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Kernel: Move Kernel mapping to 0xc0000000

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The kernel is now no longer identity mapped to the bottom 8MiB of
memory, and is now mapped at the higher address of `0xc0000000`.

The lower ~1MiB of memory (from GRUB's mmap), however is still
identity mapped to provide an easy way for the kernel to get
physical pages for things such as DMA etc. These could later be
mapped to the higher address too, as I'm not too sure how to
go about doing this elegantly without a lot of address subtractions.
This commit is contained in:
Jesse Buhagiar 2019-11-21 16:08:11 +11:00 • committed by Andreas Kling
parent 61ba19f031
commit bd33c66273
13 changed files with 132 additions and 64 deletions
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16
Kernel/Heap/kmalloc.cpp
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@ -6,11 +6,11 @@
#include <AK/Assertions.h>
#include <AK/Types.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Heap/kmalloc.h>
#include <Kernel/KSyms.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/StdLib.h>
#include <Kernel/Heap/kmalloc.h>
#define SANITIZE_KMALLOC
@ -20,11 +20,11 @@ struct [[gnu::packed]] allocation_t
size_t nchunk;
};
#define BASE_PHYSICAL (4 * MB)
#define KMALLOC_RANGE_BASE (0xc0000000 + (4 * MB))
#define CHUNK_SIZE 8
#define POOL_SIZE (3 * MB)
#define ETERNAL_BASE_PHYSICAL (2 * MB)
#define ETERNAL_RANGE_BASE (0xc0000000 + (2 * MB))
#define ETERNAL_RANGE_SIZE (2 * MB)
static u8 alloc_map[POOL_SIZE / CHUNK_SIZE / 8];
@ -42,21 +42,21 @@ static u8* s_end_of_eternal_range;
bool is_kmalloc_address(const void* ptr)
{
if (ptr >= (u8*)ETERNAL_BASE_PHYSICAL && ptr < s_next_eternal_ptr)
if (ptr >= (u8*)ETERNAL_RANGE_BASE && ptr < s_next_eternal_ptr)
return true;
return (size_t)ptr >= BASE_PHYSICAL && (size_t)ptr <= (BASE_PHYSICAL + POOL_SIZE);
return (size_t)ptr >= KMALLOC_RANGE_BASE && (size_t)ptr <= (KMALLOC_RANGE_BASE + POOL_SIZE);
}
void kmalloc_init()
{
memset(&alloc_map, 0, sizeof(alloc_map));
memset((void*)BASE_PHYSICAL, 0, POOL_SIZE);
memset((void*)KMALLOC_RANGE_BASE, 0, POOL_SIZE);
kmalloc_sum_eternal = 0;
sum_alloc = 0;
sum_free = POOL_SIZE;
s_next_eternal_ptr = (u8*)ETERNAL_BASE_PHYSICAL;
s_next_eternal_ptr = (u8*)ETERNAL_RANGE_BASE;
s_end_of_eternal_range = s_next_eternal_ptr + ETERNAL_RANGE_SIZE;
}
@ -134,7 +134,7 @@ void* kmalloc_impl(size_t size)
++chunks_here;
if (chunks_here == chunks_needed) {
auto* a = (allocation_t*)(BASE_PHYSICAL + (first_chunk * CHUNK_SIZE));
auto* a = (allocation_t*)(KMALLOC_RANGE_BASE + (first_chunk * CHUNK_SIZE));
u8* ptr = (u8*)a;
ptr += sizeof(allocation_t);
a->nchunk = chunks_needed;