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rewrite code for map/unmap

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This commit is contained in:
Eggert Jung
2026-02-24 10:02:40 +01:00
parent 48fea8f8d8
commit 50dfd49d43
1 changed files with 112 additions and 32 deletions
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130
kernel/syscall/skeleton.cc
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@@ -14,6 +14,8 @@ void *operator new(size_t, void *);
uint8_t mapNumber = 0;
uint32_t next_start_v = 0x4000;
namespace Syscall {
namespace Skeleton {
@@ -138,64 +140,142 @@ namespace Syscall {
}
uintptr_t isMapped(uintptr_t vaddr, four_lvl_paging_t* flpt){
uint16_t l4Index = (vaddr>>39) & 0x1FF;
uint16_t l3Index = (vaddr>>30) & 0x1FF;
uint16_t l2Index = (vaddr>>21) & 0x1FF;
uint16_t l1Index = (vaddr>>12) & 0x1FF;
void* getFreeVirtSpace(Vault* vault, uint8_t num_pages){
pagetable_t* subbytable = vault->scheduler.active()->subtable;
//uint32_t page_counter=0;
for (uint32_t v=0x4000; v<0x4200; v++) {
if(flpt->l4->entries[l4Index].present){
pagetable_t* lvl3 = (pagetable_t*)(flpt->l4->entries[l4Index].address<<12);
if(lvl3->entries[l3Index].present){
pagetable_t* lvl2 = (pagetable_t*)(lvl3->entries[l3Index].address<<12);
if(lvl2->entries[l2Index].present){
pagetable_t* lvl1 = (pagetable_t*)(lvl2->entries[l2Index].address<<12);
if(lvl1->entries[l1Index].present)
return lvl1->entries[l1Index].address<<12;
}
}
}
return 0;
}
void* getFreeVirtSpace(four_lvl_paging_t* search_table, uint8_t num_pages){
uint32_t start_v = 0x4000;
uint32_t stop_v = 0x6000;
//static uint32_t next_start_v = start_v;
//start from last found address
for (uint32_t v=next_start_v; v<stop_v; v++) {
bool space_is_free = true;
for(uint32_t i=0; i<num_pages; i++){
if(subbytable->entries[v-0x4000+i].present) {
if(isMapped((uintptr_t)(v+i)<<12, search_table)) {
space_is_free = false;
}
}
if(space_is_free)
if(space_is_free){
next_start_v = v+num_pages;
return (void*) ((uintptr_t) (v <<12));
}
}
//start again from the real start address
for (uint32_t v=start_v; v<next_start_v; v++) {
bool space_is_free = true;
for(uint32_t i=0; i<num_pages; i++){
if(isMapped((uintptr_t)(v+i)<<12, search_table)) {
space_is_free = false;
}
}
if(space_is_free){
next_start_v = v+num_pages;
return (void*) ((uintptr_t) (v <<12));
}
}
return 0;
}
void setMapping(uintptr_t vaddr, void* frame, four_lvl_paging_t* flpt){
uint16_t l4Index = (vaddr>>39) & 0x1FF;
uint16_t l3Index = (vaddr>>30) & 0x1FF;
uint16_t l2Index = (vaddr>>21) & 0x1FF;
uint16_t l1Index = (vaddr>>12) & 0x1FF;
if(!(flpt->l4->entries[l4Index].present)){
pagetable_t* newl3 = (pagetable_t*)PageFrameAllocator::alloc(true);
flpt->l4->entries[l4Index] = {
.present = 1,
.write = 1,
.user = 1,
.address = (uintptr_t)newl3 >> 12
};
}
pagetable_t* lvl3 = (pagetable_t*)(flpt->l4->entries[l4Index].address<<12);
if(!(lvl3->entries[l3Index].present)){
pagetable_t* newl2 = (pagetable_t*)PageFrameAllocator::alloc(true);
lvl3->entries[l3Index] = {
.present = 1,
.write = 1,
.user = 1,
.address = (uintptr_t)newl2 >> 12
};
}
pagetable_t* lvl2 = (pagetable_t*)(lvl3->entries[l3Index].address<<12);
if(!(lvl2->entries[l2Index].present)){
pagetable_t* newl1 = (pagetable_t*)PageFrameAllocator::alloc(true);
lvl2->entries[l2Index] = {
.present = 1,
.write = 1,
.user = 1,
.address = (uintptr_t)newl1 >> 12
};
}
pagetable_t* lvl1 = (pagetable_t*)(lvl2->entries[l2Index].address<<12);
assert(!(lvl1->entries[l1Index].present)); // should not be present, bc its a new mapping
if(frame)
lvl1->entries[l1Index] = {
.present = 1,
.write = 1,
.user = 1,
.address = (uintptr_t)frame >> 12
};
else //unmap if nullptr
lvl1->entries[l1Index].present = 0;
}
void* map(Vault *vault, size_t size) {
size_t num_pages = (size + 4096 - 1) / 4096;
pagetable_t* subbytable = vault->scheduler.active()->subtable;
//pagetable_t* subbytable = vault->scheduler.active()->subtable;
four_lvl_paging_t* search_table = vault->scheduler.active()->paging_tree;
void* ptr = getFreeVirtSpace(vault, num_pages);
void* ptr = getFreeVirtSpace(search_table, num_pages);
if (ptr == nullptr) {
return nullptr;
}
uintptr_t gap_start = reinterpret_cast<uintptr_t>(ptr);
// map all used pages
for (size_t i = 0; i < num_pages; ++i) {
// allocate each page with allocator
void* frame = PageFrameAllocator::alloc(false);
subbytable->entries[(( (uintptr_t) ptr-64*1024*1024) /4096)+i] ={
.present = 1,
.write =1,
.user =1,
.address = ((uintptr_t) frame >> 12)
};
setMapping((uintptr_t)ptr, frame, search_table);
}
return ptr;
}
int unmap(Vault &vault, void* start, size_t size) {
uint32_t NumberOfPages = (size/4096);
pagetable_t* subbytable = vault.scheduler.active()->subtable;
uint32_t startIndex = (((uintptr_t)start-64*1024*1024)>>12);
four_lvl_paging_t* search_table = vault.scheduler.active()->paging_tree;
uint32_t startIndex = ((uintptr_t)start)>>12;
memset(start, 0, size);
for(uint32_t i=startIndex; i<(startIndex+NumberOfPages); i++){
for (uint32_t p =0; p<512 ; p++) {
if (subbytable->entries[p].present==1 && subbytable->entries[p].address==i) {
uintptr_t frame = isMapped(i<<12, search_table);
setMapping(i<<12, 0, search_table);
PageFrameAllocator::free(frame);
invlpg(i);
PageFrameAllocator::free(subbytable->entries[p].address);
subbytable->entries[i].present =0;
}
}
}
return 0;
}