freebsd-nq/sys/dev/dcons/dcons_os.c
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

496 lines
10 KiB
C

/*-
* SPDX-License-Identifier: BSD-4-Clause
*
* Copyright (C) 2003,2004
* Hidetoshi Shimokawa. 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 Hidetoshi Shimokawa.
*
* 4. Neither the name of the author 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/kdb.h>
#include <gdb/gdb.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/consio.h>
#include <sys/tty.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/ucred.h>
#include <machine/bus.h>
#include <dev/dcons/dcons.h>
#include <dev/dcons/dcons_os.h>
#include <ddb/ddb.h>
#include <sys/reboot.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include "opt_dcons.h"
#include "opt_kdb.h"
#include "opt_gdb.h"
#include "opt_ddb.h"
#ifndef DCONS_POLL_HZ
#define DCONS_POLL_HZ 25
#endif
#ifndef DCONS_POLL_IDLE
#define DCONS_POLL_IDLE 256
#endif
#ifndef DCONS_BUF_SIZE
#define DCONS_BUF_SIZE (16*1024)
#endif
#ifndef DCONS_FORCE_CONSOLE
#define DCONS_FORCE_CONSOLE 0 /* Mostly for FreeBSD-4/DragonFly */
#endif
#ifndef KLD_MODULE
static char bssbuf[DCONS_BUF_SIZE]; /* buf in bss */
#endif
/* global data */
static struct dcons_global dg;
struct dcons_global *dcons_conf;
static int poll_hz = DCONS_POLL_HZ;
static u_int poll_idle = DCONS_POLL_HZ * DCONS_POLL_IDLE;
static struct dcons_softc sc[DCONS_NPORT];
static SYSCTL_NODE(_kern, OID_AUTO, dcons, CTLFLAG_RD, 0, "Dumb Console");
SYSCTL_INT(_kern_dcons, OID_AUTO, poll_hz, CTLFLAG_RW, &poll_hz, 0,
"dcons polling rate");
static int drv_init = 0;
static struct callout dcons_callout;
struct dcons_buf *dcons_buf; /* for local dconschat */
static void dcons_timeout(void *);
static int dcons_drv_init(int);
static cn_probe_t dcons_cnprobe;
static cn_init_t dcons_cninit;
static cn_term_t dcons_cnterm;
static cn_getc_t dcons_cngetc;
static cn_putc_t dcons_cnputc;
static cn_grab_t dcons_cngrab;
static cn_ungrab_t dcons_cnungrab;
CONSOLE_DRIVER(dcons);
#if defined(GDB)
static gdb_probe_f dcons_dbg_probe;
static gdb_init_f dcons_dbg_init;
static gdb_term_f dcons_dbg_term;
static gdb_getc_f dcons_dbg_getc;
static gdb_putc_f dcons_dbg_putc;
GDB_DBGPORT(dcons, dcons_dbg_probe, dcons_dbg_init, dcons_dbg_term,
dcons_dbg_getc, dcons_dbg_putc);
extern struct gdb_dbgport *gdb_cur;
#endif
static tsw_outwakeup_t dcons_outwakeup;
static struct ttydevsw dcons_ttydevsw = {
.tsw_flags = TF_NOPREFIX,
.tsw_outwakeup = dcons_outwakeup,
};
#if (defined(GDB) || defined(DDB))
static int
dcons_check_break(struct dcons_softc *dc, int c)
{
if (c < 0)
return (c);
#ifdef GDB
if ((dc->flags & DC_GDB) != 0 && gdb_cur == &dcons_gdb_dbgport)
kdb_alt_break_gdb(c, &dc->brk_state);
else
#endif
kdb_alt_break(c, &dc->brk_state);
return (c);
}
#else
#define dcons_check_break(dc, c) (c)
#endif
static int
dcons_os_checkc_nopoll(struct dcons_softc *dc)
{
int c;
if (dg.dma_tag != NULL)
bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_POSTREAD);
c = dcons_check_break(dc, dcons_checkc(dc));
if (dg.dma_tag != NULL)
bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_PREREAD);
return (c);
}
static int
dcons_os_checkc(struct dcons_softc *dc)
{
EVENTHANDLER_INVOKE(dcons_poll, 0);
return (dcons_os_checkc_nopoll(dc));
}
static void
dcons_os_putc(struct dcons_softc *dc, int c)
{
if (dg.dma_tag != NULL)
bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_POSTWRITE);
dcons_putc(dc, c);
if (dg.dma_tag != NULL)
bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_PREWRITE);
}
static void
dcons_outwakeup(struct tty *tp)
{
struct dcons_softc *dc;
char ch;
dc = tty_softc(tp);
while (ttydisc_getc(tp, &ch, sizeof ch) != 0)
dcons_os_putc(dc, ch);
}
static void
dcons_timeout(void *v)
{
struct tty *tp;
struct dcons_softc *dc;
int i, c, polltime;
for (i = 0; i < DCONS_NPORT; i ++) {
dc = &sc[i];
tp = dc->tty;
tty_lock(tp);
while ((c = dcons_os_checkc_nopoll(dc)) != -1) {
ttydisc_rint(tp, c, 0);
poll_idle = 0;
}
ttydisc_rint_done(tp);
tty_unlock(tp);
}
poll_idle++;
polltime = hz;
if (poll_idle <= (poll_hz * DCONS_POLL_IDLE))
polltime /= poll_hz;
callout_reset(&dcons_callout, polltime, dcons_timeout, tp);
}
static void
dcons_cnprobe(struct consdev *cp)
{
sprintf(cp->cn_name, "dcons");
#if DCONS_FORCE_CONSOLE
cp->cn_pri = CN_REMOTE;
#else
cp->cn_pri = CN_NORMAL;
#endif
}
static void
dcons_cninit(struct consdev *cp)
{
dcons_drv_init(0);
cp->cn_arg = (void *)&sc[DCONS_CON]; /* share port0 with unit0 */
}
static void
dcons_cnterm(struct consdev *cp)
{
}
static void
dcons_cngrab(struct consdev *cp)
{
}
static void
dcons_cnungrab(struct consdev *cp)
{
}
static int
dcons_cngetc(struct consdev *cp)
{
struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
return (dcons_os_checkc(dc));
}
static void
dcons_cnputc(struct consdev *cp, int c)
{
struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
dcons_os_putc(dc, c);
}
static int
dcons_drv_init(int stage)
{
#if defined(__i386__) || defined(__amd64__)
quad_t addr, size;
#endif
if (drv_init)
return(drv_init);
drv_init = -1;
bzero(&dg, sizeof(dg));
dcons_conf = &dg;
dg.cdev = &dcons_consdev;
dg.buf = NULL;
dg.size = DCONS_BUF_SIZE;
#if defined(__i386__) || defined(__amd64__)
if (getenv_quad("dcons.addr", &addr) > 0 &&
getenv_quad("dcons.size", &size) > 0) {
#ifdef __i386__
vm_paddr_t pa;
/*
* Allow read/write access to dcons buffer.
*/
for (pa = trunc_page(addr); pa < addr + size; pa += PAGE_SIZE)
*vtopte(PMAP_MAP_LOW + pa) |= PG_RW;
invltlb();
#endif
/* XXX P to V */
#ifdef __amd64__
dg.buf = (struct dcons_buf *)(vm_offset_t)(KERNBASE + addr);
#else /* __i386__ */
dg.buf = (struct dcons_buf *)((vm_offset_t)PMAP_MAP_LOW +
addr);
#endif
dg.size = size;
if (dcons_load_buffer(dg.buf, dg.size, sc) < 0)
dg.buf = NULL;
}
#endif
if (dg.buf != NULL)
goto ok;
#ifndef KLD_MODULE
if (stage == 0) { /* XXX or cold */
/*
* DCONS_FORCE_CONSOLE == 1 and statically linked.
* called from cninit(). can't use contigmalloc yet .
*/
dg.buf = (struct dcons_buf *) bssbuf;
dcons_init(dg.buf, dg.size, sc);
} else
#endif
{
/*
* DCONS_FORCE_CONSOLE == 0 or kernel module case.
* if the module is loaded after boot,
* bssbuf could be non-continuous.
*/
dg.buf = (struct dcons_buf *) contigmalloc(dg.size,
M_DEVBUF, 0, 0x10000, 0xffffffff, PAGE_SIZE, 0ul);
if (dg.buf == NULL)
return (-1);
dcons_init(dg.buf, dg.size, sc);
}
ok:
dcons_buf = dg.buf;
drv_init = 1;
return 0;
}
static int
dcons_attach_port(int port, char *name, int flags)
{
struct dcons_softc *dc;
struct tty *tp;
dc = &sc[port];
tp = tty_alloc(&dcons_ttydevsw, dc);
dc->flags = flags;
dc->tty = tp;
tty_init_console(tp, 0);
tty_makedev(tp, NULL, "%s", name);
return(0);
}
static int
dcons_attach(void)
{
int polltime;
dcons_attach_port(DCONS_CON, "dcons", 0);
dcons_attach_port(DCONS_GDB, "dgdb", DC_GDB);
callout_init(&dcons_callout, 1);
polltime = hz / poll_hz;
callout_reset(&dcons_callout, polltime, dcons_timeout, NULL);
return(0);
}
static int
dcons_detach(int port)
{
struct tty *tp;
struct dcons_softc *dc;
dc = &sc[port];
tp = dc->tty;
tty_lock(tp);
tty_rel_gone(tp);
return(0);
}
static int
dcons_modevent(module_t mode, int type, void *data)
{
int err = 0, ret;
switch (type) {
case MOD_LOAD:
ret = dcons_drv_init(1);
if (ret != -1)
dcons_attach();
if (ret == 0) {
dcons_cnprobe(&dcons_consdev);
dcons_cninit(&dcons_consdev);
cnadd(&dcons_consdev);
}
break;
case MOD_UNLOAD:
printf("dcons: unload\n");
if (drv_init == 1) {
callout_stop(&dcons_callout);
cnremove(&dcons_consdev);
dcons_detach(DCONS_CON);
dcons_detach(DCONS_GDB);
dg.buf->magic = 0;
contigfree(dg.buf, DCONS_BUF_SIZE, M_DEVBUF);
}
break;
case MOD_SHUTDOWN:
#if 0 /* Keep connection after halt */
dg.buf->magic = 0;
#endif
break;
default:
err = EOPNOTSUPP;
break;
}
return(err);
}
#if defined(GDB)
/* Debugger interface */
static int
dcons_os_getc(struct dcons_softc *dc)
{
int c;
while ((c = dcons_os_checkc(dc)) == -1);
return (c & 0xff);
}
static int
dcons_dbg_probe(void)
{
int dcons_gdb;
if (getenv_int("dcons_gdb", &dcons_gdb) == 0)
return (-1);
return (dcons_gdb);
}
static void
dcons_dbg_init(void)
{
}
static void
dcons_dbg_term(void)
{
}
static void
dcons_dbg_putc(int c)
{
struct dcons_softc *dc = &sc[DCONS_GDB];
dcons_os_putc(dc, c);
}
static int
dcons_dbg_getc(void)
{
struct dcons_softc *dc = &sc[DCONS_GDB];
return (dcons_os_getc(dc));
}
#endif
DEV_MODULE(dcons, dcons_modevent, NULL);
MODULE_VERSION(dcons, DCONS_VERSION);