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Commit bd0dbb73 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. 



When splitting a huge pmd pte, we need to mark the pmd entry invalid. We
can do that by clearing _PAGE_PRESENT bit. But then that will be taken as a
swap pte. In order to differentiate between the two use a software pte bit
when invalidating.

For regular pte, due to bd5050e3 ("powerpc/mm/radix: Change pte relax
sequence to handle nest MMU hang") we need to mark the pte entry invalid when
relaxing access permission. Instead of marking pte_none which can result in
different page table walk routines possibly skipping this pte entry, invalidate
it but still keep it marked present.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 810e9f86

arch/powerpc/include/asm/book3s/64/pgtable.h

+17 −1
Original line number Diff line number Diff line
@@ -44,6 +44,16 @@ 


#define _PAGE_PTE		0x4000000000000000UL	/* distinguishes PTEs from pointers */

#define _PAGE_PRESENT		0x8000000000000000UL	/* pte contains a translation */

/*

 * We need to mark a pmd pte invalid while splitting. We can do that by clearing

 * the _PAGE_PRESENT bit. But then that will be taken as a swap pte. In order to

 * differentiate between two use a SW field when invalidating.

 *

 * We do that temporary invalidate for regular pte entry in ptep_set_access_flags

 *

 * This is used only when _PAGE_PRESENT is cleared.

 */

#define _PAGE_INVALID		_RPAGE_SW0



/*

 * Top and bottom bits of RPN which can be used by hash
@@ -568,7 +578,13 @@ static inline pte_t pte_clear_savedwrite(pte_t pte) 


static inline int pte_present(pte_t pte)

{

	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT));

	/*

	 * A pte is considerent present if _PAGE_PRESENT is set.

	 * We also need to consider the pte present which is marked

	 * invalid during ptep_set_access_flags. Hence we look for _PAGE_INVALID

	 * if we find _PAGE_PRESENT cleared.

	 */

	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_INVALID));

}



#ifdef CONFIG_PPC_MEM_KEYS