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pmm: Significantly improve check_usable_memory() implementation

This commit is contained in:
mintsuki 2023-12-07 02:12:12 +01:00
parent c0683081d9
commit f8c06ff151
1 changed files with 32 additions and 2 deletions
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34
common/mm/pmm.c
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@ -12,14 +12,44 @@ static bool full_overlap_check(uint64_t base1, uint64_t top1,
}
bool check_usable_memory(uint64_t base, uint64_t top) {
uint64_t overlap_remaining = top - base;
for (size_t i = 0; i < memmap_entries; i++) {
if (memmap[i].type != MEMMAP_USABLE) {
if (memmap[i].type != MEMMAP_USABLE
#if defined (UEFI)
&& memmap[i].type != MEMMAP_EFI_RECLAIMABLE
#endif
&& memmap[i].type != MEMMAP_BOOTLOADER_RECLAIMABLE
&& memmap[i].type != MEMMAP_KERNEL_AND_MODULES) {
continue;
}
if (full_overlap_check(base, top, memmap[i].base, memmap[i].base + memmap[i].length)) {
uint64_t memmap_top = memmap[i].base + memmap[i].length;
if (full_overlap_check(base, top, memmap[i].base, memmap_top)) {
return true;
}
// Count how many bytes from a real-RAM entry overlap our range
if ((memmap[i].base >= base && memmap[i].base < top)
|| (memmap_top > base && memmap_top <= top)) {
uint64_t overlap_bottom = base;
if (memmap[i].base >= base && memmap[i].base < top) {
overlap_bottom = memmap[i].base;
}
uint64_t overlap_top = top;
if (memmap_top > base && memmap_top <= top) {
overlap_top = memmap_top;
}
uint64_t overlap_size = overlap_top - overlap_bottom;
overlap_remaining -= overlap_size;
if (overlap_remaining == 0) {
return true;
}
}
}
return false;