Revert "arm64: Mark kernel page ranges contiguous"
This reverts commit 348a65cdcbbf243073ee39d1f7d4413081ad7eab.
Incorrect page table manipulation that does not respect the ARM ARM
recommended break-before-make sequence may lead to TLB conflicts. The
contiguous PTE patch makes the system even more susceptible to such
errors by changing the mapping from a single page to a contiguous range
of pages. An additional TLB invalidation would reduce the risk window,
however, the correct fix is to switch to a temporary swapper_pg_dir.
Once the correct workaround is done, the reverted commit will be
re-applied.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Jeremy Linton <jeremy.linton@arm.com>
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 78d91b1..873e363 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -85,55 +85,19 @@
do {
/*
* Need to have the least restrictive permissions available
- * permissions will be fixed up later. Default the new page
- * range as contiguous ptes.
+ * permissions will be fixed up later
*/
- set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT));
+ set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
pfn++;
} while (pte++, i++, i < PTRS_PER_PTE);
}
-/*
- * Given a PTE with the CONT bit set, determine where the CONT range
- * starts, and clear the entire range of PTE CONT bits.
- */
-static void clear_cont_pte_range(pte_t *pte, unsigned long addr)
-{
- int i;
-
- pte -= CONT_RANGE_OFFSET(addr);
- for (i = 0; i < CONT_PTES; i++) {
- set_pte(pte, pte_mknoncont(*pte));
- pte++;
- }
- flush_tlb_all();
-}
-
-/*
- * Given a range of PTEs set the pfn and provided page protection flags
- */
-static void __populate_init_pte(pte_t *pte, unsigned long addr,
- unsigned long end, phys_addr_t phys,
- pgprot_t prot)
-{
- unsigned long pfn = __phys_to_pfn(phys);
-
- do {
- /* clear all the bits except the pfn, then apply the prot */
- set_pte(pte, pfn_pte(pfn, prot));
- pte++;
- pfn++;
- addr += PAGE_SIZE;
- } while (addr != end);
-}
-
static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
- unsigned long end, phys_addr_t phys,
+ unsigned long end, unsigned long pfn,
pgprot_t prot,
void *(*alloc)(unsigned long size))
{
pte_t *pte;
- unsigned long next;
if (pmd_none(*pmd) || pmd_sect(*pmd)) {
pte = alloc(PTRS_PER_PTE * sizeof(pte_t));
@@ -146,27 +110,9 @@
pte = pte_offset_kernel(pmd, addr);
do {
- next = min(end, (addr + CONT_SIZE) & CONT_MASK);
- if (((addr | next | phys) & ~CONT_MASK) == 0) {
- /* a block of CONT_PTES */
- __populate_init_pte(pte, addr, next, phys,
- __pgprot(pgprot_val(prot) | PTE_CONT));
- } else {
- /*
- * If the range being split is already inside of a
- * contiguous range but this PTE isn't going to be
- * contiguous, then we want to unmark the adjacent
- * ranges, then update the portion of the range we
- * are interrested in.
- */
- clear_cont_pte_range(pte, addr);
- __populate_init_pte(pte, addr, next, phys, prot);
- }
-
- pte += (next - addr) >> PAGE_SHIFT;
- phys += next - addr;
- addr = next;
- } while (addr != end);
+ set_pte(pte, pfn_pte(pfn, prot));
+ pfn++;
+ } while (pte++, addr += PAGE_SIZE, addr != end);
}
static void split_pud(pud_t *old_pud, pmd_t *pmd)
@@ -227,7 +173,8 @@
}
}
} else {
- alloc_init_pte(pmd, addr, next, phys, prot, alloc);
+ alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
+ prot, alloc);
}
phys += next - addr;
} while (pmd++, addr = next, addr != end);