A proper fix will require special casing it, like on MacOS. In the mean time we can avoid using this function by only allowing one page of trampolines on Fuchsia. Unfortunately, when I removed the BSS stuff from the original CL, it was necessary to duplicate even the first page, so I've had to add that stuff back just for Fuchsia. Change-Id: Id42de78ee5de126bcc83bfa4148f6efb4045f976 Bug: https://github.com/dart-lang/sdk/issues/52579 Bug: https://buganizer.corp.google.com/issues/284959841 Fixes: https://github.com/dart-lang/sdk/issues/52581 TEST=CI, especially vm-fuchsia-release-x64-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/306676 Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Liam Appelbe <liama@google.com> Reviewed-by: Daco Harkes <dacoharkes@google.com>
96 lines
3.5 KiB
C++
96 lines
3.5 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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if (AliasOffset() != 0) {
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FreeSubSegment(reinterpret_cast<void*>(alias_.start() + new_size),
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alias_.size() - new_size);
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}
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}
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}
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region_.Subregion(region_, 0, new_size);
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alias_.Subregion(alias_, 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, 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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ASSERT_LESS_OR_EQUAL(size(), target->size());
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#if defined(DART_HOST_OS_MACOS)
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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 = 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(), 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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