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Commit f1b0b8c2 authored by Christophe Leroy's avatar Christophe Leroy Committed by Greg Kroah-Hartman
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powerpc/8xx: Always fault when _PAGE_ACCESSED is not set 



commit 29daf869cbab69088fe1755d9dd224e99ba78b56 upstream.

The kernel expects pte_young() to work regardless of CONFIG_SWAP.

Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.

This adds at least 3 instructions to the TLB miss exception
handlers fast path. Following patch will reduce this overhead.

Also update the rotation instruction to the correct number of bits
to reflect all changes done to _PAGE_ACCESSED over time.

Fixes: d069cb43 ("powerpc/8xx: Don't touch ACCESSED when no SWAP.")
Fixes: 5f356497 ("powerpc/8xx: remove unused _PAGE_WRITETHRU")
Fixes: e0a8e0d9 ("powerpc/8xx: Handle PAGE_USER via APG bits")
Fixes: 5b2753fc ("powerpc/8xx: Implementation of PAGE_EXEC")
Fixes: a891c43b97d3 ("powerpc/8xx: Prepare handlers for _PAGE_HUGE for 512k pages.")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/af834e8a0f1fa97bfae65664950f0984a70c4750.1602492856.git.christophe.leroy@csgroup.eu


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5e7ceb3a

arch/powerpc/kernel/head_8xx.S

+2 −6
Original line number Diff line number Diff line
@@ -356,11 +356,9 @@ _ENTRY(ITLBMiss_cmp) 
	/* Load the MI_TWC with the attributes for this "segment." */

	mtspr	SPRN_MI_TWC, r11	/* Set segment attributes */



#ifdef CONFIG_SWAP

	rlwinm	r11, r10, 32-5, _PAGE_PRESENT

	rlwinm	r11, r10, 32-7, _PAGE_PRESENT

	and	r11, r11, r10

	rlwimi	r10, r11, 0, _PAGE_PRESENT

#endif

	li	r11, RPN_PATTERN | 0x200

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

	 * Software indicator bits 20 and 23 must be clear.
@@ -482,11 +480,9 @@ _ENTRY(DTLBMiss_jmp) 
	 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));

	 * r10 = (r10 & ~PRESENT) | r11;

	 */

#ifdef CONFIG_SWAP

	rlwinm	r11, r10, 32-5, _PAGE_PRESENT

	rlwinm	r11, r10, 32-7, _PAGE_PRESENT

	and	r11, r11, r10

	rlwimi	r10, r11, 0, _PAGE_PRESENT

#endif

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

	 * Software indicator bits 24, 25, 26, and 27 must be

	 * set.  All other Linux PTE bits control the behavior