freebsd-nq/sys/i386/include/param.h

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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
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* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* 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. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* from: @(#)param.h 5.8 (Berkeley) 6/28/91
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* $FreeBSD$
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*/
#ifndef _I386_INCLUDE_PARAM_H_
#define _I386_INCLUDE_PARAM_H_
#include <machine/_align.h>
/*
* Machine dependent constants for Intel 386.
*/
#define __HAVE_ACPI
#define __HAVE_PIR
#define __PCI_REROUTE_INTERRUPT
#ifndef MACHINE
#define MACHINE "i386"
#endif
#ifndef MACHINE_ARCH
#define MACHINE_ARCH "i386"
#endif
#define MID_MACHINE MID_I386
#if defined(SMP) || defined(KLD_MODULE)
#ifndef MAXCPU
#define MAXCPU 32
#endif
#else
#define MAXCPU 1
#endif /* SMP || KLD_MODULE */
#ifndef MAXMEMDOM
#define MAXMEMDOM 1
#endif
#define ALIGNBYTES _ALIGNBYTES
#define ALIGN(p) _ALIGN(p)
/*
* ALIGNED_POINTER is a boolean macro that checks whether an address
* is valid to fetch data elements of type t from on this architecture.
* This does not reflect the optimal alignment, just the possibility
* (within reasonable limits).
*/
#define ALIGNED_POINTER(p, t) 1
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/*
* CACHE_LINE_SIZE is the compile-time maximum cache line size for an
* architecture. It should be used with appropriate caution.
*/
#define CACHE_LINE_SHIFT 6
#define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT)
#define PAGE_SHIFT 12 /* LOG2(PAGE_SIZE) */
#define PAGE_SIZE (1 << PAGE_SHIFT) /* bytes/page */
#define PAGE_MASK (PAGE_SIZE - 1)
#define NPTEPG (PAGE_SIZE / sizeof(pt_entry_t))
/* Size in bytes of the page directory */
#define NBPTD (NPGPTD << PAGE_SHIFT)
/* Number of PDEs in page directory, 2048 for PAE, 1024 for non-PAE */
#define NPDEPTD (NBPTD / sizeof(pd_entry_t))
/* Number of PDEs in one page of the page directory, 512 vs. 1024 */
#define NPDEPG (PAGE_SIZE / sizeof(pd_entry_t))
#define PDRMASK (NBPDR - 1)
#ifndef PDRSHIFT
#define PDRSHIFT i386_pmap_PDRSHIFT
#endif
#ifndef NBPDR
#define NBPDR (1 << PDRSHIFT) /* bytes/page dir */
#endif
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#define MAXPAGESIZES 2 /* maximum number of supported page sizes */
#define IOPAGES 2 /* pages of i/o permission bitmap */
#ifndef KSTACK_PAGES
#define KSTACK_PAGES 4 /* Includes pcb! */
#endif
#define KSTACK_GUARD_PAGES 1 /* pages of kstack guard; 0 disables */
#if KSTACK_PAGES < 4
#define TD0_KSTACK_PAGES 4
#else
#define TD0_KSTACK_PAGES KSTACK_PAGES
#endif
/*
* Ceiling on amount of swblock kva space, can be changed via
* the kern.maxswzone /boot/loader.conf variable.
*
* 276 is sizeof(struct swblock), but we do not always have a definition
* in scope for struct swblock, so we have to hardcode it. Each struct
* swblock holds metadata for 32 pages, so in theory, this is enough for
* 16 GB of swap. In practice, however, the usable amount is considerably
* lower due to fragmentation.
*/
#ifndef VM_SWZONE_SIZE_MAX
#define VM_SWZONE_SIZE_MAX (276 * 128 * 1024)
#endif
/*
* Ceiling on size of buffer cache (really only effects write queueing,
* the VM page cache is not effected), can be changed via
* the kern.maxbcache /boot/loader.conf variable.
*
* The value is equal to the size of the auto-tuned buffer map for
* the machine with 4GB of RAM, see vfs_bio.c:kern_vfs_bio_buffer_alloc().
*/
#ifndef VM_BCACHE_SIZE_MAX
#define VM_BCACHE_SIZE_MAX (7224 * 16 * 1024)
#endif
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/*
* Mach derived conversion macros
*/
#define trunc_page(x) ((x) & ~PAGE_MASK)
#define round_page(x) (((x) + PAGE_MASK) & ~PAGE_MASK)
#define trunc_4mpage(x) ((x) & ~PDRMASK)
#define round_4mpage(x) ((((x)) + PDRMASK) & ~PDRMASK)
#define atop(x) ((x) >> PAGE_SHIFT)
#define ptoa(x) ((x) << PAGE_SHIFT)
#define i386_btop(x) ((x) >> PAGE_SHIFT)
#define i386_ptob(x) ((x) << PAGE_SHIFT)
#define pgtok(x) ((x) * (PAGE_SIZE / 1024))
i386 4/4G split. The change makes the user and kernel address spaces on i386 independent, giving each almost the full 4G of usable virtual addresses except for one PDE at top used for trampoline and per-CPU trampoline stacks, and system structures that must be always mapped, namely IDT, GDT, common TSS and LDT, and process-private TSS and LDT if allocated. By using 1:1 mapping for the kernel text and data, it appeared possible to eliminate assembler part of the locore.S which bootstraps initial page table and KPTmap. The code is rewritten in C and moved into the pmap_cold(). The comment in vmparam.h explains the KVA layout. There is no PCID mechanism available in protected mode, so each kernel/user switch forth and back completely flushes the TLB, except for the trampoline PTD region. The TLB invalidations for userspace becomes trivial, because IPI handlers switch page tables. On the other hand, context switches no longer need to reload %cr3. copyout(9) was rewritten to use vm_fault_quick_hold(). An issue for new copyout(9) is compatibility with wiring user buffers around sysctl handlers. This explains two kind of locks for copyout ptes and accounting of the vslock() calls. The vm_fault_quick_hold() AKA slow path, is only tried after the 'fast path' failed, which temporary changes mapping to the userspace and copies the data to/from small per-cpu buffer in the trampoline. If a page fault occurs during the copy, it is short-circuit by exception.s to not even reach C code. The change was motivated by the need to implement the Meltdown mitigation, but instead of KPTI the full split is done. The i386 architecture already shows the sizing problems, in particular, it is impossible to link clang and lld with debugging. I expect that the issues due to the virtual address space limits would only exaggerate and the split gives more liveness to the platform. Tested by: pho Discussed with: bde Sponsored by: The FreeBSD Foundation MFC after: 1 month Differential revision: https://reviews.freebsd.org/D14633
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#define INKERNEL(va) (TRUE)
#endif /* !_I386_INCLUDE_PARAM_H_ */