ladybird/Kernel/Heap/kmalloc.h

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Types.h>
#include <Kernel/Debug.h>
#include <LibC/limits.h>

#define KMALLOC_SCRUB_BYTE 0xbb
#define KFREE_SCRUB_BYTE 0xaa

#define MAKE_ALIGNED_ALLOCATED(type, alignment)                                                                                   \
public:                                                                                                                           \
    [[nodiscard]] void* operator new(size_t)                                                                                      \
    {                                                                                                                             \
        void* ptr = kmalloc_aligned<alignment>(sizeof(type));                                                                     \
        VERIFY(ptr);                                                                                                              \
        return ptr;                                                                                                               \
    }                                                                                                                             \
    [[nodiscard]] void* operator new(size_t, const std::nothrow_t&) noexcept { return kmalloc_aligned<alignment>(sizeof(type)); } \
    void operator delete(void* ptr) noexcept { kfree_aligned(ptr); }                                                              \
                                                                                                                                  \
private:

// The C++ standard specifies that the nothrow allocation tag should live in the std namespace.
// Otherwise, `new (std::nothrow)` calls wouldn't get resolved.
namespace std {
struct nothrow_t {
    explicit nothrow_t() = default;
};

extern const nothrow_t nothrow;

enum class align_val_t : size_t {};
};

void kmalloc_init();
[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_impl(size_t);
[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_eternal(size_t);

void kfree(void*);
void kfree_sized(void*, size_t);

struct kmalloc_stats {
    size_t bytes_allocated;
    size_t bytes_free;
    size_t bytes_eternal;
    size_t kmalloc_call_count;
    size_t kfree_call_count;
};
void get_kmalloc_stats(kmalloc_stats&);

extern bool g_dump_kmalloc_stacks;

inline void* operator new(size_t, void* p) { return p; }
inline void* operator new[](size_t, void* p) { return p; }

[[nodiscard]] void* operator new(size_t size);
[[nodiscard]] void* operator new(size_t size, const std::nothrow_t&) noexcept;
[[nodiscard]] void* operator new(size_t size, std::align_val_t);
[[nodiscard]] void* operator new(size_t size, std::align_val_t, const std::nothrow_t&) noexcept;

void operator delete(void* ptr) noexcept DISALLOW("All deletes in the kernel should have a known size.");
void operator delete(void* ptr, size_t) noexcept;
void operator delete(void* ptr, std::align_val_t) noexcept DISALLOW("All deletes in the kernel should have a known size.");
void operator delete(void* ptr, size_t, std::align_val_t) noexcept;

[[nodiscard]] void* operator new[](size_t size);
[[nodiscard]] void* operator new[](size_t size, const std::nothrow_t&) noexcept;

void operator delete[](void* ptrs) noexcept DISALLOW("All deletes in the kernel should have a known size.");
void operator delete[](void* ptr, size_t) noexcept;

[[gnu::malloc, gnu::alloc_size(1)]] void* kmalloc(size_t);

template<size_t ALIGNMENT>
[[gnu::malloc, gnu::alloc_size(1)]] inline void* kmalloc_aligned(size_t size)
{
    static_assert(ALIGNMENT > sizeof(ptrdiff_t));
    static_assert(ALIGNMENT <= 4096);
    void* ptr = kmalloc(size + ALIGNMENT + sizeof(ptrdiff_t));
    if (ptr == nullptr)
        return ptr;
    size_t max_addr = (size_t)ptr + ALIGNMENT;
    void* aligned_ptr = (void*)(max_addr - (max_addr % ALIGNMENT));
    ((ptrdiff_t*)aligned_ptr)[-1] = (ptrdiff_t)((u8*)aligned_ptr - (u8*)ptr);
    return aligned_ptr;
}

inline void kfree_aligned(void* ptr)
{
    if (ptr == nullptr)
        return;
    kfree((u8*)ptr - ((const ptrdiff_t*)ptr)[-1]);
}

size_t kmalloc_good_size(size_t);

void kmalloc_enable_expand();