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[arch][arm64] fix setting of UXN and PXN bits for NX permission

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Previously would only set both UXN and PXN for no execute pages, but for
pages not marked no execute, neither bit was set. Change to mask out the
other privilege mode.
This commit is contained in:
Travis Geiselbrecht
2021-12-05 23:22:54 -08:00
parent 1a54b73e84
commit a01c181ea7
1 changed files with 18 additions and 2 deletions
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20
arch/arm64/mmu.c
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@@ -71,6 +71,13 @@ static pte_t mmu_flags_to_pte_attr(uint flags) {
if (flags & ARCH_MMU_FLAG_PERM_NO_EXECUTE) {
attr |= MMU_PTE_ATTR_UXN | MMU_PTE_ATTR_PXN;
} else {
// execute permissions, so set user or privileged XN based on which mode
if (flags & ARCH_MMU_FLAG_PERM_USER) {
attr |= MMU_PTE_ATTR_PXN;
} else {
attr |= MMU_PTE_ATTR_UXN;
}
}
if (flags & ARCH_MMU_FLAG_NS) {
@@ -179,8 +186,17 @@ status_t arch_mmu_query(arch_aspace_t *aspace, vaddr_t vaddr, paddr_t *paddr, ui
*flags |= ARCH_MMU_FLAG_PERM_USER | ARCH_MMU_FLAG_PERM_RO;
break;
}
if ((pte & MMU_PTE_ATTR_UXN) && (pte & MMU_PTE_ATTR_PXN)) {
*flags |= ARCH_MMU_FLAG_PERM_NO_EXECUTE;
// if we have previously detected a user or privileged page, test
// the appropriate NX bit to determine no execute
if (*flags & ARCH_MMU_FLAG_PERM_USER) {
if (pte & MMU_PTE_ATTR_UXN) {
*flags |= ARCH_MMU_FLAG_PERM_NO_EXECUTE;
}
} else {
if (pte & MMU_PTE_ATTR_PXN) {
*flags |= ARCH_MMU_FLAG_PERM_NO_EXECUTE;
}
}
}
LTRACEF("va 0x%lx, paddr 0x%lx, flags 0x%x\n",