vfp.c revision 262941 
1/*-
2 * Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
3 * Copyright (c) 2012 Mark Tinguely
4 *
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 AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, 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__FBSDID("$FreeBSD: head/sys/arm/arm/vfp.c 262941 2014-03-09 03:00:03Z ian $");
31
32#ifdef VFP
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/proc.h>
36#include <sys/kernel.h>
37
38#include <machine/armreg.h>
39#include <machine/frame.h>
40#include <machine/fp.h>
41#include <machine/pcb.h>
42#include <machine/undefined.h>
43#include <machine/vfp.h>
44
45/* function prototypes */
46static int vfp_bounce(u_int, u_int, struct trapframe *, int);
47static void vfp_restore(struct vfp_state *);
48
49extern int vfp_exists;
50static struct undefined_handler vfp10_uh, vfp11_uh;
51/* If true the VFP unit has 32 double registers, otherwise it has 16 */
52static int is_d32;
53
54/* The VFMXR command using coprocessor commands */
55#define fmxr(reg, val) \
56    __asm __volatile("mcr p10, 7, %0, " __STRING(reg) " , c0, 0" :: "r"(val));
57
58/* The VFMRX command using coprocessor commands */
59#define fmrx(reg) \
60({ u_int val = 0;\
61    __asm __volatile("mrc p10, 7, %0, " __STRING(reg) " , c0, 0" : "=r"(val));\
62    val; \
63})
64
65/*
66 * Work around an issue with GCC where the asm it generates is not unified
67 * syntax and fails to assemble because it expects the ldcleq instruction in the
68 * form ldc<c>l, not in the UAL form ldcl<c>, and similar for stcleq.
69 */
70#ifdef __clang__
71#define	LDCLNE  "ldclne "
72#define	STCLNE  "stclne "
73#else
74#define	LDCLNE  "ldcnel "
75#define	STCLNE  "stcnel "
76#endif
77
78static u_int
79get_coprocessorACR(void)
80{
81	u_int val;
82	__asm __volatile("mrc p15, 0, %0, c1, c0, 2" : "=r" (val) : : "cc");
83	return val;
84}
85
86static void
87set_coprocessorACR(u_int val)
88{
89	__asm __volatile("mcr p15, 0, %0, c1, c0, 2\n\t"
90	 : : "r" (val) : "cc");
91	isb();
92}
93
94
95	/* called for each cpu */
96void
97vfp_init(void)
98{
99	u_int fpsid, fpexc, tmp;
100	u_int coproc, vfp_arch;
101
102	coproc = get_coprocessorACR();
103	coproc |= COPROC10 | COPROC11;
104	set_coprocessorACR(coproc);
105
106	fpsid = fmrx(VFPSID);		/* read the vfp system id */
107	fpexc = fmrx(VFPEXC);		/* read the vfp exception reg */
108
109	if (!(fpsid & VFPSID_HARDSOFT_IMP)) {
110		vfp_exists = 1;
111		is_d32 = 0;
112		PCPU_SET(vfpsid, fpsid);	/* save the VFPSID */
113
114		vfp_arch =
115		    (fpsid & VFPSID_SUBVERSION2_MASK) >> VFPSID_SUBVERSION_OFF;
116
117		if (vfp_arch >= VFP_ARCH3) {
118			tmp = fmrx(VMVFR0);
119			PCPU_SET(vfpmvfr0, tmp);
120
121			if ((tmp & VMVFR0_RB_MASK) == 2)
122				is_d32 = 1;
123
124			tmp = fmrx(VMVFR1);
125			PCPU_SET(vfpmvfr1, tmp);
126		}
127
128		/* initialize the coprocess 10 and 11 calls
129		 * These are called to restore the registers and enable
130		 * the VFP hardware.
131		 */
132		if (vfp10_uh.uh_handler == NULL) {
133			vfp10_uh.uh_handler = vfp_bounce;
134			vfp11_uh.uh_handler = vfp_bounce;
135			install_coproc_handler_static(10, &vfp10_uh);
136			install_coproc_handler_static(11, &vfp11_uh);
137		}
138	}
139}
140
141SYSINIT(vfp, SI_SUB_CPU, SI_ORDER_ANY, vfp_init, NULL);
142
143
144/* start VFP unit, restore the vfp registers from the PCB  and retry
145 * the instruction
146 */
147static int
148vfp_bounce(u_int addr, u_int insn, struct trapframe *frame, int code)
149{
150	u_int cpu, fpexc;
151	struct pcb *curpcb;
152
153	if ((code & FAULT_USER) == 0)
154		panic("undefined floating point instruction in supervisor mode");
155
156	critical_enter();
157
158	/*
159	 * If the VFP is already on and we got an undefined instruction, then
160	 * something tried to executate a truly invalid instruction that maps to
161	 * the VFP.
162	 */
163	fpexc = fmrx(VFPEXC);
164	if (fpexc & VFPEXC_EN) {
165		/* kill the process - we do not handle emulation */
166		critical_exit();
167		killproc(curthread->td_proc, "vfp emulation");
168		return 1;
169	}
170
171	/*
172	 * If the last time this thread used the VFP it was on this core, and
173	 * the last thread to use the VFP on this core was this thread, then the
174	 * VFP state is valid, otherwise restore this thread's state to the VFP.
175	 */
176	fmxr(VFPEXC, fpexc | VFPEXC_EN);
177	curpcb = curthread->td_pcb;
178	cpu = PCPU_GET(cpu);
179	if (curpcb->pcb_vfpcpu != cpu || curthread != PCPU_GET(fpcurthread)) {
180		vfp_restore(&curpcb->pcb_vfpstate);
181		curpcb->pcb_vfpcpu = cpu;
182		PCPU_SET(fpcurthread, curthread);
183	}
184
185	critical_exit();
186	return (0);
187}
188
189/*
190 * Restore the given state to the VFP hardware.
191 */
192static void
193vfp_restore(struct vfp_state *vfpsave)
194{
195	u_int vfpscr = 0;
196
197	__asm __volatile("ldc	p10, c0, [%1], #128\n" /* d0-d15 */
198			"cmp	%2, #0\n"		/* -D16 or -D32? */
199			LDCLNE "p11, c0, [%1], #128\n"	/* d16-d31 */
200			"addeq	%1, %1, #128\n"		/* skip missing regs */
201			"ldr	%0, [%1]\n"		/* set old vfpscr */
202			"mcr	p10, 7, %0, cr1, c0, 0\n"
203			: "=&r" (vfpscr) : "r" (vfpsave), "r" (is_d32) : "cc");
204}
205
206/*
207 * If the VFP is on, save its current state and turn it off if requested to do
208 * so.  If the VFP is not on, does not change the values at *vfpsave.  Caller is
209 * responsible for preventing a context switch while this is running.
210 */
211void
212vfp_store(struct vfp_state *vfpsave, boolean_t disable_vfp)
213{
214	u_int tmp, vfpscr;
215
216	tmp = fmrx(VFPEXC);		/* Is the vfp enabled? */
217	if (tmp & VFPEXC_EN) {
218		__asm __volatile(
219			"stc	p11, c0, [%1], #128\n"  /* d0-d15 */
220			"cmp	%2, #0\n"		/* -D16 or -D32? */
221			STCLNE "p11, c0, [%1], #128\n"	/* d16-d31 */
222			"addeq	%1, %1, #128\n"		/* skip missing regs */
223			"mrc	p10, 7, %0, cr1, c0, 0\n" /* fmxr(VFPSCR) */
224			"str	%0, [%1]\n"		/* save vfpscr */
225			: "=&r" (vfpscr) : "r" (vfpsave), "r" (is_d32) : "cc");
226		if (disable_vfp)
227			fmxr(VFPEXC , tmp & ~VFPEXC_EN);
228	}
229}
230
231/*
232 * If the VFP hardware is on, the current thread was using it but now that
233 * thread is dying.  Turn off the VFP and set pcpu fpcurthread to 0, to indicate
234 * that the VFP hardware state does not belong to any thread.   Called only from
235 * cpu_throw(), so we don't have to worry about a context switch here.
236 */
237void
238vfp_discard()
239{
240	u_int tmp;
241
242	tmp = fmrx(VFPEXC);
243	if (tmp & VFPEXC_EN) {
244		fmxr(VFPEXC, tmp & ~VFPEXC_EN);
245		PCPU_SET(fpcurthread, 0);
246	}
247}
248
249#endif
250
251