usr/src/sys/sparc/include/pte.h

/*
 * Copyright (c) 1992 The Regents of the University of California.
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Lawrence Berkeley Laboratory.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)pte.h       7.3 (Berkeley) %G%
 *
 * from: $Header: pte.h,v 1.5 92/11/26 02:04:43 torek Exp $
 */

/*
 * Sun-4 (sort of) and 4c (SparcStation) Page Table Entries
 * (Sun call them `Page Map Entries').
 */

#ifndef LOCORE
/*
 * Segment maps contain `pmeg' (Page Map Entry Group) numbers.
 * A PMEG is simply an index that names a group of 32 (sun4) or
 * 64 (sun4c) PTEs.
 */
#ifdef SUN4
typedef u_short pmeg_t;         /* 9 bits needed per Sun-4 segmap entry */
#else
typedef u_char pmeg_t;          /* 7 bits needed per Sun-4c segmap entry */
#endif
#endif

/*
 * Address translation works as follows:
 *
 *      1. test va<31:29> -- these must be 000 or 111 (or you get a fault)
 *      2. concatenate context_reg<2:0> and va<29:18> to get a 15 bit number;
 *         use this to index the segment maps, yeilding a 7 or 9 bit value.
 * (for sun4c)
 *      3. take the value from (2) above and concatenate va<17:12> to
 *         get a `page map entry' index.  This gives a 32-bit PTE.
 * (for sun4)
 *      3. take the value from (2) above and concatenate va<17:13> to
 *         get a `page map entry' index.  This gives a 32-bit PTE.
 *
 * In other words:
 *
 *      struct sun4_virtual_addr {
 *              u_int   :2,             (required to be the same as bit 29)
 *                      va_seg:12,      (virtual segment)
 *                      va_pg:5,        (virtual page within segment)
 *                      va_off:13;      (offset within page)
 *      };
 *      struct sun4c_virtual_addr {
 *              u_int   :2,             (required to be the same as bit 29)
 *                      va_seg:12,      (virtual segment)
 *                      va_pg:6,        (virtual page within segment)
 *                      va_off:12;      (offset within page)
 *      };
 *
 * Then, given any `va':
 *
 *      extern pmeg_t segmap[8][1<<12];         ([16][1<<12] for sun4)
 *      extern int ptetable[128][1<<6];         ([512][1<<5] for sun4)
 *
 * (the above being in the hardware, accessed as Alternate Address Spaces)
 *
 *      physseg = segmap[curr_ctx][va.va_seg];
 *      pte = ptetable[physseg][va.va_pg];
 *      if (!(pte & PG_V)) TRAP();
 *      if (writing && !pte.pg_w) TRAP();
 *      if (usermode && pte.pg_s) TRAP();
 *      if (pte & PG_NC) DO_NOT_USE_CACHE_FOR_THIS_ACCESS();
 *      pte |= PG_U;                                    (mark used/accessed)
 *      if (writing) pte |= PG_M;                       (mark modified)
 *      ptetable[physseg][va.va_pg] = pte;
 *      physadr = ((pte & PG_PFNUM) << PGSHIFT) | va.va_off;
 */

#define NBPSG   (1 << 18)       /* bytes per segment */
#define SGSHIFT 18              /* log2(NBPSG) */
#define SGOFSET (NBPSG - 1)     /* mask for segment offset */

/* number of PTEs that map one segment (not number that fit in one segment!) */
#if defined(SUN4) && defined(SUN4C)
#define NPTESG  nptesg          /* (which someone will have to init) */
#else
#define NPTESG  (NBPSG / NBPG)
#endif

/* virtual address to virtual segment number */
#define VA_VSEG(va)     (((int)(va) >> SGSHIFT) & 0xfff)

/* virtual address to virtual page number, for Sun-4 and Sun-4c */
#define VA_SUN4_VPG(va)         (((int)(va) >> 13) & 31)
#define VA_SUN4C_VPG(va)        (((int)(va) >> 12) & 63)

/* truncate virtual address to segment base */
#define VA_ROUNDDOWNTOSEG(va)   ((int)(va) & ~SGOFSET)

/* virtual segment to virtual address (must sign extend!) */
#define VSTOVA(vseg)    (((int)(vseg) << 20) >> 2)

#ifdef SUN4
#ifdef SUN4C
int     issun4c;
#define VA_VPG(va)      (issun4c ? VA_SUN4C_VPG(va) : VA_SUN4_VPG(va))
#else /* sun4 and not sun4c */
#define VA_VPG(va)      VA_SUN4_VPG(va)
#endif
#else /* not sun4; must be 4c */
#define VA_VPG(va)      VA_SUN4C_VPG(va)
#endif

/* there is no `struct pte'; we just use `int' */
#define PG_V            0x80000000
#define PG_PROT         0x60000000      /* both protection bits */
#define PG_W            0x40000000      /* allowed to write */
#define PG_S            0x20000000      /* supervisor only */
#define PG_NC           0x10000000      /* non-cacheable */
#define PG_TYPE         0x0c000000      /* both type bits */

#define PG_OBMEM        0x00000000      /* on board memory */
#define PG_OBIO         0x04000000      /* on board I/O (incl. Sbus on 4c) */
#ifdef SUN4
#define PG_VME16        0x08000000      /* 16-bit-data VME space */
#define PG_VME32        0x0c000000      /* 32-bit-data VME space */
#endif

#define PG_U            0x02000000
#define PG_M            0x01000000
#define PG_MBZ          0x00f80000      /* unused; must be zero (oh really?) */
#define PG_PFNUM        0x0007ffff      /* n.b.: only 16 bits on sun4c */

#define PG_TNC_SHIFT    26              /* shift to get PG_TYPE + PG_NC */
#define PG_M_SHIFT      24              /* shift to get PG_M, PG_U */

/*efine PG_NOACC        0               ** XXX */
#define PG_KR           0x20000000
#define PG_KW           0x60000000
#define PG_URKR         0
#define PG_UW           0x40000000

#ifdef KGDB
/* but we will define one for gdb anyway */
struct pte {
        u_int   pg_v:1,
                pg_w:1,
                pg_s:1,
                pg_nc:1;
        enum pgtype { pg_obmem, pg_obio, pg_vme16, pg_vme32 } pg_type:2;
        u_int   pg_u:1,
                pg_m:1,
                pg_mbz:5,
                pg_pfnum:19;
};
#endif

/*
 * These are needed in the register window code
 * to check the validity of (ostensible) user stack PTEs.
 */
#define PG_VSHIFT       30              /* (va>>vshift)==0 or -1 => valid */
        /* XXX fix this name, it is a va shift not a pte bit shift! */

#define PG_PROTSHIFT    29
#define PG_PROTUWRITE   6               /* PG_V,PG_W,!PG_S */
#define PG_PROTUREAD    4               /* PG_V,!PG_W,!PG_S */

/* static __inline int PG_VALID(void *va) {
        register int t = va; t >>= PG_VSHIFT; return (t == 0 || t == -1);
} */