Commit 7a1e3350 authored by Kumar Gala's avatar Kumar Gala Committed by Linus Torvalds
Browse files

[PATCH] ppc32: Fix pte_update for 64-bit PTEs 



While the existing pte_update code handled atomically modifying a 64-bit PTE,
it did not return all 64-bits of the PTE before it was modified.  This causes
problems in some places that expect the full PTE to be returned, like
ptep_get_and_clear().

Created a new pte_update function that is conditional on CONFIG_PTE_64BIT.  It
atomically reads the low PTE word which all PTE flags are required to be in
and returns a premodified full 64-bit PTE.

Since we now have an explicit 64-bit PTE version of pte_update we can also
remove the hack that existed to get the low PTE word regardless of size.

Signed-off-by: default avatarKumar Gala <kumar.gala@freescale.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0c541b44

include/asm-ppc/pgtable.h

+25 −4
Original line number Diff line number Diff line
@@ -526,10 +526,10 @@ extern void add_hash_page(unsigned context, unsigned long va, 
 * Atomic PTE updates.

 *

 * pte_update clears and sets bit atomically, and returns

 * the old pte value.

 * The ((unsigned long)(p+1) - 4) hack is to get to the least-significant

 * 32 bits of the PTE regardless of whether PTEs are 32 or 64 bits.

 * the old pte value.  In the 64-bit PTE case we lock around the

 * low PTE word since we expect ALL flag bits to be there

 */

#ifndef CONFIG_PTE_64BIT

static inline unsigned long pte_update(pte_t *p, unsigned long clr,

				       unsigned long set)

{
@@ -543,10 +543,31 @@ static inline unsigned long pte_update(pte_t *p, unsigned long clr, 
"	stwcx.	%1,0,%3\n\

	bne-	1b"

	: "=&r" (old), "=&r" (tmp), "=m" (*p)

	: "r" ((unsigned long)(p+1) - 4), "r" (clr), "r" (set), "m" (*p)

	: "r" (p), "r" (clr), "r" (set), "m" (*p)

	: "cc" );

	return old;

}

#else

static inline unsigned long long pte_update(pte_t *p, unsigned long clr,

				       unsigned long set)

{

	unsigned long long old;

	unsigned long tmp;



	__asm__ __volatile__("\

1:	lwarx	%L0,0,%4\n\

	lwzx	%0,0,%3\n\

	andc	%1,%L0,%5\n\

	or	%1,%1,%6\n"

	PPC405_ERR77(0,%3)

"	stwcx.	%1,0,%4\n\

	bne-	1b"

	: "=&r" (old), "=&r" (tmp), "=m" (*p)

	: "r" (p), "r" ((unsigned long)(p) + 4), "r" (clr), "r" (set), "m" (*p)

	: "cc" );

	return old;

}

#endif



/*

 * set_pte stores a linux PTE into the linux page table.