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LibC: Move some of malloc's data structures into mallocdefs.h

This allows UE to see what the heap metadata looks like.
This commit is contained in:
Andreas Kling 2020-11-14 18:25:48 +01:00
parent 53cffb5ad9
commit b494cfea38
2 changed files with 75 additions and 71 deletions

View file

@ -26,5 +26,70 @@
#pragma once
#include <AK/InlineLinkedList.h>
#include <AK/Types.h>
#define MAGIC_PAGE_HEADER 0x42657274 // 'Bert'
#define MAGIC_BIGALLOC_HEADER 0x42697267 // 'Birg'
#define MALLOC_SCRUB_BYTE 0xdc
#define FREE_SCRUB_BYTE 0xed
static constexpr unsigned short size_classes[] = { 8, 16, 32, 64, 128, 256, 500, 1016, 2032, 4088, 8184, 16376, 32752, 0 };
static constexpr size_t num_size_classes = (sizeof(size_classes) / sizeof(unsigned short)) - 1;
struct CommonHeader {
size_t m_magic;
size_t m_size;
};
struct BigAllocationBlock : public CommonHeader {
BigAllocationBlock(size_t size)
{
m_magic = MAGIC_BIGALLOC_HEADER;
m_size = size;
}
unsigned char* m_slot[0];
};
struct FreelistEntry {
FreelistEntry* next;
};
struct ChunkedBlock
: public CommonHeader
, public InlineLinkedListNode<ChunkedBlock> {
static constexpr size_t block_size = 64 * KiB;
static constexpr size_t block_mask = ~(block_size - 1);
ChunkedBlock(size_t bytes_per_chunk)
{
m_magic = MAGIC_PAGE_HEADER;
m_size = bytes_per_chunk;
m_free_chunks = chunk_capacity();
m_freelist = (FreelistEntry*)chunk(0);
for (size_t i = 0; i < chunk_capacity(); ++i) {
auto* entry = (FreelistEntry*)chunk(i);
if (i != chunk_capacity() - 1)
entry->next = (FreelistEntry*)chunk(i + 1);
else
entry->next = nullptr;
}
}
ChunkedBlock* m_prev { nullptr };
ChunkedBlock* m_next { nullptr };
FreelistEntry* m_freelist { nullptr };
size_t m_free_chunks { 0 };
[[gnu::aligned(8)]] unsigned char m_slot[0];
void* chunk(size_t index)
{
return &m_slot[index * m_size];
}
bool is_full() const { return m_free_chunks == 0; }
size_t bytes_per_chunk() const { return m_size; }
size_t free_chunks() const { return m_free_chunks; }
size_t used_chunks() const { return chunk_capacity() - m_free_chunks; }
size_t chunk_capacity() const { return (block_size - sizeof(ChunkedBlock)) / m_size; }
};