[PATCH] ppc64: support 64k pages

Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel
base page size to 64K.  The resulting kernel still boots on any
hardware.  On current machines with 4K pages support only, the kernel
will maintain 16 "subpages" for each 64K page transparently.

Note that while real 64K capable HW has been tested, the current patch
will not enable it yet as such hardware is not released yet, and I'm
still verifying with the firmware architects the proper to get the
information from the newer hypervisors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 152 insertions, 68 deletions

diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index a3a03da..3e18241 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -18,61 +18,28 @@
 
 #include <linux/config.h>
 #include <asm/processor.h>
-#include <asm/page.h>
-#include <asm/mmu.h>
 #include <asm/ppc_asm.h>
 #include <asm/asm-offsets.h>
 #include <asm/cputable.h>
+#include <asm/page.h>
+#include <asm/mmu.h>
+#include <asm/pgtable.h>
 
-/* void slb_allocate(unsigned long ea);
+/* void slb_allocate_realmode(unsigned long ea);
  *
  * Create an SLB entry for the given EA (user or kernel).
  * 	r3 = faulting address, r13 = PACA
  *	r9, r10, r11 are clobbered by this function
  * No other registers are examined or changed.
  */
-_GLOBAL(slb_allocate)
-	/*
-	 * First find a slot, round robin. Previously we tried to find
-	 * a free slot first but that took too long. Unfortunately we
-	 * dont have any LRU information to help us choose a slot.
-	 */
-#ifdef CONFIG_PPC_ISERIES
-	/*
-	 * On iSeries, the "bolted" stack segment can be cast out on
-	 * shared processor switch so we need to check for a miss on
-	 * it and restore it to the right slot.
-	 */
-	ld	r9,PACAKSAVE(r13)
-	clrrdi	r9,r9,28
-	clrrdi	r11,r3,28
-	li	r10,SLB_NUM_BOLTED-1	/* Stack goes in last bolted slot */
-	cmpld	r9,r11
-	beq	3f
-#endif /* CONFIG_PPC_ISERIES */
-
-	ld	r10,PACASTABRR(r13)
-	addi	r10,r10,1
-	/* use a cpu feature mask if we ever change our slb size */
-	cmpldi	r10,SLB_NUM_ENTRIES
-
-	blt+	4f
-	li	r10,SLB_NUM_BOLTED
-
-4:
-	std	r10,PACASTABRR(r13)
-3:
-	/* r3 = faulting address, r10 = entry */
+_GLOBAL(slb_allocate_realmode)
+	/* r3 = faulting address */
 
 	srdi	r9,r3,60		/* get region */
-	srdi	r3,r3,28		/* get esid */
+	srdi	r10,r3,28		/* get esid */
 	cmpldi	cr7,r9,0xc		/* cmp KERNELBASE for later use */
 
-	rldimi	r10,r3,28,0		/* r10= ESID<<28 | entry */
-	oris	r10,r10,SLB_ESID_V@h	/* r10 |= SLB_ESID_V */
-
-	/* r3 = esid, r10 = esid_data, cr7 = <>KERNELBASE */
-
+	/* r3 = address, r10 = esid, cr7 = <>KERNELBASE */
 	blt	cr7,0f			/* user or kernel? */
 
 	/* kernel address: proto-VSID = ESID */
@@ -81,43 +48,161 @@ _GLOBAL(slb_allocate)
 	 * top segment.  That's ok, the scramble below will translate
 	 * it to VSID 0, which is reserved as a bad VSID - one which
 	 * will never have any pages in it.  */
-	li	r11,SLB_VSID_KERNEL
-BEGIN_FTR_SECTION
-	bne	cr7,9f
-	li	r11,(SLB_VSID_KERNEL|SLB_VSID_L)
-END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
-	b	9f
 
-0:	/* user address: proto-VSID = context<<15 | ESID */
-	srdi.	r9,r3,USER_ESID_BITS
+	/* Check if hitting the linear mapping of the vmalloc/ioremap
+	 * kernel space
+	*/
+	bne	cr7,1f
+
+	/* Linear mapping encoding bits, the "li" instruction below will
+	 * be patched by the kernel at boot
+	 */
+_GLOBAL(slb_miss_kernel_load_linear)
+	li	r11,0
+	b	slb_finish_load
+
+1:	/* vmalloc/ioremap mapping encoding bits, the "li" instruction below
+	 * will be patched by the kernel at boot
+	 */
+_GLOBAL(slb_miss_kernel_load_virtual)
+	li	r11,0
+	b	slb_finish_load
+
+
+0:	/* user address: proto-VSID = context << 15 | ESID. First check
+	 * if the address is within the boundaries of the user region
+	 */
+	srdi.	r9,r10,USER_ESID_BITS
 	bne-	8f			/* invalid ea bits set */
 
+	/* Figure out if the segment contains huge pages */
 #ifdef CONFIG_HUGETLB_PAGE
 BEGIN_FTR_SECTION
+	b	1f
+END_FTR_SECTION_IFCLR(CPU_FTR_16M_PAGE)
 	lhz	r9,PACAHIGHHTLBAREAS(r13)
-	srdi	r11,r3,(HTLB_AREA_SHIFT-SID_SHIFT)
+	srdi	r11,r10,(HTLB_AREA_SHIFT-SID_SHIFT)
 	srd	r9,r9,r11
 	lhz	r11,PACALOWHTLBAREAS(r13)
-	srd	r11,r11,r3
-	or	r9,r9,r11
-END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
+	srd	r11,r11,r10
+	or.	r9,r9,r11
+	beq	1f
+_GLOBAL(slb_miss_user_load_huge)
+	li	r11,0
+	b	2f
+1:
 #endif /* CONFIG_HUGETLB_PAGE */
 
-	li	r11,SLB_VSID_USER
+_GLOBAL(slb_miss_user_load_normal)
+	li	r11,0
 
-#ifdef CONFIG_HUGETLB_PAGE
-BEGIN_FTR_SECTION
-	rldimi	r11,r9,8,55		/* shift masked bit into SLB_VSID_L */
-END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
-#endif /* CONFIG_HUGETLB_PAGE */
+2:
+	ld	r9,PACACONTEXTID(r13)
+	rldimi	r10,r9,USER_ESID_BITS,0
+	b	slb_finish_load
+
+8:	/* invalid EA */
+	li	r10,0			/* BAD_VSID */
+	li	r11,SLB_VSID_USER	/* flags don't much matter */
+	b	slb_finish_load
+
+#ifdef __DISABLED__
+
+/* void slb_allocate_user(unsigned long ea);
+ *
+ * Create an SLB entry for the given EA (user or kernel).
+ * 	r3 = faulting address, r13 = PACA
+ *	r9, r10, r11 are clobbered by this function
+ * No other registers are examined or changed.
+ *
+ * It is called with translation enabled in order to be able to walk the
+ * page tables. This is not currently used.
+ */
+_GLOBAL(slb_allocate_user)
+	/* r3 = faulting address */
+	srdi	r10,r3,28		/* get esid */
+
+	crset	4*cr7+lt		/* set "user" flag for later */
+
+	/* check if we fit in the range covered by the pagetables*/
+	srdi.	r9,r3,PGTABLE_EADDR_SIZE
+	crnot	4*cr0+eq,4*cr0+eq
+	beqlr
 
+	/* now we need to get to the page tables in order to get the page
+	 * size encoding from the PMD. In the future, we'll be able to deal
+	 * with 1T segments too by getting the encoding from the PGD instead
+	 */
+	ld	r9,PACAPGDIR(r13)
+	cmpldi	cr0,r9,0
+	beqlr
+	rlwinm	r11,r10,8,25,28
+	ldx	r9,r9,r11		/* get pgd_t */
+	cmpldi	cr0,r9,0
+	beqlr
+	rlwinm	r11,r10,3,17,28
+	ldx	r9,r9,r11		/* get pmd_t */
+	cmpldi	cr0,r9,0
+	beqlr
+
+	/* build vsid flags */
+	andi.	r11,r9,SLB_VSID_LLP
+	ori	r11,r11,SLB_VSID_USER
+
+	/* get context to calculate proto-VSID */
 	ld	r9,PACACONTEXTID(r13)
-	rldimi	r3,r9,USER_ESID_BITS,0
+	rldimi	r10,r9,USER_ESID_BITS,0
+
+	/* fall through slb_finish_load */
+
+#endif /* __DISABLED__ */
 
-9:	/* r3 = protovsid, r11 = flags, r10 = esid_data, cr7 = <>KERNELBASE */
-	ASM_VSID_SCRAMBLE(r3,r9)
 
-	rldimi	r11,r3,SLB_VSID_SHIFT,16	/* combine VSID and flags */
+/*
+ * Finish loading of an SLB entry and return
+ *
+ * r3 = EA, r10 = proto-VSID, r11 = flags, clobbers r9, cr7 = <>KERNELBASE
+ */
+slb_finish_load:
+	ASM_VSID_SCRAMBLE(r10,r9)
+	rldimi	r11,r10,SLB_VSID_SHIFT,16	/* combine VSID and flags */
+
+	/* r3 = EA, r11 = VSID data */
+	/*
+	 * Find a slot, round robin. Previously we tried to find a
+	 * free slot first but that took too long. Unfortunately we
+ 	 * dont have any LRU information to help us choose a slot.
+ 	 */
+#ifdef CONFIG_PPC_ISERIES
+	/*
+	 * On iSeries, the "bolted" stack segment can be cast out on
+	 * shared processor switch so we need to check for a miss on
+	 * it and restore it to the right slot.
+	 */
+	ld	r9,PACAKSAVE(r13)
+	clrrdi	r9,r9,28
+	clrrdi	r3,r3,28
+	li	r10,SLB_NUM_BOLTED-1	/* Stack goes in last bolted slot */
+	cmpld	r9,r3
+	beq	3f
+#endif /* CONFIG_PPC_ISERIES */
+
+	ld	r10,PACASTABRR(r13)
+	addi	r10,r10,1
+	/* use a cpu feature mask if we ever change our slb size */
+	cmpldi	r10,SLB_NUM_ENTRIES
+
+	blt+	4f
+	li	r10,SLB_NUM_BOLTED
+
+4:
+	std	r10,PACASTABRR(r13)
+
+3:
+	rldimi	r3,r10,0,36		/* r3= EA[0:35] | entry */
+	oris	r10,r3,SLB_ESID_V@h	/* r3 |= SLB_ESID_V */
+
+	/* r3 = ESID data, r11 = VSID data */
 
 	/*
 	 * No need for an isync before or after this slbmte. The exception
@@ -125,7 +210,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
 	 */
 	slbmte	r11,r10
 
-	bgelr	cr7			/* we're done for kernel addresses */
+	/* we're done for kernel addresses */
+	crclr	4*cr0+eq		/* set result to "success" */
+	bgelr	cr7
 
 	/* Update the slb cache */
 	lhz	r3,PACASLBCACHEPTR(r13)	/* offset = paca->slb_cache_ptr */
@@ -143,9 +230,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
 	li	r3,SLB_CACHE_ENTRIES+1
 2:
 	sth	r3,PACASLBCACHEPTR(r13)	/* paca->slb_cache_ptr = offset */
+	crclr	4*cr0+eq		/* set result to "success" */
 	blr
 
-8:	/* invalid EA */
-	li	r3,0			/* BAD_VSID */
-	li	r11,SLB_VSID_USER	/* flags don't much matter */
-	b	9b