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Revert "arm64: Mark kernel page ranges contiguous"

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This reverts commit 348a65cdcb.

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>
This commit is contained in:
Catalin Marinas 2015-11-26 15:42:41 +00:00
parent 0ebea80880
commit 667c27597c
1 changed files with 8 additions and 61 deletions
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69
arch/arm64/mm/mmu.c
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@ -85,55 +85,19 @@ static void split_pmd(pmd_t *pmd, pte_t *pte)
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 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
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 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
}
}
} 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);