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Commit 6a72dc03 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/64s/hash: Fix 128TB-512TB virtual address boundary case allocation 



When allocating VA space with a hint that crosses 128TB, the SLB
addr_limit variable is not expanded if addr is not > 128TB, but the
slice allocation looks at task_size, which is 512TB. This results in
slice_check_fit() incorrectly succeeding because the slice_count
truncates off bit 128 of the requested mask, so the comparison to the
available mask succeeds.

Fix this by using mm->context.addr_limit instead of mm->task_size for
testing allocation limits. This causes such allocations to fail.

Fixes: f4ea6dcb ("powerpc/mm: Enable mappings above 128TB")
Cc: stable@vger.kernel.org # v4.12+
Reported-by: default avatarFlorian Weimer <fweimer@redhat.com>
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 7ece3709

arch/powerpc/mm/slice.c

+24 −26
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr, 
{

	struct vm_area_struct *vma;



	if ((mm->task_size - len) < addr)

	if ((mm->context.addr_limit - len) < addr)

		return 0;

	vma = find_vma(mm, addr);

	return (!vma || (addr + len) <= vm_start_gap(vma));
@@ -133,7 +133,7 @@ static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret) 
		if (!slice_low_has_vma(mm, i))

			ret->low_slices |= 1u << i;



	if (mm->task_size <= SLICE_LOW_TOP)

	if (mm->context.addr_limit <= SLICE_LOW_TOP)

		return;



	for (i = 0; i < GET_HIGH_SLICE_INDEX(mm->context.addr_limit); i++)
@@ -412,25 +412,31 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len, 
	struct slice_mask compat_mask;

	int fixed = (flags & MAP_FIXED);

	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

	unsigned long page_size = 1UL << pshift;

	struct mm_struct *mm = current->mm;

	unsigned long newaddr;

	unsigned long high_limit;



	/*

	 * Check if we need to expland slice area.

	 */

	if (unlikely(addr >= mm->context.addr_limit &&

		     mm->context.addr_limit != TASK_SIZE)) {

		mm->context.addr_limit = TASK_SIZE;

	high_limit = DEFAULT_MAP_WINDOW;

	if (addr >= high_limit)

		high_limit = TASK_SIZE;



	if (len > high_limit)

		return -ENOMEM;

	if (len & (page_size - 1))

		return -EINVAL;

	if (fixed) {

		if (addr & (page_size - 1))

			return -EINVAL;

		if (addr > high_limit - len)

			return -ENOMEM;

	}



	if (high_limit > mm->context.addr_limit) {

		mm->context.addr_limit = high_limit;

		on_each_cpu(slice_flush_segments, mm, 1);

	}

	/*

	 * This mmap request can allocate upt to 512TB

	 */

	if (addr >= DEFAULT_MAP_WINDOW)

		high_limit = mm->context.addr_limit;

	else

		high_limit = DEFAULT_MAP_WINDOW;



	/*

	 * init different masks

	 */
@@ -446,27 +452,19 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len, 


	/* Sanity checks */

	BUG_ON(mm->task_size == 0);

	BUG_ON(mm->context.addr_limit == 0);

	VM_BUG_ON(radix_enabled());



	slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize);

	slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n",

		  addr, len, flags, topdown);



	if (len > mm->task_size)

		return -ENOMEM;

	if (len & ((1ul << pshift) - 1))

		return -EINVAL;

	if (fixed && (addr & ((1ul << pshift) - 1)))

		return -EINVAL;

	if (fixed && addr > (mm->task_size - len))

		return -ENOMEM;



	/* If hint, make sure it matches our alignment restrictions */

	if (!fixed && addr) {

		addr = _ALIGN_UP(addr, 1ul << pshift);

		addr = _ALIGN_UP(addr, page_size);

		slice_dbg(" aligned addr=%lx\n", addr);

		/* Ignore hint if it's too large or overlaps a VMA */

		if (addr > mm->task_size - len ||

		if (addr > high_limit - len ||

		    !slice_area_is_free(mm, addr, len))

			addr = 0;

	}