toaruos/kernel/core/mem.c

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/*
* Kernel Memory Manager
* vim:tabstop=4
* vim:noexpandtab
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*/
#include <system.h>
extern uintptr_t end;
uintptr_t placement_pointer = (uintptr_t)&end;
uintptr_t heap_end = (uintptr_t)NULL;
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void
kmalloc_startat(
uintptr_t address
) {
placement_pointer = address;
}
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/*
* kmalloc() is the kernel's dumb placement allocator
*/
uintptr_t
kmalloc_real(
size_t size,
int align,
uintptr_t * phys
) {
if (heap_end) {
void * address;
if (align) {
address = valloc(size);
} else {
address = malloc(size);
}
if (phys) {
page_t *page = get_page((uintptr_t)address, 0, kernel_directory);
*phys = page->frame * 0x1000 + ((uintptr_t)address & 0xFFF);
}
return (uintptr_t)address;
}
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if (align && (placement_pointer & 0xFFFFF000)) {
placement_pointer &= 0xFFFFF000;
}
if (phys) {
*phys = placement_pointer;
}
uintptr_t address = placement_pointer;
placement_pointer += size;
return (uintptr_t)address;
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}
/*
* Normal
*/
uintptr_t
kmalloc(
size_t size
) {
return kmalloc_real(size, 0, NULL);
}
/*
* Aligned
*/
uintptr_t
kvmalloc(
size_t size
) {
return kmalloc_real(size, 1, NULL);
}
/*
* With a physical address
*/
uintptr_t
kmalloc_p(
size_t size,
uintptr_t *phys
) {
return kmalloc_real(size, 0, phys);
}
/*
* Aligned, with a physical address
*/
uintptr_t
kvmalloc_p(
size_t size,
uintptr_t *phys
) {
return kmalloc_real(size, 1, phys);
}
/*
* Frame Allocation
*/
uint32_t *frames;
uint32_t nframes;
#define INDEX_FROM_BIT(b) (b / 0x20)
#define OFFSET_FROM_BIT(b) (b % 0x20)
static void
set_frame(
uintptr_t frame_addr
) {
uint32_t frame = frame_addr / 0x1000;
uint32_t index = INDEX_FROM_BIT(frame);
uint32_t offset = OFFSET_FROM_BIT(frame);
frames[index] |= (0x1 << offset);
}
static void
clear_frame(
uintptr_t frame_addr
) {
uint32_t frame = frame_addr / 0x1000;
uint32_t index = INDEX_FROM_BIT(frame);
uint32_t offset = OFFSET_FROM_BIT(frame);
frames[index] &= ~(0x1 << offset);
}
static uint32_t
test_frame(
uintptr_t frame_addr
) {
uint32_t frame = frame_addr / 0x1000;
uint32_t index = INDEX_FROM_BIT(frame);
uint32_t offset = OFFSET_FROM_BIT(frame);
return (frames[index] & (0x1 << offset));
}
static uint32_t
first_frame() {
uint32_t i, j;
for (i = 0; i < INDEX_FROM_BIT(nframes); ++i) {
if (frames[i] != 0xFFFFFFFF) {
for (j = 0; j < 32; ++j) {
uint32_t test_frame = 0x1 << j;
if (!(frames[i] & test_frame)) {
return i * 0x20 + j;
}
}
}
}
return -1;
}
void
alloc_frame(
page_t *page,
int is_kernel,
int is_writeable
) {
if (page->frame) {
page->rw = (is_writeable == 1) ? 1 : 0;
page->user = (is_kernel == 1) ? 0 : 1;
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return;
} else {
uint32_t index = first_frame();
if (index == (uint32_t)-1) {
HALT_AND_CATCH_FIRE("Failed to allocate a frame: out of frames");
}
set_frame(index * 0x1000);
page->present = 1;
page->rw = (is_writeable == 1) ? 1 : 0;
page->user = (is_kernel == 1) ? 0 : 1;
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page->frame = index;
}
}
void
free_frame(
page_t *page
) {
uint32_t frame;
if (!(frame = page->frame)) {
return;
} else {
clear_frame(frame);
page->frame = 0x0;
}
}
void
paging_install(uint32_t memsize) {
nframes = memsize / 4;
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frames = (uint32_t *)kmalloc(INDEX_FROM_BIT(nframes));
memset(frames, 0, INDEX_FROM_BIT(nframes));
uintptr_t phys;
kernel_directory = (page_directory_t *)kvmalloc_p(sizeof(page_directory_t),&phys);
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memset(kernel_directory, 0, sizeof(page_directory_t));
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uint32_t i = 0;
while (i < placement_pointer + 0x1000) {
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alloc_frame(get_page(i, 1, kernel_directory), 0, 0);
i += 0x1000;
}
isrs_install_handler(14, page_fault);
kernel_directory->physical_address = (uintptr_t)kernel_directory->physical_tables;
current_directory = clone_directory(kernel_directory);
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switch_page_directory(kernel_directory);
}
void
switch_page_directory(
page_directory_t * dir
) {
current_directory = dir;
__asm__ __volatile__ ("mov %0, %%cr3":: "r"(dir->physical_address));
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uint32_t cr0;
__asm__ __volatile__ ("mov %%cr0, %0": "=r"(cr0));
cr0 |= 0x80000000;
__asm__ __volatile__ ("mov %0, %%cr0":: "r"(cr0));
}
page_t *
get_page(
uintptr_t address,
int make,
page_directory_t * dir
) {
address /= 0x1000;
uint32_t table_index = address / 1024;
if (dir->tables[table_index]) {
return &dir->tables[table_index]->pages[address % 1024];
} else if(make) {
uint32_t temp;
dir->tables[table_index] = (page_table_t *)kvmalloc_p(sizeof(page_table_t), (uintptr_t *)(&temp));
memset(dir->tables[table_index], 0, 0x1000);
dir->physical_tables[table_index] = temp | 0x7; /* Present, R/w, User */
return &dir->tables[table_index]->pages[address % 1024];
} else {
return 0;
}
}
void
page_fault(
struct regs *r) {
uint32_t faulting_address;
__asm__ __volatile__("mov %%cr2, %0" : "=r"(faulting_address));
int present = !(r->err_code & 0x1);
int rw = r->err_code & 0x2;
int user = r->err_code & 0x4;
int reserved = r->err_code & 0x8;
int id = r->err_code & 0x10;
if (faulting_address == 0) {
kprintf("Null pointer dereference in the kernel.\n");
}
kprintf("Page fault! (p:%d,rw:%d,user:%d,res:%d,id:%d) at 0x%x\n", present, rw, user, reserved, id, faulting_address);
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HALT_AND_CATCH_FIRE("Page fault");
}
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/*
* Heap
* Stop using kalloc and friends after installing the heap
* otherwise shit will break. I've conveniently broken
* kalloc when installing the heap, just for those of you
* who feel the need to screw up.
*/
void
heap_install() {
heap_end = (placement_pointer + 0x1000) & ~0xFFF;
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placement_pointer = 0;
}
void *
sbrk(
uintptr_t increment
) {
ASSERT(increment % 0x1000 == 0);
ASSERT(heap_end % 0x1000 == 0);
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uintptr_t address = heap_end;
heap_end += increment;
uintptr_t i;
for (i = address; i < heap_end; i += 0x1000) {
get_page(i, 1, kernel_directory);
alloc_frame(get_page(i, 1, kernel_directory), 0, 1);
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}
return (void *)address;
}