196 lines
8.3 KiB
C
196 lines
8.3 KiB
C
/* $NetBSD: pte.h,v 1.4 2001/11/30 17:52:34 fredette Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 1998 The NetBSD Foundation, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the NetBSD
|
|
* Foundation, Inc. and its contributors.
|
|
* 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
* contributors may be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#ifndef _MACHINE_PTE_H
|
|
#define _MACHINE_PTE_H
|
|
|
|
#define NCONTEXT 8
|
|
#define NPMEG 256
|
|
#define SEGINV (NPMEG-1)
|
|
#define NPAGSEG 16
|
|
#define NSEGMAP 512
|
|
|
|
/*
|
|
* In our zeal to use the sun3 pmap with as few changes as possible,
|
|
* we pretend that sun2 page table entries work more like their sun3
|
|
* counterparts. Namely, we pretend that they simply have PG_WRITE
|
|
* and PG_SYSTEM bits, and we use get_pte and set_pte to translate
|
|
* entries between the two styles.
|
|
*
|
|
* All known valid protections in a real sun2 PTE are given in
|
|
* (disabled) defines below, and are displayed as bitmaps here:
|
|
*
|
|
* 3 2 2 2 2
|
|
* 0 9 8 7 6 meaning
|
|
* -------------------
|
|
* 1 1 1 0 0 PG_KW => a read/write kernel-only page.
|
|
* 1 0 1 0 0 PG_KR => a read-only kernel-only page.
|
|
* 1 1 1 1 1 PG_UW => a read/write kernel/user page.
|
|
* 1 0 1 1 0 PG_URKR => a read-only kernel/user page.
|
|
*
|
|
* The sun3 PTE protections we want to emulate are:
|
|
*
|
|
* PG_SYSTEM | PG_WRITE => a read/write kernel-only page.
|
|
* PG_SYSTEM => a read-only kernel-only page.
|
|
* PG_WRITE => a read/write kernel/user page.
|
|
* => a read-only kernel/user page.
|
|
*
|
|
* We want to assign values to PG_SYSTEM and PG_WRITE, and
|
|
* craft get_pte and set_pte to do a translation from and to the real
|
|
* hardware protections.
|
|
*
|
|
* We begin by noting that bits 30 and 28 are set in all known valid
|
|
* sun2 protections. Since we assume that the kernel can always read
|
|
* all pages in the system, we might as well call one of them the
|
|
* "kernel readable" bit, and say that the other is just always on.
|
|
* We deem bit 30 the "kernel readable" bit. There is some evidence
|
|
* that bit 28 may mean "not a device" (the PROM makes PTEs for its
|
|
* device mappings with bit 28 clear), but I'm not sure enough about
|
|
* this to do anything about it. So, set_pte will always set these
|
|
* bits when it loads a valid PTE, and get_pte will always clear them
|
|
* when it unloads a valid PTE.
|
|
*
|
|
* Bit 25, which SunOS calles the "fill on demand" bit, also needs
|
|
* to be set on all valid PTEs. Dunno any more about this bit.
|
|
*
|
|
* Next, we see that bit 27 is set for all pages the user can access,
|
|
* and clear otherwise. This bit has the opposite meaning of the sun3
|
|
* PG_SYSTEM bit, but that's OK - we will just define PG_SYSTEM to be
|
|
* bit 27, and set_pte and get_pte will invert it when loading or
|
|
* unloading a valid PTE.
|
|
*
|
|
* Bit 29 is set for all pages the kernel can write to. We define
|
|
* PG_WRITE to be bit 29. No inverting is done.
|
|
*
|
|
* That leaves us to take care of bit 26. This bit, and bit 27, need
|
|
* to be set for all pages the user can write to. On the sun3, all
|
|
* user-accessible pages that the kernel can write to, the user can
|
|
* also write to. We can use this fact to make set_pte set bit 26 iff
|
|
* the kernel can write to the page (PG_WRITE is set), and the user
|
|
* can also access the page (bit 27 is set, i.e., PG_SYSTEM was clear
|
|
* before set_pte inverted it).
|
|
*
|
|
* This is what makes set_pte tricky. It begins by clearing bit 26
|
|
* (this is paranoia, if all is working well, this bit should never be
|
|
* set in our pseudo-sun3 PTEs). It then flips PG_SYSTEM to become
|
|
* the user-accessible bit. Lastly, as the tricky part, it sets bits
|
|
* 30 and 28, *and* sets bit 26 by shifting the expression (pte &
|
|
* PG_WRITE) right by two to move the resulting "single bit" into the
|
|
* bit 27 position, ANDing that with bit 27 in the PTE (the
|
|
* user-accessible bit), shifting that right once more to line up with
|
|
* the target bit 26 in the PTE, and ORing it in. This will result in
|
|
* bit 26 being set if the pseudo-sun3 protection was simply PG_WRITE.
|
|
*
|
|
* This could be expressed with if .. else.. logic, but the bit
|
|
* shifts should compile into something that needs no branching.
|
|
*
|
|
* get_pte's job is easier. All it has to do is clear the always-set
|
|
* bits 30, 28, and 25, *and* clear bit 26, and flip PG_SYSTEM. It can
|
|
* clear bit 26 because the value that was there can always be derived
|
|
* from the resulting pseudo-sun3 PG_SYSTEM and PG_WRITE combination.
|
|
*
|
|
* And that's how we reuse the sun3 pmap.
|
|
*/
|
|
#define PG_VALID 0x80000000
|
|
#define PG_WRITE 0x20000000
|
|
#define PG_NC 0x00000000
|
|
#define PG_SYSTEM 0x08000000
|
|
#if 0
|
|
#define PG_KW 0x70000000
|
|
#define PG_KR 0x50000000
|
|
#define PG_UW 0x7C000000
|
|
#define PG_URKR 0x58000000
|
|
#endif
|
|
#define PG_TYPE 0x00C00000
|
|
#define PG_REF 0x00200000
|
|
#define PG_MOD 0x00100000
|
|
|
|
#define PG_SPECIAL (PG_VALID|PG_WRITE|PG_SYSTEM|PG_NC|PG_REF|PG_MOD)
|
|
#define PG_PERM (PG_VALID|PG_WRITE|PG_SYSTEM|PG_NC)
|
|
#define PG_MODREF (PG_REF|PG_MOD)
|
|
#define PG_FRAME 0x00000FFF
|
|
|
|
#define PG_MOD_SHIFT 20
|
|
|
|
/*
|
|
* At first glance, the need for two page types for the VME
|
|
* bus on the sun2 isn't obvious - it's a single 16 bit wide
|
|
* bus with 24 address lines, with the A16 devices simply
|
|
* found starting at addresses 0xff0000. No problem - use
|
|
* only one page type. But the sun2 VM page frame is only 12
|
|
* bits wide, with 11 bit wide page offsets, meaning only 23
|
|
* address bits, not enough to cover the entire VME bus. So
|
|
* we have two page types, with the low bit of the page type
|
|
* representing the 24th VME bus address bit.
|
|
*/
|
|
#define OBMEM 0
|
|
#define OBIO 1
|
|
#define MBMEM 2 /* on the 2/120 */
|
|
#define VME0 2 /* on the 2/50 (VME addresses [0..0x7fffff]) */
|
|
#define MBIO 3 /* on the 2/120 */
|
|
#define VME8 3 /* on the 2/50 (VME addresses [0x800000..0xffffff]) */
|
|
#define PG_TYPE_SHIFT 22
|
|
|
|
#define PG_INVAL 0x0
|
|
|
|
#define MAKE_PGTYPE(x) ((x) << PG_TYPE_SHIFT)
|
|
#define PG_PFNUM(pte) (pte & PG_FRAME)
|
|
#define PG_PA(pte) (PG_PFNUM(pte) << PGSHIFT)
|
|
|
|
#define PGT_MASK MAKE_PGTYPE(3)
|
|
#define PGT_OBMEM MAKE_PGTYPE(OBMEM) /* onboard memory */
|
|
#define PGT_OBIO MAKE_PGTYPE(OBIO) /* onboard I/O */
|
|
#define PGT_MBMEM MAKE_PGTYPE(MBMEM) /* on the 2/120 */
|
|
#define PGT_VME0 MAKE_PGTYPE(VME0) /* on the 2/50 */
|
|
#define PGT_MBIO MAKE_PGTYPE(MBIO) /* on the 2/120 */
|
|
#define PGT_VME8 MAKE_PGTYPE(VME8) /* on the 2/50 */
|
|
|
|
#define VA_SEGNUM(x) ((u_int)(x) >> SEGSHIFT)
|
|
|
|
#define VA_PTE_NUM_SHIFT PGSHIFT
|
|
#define VA_PTE_NUM_MASK (((1 << SEGSHIFT) - 1) ^ ((1 << PGSHIFT) - 1))
|
|
#define VA_PTE_NUM(va) ((va & VA_PTE_NUM_MASK) >> VA_PTE_NUM_SHIFT)
|
|
|
|
#define PA_PGNUM(pa) ((unsigned)pa >> PGSHIFT)
|
|
|
|
#if defined(_KERNEL) || defined(_STANDALONE)
|
|
#define kernel_context() get_context(); set_context(0)
|
|
#define restore_context set_context
|
|
u_int get_pte __P((vaddr_t va));
|
|
void set_pte __P((vaddr_t va, u_int pte));
|
|
#endif /* _KERNEL */
|
|
|
|
#endif /* _MACHINE_PTE_H */
|