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Commit 56dd4709 authored by Russell King's avatar Russell King
Browse files

ARM: make_coherent: fix problems with highpte, part 1 



update_mmu_cache() is called with a page table already mapped.  We
call make_coherent(), which then calls adjust_pte() which wants to
map other page tables.  This causes kmap_atomic() to BUG() because
the slot its trying to use is already taken.

Since do_adjust_pte() modifies the page tables, we are also missing
any form of locking, so we're risking corrupting the page tables.

Fix this by using pte_offset_map_nested(), and taking the pte page
table lock around do_adjust_pte().

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent f8a85f11

arch/arm/mm/fault-armv.c

+11 −2
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address, 


static int adjust_pte(struct vm_area_struct *vma, unsigned long address)

{

	spinlock_t *ptl;

	pgd_t *pgd;

	pmd_t *pmd;

	pte_t *pte;
@@ -80,11 +81,19 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address) 
	if (pmd_none_or_clear_bad(pmd))

		return 0;



	pte = pte_offset_map(pmd, address);

	/*

	 * This is called while another page table is mapped, so we

	 * must use the nested version.  This also means we need to

	 * open-code the spin-locking.

	 */

	ptl = pte_lockptr(vma->vm_mm, pmd);

	pte = pte_offset_map_nested(pmd, address);

	spin_lock(ptl);



	ret = do_adjust_pte(vma, address, pte);



	pte_unmap(pte);

	spin_unlock(ptl);

	pte_unmap_nested(pte);



	return ret;

}