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Kernel: Make Heap implementation reusable, and make kmalloc expandable

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Add an ExpandableHeap and switch kmalloc to use it, which allows
for the kmalloc heap to grow as needed.

In order to make heap expansion to work, we keep around a 1 MiB backup
memory region, because creating a region would require space in the
same heap. This means, the heap will grow as soon as the reported
utilization is less than 1 MiB. It will also return memory if an entire
subheap is no longer needed, although that is rarely possible.
This commit is contained in:
Tom 2020-08-29 16:41:30 -06:00 • committed by Andreas Kling
parent 8ecc3d31d1
commit 4b66692a55
7 changed files with 541 additions and 132 deletions
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37
Kernel/Heap/kmalloc.h
View file

@ -36,17 +36,19 @@
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);
[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_page_aligned(size_t);
[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_aligned(size_t, size_t alignment);
void* krealloc(void*, size_t);
void kfree(void*);
void kfree_aligned(void*);
extern size_t g_kmalloc_bytes_allocated;
extern size_t g_kmalloc_bytes_free;
extern size_t g_kmalloc_bytes_eternal;
extern size_t g_kmalloc_call_count;
extern size_t g_kfree_call_count;
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; }
@ -62,5 +64,24 @@ inline void* operator new[](size_t, void* p) { return p; }
return kmalloc_impl(size);
}
template<size_t ALIGNMENT>
[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] inline void* kmalloc_aligned(size_t size)
{
static_assert(ALIGNMENT > 1);
static_assert(ALIGNMENT < 255);
void* ptr = kmalloc(size + ALIGNMENT + sizeof(u8));
size_t max_addr = (size_t)ptr + ALIGNMENT;
void* aligned_ptr = (void*)(max_addr - (max_addr % ALIGNMENT));
((u8*)aligned_ptr)[-1] = (u8)((u8*)aligned_ptr - (u8*)ptr);
return aligned_ptr;
}
inline void kfree_aligned(void* ptr)
{
kfree((u8*)ptr - ((u8*)ptr)[-1]);
}
void kmalloc_enable_expand();
extern u8* const kmalloc_start;
extern u8* const kmalloc_end;