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Fix sys_mmap_metal() for non-MAP_FIXED case (#651)

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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
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tkchia 2022-10-07 07:27:52 +08:00 • committed by GitHub
parent 7bc24888fe
commit bc353f454b
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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;