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Kernel: Repair unaligned regions supplied by the boot loader

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We were just blindly trusting that the bootloader would only give us
page-aligned memory regions. This is apparently not always the case,
so now we can try to repair those regions.

Fixes #601
This commit is contained in:
Conrad Pankoff 2019-09-28 16:22:50 +10:00 • committed by Andreas Kling
parent 24a51136fa
commit fa20a447a9
1 changed files with 16 additions and 0 deletions
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16
Kernel/VM/MemoryManager.cpp
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@ -102,6 +102,22 @@ void MemoryManager::initialize_paging()
if ((mmap->addr + mmap->len) > 0xffffffff) if ((mmap->addr + mmap->len) > 0xffffffff)
continue; continue;
auto diff = (u32)mmap->addr % PAGE_SIZE;
if (diff != 0) {
kprintf("MM: got an unaligned region base from the bootloader; correcting %p by %d bytes\n", mmap->addr, diff);
diff = PAGE_SIZE - diff;
mmap->addr += diff;
mmap->len -= diff;
}
if ((mmap->len % PAGE_SIZE) != 0) {
kprintf("MM: got an unaligned region length from the bootloader; correcting %d by %d bytes\n", mmap->len, mmap->len % PAGE_SIZE);
mmap->len -= mmap->len % PAGE_SIZE;
}
if (mmap->len < PAGE_SIZE) {
kprintf("MM: memory region from bootloader is too small; we want >= %d bytes, but got %d bytes\n", PAGE_SIZE, mmap->len);
continue;
}
#ifdef MM_DEBUG #ifdef MM_DEBUG
kprintf("MM: considering memory at %p - %p\n", kprintf("MM: considering memory at %p - %p\n",
(u32)mmap->addr, (u32)(mmap->addr + mmap->len)); (u32)mmap->addr, (u32)(mmap->addr + mmap->len));