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Commit 1757f2d1 authored by Yuri Tikhonov's avatar Yuri Tikhonov Committed by Kumar Gala
Browse files

[PPC] 8xx: swap bug-fix 



This makes swap routines operate correctly on the ppc_8xx based machines.

Recent kernel's size makes swap feature very important on low-memory platfor
those are actually non-operable without it.

Signed-off-by: default avatarYuri Tikhonov <yur@emcraft.com>
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
parent 3e0d65bf

arch/ppc/kernel/head_8xx.S

+29 −1
Original line number Diff line number Diff line
@@ -329,8 +329,18 @@ InstructionTLBMiss: 
	mfspr	r11, SPRN_MD_TWC	/* ....and get the pte address */

	lwz	r10, 0(r11)	/* Get the pte */



#ifdef CONFIG_SWAP

	/* do not set the _PAGE_ACCESSED bit of a non-present page */

	andi.	r11, r10, _PAGE_PRESENT

	beq	4f

	ori	r10, r10, _PAGE_ACCESSED

	mfspr	r11, SPRN_MD_TWC	/* get the pte address again */

	stw	r10, 0(r11)

4:

#else

	ori	r10, r10, _PAGE_ACCESSED

	stw	r10, 0(r11)

#endif



	/* The Linux PTE won't go exactly into the MMU TLB.

	 * Software indicator bits 21, 22 and 28 must be clear.
@@ -395,8 +405,17 @@ DataStoreTLBMiss: 
	DO_8xx_CPU6(0x3b80, r3)

	mtspr	SPRN_MD_TWC, r11



	mfspr	r11, SPRN_MD_TWC	/* get the pte address again */

#ifdef CONFIG_SWAP

	/* do not set the _PAGE_ACCESSED bit of a non-present page */

	andi.	r11, r10, _PAGE_PRESENT

	beq	4f

	ori	r10, r10, _PAGE_ACCESSED

4:

	/* and update pte in table */

#else

	ori	r10, r10, _PAGE_ACCESSED

#endif

	mfspr	r11, SPRN_MD_TWC	/* get the pte address again */

	stw	r10, 0(r11)



	/* The Linux PTE won't go exactly into the MMU TLB.
@@ -575,7 +594,16 @@ DataTLBError: 


	/* Update 'changed', among others.

	*/

#ifdef CONFIG_SWAP

	ori	r10, r10, _PAGE_DIRTY|_PAGE_HWWRITE

	/* do not set the _PAGE_ACCESSED bit of a non-present page */

	andi.	r11, r10, _PAGE_PRESENT

	beq	4f

	ori	r10, r10, _PAGE_ACCESSED

4:

#else

	ori	r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE

#endif

	mfspr	r11, SPRN_MD_TWC		/* Get pte address again */

	stw	r10, 0(r11)		/* and update pte in table */

include/asm-ppc/pgtable.h

+0 −8
Original line number Diff line number Diff line
@@ -299,14 +299,6 @@ extern unsigned long ioremap_bot, ioremap_base; 
#define _PMD_PAGE_MASK	0x000c

#define _PMD_PAGE_8M	0x000c



/*

 * The 8xx TLB miss handler allegedly sets _PAGE_ACCESSED in the PTE

 * for an address even if _PAGE_PRESENT is not set, as a performance

 * optimization.  This is a bug if you ever want to use swap unless

 * _PAGE_ACCESSED is 2, which it isn't, or unless you have 8xx-specific

 * definitions for __swp_entry etc. below, which would be gross.

 *  -- paulus

 */

#define _PTE_NONE_MASK _PAGE_ACCESSED



#else /* CONFIG_6xx */