freebsd-dev/sys/amd64/include/proc.h
Alan Cox 5730afc9b6 Handle spurious page faults that may occur in no-fault sections of the
kernel.

When access restrictions are added to a page table entry, we flush the
corresponding virtual address mapping from the TLB.  In contrast, when
access restrictions are removed from a page table entry, we do not
flush the virtual address mapping from the TLB.  This is exactly as
recommended in AMD's documentation.  In effect, when access
restrictions are removed from a page table entry, AMD's MMUs will
transparently refresh a stale TLB entry.  In short, this saves us from
having to perform potentially costly TLB flushes.  In contrast,
Intel's MMUs are allowed to generate a spurious page fault based upon
the stale TLB entry.  Usually, such spurious page faults are handled
by vm_fault() without incident.  However, when we are executing
no-fault sections of the kernel, we are not allowed to execute
vm_fault().  This change introduces special-case handling for spurious
page faults that occur in no-fault sections of the kernel.

In collaboration with:	kib
Tested by:		gibbs (an earlier version)

I would also like to acknowledge Hiroki Sato's assistance in
diagnosing this problem.

MFC after:	1 week
2012-03-22 04:52:51 +00:00

92 lines
3.0 KiB
C

/*-
* Copyright (c) 1991 Regents of the University of California.
* 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.
* 4. 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.
*
* from: @(#)proc.h 7.1 (Berkeley) 5/15/91
* $FreeBSD$
*/
#ifndef _MACHINE_PROC_H_
#define _MACHINE_PROC_H_
#include <machine/segments.h>
struct proc_ldt {
caddr_t ldt_base;
int ldt_refcnt;
};
/*
* Machine-dependent part of the proc structure for AMD64.
*/
struct mdthread {
int md_spinlock_count; /* (k) */
register_t md_saved_flags; /* (k) */
register_t md_spurflt_addr; /* (k) Spurious page fault address. */
};
struct mdproc {
struct proc_ldt *md_ldt; /* (t) per-process ldt */
struct system_segment_descriptor md_ldt_sd;
};
#define KINFO_PROC_SIZE 1088
#define KINFO_PROC32_SIZE 768
#ifdef _KERNEL
/* Get the current kernel thread stack usage. */
#define GET_STACK_USAGE(total, used) do { \
struct thread *td = curthread; \
(total) = td->td_kstack_pages * PAGE_SIZE; \
(used) = (char *)td->td_kstack + \
td->td_kstack_pages * PAGE_SIZE - \
(char *)&td; \
} while (0)
void set_user_ldt(struct mdproc *);
struct proc_ldt *user_ldt_alloc(struct proc *, int);
void user_ldt_free(struct thread *);
void user_ldt_deref(struct proc_ldt *);
struct sysarch_args;
int sysarch_ldt(struct thread *td, struct sysarch_args *uap, int uap_space);
int amd64_set_ldt_data(struct thread *td, int start, int num,
struct user_segment_descriptor *descs);
extern struct mtx dt_lock;
extern int max_ldt_segment;
struct syscall_args {
u_int code;
struct sysent *callp;
register_t args[8];
int narg;
};
#endif /* _KERNEL */
#endif /* !_MACHINE_PROC_H_ */