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: 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/af834e8a0f1fa97bfae65664950f0984a70c4750.1602492856.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 9fd2ff28b8ff26b4ee3bc36aa18f038ae3d58c21..dc99258f2e8c6f26bfdb54da6ca95a09e4f0e285 100644 (file)
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -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