xref: /titanic_44/usr/src/uts/sun4/os/mp_call.c (revision f6e214c7418f43af38bd8c3a557e3d0a1d311cfa)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 /*
27  * Facilities for cross-processor subroutine calls using "mailbox" interrupts.
28  */
29 
30 #include <sys/types.h>
31 #include <sys/thread.h>
32 #include <sys/cpuvar.h>
33 #include <sys/x_call.h>
34 #include <sys/systm.h>
35 #include <sys/machsystm.h>
36 #include <sys/intr.h>
37 #include <sys/xc_impl.h>
38 
39 /*
40  * Interrupt another CPU.
41  * 	This is useful to make the other CPU go through a trap so that
42  *	it recognizes an address space trap (AST) for preempting a thread.
43  *
44  *	It is possible to be preempted here and be resumed on the CPU
45  *	being poked, so it isn't an error to poke the current CPU.
46  *	We could check this and still get preempted after the check, so
47  *	we don't bother.
48  */
49 void
50 poke_cpu(int cpun)
51 {
52 	uint32_t *ptr = (uint32_t *)&cpu[cpun]->cpu_m.poke_cpu_outstanding;
53 
54 	/*
55 	 * If panicstr is set or a poke_cpu is already pending,
56 	 * no need to send another one. Use atomic swap to protect
57 	 * against multiple CPUs sending redundant pokes.
58 	 */
59 	if (panicstr || *ptr == B_TRUE ||
60 	    atomic_swap_32(ptr, B_TRUE) == B_TRUE)
61 		return;
62 
63 	xt_one(cpun, setsoftint_tl1, poke_cpu_inum, 0);
64 }
65 
66 extern int xc_spl_enter[];
67 
68 /*
69  * Call a function on a target CPU
70  */
71 void
72 cpu_call(cpu_t *cp, cpu_call_func_t func, uintptr_t arg1, uintptr_t arg2)
73 {
74 	if (panicstr)
75 		return;
76 
77 	/*
78 	 * Prevent CPU from going offline
79 	 */
80 	kpreempt_disable();
81 
82 	/*
83 	 * If we are on the target CPU, call the function directly, but raise
84 	 * the PIL to XC_PIL.
85 	 * This guarantees that functions called via cpu_call() can not ever
86 	 * interrupt each other.
87 	 */
88 	if (CPU != cp) {
89 		xc_one(cp->cpu_id, (xcfunc_t *)func, (uint64_t)arg1,
90 		    (uint64_t)arg2);
91 	} else {
92 		int lcx;
93 		int opl;
94 
95 		XC_SPL_ENTER(lcx, opl);
96 		func(arg1, arg2);
97 		XC_SPL_EXIT(lcx, opl);
98 	}
99 
100 	kpreempt_enable();
101 }
102