FreeBSD/Linux Kernel Cross Reference
sys/arm/arm/vfp.c
1 /*
2 * Copyright (c) 2012 Mark Tinguely
3 *
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD: releng/10.0/sys/arm/arm/vfp.c 254461 2013-08-17 18:51:38Z andrew $");
30
31 #ifdef VFP
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/proc.h>
35 #include <sys/kernel.h>
36
37 #include <machine/fp.h>
38 #include <machine/pcb.h>
39 #include <machine/undefined.h>
40 #include <machine/vfp.h>
41
42 /* function prototypes */
43 unsigned int get_coprocessorACR(void);
44 int vfp_bounce(u_int, u_int, struct trapframe *, int);
45 void vfp_discard(void);
46 void vfp_enable(void);
47 void vfp_restore(struct vfp_state *);
48 void vfp_store(struct vfp_state *);
49 void set_coprocessorACR(u_int);
50
51 extern int vfp_exists;
52 static struct undefined_handler vfp10_uh, vfp11_uh;
53 /* If true the VFP unit has 32 double registers, otherwise it has 16 */
54 static int is_d32;
55
56 /* The VFMXR command using coprocessor commands */
57 #define fmxr(reg, val) \
58 __asm __volatile("mcr p10, 7, %0, " __STRING(reg) " , c0, 0" :: "r"(val));
59
60 /* The VFMRX command using coprocessor commands */
61 #define fmrx(reg) \
62 ({ u_int val = 0;\
63 __asm __volatile("mrc p10, 7, %0, " __STRING(reg) " , c0, 0" : "=r"(val));\
64 val; \
65 })
66
67 u_int
68 get_coprocessorACR(void)
69 {
70 u_int val;
71 __asm __volatile("mrc p15, 0, %0, c1, c0, 2" : "=r" (val) : : "cc");
72 return val;
73 }
74
75 void
76 set_coprocessorACR(u_int val)
77 {
78 __asm __volatile("mcr p15, 0, %0, c1, c0, 2\n\t"
79 : : "r" (val) : "cc");
80 isb();
81 }
82
83
84 /* called for each cpu */
85 void
86 vfp_init(void)
87 {
88 u_int fpsid, fpexc, tmp;
89 u_int coproc, vfp_arch;
90
91 coproc = get_coprocessorACR();
92 coproc |= COPROC10 | COPROC11;
93 set_coprocessorACR(coproc);
94
95 fpsid = fmrx(VFPSID); /* read the vfp system id */
96 fpexc = fmrx(VFPEXC); /* read the vfp exception reg */
97
98 if (!(fpsid & VFPSID_HARDSOFT_IMP)) {
99 vfp_exists = 1;
100 is_d32 = 0;
101 PCPU_SET(vfpsid, fpsid); /* save the VFPSID */
102
103 vfp_arch =
104 (fpsid & VFPSID_SUBVERSION2_MASK) >> VFPSID_SUBVERSION_OFF;
105
106 if (vfp_arch >= VFP_ARCH3) {
107 tmp = fmrx(VMVFR0);
108 PCPU_SET(vfpmvfr0, tmp);
109
110 if ((tmp & VMVFR0_RB_MASK) == 2)
111 is_d32 = 1;
112
113 tmp = fmrx(VMVFR1);
114 PCPU_SET(vfpmvfr1, tmp);
115 }
116
117 /* initialize the coprocess 10 and 11 calls
118 * These are called to restore the registers and enable
119 * the VFP hardware.
120 */
121 if (vfp10_uh.uh_handler == NULL) {
122 vfp10_uh.uh_handler = vfp_bounce;
123 vfp11_uh.uh_handler = vfp_bounce;
124 install_coproc_handler_static(10, &vfp10_uh);
125 install_coproc_handler_static(11, &vfp11_uh);
126 }
127 }
128 }
129
130 SYSINIT(vfp, SI_SUB_CPU, SI_ORDER_ANY, vfp_init, NULL);
131
132
133 /* start VFP unit, restore the vfp registers from the PCB and retry
134 * the instruction
135 */
136 int
137 vfp_bounce(u_int addr, u_int insn, struct trapframe *frame, int code)
138 {
139 u_int fpexc;
140 struct pcb *curpcb;
141 struct thread *vfptd;
142
143 if (!vfp_exists)
144 return 1; /* vfp does not exist */
145 fpexc = fmrx(VFPEXC); /* read the vfp exception reg */
146 if (fpexc & VFPEXC_EN) {
147 vfptd = PCPU_GET(vfpcthread);
148 /* did the kernel call the vfp or exception that expect us
149 * to emulate the command. Newer hardware does not require
150 * emulation, so we don't emulate yet.
151 */
152 #ifdef SMP
153 /* don't save if newer registers are on another processor */
154 if (vfptd /* && (vfptd == curthread) */ &&
155 (vfptd->td_pcb->pcb_vfpcpu == PCPU_GET(cpu)))
156 #else
157 /* someone did not save their registers, */
158 if (vfptd /* && (vfptd == curthread) */)
159 #endif
160 vfp_store(&vfptd->td_pcb->pcb_vfpstate);
161
162 fpexc &= ~VFPEXC_EN;
163 fmxr(VFPEXC, fpexc); /* turn vfp hardware off */
164 if (vfptd == curthread) {
165 /* kill the process - we do not handle emulation */
166 killproc(curthread->td_proc, "vfp emulation");
167 return 1;
168 }
169 /* should not happen. someone did not save their context */
170 printf("vfp_bounce: vfpcthread: %p curthread: %p\n",
171 vfptd, curthread);
172 }
173 fpexc |= VFPEXC_EN;
174 fmxr(VFPEXC, fpexc); /* enable the vfp and repeat command */
175 curpcb = PCPU_GET(curpcb);
176 /* If we were the last process to use the VFP, the process did not
177 * use a VFP on another processor, then the registers in the VFP
178 * will still be ours and are current. Eventually, we will make the
179 * restore smarter.
180 */
181 vfp_restore(&curpcb->pcb_vfpstate);
182 #ifdef SMP
183 curpcb->pcb_vfpcpu = PCPU_GET(cpu);
184 #endif
185 PCPU_SET(vfpcthread, PCPU_GET(curthread));
186 return 0;
187 }
188
189 /* vfs_store is called from from a VFP command to restore the registers and
190 * turn on the VFP hardware.
191 * Eventually we will use the information that this process was the last
192 * to use the VFP hardware and bypass the restore, just turn on the hardware.
193 */
194 void
195 vfp_restore(struct vfp_state *vfpsave)
196 {
197 u_int vfpscr = 0;
198
199 /*
200 * Work around an issue with GCC where the asm it generates is
201 * not unified syntax and fails to assemble because it expects
202 * the ldcleq instruction in the form ldc<c>l, not in the UAL
203 * form ldcl<c>, and similar for stcleq.
204 */
205 #ifdef __clang__
206 #define ldclne "ldclne"
207 #define stclne "stclne"
208 #else
209 #define ldclne "ldcnel"
210 #define stclne "stcnel"
211 #endif
212 if (vfpsave) {
213 __asm __volatile("ldc p10, c0, [%1], #128\n" /* d0-d15 */
214 "cmp %2, #0\n" /* -D16 or -D32? */
215 ldclne" p11, c0, [%1], #128\n" /* d16-d31 */
216 "addeq %1, %1, #128\n" /* skip missing regs */
217 "ldr %0, [%1]\n" /* set old vfpscr */
218 "mcr p10, 7, %0, cr1, c0, 0\n"
219 : "=&r" (vfpscr) : "r" (vfpsave), "r" (is_d32) : "cc");
220 PCPU_SET(vfpcthread, PCPU_GET(curthread));
221 }
222 }
223
224 /* vfs_store is called from switch to save the vfp hardware registers
225 * into the pcb before switching to another process.
226 * we already know that the new process is different from this old
227 * process and that this process last used the VFP registers.
228 * Below we check to see if the VFP has been enabled since the last
229 * register save.
230 * This routine will exit with the VFP turned off. The next VFP user
231 * will trap to restore its registers and turn on the VFP hardware.
232 */
233 void
234 vfp_store(struct vfp_state *vfpsave)
235 {
236 u_int tmp, vfpscr = 0;
237
238 tmp = fmrx(VFPEXC); /* Is the vfp enabled? */
239 if (vfpsave && tmp & VFPEXC_EN) {
240 __asm __volatile("stc p11, c0, [%1], #128\n" /* d0-d15 */
241 "cmp %2, #0\n" /* -D16 or -D32? */
242 stclne" p11, c0, [%1], #128\n" /* d16-d31 */
243 "addeq %1, %1, #128\n" /* skip missing regs */
244 "mrc p10, 7, %0, cr1, c0, 0\n" /* fmxr(VFPSCR) */
245 "str %0, [%1]\n" /* save vfpscr */
246 : "=&r" (vfpscr) : "r" (vfpsave), "r" (is_d32) : "cc");
247 }
248 #undef ldcleq
249 #undef stcleq
250
251 #ifndef SMP
252 /* eventually we will use this information for UP also */
253 PCPU_SET(vfpcthread, 0);
254 #endif
255 tmp &= ~VFPEXC_EN; /* disable the vfp hardware */
256 fmxr(VFPEXC , tmp);
257 }
258
259 /* discard the registers at cpu_thread_free() when fpcurthread == td.
260 * Turn off the VFP hardware.
261 */
262 void
263 vfp_discard()
264 {
265 u_int tmp = 0;
266
267 PCPU_SET(vfpcthread, 0); /* permanent forget about reg */
268 tmp = fmrx(VFPEXC);
269 tmp &= ~VFPEXC_EN; /* turn off VFP hardware */
270 fmxr(VFPEXC, tmp);
271 }
272
273 /* Enable the VFP hardware without restoring registers.
274 * Called when the registers are still in the VFP unit
275 */
276 void
277 vfp_enable()
278 {
279 u_int tmp = 0;
280
281 tmp = fmrx(VFPEXC);
282 tmp |= VFPEXC_EN;
283 fmxr(VFPEXC, tmp);
284 }
285 #endif
286
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