1 // Copyright 2024, Linaro Limited 2 // Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org> 3 // SPDX-License-Identifier: GPL-2.0-or-later 4 5 #![cfg_attr(not(MESON), doc = include_str!("../README.md"))] 6 7 #[rustfmt::skip] 8 pub mod bindings; 9 10 // preserve one-item-per-"use" syntax, it is clearer 11 // for prelude-like modules 12 #[rustfmt::skip] 13 pub mod prelude; 14 15 pub mod c_str; 16 pub mod cell; 17 pub mod definitions; 18 pub mod device_class; 19 pub mod offset_of; 20 pub mod vmstate; 21 pub mod zeroable; 22 23 use std::{ 24 alloc::{GlobalAlloc, Layout}, 25 os::raw::c_void, 26 }; 27 28 #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] 29 extern "C" { 30 fn g_aligned_alloc0( 31 n_blocks: bindings::gsize, 32 n_block_bytes: bindings::gsize, 33 alignment: bindings::gsize, 34 ) -> bindings::gpointer; 35 fn g_aligned_free(mem: bindings::gpointer); 36 } 37 38 #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] 39 extern "C" { 40 fn qemu_memalign(alignment: usize, size: usize) -> *mut c_void; 41 fn qemu_vfree(ptr: *mut c_void); 42 } 43 44 extern "C" { 45 fn g_malloc0(n_bytes: bindings::gsize) -> bindings::gpointer; 46 fn g_free(mem: bindings::gpointer); 47 } 48 49 /// An allocator that uses the same allocator as QEMU in C. 50 /// 51 /// It is enabled by default with the `allocator` feature. 52 /// 53 /// To set it up manually as a global allocator in your crate: 54 /// 55 /// ```ignore 56 /// use qemu_api::QemuAllocator; 57 /// 58 /// #[global_allocator] 59 /// static GLOBAL: QemuAllocator = QemuAllocator::new(); 60 /// ``` 61 #[derive(Clone, Copy, Debug)] 62 #[repr(C)] 63 pub struct QemuAllocator { 64 _unused: [u8; 0], 65 } 66 67 #[cfg_attr(all(feature = "allocator", not(test)), global_allocator)] 68 pub static GLOBAL: QemuAllocator = QemuAllocator::new(); 69 70 impl QemuAllocator { 71 // From the glibc documentation, on GNU systems, malloc guarantees 16-byte 72 // alignment on 64-bit systems and 8-byte alignment on 32-bit systems. See 73 // https://www.gnu.org/software/libc/manual/html_node/Malloc-Examples.html. 74 // This alignment guarantee also applies to Windows and Android. On Darwin 75 // and OpenBSD, the alignment is 16 bytes on both 64-bit and 32-bit systems. 76 #[cfg(all( 77 target_pointer_width = "32", 78 not(any(target_os = "macos", target_os = "openbsd")) 79 ))] 80 pub const DEFAULT_ALIGNMENT_BYTES: Option<usize> = Some(8); 81 #[cfg(all( 82 target_pointer_width = "64", 83 not(any(target_os = "macos", target_os = "openbsd")) 84 ))] 85 pub const DEFAULT_ALIGNMENT_BYTES: Option<usize> = Some(16); 86 #[cfg(all( 87 any(target_pointer_width = "32", target_pointer_width = "64"), 88 any(target_os = "macos", target_os = "openbsd") 89 ))] 90 pub const DEFAULT_ALIGNMENT_BYTES: Option<usize> = Some(16); 91 #[cfg(not(any(target_pointer_width = "32", target_pointer_width = "64")))] 92 pub const DEFAULT_ALIGNMENT_BYTES: Option<usize> = None; 93 94 pub const fn new() -> Self { 95 Self { _unused: [] } 96 } 97 } 98 99 impl Default for QemuAllocator { 100 fn default() -> Self { 101 Self::new() 102 } 103 } 104 105 // Sanity check. 106 const _: [(); 8] = [(); ::core::mem::size_of::<*mut c_void>()]; 107 108 unsafe impl GlobalAlloc for QemuAllocator { 109 unsafe fn alloc(&self, layout: Layout) -> *mut u8 { 110 if matches!(Self::DEFAULT_ALIGNMENT_BYTES, Some(default) if default.checked_rem(layout.align()) == Some(0)) 111 { 112 // SAFETY: g_malloc0() is safe to call. 113 unsafe { g_malloc0(layout.size().try_into().unwrap()).cast::<u8>() } 114 } else { 115 #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] 116 { 117 // SAFETY: g_aligned_alloc0() is safe to call. 118 unsafe { 119 g_aligned_alloc0( 120 layout.size().try_into().unwrap(), 121 1, 122 layout.align().try_into().unwrap(), 123 ) 124 .cast::<u8>() 125 } 126 } 127 #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] 128 { 129 // SAFETY: qemu_memalign() is safe to call. 130 unsafe { qemu_memalign(layout.align(), layout.size()).cast::<u8>() } 131 } 132 } 133 } 134 135 unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { 136 if matches!(Self::DEFAULT_ALIGNMENT_BYTES, Some(default) if default.checked_rem(layout.align()) == Some(0)) 137 { 138 // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid 139 // glib-allocated pointer, so `g_free`ing is safe. 140 unsafe { g_free(ptr.cast::<_>()) } 141 } else { 142 #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] 143 { 144 // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid aligned 145 // glib-allocated pointer, so `g_aligned_free`ing is safe. 146 unsafe { g_aligned_free(ptr.cast::<_>()) } 147 } 148 #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] 149 { 150 // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid aligned 151 // glib-allocated pointer, so `qemu_vfree`ing is safe. 152 unsafe { qemu_vfree(ptr.cast::<_>()) } 153 } 154 } 155 } 156 } 157 158 #[cfg(has_offset_of)] 159 pub use core::mem::offset_of; 160