kern_ras.c revision 1.33 
1/*	$NetBSD: kern_ras.c,v 1.33 2008/06/09 11:49:40 ad Exp $	*/
2
3/*-
4 * Copyright (c) 2002, 2006, 2007, 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Gregory McGarry, and by Andrew Doran.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.33 2008/06/09 11:49:40 ad Exp $");
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/kernel.h>
38#include <sys/kmem.h>
39#include <sys/proc.h>
40#include <sys/ras.h>
41#include <sys/xcall.h>
42#include <sys/syscallargs.h>
43
44#include <uvm/uvm_extern.h>
45
46#define MAX_RAS_PER_PROC	16
47
48u_int ras_per_proc = MAX_RAS_PER_PROC;
49
50#ifdef DEBUG
51int ras_debug = 0;
52#define DPRINTF(x)	if (ras_debug) printf x
53#else
54#define DPRINTF(x)	/* nothing */
55#endif
56
57/*
58 * Force all CPUs through cpu_switchto(), waiting until complete.
59 * Context switching will drain the write buffer on the calling
60 * CPU.
61 */
62static void
63ras_sync(void)
64{
65
66	/* No need to sync if exiting or single threaded. */
67	if (curproc->p_nlwps > 1 && ncpu > 1) {
68#ifdef NO_SOFTWARE_PATENTS
69		uint64_t where;
70		where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
71		xc_wait(where);
72#else
73		/*
74		 * Assumptions:
75		 *
76		 * o preemption is disabled by the thread in
77		 *   ras_lookup().
78		 * o proc::p_raslist is only inspected with
79		 *   preemption disabled.
80		 * o ras_lookup() plus loads reordered in advance
81		 *   will take no longer than 1/8s to complete.
82		 */
83		const int delta = hz >> 3;
84		int target = hardclock_ticks + delta;
85		do {
86			kpause("ras", false, delta, NULL);
87		} while (hardclock_ticks < target);
88#endif
89	}
90}
91
92/*
93 * Check the specified address to see if it is within the
94 * sequence.  If it is found, we return the restart address,
95 * otherwise we return -1.  If we do perform a restart, we
96 * mark the sequence as hit.
97 *
98 * No locking required: we disable preemption and ras_sync()
99 * guarantees that individual entries are valid while we still
100 * have visibility of them.
101 */
102void *
103ras_lookup(struct proc *p, void *addr)
104{
105	struct ras *rp;
106	void *startaddr;
107	lwp_t *l;
108
109	startaddr = (void *)-1;
110	l = curlwp;
111
112	KPREEMPT_DISABLE(l);
113	for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) {
114		if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) {
115			startaddr = rp->ras_startaddr;
116			DPRINTF(("RAS hit: p=%p %p\n", p, addr));
117			break;
118		}
119	}
120	KPREEMPT_ENABLE(l);
121
122	return startaddr;
123}
124
125/*
126 * During a fork, we copy all of the sequences from parent p1 to
127 * the child p2.
128 *
129 * No locking required as the parent must be paused.
130 */
131int
132ras_fork(struct proc *p1, struct proc *p2)
133{
134	struct ras *rp, *nrp;
135
136	for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) {
137		nrp = kmem_alloc(sizeof(*nrp), KM_SLEEP);
138		nrp->ras_startaddr = rp->ras_startaddr;
139		nrp->ras_endaddr = rp->ras_endaddr;
140		nrp->ras_next = p2->p_raslist;
141		p2->p_raslist = nrp;
142	}
143
144	DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2));
145
146	return 0;
147}
148
149/*
150 * Nuke all sequences for this process.
151 */
152int
153ras_purgeall(void)
154{
155	struct ras *rp, *nrp;
156	proc_t *p;
157
158	p = curproc;
159
160	if (p->p_raslist == NULL)
161		return 0;
162
163	mutex_enter(&p->p_auxlock);
164	if ((rp = p->p_raslist) != NULL) {
165		p->p_raslist = NULL;
166		ras_sync();
167		for(; rp != NULL; rp = nrp) {
168			nrp = rp->ras_next;
169			kmem_free(rp, sizeof(*rp));
170		}
171	}
172	mutex_exit(&p->p_auxlock);
173
174	return 0;
175}
176
177#if defined(__HAVE_RAS)
178
179/*
180 * Install the new sequence.  If it already exists, return
181 * an error.
182 */
183static int
184ras_install(void *addr, size_t len)
185{
186	struct ras *rp;
187	struct ras *newrp;
188	void *endaddr;
189	int nras, error;
190	proc_t *p;
191
192	endaddr = (char *)addr + len;
193
194	if (addr < (void *)VM_MIN_ADDRESS ||
195	    endaddr > (void *)VM_MAXUSER_ADDRESS)
196		return (EINVAL);
197
198	if (len <= 0)
199		return (EINVAL);
200
201	newrp = kmem_alloc(sizeof(*newrp), KM_SLEEP);
202	newrp->ras_startaddr = addr;
203	newrp->ras_endaddr = endaddr;
204	error = 0;
205	nras = 0;
206	p = curproc;
207
208	mutex_enter(&p->p_auxlock);
209	for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) {
210		if (++nras >= ras_per_proc) {
211			error = EINVAL;
212			break;
213		}
214		if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) {
215			error = EEXIST;
216			break;
217		}
218	}
219	if (rp == NULL) {
220		newrp->ras_next = p->p_raslist;
221		p->p_raslist = newrp;
222		ras_sync();
223	 	mutex_exit(&p->p_auxlock);
224	} else {
225	 	mutex_exit(&p->p_auxlock);
226 		kmem_free(newrp, sizeof(*newrp));
227	}
228
229	return error;
230}
231
232/*
233 * Nuke the specified sequence.  Both address and len must
234 * match, otherwise we return an error.
235 */
236static int
237ras_purge(void *addr, size_t len)
238{
239	struct ras *rp, **link;
240	void *endaddr;
241	proc_t *p;
242
243	endaddr = (char *)addr + len;
244	p = curproc;
245
246	mutex_enter(&p->p_auxlock);
247	link = &p->p_raslist;
248	for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) {
249		if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr)
250			break;
251	}
252	if (rp != NULL) {
253		*link = rp->ras_next;
254		ras_sync();
255		mutex_exit(&p->p_auxlock);
256		kmem_free(rp, sizeof(*rp));
257		return 0;
258	} else {
259		mutex_exit(&p->p_auxlock);
260		return ESRCH;
261	}
262}
263
264#endif /* defined(__HAVE_RAS) */
265
266/*ARGSUSED*/
267int
268sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval)
269{
270
271#if defined(__HAVE_RAS)
272	/* {
273		syscallarg(void *) addr;
274		syscallarg(size_t) len;
275		syscallarg(int) op;
276	} */
277	void *addr;
278	size_t len;
279	int op;
280	int error;
281
282	/*
283	 * first, extract syscall args from the uap.
284	 */
285
286	addr = (void *)SCARG(uap, addr);
287	len = (size_t)SCARG(uap, len);
288	op = SCARG(uap, op);
289
290	DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n",
291	    curproc, addr, (long)len, op));
292
293	switch (op) {
294	case RAS_INSTALL:
295		error = ras_install(addr, len);
296		break;
297	case RAS_PURGE:
298		error = ras_purge(addr, len);
299		break;
300	case RAS_PURGE_ALL:
301		error = ras_purgeall();
302		break;
303	default:
304		error = EINVAL;
305		break;
306	}
307
308	return (error);
309
310#else
311
312	return (EOPNOTSUPP);
313
314#endif
315
316}
317