[This is backport for 4.9 of 29daf869cbab69088fe1755d9dd224e99ba78b56]

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: d069cb4373fe ("powerpc/8xx: Don't touch ACCESSED when no SWAP.") Fixes: 5f356497c384 ("powerpc/8xx: remove unused _PAGE_WRITETHRU") Fixes: e0a8e0d90a9f ("powerpc/8xx: Handle PAGE_USER via APG bits") Fixes: 5b2753fc3e8a ("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: Christophe Leroy christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/af834e8a0f1fa97bfae65664950f0984a70c4750.160249285... --- arch/powerpc/kernel/head_8xx.S | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 2274be535dda..3801b32b1642 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -359,11 +359,9 @@ InstructionTLBMiss: /* Load the MI_TWC with the attributes for this "segment." */ MTSPR_CPU6(SPRN_MI_TWC, r11, r3) /* Set segment attributes */

-#ifdef CONFIG_SWAP - rlwinm r11, r10, 32-5, _PAGE_PRESENT + rlwinm r11, r10, 32-11, _PAGE_PRESENT and r11, r11, r10 rlwimi r10, r11, 0, _PAGE_PRESENT -#endif li r11, RPN_PATTERN /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 20-23 and 28 must be clear. @@ -443,11 +441,9 @@ _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, 32-11, _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 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be