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freebsd-dev/sys/i386/include/pmap.h
Konstantin Belousov d86c1f0dc1 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
2018-04-13 20:30:49 +00:00

409 lines
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1991 Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department and William Jolitz of UUNET Technologies Inc.
*
* 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
* 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.
*
* Derived from hp300 version by Mike Hibler, this version by William
* Jolitz uses a recursive map [a pde points to the page directory] to
* map the page tables using the pagetables themselves. This is done to
* reduce the impact on kernel virtual memory for lots of sparse address
* space, and to reduce the cost of memory to each process.
*
* from: hp300: @(#)pmap.h 7.2 (Berkeley) 12/16/90
* from: @(#)pmap.h 7.4 (Berkeley) 5/12/91
* $FreeBSD$
*/
#ifndef _MACHINE_PMAP_H_
#define _MACHINE_PMAP_H_
/*
* Page-directory and page-table entries follow this format, with a few
* of the fields not present here and there, depending on a lot of things.
*/
/* ---- Intel Nomenclature ---- */
#define PG_V 0x001 /* P Valid */
#define PG_RW 0x002 /* R/W Read/Write */
#define PG_U 0x004 /* U/S User/Supervisor */
#define PG_NC_PWT 0x008 /* PWT Write through */
#define PG_NC_PCD 0x010 /* PCD Cache disable */
#define PG_A 0x020 /* A Accessed */
#define PG_M 0x040 /* D Dirty */
#define PG_PS 0x080 /* PS Page size (0=4k,1=4M) */
#define PG_PTE_PAT 0x080 /* PAT PAT index */
#define PG_G 0x100 /* G Global */
#define PG_AVAIL1 0x200 /* / Available for system */
#define PG_AVAIL2 0x400 /* < programmers use */
#define PG_AVAIL3 0x800 /* \ */
#define PG_PDE_PAT 0x1000 /* PAT PAT index */
#if defined(PAE) || defined(PAE_TABLES)
#define PG_NX (1ull<<63) /* No-execute */
#endif
/* Our various interpretations of the above */
#define PG_W PG_AVAIL1 /* "Wired" pseudoflag */
#define PG_MANAGED PG_AVAIL2
#define PG_PROMOTED PG_AVAIL3 /* PDE only */
#if defined(PAE) || defined(PAE_TABLES)
#define PG_FRAME (0x000ffffffffff000ull)
#define PG_PS_FRAME (0x000fffffffe00000ull)
#else
#define PG_FRAME (~PAGE_MASK)
#define PG_PS_FRAME (0xffc00000)
#endif
#define PG_PROT (PG_RW|PG_U) /* all protection bits . */
#define PG_N (PG_NC_PWT|PG_NC_PCD) /* Non-cacheable */
/* Page level cache control fields used to determine the PAT type */
#define PG_PDE_CACHE (PG_PDE_PAT | PG_NC_PWT | PG_NC_PCD)
#define PG_PTE_CACHE (PG_PTE_PAT | PG_NC_PWT | PG_NC_PCD)
/*
* Promotion to a 2 or 4MB (PDE) page mapping requires that the corresponding
* 4KB (PTE) page mappings have identical settings for the following fields:
*/
#define PG_PTE_PROMOTE (PG_MANAGED | PG_W | PG_G | PG_PTE_PAT | \
PG_M | PG_A | PG_NC_PCD | PG_NC_PWT | PG_U | PG_RW | PG_V)
/*
* Page Protection Exception bits
*/
#define PGEX_P 0x01 /* Protection violation vs. not present */
#define PGEX_W 0x02 /* during a Write cycle */
#define PGEX_U 0x04 /* access from User mode (UPL) */
#define PGEX_RSV 0x08 /* reserved PTE field is non-zero */
#define PGEX_I 0x10 /* during an instruction fetch */
/*
* Size of Kernel address space. This is the number of page table pages
* (4MB each) to use for the kernel. 256 pages == 1 Gigabyte.
* This **MUST** be a multiple of 4 (eg: 252, 256, 260, etc).
* For PAE, the page table page unit size is 2MB. This means that 512 pages
* is 1 Gigabyte. Double everything. It must be a multiple of 8 for PAE.
*/
#if defined(PAE) || defined(PAE_TABLES)
#define KVA_PAGES (512*4)
#else
#define KVA_PAGES (256*4)
#endif
/*
* Pte related macros
*/
#define VADDR(pdi, pti) ((vm_offset_t)(((pdi)<<PDRSHIFT)|((pti)<<PAGE_SHIFT)))
/*
* The initial number of kernel page table pages that are constructed
* by locore must be sufficient to map vm_page_array. That number can
* be calculated as follows:
* max_phys / PAGE_SIZE * sizeof(struct vm_page) / NBPDR
* PAE: max_phys 16G, sizeof(vm_page) 76, NBPDR 2M, 152 page table pages.
* PAE_TABLES: max_phys 4G, sizeof(vm_page) 68, NBPDR 2M, 36 page table pages.
* Non-PAE: max_phys 4G, sizeof(vm_page) 68, NBPDR 4M, 18 page table pages.
*/
#ifndef NKPT
#if defined(PAE)
#define NKPT 240
#elif defined(PAE_TABLES)
#define NKPT 60
#else
#define NKPT 30
#endif
#endif
#ifndef NKPDE
#define NKPDE (KVA_PAGES) /* number of page tables/pde's */
#endif
/*
* The *PTDI values control the layout of virtual memory
*/
#define KPTDI 0 /* start of kernel virtual pde's */
#define LOWPTDI 1 /* low memory map pde */
#define KERNPTDI 2 /* start of kernel text pde */
#define PTDPTDI (NPDEPTD - 1 - NPGPTD) /* ptd entry that points
to ptd! */
#define TRPTDI (NPDEPTD - 1) /* u/k trampoline ptd */
/*
* XXX doesn't really belong here I guess...
*/
#define ISA_HOLE_START 0xa0000
#define ISA_HOLE_LENGTH (0x100000-ISA_HOLE_START)
#ifndef LOCORE
#include <sys/queue.h>
#include <sys/_cpuset.h>
#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <vm/_vm_radix.h>
#if defined(PAE) || defined(PAE_TABLES)
typedef uint64_t pdpt_entry_t;
typedef uint64_t pd_entry_t;
typedef uint64_t pt_entry_t;
#define PTESHIFT (3)
#define PDESHIFT (3)
#else
typedef uint32_t pd_entry_t;
typedef uint32_t pt_entry_t;
#define PTESHIFT (2)
#define PDESHIFT (2)
#endif
/*
* Address of current address space page table maps and directories.
*/
#ifdef _KERNEL
extern pt_entry_t PTmap[];
extern pd_entry_t PTD[];
extern pd_entry_t PTDpde[];
#if defined(PAE) || defined(PAE_TABLES)
extern pdpt_entry_t *IdlePDPT;
#endif
extern pd_entry_t *IdlePTD; /* physical address of "Idle" state directory */
/*
* Translate a virtual address to the kernel virtual address of its page table
* entry (PTE). This can be used recursively. If the address of a PTE as
* previously returned by this macro is itself given as the argument, then the
* address of the page directory entry (PDE) that maps the PTE will be
* returned.
*
* This macro may be used before pmap_bootstrap() is called.
*/
#define vtopte(va) (PTmap + i386_btop(va))
/*
* Translate a virtual address to its physical address.
*
* This macro may be used before pmap_bootstrap() is called.
*/
#define vtophys(va) pmap_kextract((vm_offset_t)(va))
/*
* KPTmap is a linear mapping of the kernel page table. It differs from the
* recursive mapping in two ways: (1) it only provides access to kernel page
* table pages, and not user page table pages, and (2) it provides access to
* a kernel page table page after the corresponding virtual addresses have
* been promoted to a 2/4MB page mapping.
*
* KPTmap is first initialized by locore to support just NPKT page table
* pages. Later, it is reinitialized by pmap_bootstrap() to allow for
* expansion of the kernel page table.
*/
extern pt_entry_t *KPTmap;
/*
* Extract from the kernel page table the physical address that is mapped by
* the given virtual address "va".
*
* This function may be used before pmap_bootstrap() is called.
*/
static __inline vm_paddr_t
pmap_kextract(vm_offset_t va)
{
vm_paddr_t pa;
if ((pa = PTD[va >> PDRSHIFT]) & PG_PS) {
pa = (pa & PG_PS_FRAME) | (va & PDRMASK);
} else {
/*
* Beware of a concurrent promotion that changes the PDE at
* this point! For example, vtopte() must not be used to
* access the PTE because it would use the new PDE. It is,
* however, safe to use the old PDE because the page table
* page is preserved by the promotion.
*/
pa = KPTmap[i386_btop(va)];
pa = (pa & PG_FRAME) | (va & PAGE_MASK);
}
return (pa);
}
#if (defined(PAE) || defined(PAE_TABLES))
#define pde_cmpset(pdep, old, new) atomic_cmpset_64_i586(pdep, old, new)
#define pte_load_store(ptep, pte) atomic_swap_64_i586(ptep, pte)
#define pte_load_clear(ptep) atomic_swap_64_i586(ptep, 0)
#define pte_store(ptep, pte) atomic_store_rel_64_i586(ptep, pte)
extern pt_entry_t pg_nx;
#else /* !(PAE || PAE_TABLES) */
#define pde_cmpset(pdep, old, new) atomic_cmpset_int(pdep, old, new)
#define pte_load_store(ptep, pte) atomic_swap_int(ptep, pte)
#define pte_load_clear(ptep) atomic_swap_int(ptep, 0)
#define pte_store(ptep, pte) do { \
*(u_int *)(ptep) = (u_int)(pte); \
} while (0)
#endif /* !(PAE || PAE_TABLES) */
#define pte_clear(ptep) pte_store(ptep, 0)
#define pde_store(pdep, pde) pte_store(pdep, pde)
#endif /* _KERNEL */
/*
* Pmap stuff
*/
struct pv_entry;
struct pv_chunk;
struct md_page {
TAILQ_HEAD(,pv_entry) pv_list;
int pat_mode;
};
struct pmap {
struct mtx pm_mtx;
pd_entry_t *pm_pdir; /* KVA of page directory */
TAILQ_HEAD(,pv_chunk) pm_pvchunk; /* list of mappings in pmap */
cpuset_t pm_active; /* active on cpus */
struct pmap_statistics pm_stats; /* pmap statistics */
LIST_ENTRY(pmap) pm_list; /* List of all pmaps */
#if defined(PAE) || defined(PAE_TABLES)
pdpt_entry_t *pm_pdpt; /* KVA of page directory pointer
table */
#endif
struct vm_radix pm_root; /* spare page table pages */
vm_page_t pm_ptdpg[NPGPTD];
};
typedef struct pmap *pmap_t;
#ifdef _KERNEL
extern struct pmap kernel_pmap_store;
#define kernel_pmap (&kernel_pmap_store)
#define PMAP_LOCK(pmap) mtx_lock(&(pmap)->pm_mtx)
#define PMAP_LOCK_ASSERT(pmap, type) \
mtx_assert(&(pmap)->pm_mtx, (type))
#define PMAP_LOCK_DESTROY(pmap) mtx_destroy(&(pmap)->pm_mtx)
#define PMAP_LOCK_INIT(pmap) mtx_init(&(pmap)->pm_mtx, "pmap", \
NULL, MTX_DEF | MTX_DUPOK)
#define PMAP_LOCKED(pmap) mtx_owned(&(pmap)->pm_mtx)
#define PMAP_MTX(pmap) (&(pmap)->pm_mtx)
#define PMAP_TRYLOCK(pmap) mtx_trylock(&(pmap)->pm_mtx)
#define PMAP_UNLOCK(pmap) mtx_unlock(&(pmap)->pm_mtx)
#endif
/*
* For each vm_page_t, there is a list of all currently valid virtual
* mappings of that page. An entry is a pv_entry_t, the list is pv_list.
*/
typedef struct pv_entry {
vm_offset_t pv_va; /* virtual address for mapping */
TAILQ_ENTRY(pv_entry) pv_next;
} *pv_entry_t;
/*
* pv_entries are allocated in chunks per-process. This avoids the
* need to track per-pmap assignments.
*/
#define _NPCM 11
#define _NPCPV 336
struct pv_chunk {
pmap_t pc_pmap;
TAILQ_ENTRY(pv_chunk) pc_list;
uint32_t pc_map[_NPCM]; /* bitmap; 1 = free */
TAILQ_ENTRY(pv_chunk) pc_lru;
struct pv_entry pc_pventry[_NPCPV];
};
#ifdef _KERNEL
extern caddr_t CADDR3;
extern pt_entry_t *CMAP3;
extern vm_paddr_t phys_avail[];
extern vm_paddr_t dump_avail[];
extern int pseflag;
extern int pgeflag;
extern char *ptvmmap; /* poor name! */
extern vm_offset_t virtual_avail;
extern vm_offset_t virtual_end;
#define pmap_page_get_memattr(m) ((vm_memattr_t)(m)->md.pat_mode)
#define pmap_page_is_write_mapped(m) (((m)->aflags & PGA_WRITEABLE) != 0)
#define pmap_unmapbios(va, sz) pmap_unmapdev((va), (sz))
/*
* Only the following functions or macros may be used before pmap_bootstrap()
* is called: pmap_kenter(), pmap_kextract(), pmap_kremove(), vtophys(), and
* vtopte().
*/
void pmap_bootstrap(vm_paddr_t);
int pmap_cache_bits(int mode, boolean_t is_pde);
int pmap_change_attr(vm_offset_t, vm_size_t, int);
void pmap_init_pat(void);
void pmap_kenter(vm_offset_t va, vm_paddr_t pa);
void *pmap_kenter_temporary(vm_paddr_t pa, int i);
void pmap_kremove(vm_offset_t);
void *pmap_mapbios(vm_paddr_t, vm_size_t);
void *pmap_mapdev(vm_paddr_t, vm_size_t);
void *pmap_mapdev_attr(vm_paddr_t, vm_size_t, int);
boolean_t pmap_page_is_mapped(vm_page_t m);
void pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma);
void pmap_unmapdev(vm_offset_t, vm_size_t);
pt_entry_t *pmap_pte(pmap_t, vm_offset_t) __pure2;
void pmap_invalidate_page(pmap_t, vm_offset_t);
void pmap_invalidate_range(pmap_t, vm_offset_t, vm_offset_t);
void pmap_invalidate_all(pmap_t);
void pmap_invalidate_cache(void);
void pmap_invalidate_cache_pages(vm_page_t *pages, int count);
void pmap_invalidate_cache_range(vm_offset_t sva, vm_offset_t eva,
boolean_t force);
void *pmap_trm_alloc(size_t size, int flags);
void pmap_trm_free(void *addr, size_t size);
void invltlb_glob(void);
#endif /* _KERNEL */
#endif /* !LOCORE */
#endif /* !_MACHINE_PMAP_H_ */
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