[PATCH] ppc64: pgtable.h and other header cleanups

This patch started as simply removing a few never-used macros from
asm-ppc64/pgtable.h, then kind of grew.  It now makes a bunch of
cleanups to the ppc64 low-level header files (with corresponding
changes to .c files where necessary) such as:
	- Abolishing never-used macros
	- Eliminating multiple #defines with the same purpose
	- Removing pointless macros (cases where just expanding the
macro everywhere turns out clearer and more sensible)
	- Removing some cases where macros which could be defined in
terms of each other weren't
	- Moving imalloc() related definitions from pgtable.h to their
own header file (imalloc.h)
	- Re-arranging headers to group things more logically
	- Moving all VSID allocation related things to mmu.h, instead
of being split between mmu.h and mmu_context.h
	- Removing some reserved space for flags from the PMD - we're
not using it.
	- Fix some bugs which broke compile with STRICT_MM_TYPECHECKS.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 147 insertions, 46 deletions

diff --git a/include/asm-ppc64/mmu.h b/include/asm-ppc64/mmu.h
index 188987e9d9d4..c78282a67d8e 100644
--- a/include/asm-ppc64/mmu.h
+++ b/include/asm-ppc64/mmu.h
@@ -15,19 +15,10 @@
 
 #include <linux/config.h>
 #include <asm/page.h>
-#include <linux/stringify.h>
 
-#ifndef __ASSEMBLY__
-
-/* Time to allow for more things here */
-typedef unsigned long mm_context_id_t;
-typedef struct {
-        mm_context_id_t id;
-#ifdef CONFIG_HUGETLB_PAGE
-        pgd_t *huge_pgdir;
-        u16 htlb_segs; /* bitmask */
-#endif
-} mm_context_t;
+/*
+ * Segment table
+ */
 
 #define STE_ESID_V      0x80
 #define STE_ESID_KS     0x20
@@ -36,15 +27,48 @@ typedef struct {
 
 #define STE_VSID_SHIFT  12
 
-struct stab_entry {
-        unsigned long esid_data;
-        unsigned long vsid_data;
-};
+/* Location of cpu0's segment table */
+#define STAB0_PAGE      0x9
+#define STAB0_PHYS_ADDR (STAB0_PAGE<<PAGE_SHIFT)
+#define STAB0_VIRT_ADDR (KERNELBASE+STAB0_PHYS_ADDR)
+
+/*
+ * SLB
+ */
 
-/* Hardware Page Table Entry */
+#define SLB_NUM_BOLTED          3
+#define SLB_CACHE_ENTRIES       8
+
+/* Bits in the SLB ESID word */
+#define SLB_ESID_V              ASM_CONST(0x0000000008000000) /* valid */
+
+/* Bits in the SLB VSID word */
+#define SLB_VSID_SHIFT          12
+#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 16M */
+#define SLB_VSID_C              ASM_CONST(0x0000000000000080) /* class */
+
+#define SLB_VSID_KERNEL         (SLB_VSID_KP|SLB_VSID_C)
+#define SLB_VSID_USER           (SLB_VSID_KP|SLB_VSID_KS)
+
+/*
+ * Hash table
+ */
 
 #define HPTES_PER_GROUP 8
 
+/* Values for PP (assumes Ks=0, Kp=1) */
+/* pp0 will always be 0 for linux     */
+#define PP_RWXX 0       /* Supervisor read/write, User none */
+#define PP_RWRX 1       /* Supervisor read/write, User read */
+#define PP_RWRW 2       /* Supervisor read/write, User read/write */
+#define PP_RXRX 3       /* Supervisor read,       User read */
+
+#ifndef __ASSEMBLY__
+
+/* Hardware Page Table Entry */
 typedef struct {
         unsigned long avpn:57; /* vsid | api == avpn  */
         unsigned long :     2; /* Software use */
@@ -90,14 +114,6 @@ typedef struct {
         } dw1;
 } HPTE; 
 
-/* Values for PP (assumes Ks=0, Kp=1) */
-/* pp0 will always be 0 for linux     */
-#define PP_RWXX 0       /* Supervisor read/write, User none */
-#define PP_RWRX 1       /* Supervisor read/write, User read */
-#define PP_RWRW 2       /* Supervisor read/write, User read/write */
-#define PP_RXRX 3       /* Supervisor read,       User read */
-
-
 extern HPTE *           htab_address;
 extern unsigned long    htab_hash_mask;
 
@@ -174,31 +190,70 @@ extern int __hash_page(unsigned long ea, unsigned long access,
 
 extern void htab_finish_init(void);
 
+extern void hpte_init_native(void);
+extern void hpte_init_lpar(void);
+extern void hpte_init_iSeries(void);
+
+extern long pSeries_lpar_hpte_insert(unsigned long hpte_group,
+                                     unsigned long va, unsigned long prpn,
+                                     int secondary, unsigned long hpteflags,
+                                     int bolted, int large);
+extern long native_hpte_insert(unsigned long hpte_group, unsigned long va,
+                               unsigned long prpn, int secondary,
+                               unsigned long hpteflags, int bolted, int large);
+
 #endif /* __ASSEMBLY__ */
 
 /*
- * Location of cpu0's segment table
+ * VSID allocation
+ *
+ * We first generate a 36-bit "proto-VSID".  For kernel addresses this
+ * is equal to the ESID, for user addresses it is:
+ *      (context << 15) | (esid & 0x7fff)
+ *
+ * The two forms are distinguishable because the top bit is 0 for user
+ * addresses, whereas the top two bits are 1 for kernel addresses.
+ * Proto-VSIDs with the top two bits equal to 0b10 are reserved for
+ * now.
+ *
+ * The proto-VSIDs are then scrambled into real VSIDs with the
+ * multiplicative hash:
+ *
+ *      VSID = (proto-VSID * VSID_MULTIPLIER) % VSID_MODULUS
+ *      where   VSID_MULTIPLIER = 268435399 = 0xFFFFFC7
+ *              VSID_MODULUS = 2^36-1 = 0xFFFFFFFFF
+ *
+ * This scramble is only well defined for proto-VSIDs below
+ * 0xFFFFFFFFF, so both proto-VSID and actual VSID 0xFFFFFFFFF are
+ * reserved.  VSID_MULTIPLIER is prime, so in particular it is
+ * co-prime to VSID_MODULUS, making this a 1:1 scrambling function.
+ * Because the modulus is 2^n-1 we can compute it efficiently without
+ * a divide or extra multiply (see below).
+ *
+ * This scheme has several advantages over older methods:
+ *
+ *      - We have VSIDs allocated for every kernel address
+ * (i.e. everything above 0xC000000000000000), except the very top
+ * segment, which simplifies several things.
+ *
+ *      - We allow for 15 significant bits of ESID and 20 bits of
+ * context for user addresses.  i.e. 8T (43 bits) of address space for
+ * up to 1M contexts (although the page table structure and context
+ * allocation will need changes to take advantage of this).
+ *
+ *      - The scramble function gives robust scattering in the hash
+ * table (at least based on some initial results).  The previous
+ * method was more susceptible to pathological cases giving excessive
+ * hash collisions.
+ */
+/*
+ * WARNING - If you change these you must make sure the asm
+ * implementations in slb_allocate (slb_low.S), do_stab_bolted
+ * (head.S) and ASM_VSID_SCRAMBLE (below) are changed accordingly.
+ *
+ * You'll also need to change the precomputed VSID values in head.S
+ * which are used by the iSeries firmware.
  */
-#define STAB0_PAGE      0x9
-#define STAB0_PHYS_ADDR (STAB0_PAGE<<PAGE_SHIFT)
-#define STAB0_VIRT_ADDR (KERNELBASE+STAB0_PHYS_ADDR)
-
-#define SLB_NUM_BOLTED          3
-#define SLB_CACHE_ENTRIES       8
-
-/* Bits in the SLB ESID word */
-#define SLB_ESID_V              0x0000000008000000      /* entry is valid */
-
-/* Bits in the SLB VSID word */
-#define SLB_VSID_SHIFT          12
-#define SLB_VSID_KS             0x0000000000000800
-#define SLB_VSID_KP             0x0000000000000400
-#define SLB_VSID_N              0x0000000000000200      /* no-execute */
-#define SLB_VSID_L              0x0000000000000100      /* largepage (4M) */
-#define SLB_VSID_C              0x0000000000000080      /* class */
-
-#define SLB_VSID_KERNEL         (SLB_VSID_KP|SLB_VSID_C)
-#define SLB_VSID_USER           (SLB_VSID_KP|SLB_VSID_KS)
 
 #define VSID_MULTIPLIER ASM_CONST(200730139)    /* 28-bit prime */
 #define VSID_BITS       36
@@ -239,4 +294,50 @@ extern void htab_finish_init(void);
         srdi    rx,rx,VSID_BITS;        /* extract 2^36 bit */          \
         add     rt,rt,rx
 
+
+#ifndef __ASSEMBLY__
+
+typedef unsigned long mm_context_id_t;
+
+typedef struct {
+        mm_context_id_t id;
+#ifdef CONFIG_HUGETLB_PAGE
+        pgd_t *huge_pgdir;
+        u16 htlb_segs; /* bitmask */
+#endif
+} mm_context_t;
+
+
+static inline unsigned long vsid_scramble(unsigned long protovsid)
+{
+#if 0
+        /* The code below is equivalent to this function for arguments
+         * < 2^VSID_BITS, which is all this should ever be called
+         * with.  However gcc is not clever enough to compute the
+         * modulus (2^n-1) without a second multiply. */
+        return ((protovsid * VSID_MULTIPLIER) % VSID_MODULUS);
+#else /* 1 */
+        unsigned long x;
+
+        x = protovsid * VSID_MULTIPLIER;
+        x = (x >> VSID_BITS) + (x & VSID_MODULUS);
+        return (x + ((x+1) >> VSID_BITS)) & VSID_MODULUS;
+#endif /* 1 */
+}
+
+/* This is only valid for addresses >= KERNELBASE */
+static inline unsigned long get_kernel_vsid(unsigned long ea)
+{
+        return vsid_scramble(ea >> SID_SHIFT);
+}
+
+/* This is only valid for user addresses (which are below 2^41) */
+static inline unsigned long get_vsid(unsigned long context, unsigned long ea)
+{
+        return vsid_scramble((context << USER_ESID_BITS)
+                             | (ea >> SID_SHIFT));
+}
+
+#endif /* __ASSEMBLY */
+
 #endif /* _PPC64_MMU_H_ */