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Kernel: Move kmalloc heaps and super pages inside .bss segment

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The kernel ignored the first 8 MiB of RAM while parsing the memory map
because the kmalloc heaps and the super physical pages lived here. Move
all that stuff inside the .bss segment so that those memory regions are
accounted for, otherwise we risk overwriting boot modules placed next
to the kernel.
This commit is contained in:
Jean-Baptiste Boric 2021-01-20 17:49:55 +01:00 • committed by Andreas Kling
parent 5cd1217b6e
commit 3cbe805486
4 changed files with 45 additions and 44 deletions
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21
Kernel/Heap/kmalloc.cpp
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@ -186,14 +186,11 @@ struct KmallocGlobalHeap {
};
static KmallocGlobalHeap* g_kmalloc_global;
static u8 g_kmalloc_global_heap[sizeof(KmallocGlobalHeap)];
// We need to make sure to not stomp on global variables or other parts
// of the kernel image!
extern u32 end_of_kernel_image;
u8* const kmalloc_start = (u8*)PAGE_ROUND_UP(&end_of_kernel_image);
u8* const kmalloc_end = kmalloc_start + (ETERNAL_RANGE_SIZE + POOL_SIZE) + sizeof(KmallocGlobalHeap);
#define ETERNAL_BASE (kmalloc_start + sizeof(KmallocGlobalHeap))
#define KMALLOC_BASE (ETERNAL_BASE + ETERNAL_RANGE_SIZE)
// Treat the heap as logically separate from .bss
__attribute__((section(".heap"))) static u8 kmalloc_eternal_heap[ETERNAL_RANGE_SIZE];
__attribute__((section(".heap"))) static u8 kmalloc_pool_heap[POOL_SIZE];
static size_t g_kmalloc_bytes_eternal = 0;
static size_t g_kmalloc_call_count;
@ -215,13 +212,15 @@ void kmalloc_enable_expand()
void kmalloc_init()
{
memset((void*)KMALLOC_BASE, 0, POOL_SIZE);
g_kmalloc_global = new (kmalloc_start) KmallocGlobalHeap(KMALLOC_BASE, POOL_SIZE); // Place heap at kmalloc_start
// Zero out heap since it's placed after end_of_kernel_bss.
memset(kmalloc_eternal_heap, 0, sizeof(kmalloc_eternal_heap));
memset(kmalloc_pool_heap, 0, sizeof(kmalloc_pool_heap));
g_kmalloc_global = new (g_kmalloc_global_heap) KmallocGlobalHeap(kmalloc_pool_heap, sizeof(kmalloc_pool_heap));
s_lock.initialize();
s_next_eternal_ptr = (u8*)ETERNAL_BASE;
s_end_of_eternal_range = s_next_eternal_ptr + ETERNAL_RANGE_SIZE;
s_next_eternal_ptr = kmalloc_eternal_heap;
s_end_of_eternal_range = s_next_eternal_ptr + sizeof(kmalloc_pool_heap);
}
void* kmalloc_eternal(size_t size)