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Subject[PATCH v3] powerpc/32s: reorder Linux PTE bits to better match Hash PTE bits.
Date
Reorder Linux PTE bits to (almost) match Hash PTE bits.

RW Kernel : PP = 00
RO Kernel : PP = 00
RW User : PP = 01
RO User : PP = 11

So naturally, we should have
_PAGE_USER = 0x001
_PAGE_RW = 0x002

Today 0x001 and 0x002 and _PAGE_PRESENT and _PAGE_HASHPTE which
both are software only bits.

Switch _PAGE_USER and _PAGE_PRESET
Switch _PAGE_RW and _PAGE_HASHPTE

This allows to remove a few insns.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v3: rebased on today's powerpc/merge

v2: rebased on today's powerpc/merge
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/include/asm/book3s/32/hash.h | 8 ++++----
arch/powerpc/kernel/head_32.S | 9 +++------
arch/powerpc/mm/book3s32/hash_low.S | 14 ++++++--------
3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/hash.h b/arch/powerpc/include/asm/book3s/32/hash.h
index 2a0a467d2985..34a7215ae81e 100644
--- a/arch/powerpc/include/asm/book3s/32/hash.h
+++ b/arch/powerpc/include/asm/book3s/32/hash.h
@@ -17,9 +17,9 @@
* updating the accessed and modified bits in the page table tree.
*/

-#define _PAGE_PRESENT 0x001 /* software: pte contains a translation */
-#define _PAGE_HASHPTE 0x002 /* hash_page has made an HPTE for this pte */
-#define _PAGE_USER 0x004 /* usermode access allowed */
+#define _PAGE_USER 0x001 /* usermode access allowed */
+#define _PAGE_RW 0x002 /* software: user write access allowed */
+#define _PAGE_PRESENT 0x004 /* software: pte contains a translation */
#define _PAGE_GUARDED 0x008 /* G: prohibit speculative access */
#define _PAGE_COHERENT 0x010 /* M: enforce memory coherence (SMP systems) */
#define _PAGE_NO_CACHE 0x020 /* I: cache inhibit */
@@ -27,7 +27,7 @@
#define _PAGE_DIRTY 0x080 /* C: page changed */
#define _PAGE_ACCESSED 0x100 /* R: page referenced */
#define _PAGE_EXEC 0x200 /* software: exec allowed */
-#define _PAGE_RW 0x400 /* software: user write access allowed */
+#define _PAGE_HASHPTE 0x400 /* hash_page has made an HPTE for this pte */
#define _PAGE_SPECIAL 0x800 /* software: Special page */

#ifdef CONFIG_PTE_64BIT
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 97c887950c3c..daaa153950c2 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -348,7 +348,7 @@ BEGIN_MMU_FTR_SECTION
andis. r0, r5, (DSISR_BAD_FAULT_32S | DSISR_DABRMATCH)@h
#endif
bne handle_page_fault_tramp_2 /* if not, try to put a PTE */
- rlwinm r3, r5, 32 - 15, 21, 21 /* DSISR_STORE -> _PAGE_RW */
+ rlwinm r3, r5, 32 - 24, 30, 30 /* DSISR_STORE -> _PAGE_RW */
bl hash_page
b handle_page_fault_tramp_1
FTR_SECTION_ELSE
@@ -497,7 +497,6 @@ InstructionTLBMiss:
andc. r1,r1,r0 /* check access & ~permission */
bne- InstructionAddressInvalid /* return if access not permitted */
/* Convert linux-style PTE to low word of PPC-style PTE */
- rlwimi r0,r0,32-2,31,31 /* _PAGE_USER -> PP lsb */
ori r1, r1, 0xe06 /* clear out reserved bits */
andc r1, r0, r1 /* PP = user? 1 : 0 */
BEGIN_FTR_SECTION
@@ -565,9 +564,8 @@ DataLoadTLBMiss:
* we would need to update the pte atomically with lwarx/stwcx.
*/
/* Convert linux-style PTE to low word of PPC-style PTE */
- rlwinm r1,r0,32-9,30,30 /* _PAGE_RW -> PP msb */
- rlwimi r0,r0,32-1,30,30 /* _PAGE_USER -> PP msb */
- rlwimi r0,r0,32-1,31,31 /* _PAGE_USER -> PP lsb */
+ rlwinm r1,r0,0,30,30 /* _PAGE_RW -> PP msb */
+ rlwimi r0,r0,1,30,30 /* _PAGE_USER -> PP msb */
ori r1,r1,0xe04 /* clear out reserved bits */
andc r1,r0,r1 /* PP = user? rw? 1: 3: 0 */
BEGIN_FTR_SECTION
@@ -645,7 +643,6 @@ DataStoreTLBMiss:
* we would need to update the pte atomically with lwarx/stwcx.
*/
/* Convert linux-style PTE to low word of PPC-style PTE */
- rlwimi r0,r0,32-2,31,31 /* _PAGE_USER -> PP lsb */
li r1,0xe06 /* clear out reserved bits & PP msb */
andc r1,r0,r1 /* PP = user? 1: 0 */
BEGIN_FTR_SECTION
diff --git a/arch/powerpc/mm/book3s32/hash_low.S b/arch/powerpc/mm/book3s32/hash_low.S
index 877d880890fe..6d236080cb1a 100644
--- a/arch/powerpc/mm/book3s32/hash_low.S
+++ b/arch/powerpc/mm/book3s32/hash_low.S
@@ -35,7 +35,7 @@ mmu_hash_lock:
/*
* Load a PTE into the hash table, if possible.
* The address is in r4, and r3 contains an access flag:
- * _PAGE_RW (0x400) if a write.
+ * _PAGE_RW (0x002) if a write.
* r9 contains the SRR1 value, from which we use the MSR_PR bit.
* SPRG_THREAD contains the physical address of the current task's thread.
*
@@ -69,7 +69,7 @@ _GLOBAL(hash_page)
blt+ 112f /* assume user more likely */
lis r5, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */
addi r5 ,r5 ,(swapper_pg_dir - PAGE_OFFSET)@l /* kernel page table */
- rlwimi r3,r9,32-12,29,29 /* MSR_PR -> _PAGE_USER */
+ rlwimi r3,r9,32-14,31,31 /* MSR_PR -> _PAGE_USER */
112:
#ifndef CONFIG_PTE_64BIT
rlwimi r5,r4,12,20,29 /* insert top 10 bits of address */
@@ -94,7 +94,7 @@ _GLOBAL(hash_page)
#else
rlwimi r8,r4,23,20,28 /* compute pte address */
#endif
- rlwinm r0,r3,32-3,24,24 /* _PAGE_RW access -> _PAGE_DIRTY */
+ rlwinm r0,r3,6,24,24 /* _PAGE_RW access -> _PAGE_DIRTY */
ori r0,r0,_PAGE_ACCESSED|_PAGE_HASHPTE

/*
@@ -310,11 +310,9 @@ Hash_msk = (((1 << Hash_bits) - 1) * 64)

_GLOBAL(create_hpte)
/* Convert linux-style PTE (r5) to low word of PPC-style PTE (r8) */
- rlwinm r8,r5,32-9,30,30 /* _PAGE_RW -> PP msb */
rlwinm r0,r5,32-6,30,30 /* _PAGE_DIRTY -> PP msb */
- and r8,r8,r0 /* writable if _RW & _DIRTY */
- rlwimi r5,r5,32-1,30,30 /* _PAGE_USER -> PP msb */
- rlwimi r5,r5,32-2,31,31 /* _PAGE_USER -> PP lsb */
+ and r8,r5,r0 /* writable if _RW & _DIRTY */
+ rlwimi r5,r5,1,30,30 /* _PAGE_USER -> PP msb */
ori r8,r8,0xe04 /* clear out reserved bits */
andc r8,r5,r8 /* PP = user? (rw&dirty? 1: 3): 0 */
BEGIN_FTR_SECTION
@@ -566,7 +564,7 @@ _GLOBAL(flush_hash_pages)
33: lwarx r8,0,r5 /* fetch the pte flags word */
andi. r0,r8,_PAGE_HASHPTE
beq 8f /* done if HASHPTE is already clear */
- rlwinm r8,r8,0,31,29 /* clear HASHPTE bit */
+ rlwinm r8,r8,0,~_PAGE_HASHPTE /* clear HASHPTE bit */
stwcx. r8,0,r5 /* update the pte */
bne- 33b

--
2.25.0
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