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Did some preliminary work on memory management

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Simon 2024-01-27 18:30:34 -05:00
parent 90c70043be
commit 03b5672a01
2 changed files with 141 additions and 7 deletions
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143
src/arch/amd64/shim.c
View file

@ -1,5 +1,7 @@
#include <stdint.h>
#include <serial.h>
#include <cpuid.h>
#include <lib.h>
#define F_PRESENT 0x001
#define F_WRITEABLE 0x002
@ -52,19 +54,150 @@ struct pte {
uint64_t execute_disable : 1;
};
static inline void invlpg(unsigned long addr) {
__asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
}
static int get_maxphysaddr() {
uint32_t eax, ebx, ecx, edx;
__cpuid(0x80000008, eax, ebx, ecx, edx);
return eax & 0xFF;
}
int find_phys_addr(struct pml4e *pml4, void *virt_addr, void **phys_addr) {
uint64_t pml4_offset = ((uint64_t)virt_addr) >> 39;
uint64_t pdpt_offset = (((uint64_t)virt_addr) >> 30) & 0x1FF;
uint64_t pd_offset = (((uint64_t)virt_addr) >> 21) & 0x1FF;
uint64_t pt_offset = (((uint64_t)virt_addr) >> 12) & 0x1FF;
uint64_t page_offset = (((uint64_t)virt_addr) ) & 0xFFF;
if (!pml4[pml4_offset].flags & F_PRESENT)
return -1;
struct pdpte *pdpt = (struct pdpte *)(pml4[pml4_offset].address << 12);
if (!pdpt[pdpt_offset].flags & F_PRESENT)
return -1;
struct pde *pd = (struct pde *)(pdpt[pdpt_offset].address << 12);
if (!pd[pd_offset].flags & F_PRESENT)
return -1;
struct pte *pt = (struct pte *)(pd[pd_offset].address << 12);
if (!pt[pt_offset].flags & F_PRESENT)
return -1;
*phys_addr = (void *)((pt[pt_offset].address << 12) + page_offset);
return 0;
}
char *curr_alloc = 0x5000;
void *alloc_phys_page() {
void *ret = curr_alloc;
curr_alloc += 4096;
return ret;
}
int map_page(struct pml4e *pml4, void *virt_addr, void *phys_addr, unsigned int flags) {
uint64_t pml4_offset = ((uint64_t)virt_addr) >> 39;
uint64_t pdpt_offset = (((uint64_t)virt_addr) >> 30) & 0x1FF;
uint64_t pd_offset = (((uint64_t)virt_addr) >> 21) & 0x1FF;
uint64_t pt_offset = (((uint64_t)virt_addr) >> 12) & 0x1FF;
uint64_t page_offset = (((uint64_t)virt_addr) ) & 0xFFF;
if (!pml4[pml4_offset].flags & F_PRESENT) {
void *new_page = alloc_phys_page();
memset(new_page, 0, 4096);
pml4[pml4_offset].address = ((uint64_t)new_page) >> 12;
pml4[pml4_offset].flags = F_PRESENT | flags;
}
struct pdpte *pdpt = (struct pdpte *)(pml4[pml4_offset].address << 12);
if (!pdpt[pdpt_offset].flags & F_PRESENT) {
void *new_page = alloc_phys_page();
memset(new_page, 0, 4096);
pdpt[pdpt_offset].address = ((uint64_t)new_page) >> 12;
pdpt[pdpt_offset].flags = F_PRESENT | flags;
}
struct pde *pd = (struct pde *)(pdpt[pdpt_offset].address << 12);
if (!pd[pd_offset].flags & F_PRESENT) {
void *new_page = alloc_phys_page();
memset(new_page, 0, 4096);
pd[pd_offset].address = ((uint64_t)new_page) >> 12;
pd[pd_offset].flags = F_PRESENT | flags;
}
struct pte *pt = (struct pte *)(pd[pd_offset].address << 12);
if (!pt[pt_offset].flags & F_PRESENT) {
pt[pt_offset].flags |= F_PRESENT | flags;
}
pt[pt_offset].address = (((uint64_t)phys_addr) >> 12);
invlpg(virt_addr);
return 0;
}
int unmap_page(struct pml4e *pml4, void *virt_addr) {
uint64_t pml4_offset = ((uint64_t)virt_addr) >> 39;
uint64_t pdpt_offset = (((uint64_t)virt_addr) >> 30) & 0x1FF;
uint64_t pd_offset = (((uint64_t)virt_addr) >> 21) & 0x1FF;
uint64_t pt_offset = (((uint64_t)virt_addr) >> 12) & 0x1FF;
uint64_t page_offset = (((uint64_t)virt_addr) ) & 0xFFF;
if (!pml4[pml4_offset].flags & F_PRESENT)
return -1;
struct pdpte *pdpt = (struct pdpte *)(pml4[pml4_offset].address << 12);
if (!pdpt[pdpt_offset].flags & F_PRESENT)
return -1;
struct pde *pd = (struct pde *)(pdpt[pdpt_offset].address << 12);
if (!pd[pd_offset].flags & F_PRESENT)
return -1;
struct pte *pt = (struct pte *)(pd[pd_offset].address << 12);
if (!pt[pt_offset].flags & F_PRESENT)
return -1;
pt[pt_offset].flags = 0;
int i = 0;
for(; i < 512; i++) {
if (pt[i].flags & F_PRESENT)
break;
}
if (i == 512)
goto done;
pd[pd_offset].flags = 0;
for(i = 0; i < 512; i++) {
if (pd[i].flags & F_PRESENT)
break;
}
if (i == 512)
goto done;
pdpt[pdpt_offset].flags = 0;
for(i = 0; i < 512; i++) {
if(pdpt[i].flags & F_PRESENT)
break;
}
if (i == 512)
goto done;
pml4[pml4_offset].flags = 0;
//TODO: Return memory used for page structures
done:
invlpg(virt_addr);
return 0;
}
// entry point for amd64
void* amd64_shim(void *boot_info) {
struct pml4e *pml4 = (struct pml4e *)0x1000;
struct pdpte *pdpt = (struct pdpte *)0x2000;
struct pde *pd = (struct pd *)0x3000;
struct pte *pt = (struct pt *)0x4000;
pd[1].flags = F_PRESENT | F_WRITEABLE;
pd[1].address = ((uint64_t)pt) >> 12;
__asm("invlpg 0x200000");
struct pde *pd = (struct pde *)0x3000;
struct pte *pt = (struct pte *)0x4000;
//pd[1].flags = F_PRESENT | F_WRITEABLE;
//pd[1].address = ((uint64_t)pt) >> 12;
map_page(pml4, 0x80000000, 0xB8002, F_WRITEABLE);
//__asm("invlpg 0x200000");
void *ret;
find_phys_addr(pml4, 0x80000000, &ret);
return ret;
}

5
src/kmain.c
View file

@ -1,9 +1,10 @@
#include <lib.h>
#include <serial.h>
void kmain(void *info) {
char buf[20];
*(char*)0xB8000 = 'c';
*(char*)(0xB8002 + 0x20'0000) = 'd';
itoa((long)info, buf, 10);
//*(char*)(0xB8002 + 0x20'0000) = 'd';
itoa((long)info, buf, 16);
serial_out_str(buf);
}