[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, 121 insertions, 87 deletions

diff --git a/include/asm-ppc64/mmu.h b/include/asm-ppc64/mmu.h
index e0505acb77d997..4c18a5cb69f59f 100644
--- a/include/asm-ppc64/mmu.h
+++ b/include/asm-ppc64/mmu.h
@@ -48,13 +48,21 @@ extern char initial_stab[];
 
 /* Bits in the SLB VSID word */
 #define SLB_VSID_SHIFT		12
+#define SLB_VSID_B		ASM_CONST(0xc000000000000000)
+#define SLB_VSID_B_256M		ASM_CONST(0x0000000000000000)
+#define SLB_VSID_B_1T		ASM_CONST(0x4000000000000000)
 #define SLB_VSID_KS		ASM_CONST(0x0000000000000800)
 #define SLB_VSID_KP		ASM_CONST(0x0000000000000400)
 #define SLB_VSID_N		ASM_CONST(0x0000000000000200) /* no-execute */
-#define SLB_VSID_L		ASM_CONST(0x0000000000000100) /* largepage */
+#define SLB_VSID_L		ASM_CONST(0x0000000000000100)
 #define SLB_VSID_C		ASM_CONST(0x0000000000000080) /* class */
-#define SLB_VSID_LS		ASM_CONST(0x0000000000000070) /* size of largepage */
- 
+#define SLB_VSID_LP		ASM_CONST(0x0000000000000030)
+#define SLB_VSID_LP_00		ASM_CONST(0x0000000000000000)
+#define SLB_VSID_LP_01		ASM_CONST(0x0000000000000010)
+#define SLB_VSID_LP_10		ASM_CONST(0x0000000000000020)
+#define SLB_VSID_LP_11		ASM_CONST(0x0000000000000030)
+#define SLB_VSID_LLP		(SLB_VSID_L|SLB_VSID_LP)
+
 #define SLB_VSID_KERNEL		(SLB_VSID_KP)
 #define SLB_VSID_USER		(SLB_VSID_KP|SLB_VSID_KS|SLB_VSID_C)
 
@@ -69,6 +77,7 @@ extern char initial_stab[];
 #define HPTE_V_AVPN_SHIFT	7
 #define HPTE_V_AVPN		ASM_CONST(0xffffffffffffff80)
 #define HPTE_V_AVPN_VAL(x)	(((x) & HPTE_V_AVPN) >> HPTE_V_AVPN_SHIFT)
+#define HPTE_V_COMPARE(x,y)	(!(((x) ^ (y)) & HPTE_V_AVPN))
 #define HPTE_V_BOLTED		ASM_CONST(0x0000000000000010)
 #define HPTE_V_LOCK		ASM_CONST(0x0000000000000008)
 #define HPTE_V_LARGE		ASM_CONST(0x0000000000000004)
@@ -81,6 +90,7 @@ extern char initial_stab[];
 #define HPTE_R_RPN		ASM_CONST(0x3ffffffffffff000)
 #define HPTE_R_FLAGS		ASM_CONST(0x00000000000003ff)
 #define HPTE_R_PP		ASM_CONST(0x0000000000000003)
+#define HPTE_R_N		ASM_CONST(0x0000000000000004)
 
 /* Values for PP (assumes Ks=0, Kp=1) */
 /* pp0 will always be 0 for linux     */
@@ -99,100 +109,120 @@ typedef struct {
 extern hpte_t *htab_address;
 extern unsigned long htab_hash_mask;
 
-static inline unsigned long hpt_hash(unsigned long vpn, int large)
+/*
+ * Page size definition
+ *
+ *    shift : is the "PAGE_SHIFT" value for that page size
+ *    sllp  : is a bit mask with the value of SLB L || LP to be or'ed
+ *            directly to a slbmte "vsid" value
+ *    penc  : is the HPTE encoding mask for the "LP" field:
+ *
+ */
+struct mmu_psize_def
 {
-	unsigned long vsid;
-	unsigned long page;
-
-	if (large) {
-		vsid = vpn >> 4;
-		page = vpn & 0xf;
-	} else {
-		vsid = vpn >> 16;
-		page = vpn & 0xffff;
-	}
+	unsigned int	shift;	/* number of bits */
+	unsigned int	penc;	/* HPTE encoding */
+	unsigned int	tlbiel;	/* tlbiel supported for that page size */
+	unsigned long	avpnm;	/* bits to mask out in AVPN in the HPTE */
+	unsigned long	sllp;	/* SLB L||LP (exact mask to use in slbmte) */
+};
 
-	return (vsid & 0x7fffffffffUL) ^ page;
-}
-
-static inline void __tlbie(unsigned long va, int large)
-{
-	/* clear top 16 bits, non SLS segment */
-	va &= ~(0xffffULL << 48);
-
-	if (large) {
-		va &= HPAGE_MASK;
-		asm volatile("tlbie %0,1" : : "r"(va) : "memory");
-	} else {
-		va &= PAGE_MASK;
-		asm volatile("tlbie %0,0" : : "r"(va) : "memory");
-	}
-}
+#endif /* __ASSEMBLY__ */
 
-static inline void tlbie(unsigned long va, int large)
-{
-	asm volatile("ptesync": : :"memory");
-	__tlbie(va, large);
-	asm volatile("eieio; tlbsync; ptesync": : :"memory");
-}
+/*
+ * The kernel use the constants below to index in the page sizes array.
+ * The use of fixed constants for this purpose is better for performances
+ * of the low level hash refill handlers.
+ *
+ * A non supported page size has a "shift" field set to 0
+ *
+ * Any new page size being implemented can get a new entry in here. Whether
+ * the kernel will use it or not is a different matter though. The actual page
+ * size used by hugetlbfs is not defined here and may be made variable
+ */
 
-static inline void __tlbiel(unsigned long va)
-{
-	/* clear top 16 bits, non SLS segment */
-	va &= ~(0xffffULL << 48);
-	va &= PAGE_MASK;
-
-	/* 
-	 * Thanks to Alan Modra we are now able to use machine specific 
-	 * assembly instructions (like tlbiel) by using the gas -many flag.
-	 * However we have to support older toolchains so for the moment 
-	 * we hardwire it.
-	 */
-#if 0
-	asm volatile("tlbiel %0" : : "r"(va) : "memory");
-#else
-	asm volatile(".long 0x7c000224 | (%0 << 11)" : : "r"(va) : "memory");
-#endif
-}
+#define MMU_PAGE_4K		0	/* 4K */
+#define MMU_PAGE_64K		1	/* 64K */
+#define MMU_PAGE_64K_AP		2	/* 64K Admixed (in a 4K segment) */
+#define MMU_PAGE_1M		3	/* 1M */
+#define MMU_PAGE_16M		4	/* 16M */
+#define MMU_PAGE_16G		5	/* 16G */
+#define MMU_PAGE_COUNT		6
 
-static inline void tlbiel(unsigned long va)
-{
-	asm volatile("ptesync": : :"memory");
-	__tlbiel(va);
-	asm volatile("ptesync": : :"memory");
-}
+#ifndef __ASSEMBLY__
 
-static inline unsigned long slot2va(unsigned long hpte_v, unsigned long slot)
-{
-	unsigned long avpn = HPTE_V_AVPN_VAL(hpte_v);
-	unsigned long va;
+/*
+ * The current system page sizes
+ */
+extern struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
+extern int mmu_linear_psize;
+extern int mmu_virtual_psize;
 
-	va = avpn << 23;
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * The page size index of the huge pages for use by hugetlbfs
+ */
+extern int mmu_huge_psize;
 
-	if (! (hpte_v & HPTE_V_LARGE)) {
-		unsigned long vpi, pteg;
+#endif /* CONFIG_HUGETLB_PAGE */
 
-		pteg = slot / HPTES_PER_GROUP;
-		if (hpte_v & HPTE_V_SECONDARY)
-			pteg = ~pteg;
+/*
+ * This function sets the AVPN and L fields of the HPTE  appropriately
+ * for the page size
+ */
+static inline unsigned long hpte_encode_v(unsigned long va, int psize)
+{
+	unsigned long v =
+	v = (va >> 23) & ~(mmu_psize_defs[psize].avpnm);
+	v <<= HPTE_V_AVPN_SHIFT;
+	if (psize != MMU_PAGE_4K)
+		v |= HPTE_V_LARGE;
+	return v;
+}
 
-		vpi = ((va >> 28) ^ pteg) & htab_hash_mask;
+/*
+ * This function sets the ARPN, and LP fields of the HPTE appropriately
+ * for the page size. We assume the pa is already "clean" that is properly
+ * aligned for the requested page size
+ */
+static inline unsigned long hpte_encode_r(unsigned long pa, int psize)
+{
+	unsigned long r;
 
-		va |= vpi << PAGE_SHIFT;
+	/* A 4K page needs no special encoding */
+	if (psize == MMU_PAGE_4K)
+		return pa & HPTE_R_RPN;
+	else {
+		unsigned int penc = mmu_psize_defs[psize].penc;
+		unsigned int shift = mmu_psize_defs[psize].shift;
+		return (pa & ~((1ul << shift) - 1)) | (penc << 12);
 	}
-
-	return va;
+	return r;
 }
 
 /*
- * Handle a fault by adding an HPTE. If the address can't be determined
- * to be valid via Linux page tables, return 1. If handled return 0
+ * This hashes a virtual address for a 256Mb segment only for now
  */
-extern int __hash_page(unsigned long ea, unsigned long access,
-		       unsigned long vsid, pte_t *ptep, unsigned long trap,
-		       int local);
+
+static inline unsigned long hpt_hash(unsigned long va, unsigned int shift)
+{
+	return ((va >> 28) & 0x7fffffffffUL) ^ ((va & 0x0fffffffUL) >> shift);
+}
+
+extern int __hash_page_4K(unsigned long ea, unsigned long access,
+			  unsigned long vsid, pte_t *ptep, unsigned long trap,
+			  unsigned int local);
+extern int __hash_page_64K(unsigned long ea, unsigned long access,
+			   unsigned long vsid, pte_t *ptep, unsigned long trap,
+			   unsigned int local);
+struct mm_struct;
+extern int hash_huge_page(struct mm_struct *mm, unsigned long access,
+			  unsigned long ea, unsigned long vsid, int local);
 
 extern void htab_finish_init(void);
+extern int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
+			     unsigned long pstart, unsigned long mode,
+			     int psize);
 
 extern void hpte_init_native(void);
 extern void hpte_init_lpar(void);
@@ -200,17 +230,21 @@ extern void hpte_init_iSeries(void);
 
 extern long pSeries_lpar_hpte_insert(unsigned long hpte_group,
 				     unsigned long va, unsigned long prpn,
-				     unsigned long vflags,
-				     unsigned long rflags);
-extern long native_hpte_insert(unsigned long hpte_group, unsigned long va,
-			       unsigned long prpn,
-			       unsigned long vflags, unsigned long rflags);
+				     unsigned long rflags,
+				     unsigned long vflags, int psize);
+
+extern long native_hpte_insert(unsigned long hpte_group,
+			       unsigned long va, unsigned long prpn,
+			       unsigned long rflags,
+			       unsigned long vflags, int psize);
 
-extern long iSeries_hpte_bolt_or_insert(unsigned long hpte_group,
-		unsigned long va, unsigned long prpn,
-		unsigned long vflags, unsigned long rflags);
+extern long iSeries_hpte_insert(unsigned long hpte_group,
+				unsigned long va, unsigned long prpn,
+				unsigned long rflags,
+				unsigned long vflags, int psize);
 
 extern void stabs_alloc(void);
+extern void slb_initialize(void);
 
 #endif /* __ASSEMBLY__ */