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[metal] Fix sys_mmap_metal() issues for non-MAP_FIXED case

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- correctly check that virtual region we want to use is
  unmapped, rather than accidentally clobbering existing pages
- avoid placing mmap'd memory at null virtual address
This commit is contained in:
tkchia 2022-10-06 10:31:04 +00:00
parent 81ee11a16e
commit df37488ebd
1 changed files with 3 additions and 1 deletions
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4
libc/intrin/directmap-metal.c
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@ -39,8 +39,10 @@ noasan struct DirectMap sys_mmap_metal(void *paddr, size_t size, int prot,
size = ROUNDUP(size, 4096);
addr = (uint64_t)paddr;
if (!(flags & MAP_FIXED)) {
if (!addr)
addr = 4096;
for (i = 0; i < size; i += 4096) {
pte = __get_virtual(mm, pml4t, addr, false);
pte = __get_virtual(mm, pml4t, addr + i, false);
if (pte && (*pte & PAGE_V)) {
addr = MAX(addr, sys_mmap_metal_break) + i + 4096;
i = 0;