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385f6f93bf
This is a fix for the crash issue in 64-bit ARM [#32175][1]. When targeting Android 11 and above, 64-bit ARM platforms have the 'Tagged Pointer' feature enabled by default which causes memory allocated using the system allocator to have a non-zero 'tag' set in the highest byte of heap addresses. This is incompatible with SpiderMonkey which assumes that only the bottom 48 bits are set and asserts this at various points. Both Servo and Gecko have a similar architecture where the pointer to a heap allocated DOM struct is encoded as a JS::Value and stored in the DOM_OBJECT_SLOT (reserved slot) of the JSObject which reflects the native DOM struct. As observed in #32175, even Gecko crashes with `jemalloc` disabled which suggests that support for using the native system allocator with tagged pointers enabled by default is not present at the moment. [1]: https://github.com/servo/servo/issues/32175 Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>
80 lines
2.2 KiB
Rust
80 lines
2.2 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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//! Selecting the default global allocator for Servo
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#[global_allocator]
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static ALLOC: Allocator = Allocator;
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pub use crate::platform::*;
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#[cfg(not(any(windows, feature = "use-system-allocator", target_env = "ohos")))]
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mod platform {
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use std::os::raw::c_void;
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pub use jemallocator::Jemalloc as Allocator;
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/// Get the size of a heap block.
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///
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/// # Safety
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///
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/// Passing a non-heap allocated pointer to this function results in undefined behavior.
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pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
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jemallocator::usable_size(ptr)
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}
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/// Memory allocation APIs compatible with libc
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pub mod libc_compat {
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pub use jemalloc_sys::{free, malloc, realloc};
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}
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}
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#[cfg(all(
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not(windows),
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any(feature = "use-system-allocator", target_env = "ohos")
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))]
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mod platform {
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pub use std::alloc::System as Allocator;
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use std::os::raw::c_void;
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/// Get the size of a heap block.
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///
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/// # Safety
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///
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/// Passing a non-heap allocated pointer to this function results in undefined behavior.
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pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
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#[cfg(target_vendor = "apple")]
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return libc::malloc_size(ptr);
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#[cfg(not(target_vendor = "apple"))]
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return libc::malloc_usable_size(ptr as *mut _);
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}
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pub mod libc_compat {
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pub use libc::{free, malloc, realloc};
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}
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}
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#[cfg(windows)]
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mod platform {
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pub use std::alloc::System as Allocator;
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use std::os::raw::c_void;
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use winapi::um::heapapi::{GetProcessHeap, HeapSize, HeapValidate};
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/// Get the size of a heap block.
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///
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/// # Safety
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///
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/// Passing a non-heap allocated pointer to this function results in undefined behavior.
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pub unsafe extern "C" fn usable_size(mut ptr: *const c_void) -> usize {
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let heap = GetProcessHeap();
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if HeapValidate(heap, 0, ptr) == 0 {
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ptr = *(ptr as *const *const c_void).offset(-1);
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}
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HeapSize(heap, 0, ptr) as usize
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}
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}
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