gic_splfuncs.c revision 1.4 
1/* $NetBSD: gic_splfuncs.c,v 1.4 2021/09/26 20:55:15 jmcneill Exp $ */
2
3/*-
4 * Copyright (c) 2021 Jared McNeill <jmcneill@invisible.ca>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: gic_splfuncs.c,v 1.4 2021/09/26 20:55:15 jmcneill Exp $");
31
32#include <sys/param.h>
33#include <sys/atomic.h>
34#include <sys/kernel.h>
35#include <sys/lwp.h>
36
37#include <arm/pic/picvar.h>
38#include <arm/cpu.h>
39#include <arm/cpufunc.h>
40#include <arm/locore.h>
41
42#include <arm/cortex/gic_splfuncs.h>
43
44static int
45gic_splraise(int newipl)
46{
47	struct cpu_info * const ci = curcpu();
48	const int oldipl = ci->ci_cpl;
49	if (__predict_true(newipl > oldipl)) {
50		ci->ci_cpl = newipl;
51	}
52	return oldipl;
53}
54
55static int
56gic_spllower(int newipl)
57{
58	struct cpu_info * const ci = curcpu();
59	const int oldipl = ci->ci_cpl;
60	KASSERT(panicstr || newipl <= ci->ci_cpl);
61	if (newipl < ci->ci_cpl) {
62		register_t psw = DISABLE_INTERRUPT_SAVE();
63		ci->ci_intr_depth++;
64		pic_do_pending_ints(psw, newipl, NULL);
65		ci->ci_intr_depth--;
66		if ((psw & I32_bit) == 0 || newipl == IPL_NONE) {
67			ENABLE_INTERRUPT();
68		}
69		cpu_dosoftints();
70	}
71
72	return oldipl;
73}
74
75static void
76gic_splx(int newipl)
77{
78	struct cpu_info *ci = curcpu();
79	register_t psw;
80
81	if (newipl >= ci->ci_cpl) {
82		return;
83	}
84
85	/*
86	 * Try to avoid touching any hardware registers (DAIF, PMR) as an
87	 * optimization for the common case of splraise followed by splx
88	 * with no interrupts in between.
89	 *
90	 * If an interrupt fires in this critical section, the vector
91	 * handler is responsible for returning to the address pointed
92	 * to by ci_splx_restart to restart the sequence.
93	 */
94	if (__predict_true(ci->ci_intr_depth == 0)) {
95		ci->ci_splx_savedipl = newipl;
96		__insn_barrier();
97		ci->ci_splx_restart = &&restart;
98		__insn_barrier();
99checkhwpl:
100		if (ci->ci_hwpl <= newipl) {
101			ci->ci_cpl = newipl;
102			__insn_barrier();
103			ci->ci_splx_restart = NULL;
104			goto dosoft;
105		} else {
106			ci->ci_splx_restart = NULL;
107			goto dohard;
108		}
109restart:
110		ci = curcpu();
111		newipl = ci->ci_splx_savedipl;
112		goto checkhwpl;
113	}
114
115dohard:
116	psw = DISABLE_INTERRUPT_SAVE();
117	ci->ci_intr_depth++;
118	pic_do_pending_ints(psw, newipl, NULL);
119	ci->ci_intr_depth--;
120	if ((psw & I32_bit) == 0) {
121		ENABLE_INTERRUPT();
122	}
123
124dosoft:
125	cpu_dosoftints();
126}
127
128void
129gic_spl_init(void)
130{
131	pic_splraise = gic_splraise;
132	pic_spllower = gic_spllower;
133	pic_splx = gic_splx;
134}
135