powerpc/8xx: Remove _PAGE_USER and handle user access at PMD level

As Linux kernel separates KERNEL and USER address spaces, there is
therefore no need to flag USER access at page level.

Today, the 8xx TLB handlers already handle user access in the L1 entry
through Access Protection Groups, it is then natural to move the user
access handling at PMD level once _PAGE_NA allows to handle PAGE_NONE
protection without _PAGE_USER

In the mean time, as we free up one bit in the PTE, we can use it to
include SPS (page size flag) in the PTE and avoid handling it at every
TLB miss hence removing special handling based on compiled page size.

For _PAGE_EXEC, we rework it to use PP PTE bits, avoiding the copy
of _PAGE_EXEC bit into the L1 entry. Unfortunatly we are not
able to put it at the correct location as it conflicts with
NA/RO/RW bits for data entries.

Upper bits of APG in L1 entry overlap with PMD base address. In
order to avoid having to filter that out, we set up all groups so that
upper bits can have any value.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 10 insertions, 36 deletions

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 642680389b7e..c3b831bb8bad 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -52,11 +52,7 @@
  * Value for the bits that have fixed value in RPN entries.
  * Also used for tagging DAR for DTLBerror.
  */
-#ifdef CONFIG_PPC_16K_PAGES
-#define RPN_PATTERN	(0x00f0 | MD_SPS16K)
-#else
 #define RPN_PATTERN	0x00f0
-#endif
 
 #define PAGE_SHIFT_512K		19
 #define PAGE_SHIFT_8M		23
@@ -358,31 +354,23 @@ _ENTRY(ITLBMiss_cmp)
 #if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
 	mtcr	r12
 #endif
-	/* Insert the APG into the TWC from the Linux PTE. */
-	rlwimi	r11, r10, 0, 25, 26
 	/* Load the MI_TWC with the attributes for this "segment." */
 	mtspr	SPRN_MI_TWC, r11	/* Set segment attributes */
 
-#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
-	rlwimi	r10, r11, 1, MI_SPS16K
-#endif
 #ifdef CONFIG_SWAP
 	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
 	and	r11, r11, r10
 	rlwimi	r10, r11, 0, _PAGE_PRESENT
 #endif
-	li	r11, RPN_PATTERN
+	li	r11, RPN_PATTERN | 0x200
 	/* The Linux PTE won't go exactly into the MMU TLB.
-	 * Software indicator bits 20-23 and 28 must be clear.
-	 * Software indicator bits 24, 25, 26, and 27 must be
+	 * Software indicator bits 20 and 23 must be clear.
+	 * Software indicator bits 22, 24, 25, 26, and 27 must be
 	 * set.  All other Linux PTE bits control the behavior
 	 * of the MMU.
 	 */
-#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
-	rlwimi	r10, r11, 0, 0x0ff0	/* Set 24-27, clear 20-23 */
-#else
-	rlwimi	r10, r11, 0, 0x0ff8	/* Set 24-27, clear 20-23,28 */
-#endif
+	rlwimi	r11, r10, 4, 0x0400	/* Copy _PAGE_EXEC into bit 21 */
+	rlwimi	r10, r11, 0, 0x0ff0	/* Set 22, 24-27, clear 20,23 */
 	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */
 
 	/* Restore registers */
@@ -419,7 +407,6 @@ _ENTRY(itlb_miss_perf)
 	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
 #endif
 	lwz	r10, 0(r10)	/* Get the pte */
-	rlwinm	r11, r11, 0, 0xf
 	b	4b
 
 20:	/* 512k pages */
@@ -428,7 +415,6 @@ _ENTRY(itlb_miss_perf)
 	/* Add level 2 base */
 	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
 	lwz	r10, 0(r10)	/* Get the pte */
-	rlwinm	r11, r11, 0, 0xf
 	b	4b
 #endif
 
@@ -479,20 +465,15 @@ _ENTRY(DTLBMiss_jmp)
 4:
 	mtcr	r12
 
-	/* Insert the Guarded flag and APG into the TWC from the Linux PTE.
-	 * It is bit 26-27 of both the Linux PTE and the TWC (at least
+	/* Insert the Guarded flag into the TWC from the Linux PTE.
+	 * It is bit 27 of both the Linux PTE and the TWC (at least
 	 * I got that right :-).  It will be better when we can put
 	 * this into the Linux pgd/pmd and load it in the operation
 	 * above.
 	 */
-	rlwimi	r11, r10, 0, 26, 27
+	rlwimi	r11, r10, 0, _PAGE_GUARDED
 	mtspr	SPRN_MD_TWC, r11
 
-	/* In 4k pages mode, SPS (bit 28) in RPN must match PS[1] (bit 29)
-	 * In 16k pages mode, SPS is always 1 */
-#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
-	rlwimi	r10, r11, 1, MD_SPS16K
-#endif
 	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
 	 * We also need to know if the insn is a load/store, so:
 	 * Clear _PAGE_PRESENT and load that which will
@@ -508,17 +489,12 @@ _ENTRY(DTLBMiss_jmp)
 	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
 	 * set.  All other Linux PTE bits control the behavior
 	 * of the MMU.
 	 */
 	li	r11, RPN_PATTERN
-#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
 	rlwimi	r10, r11, 0, 24, 27	/* Set 24-27 */
-#else
-	rlwimi	r10, r11, 0, 24, 28	/* Set 24-27, clear 28 */
-#endif
 	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
 
 	/* Restore registers */
@@ -552,7 +528,6 @@ _ENTRY(dtlb_miss_perf)
 	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
 #endif
 	lwz	r10, 0(r10)	/* Get the pte */
-	rlwinm	r11, r11, 0, 0xf
 	b	4b
 
 20:	/* 512k pages */
@@ -561,7 +536,6 @@ _ENTRY(dtlb_miss_perf)
 	/* Add level 2 base */
 	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
 	lwz	r10, 0(r10)	/* Get the pte */
-	rlwinm	r11, r11, 0, 0xf
 	b	4b
 #endif
 
@@ -712,7 +686,7 @@ _ENTRY(dtlb_miss_exit_3)
 ITLBMissLinear:
 	mtcr	r12
 	/* Set 8M byte page and mark it valid */
-	li	r11, MI_PS8MEG | MI_SVALID | _PAGE_EXEC
+	li	r11, MI_PS8MEG | MI_SVALID
 	mtspr	SPRN_MI_TWC, r11
 	rlwinm	r10, r10, 0, 0x0f800000	/* 8xx supports max 256Mb RAM */
 	ori	r10, r10, 0xf0 | MI_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
@@ -994,7 +968,7 @@ initial_mmu:
 	lis	r8, KERNELBASE@h	/* Create vaddr for TLB */
 	ori	r8, r8, MI_EVALID	/* Mark it valid */
 	mtspr	SPRN_MI_EPN, r8
-	li	r8, MI_PS8MEG | (2 << 5)	/* Set 8M byte page, APG 2 */
+	li	r8, MI_PS8MEG /* Set 8M byte page */
 	ori	r8, r8, MI_SVALID	/* Make it valid */
 	mtspr	SPRN_MI_TWC, r8
 	li	r8, MI_BOOTINIT		/* Create RPN for address 0 */