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efi: Rework EFI memory map sanitisation

This commit is contained in:
mintsuki 2021-08-22 15:02:33 +02:00
parent ee3131bdfa
commit dadca8fe17
1 changed files with 63 additions and 6 deletions
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69
stage23/lib/blib.c
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@ -125,24 +125,81 @@ bool efi_exit_boot_services(void) {
// Go through new EFI memmap and free up bootloader entries
size_t entry_count = efi_mmap_size / efi_desc_size;
for (size_t i = 0; i < entry_count; i++) {
EFI_MEMORY_DESCRIPTOR *entry = (void *)efi_mmap + i * efi_desc_size;
EFI_MEMORY_DESCRIPTOR *efi_copy = ext_mem_alloc(256 * efi_desc_size);
size_t efi_copy_i = 0;
uint64_t base = entry->PhysicalStart;
for (size_t i = 0; i < entry_count; i++) {
EFI_MEMORY_DESCRIPTOR *orig_entry = (void *)efi_mmap + i * efi_desc_size;
EFI_MEMORY_DESCRIPTOR *new_entry = (void *)efi_copy + efi_copy_i * efi_desc_size;
memcpy(new_entry, orig_entry, efi_desc_size);
uint64_t base = orig_entry->PhysicalStart;
uint64_t length = orig_entry->NumberOfPages * 4096;
uint64_t top = base + length;
// Find for a match in the untouched memory map
for (size_t j = 0; j < untouched_memmap_entries; j++) {
if (untouched_memmap[j].type != MEMMAP_USABLE)
continue;
if (untouched_memmap[j].base == base) {
// It's a match!
entry->Type = EfiConventionalMemory;
if (untouched_memmap[j].base >= base && untouched_memmap[j].base < top) {
if (untouched_memmap[j].base > base) {
new_entry->NumberOfPages = (untouched_memmap[j].base - base) / 4096;
efi_copy_i++;
if (efi_copy_i == 256) {
panic("efi: New memory map exhausted");
}
new_entry = (void *)efi_copy + efi_copy_i * efi_desc_size;
memcpy(new_entry, orig_entry, efi_desc_size);
new_entry->NumberOfPages -= (untouched_memmap[j].base - base) / 4096;
new_entry->PhysicalStart = untouched_memmap[j].base;
new_entry->VirtualStart = new_entry->PhysicalStart;
base = new_entry->PhysicalStart;
length = new_entry->NumberOfPages * 4096;
top = base + length;
}
if (length < untouched_memmap[j].length) {
panic("efi: Memory map corruption");
}
new_entry->Type = EfiConventionalMemory;
if (length == untouched_memmap[j].length) {
// It's a perfect match!
break;
}
new_entry->NumberOfPages = untouched_memmap[j].length / 4096;
efi_copy_i++;
if (efi_copy_i == 256) {
panic("efi: New memory map exhausted");
}
new_entry = (void *)efi_copy + efi_copy_i * efi_desc_size;
memcpy(new_entry, orig_entry, efi_desc_size);
new_entry->NumberOfPages = (length - untouched_memmap[j].length) / 4096;
new_entry->PhysicalStart = base + untouched_memmap[j].length;
new_entry->VirtualStart = new_entry->PhysicalStart;
break;
}
}
efi_copy_i++;
if (efi_copy_i == 256) {
panic("efi: New memory map exhausted");
}
}
efi_mmap = efi_copy;
efi_mmap_size = efi_copy_i * efi_desc_size;
efi_boot_services_exited = true;
printv("efi: Exited boot services.\n");