1 // SPDX-License-Identifier: GPL-2.0
2 #define DEBUG
3 
4 #include <linux/wait.h>
5 #include <linux/ptrace.h>
6 
7 #include <asm/spu.h>
8 #include <asm/spu_priv1.h>
9 #include <asm/io.h>
10 #include <asm/unistd.h>
11 
12 #include "spufs.h"
13 
14 /* interrupt-level stop callback function. */
15 void spufs_stop_callback(struct spu *spu, int irq)
16 {
17 	struct spu_context *ctx = spu->ctx;
18 
19 	/*
20 	 * It should be impossible to preempt a context while an exception
21 	 * is being processed, since the context switch code is specially
22 	 * coded to deal with interrupts ... But, just in case, sanity check
23 	 * the context pointer.  It is OK to return doing nothing since
24 	 * the exception will be regenerated when the context is resumed.
25 	 */
26 	if (ctx) {
27 		/* Copy exception arguments into module specific structure */
28 		switch(irq) {
29 		case 0 :
30 			ctx->csa.class_0_pending = spu->class_0_pending;
31 			ctx->csa.class_0_dar = spu->class_0_dar;
32 			break;
33 		case 1 :
34 			ctx->csa.class_1_dsisr = spu->class_1_dsisr;
35 			ctx->csa.class_1_dar = spu->class_1_dar;
36 			break;
37 		case 2 :
38 			break;
39 		}
40 
41 		/* ensure that the exception status has hit memory before a
42 		 * thread waiting on the context's stop queue is woken */
43 		smp_wmb();
44 
45 		wake_up_all(&ctx->stop_wq);
46 	}
47 }
48 
49 int spu_stopped(struct spu_context *ctx, u32 *stat)
50 {
51 	u64 dsisr;
52 	u32 stopped;
53 
54 	stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
55 		SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
56 
57 top:
58 	*stat = ctx->ops->status_read(ctx);
59 	if (*stat & stopped) {
60 		/*
61 		 * If the spu hasn't finished stopping, we need to
62 		 * re-read the register to get the stopped value.
63 		 */
64 		if (*stat & SPU_STATUS_RUNNING)
65 			goto top;
66 		return 1;
67 	}
68 
69 	if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
70 		return 1;
71 
72 	dsisr = ctx->csa.class_1_dsisr;
73 	if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
74 		return 1;
75 
76 	if (ctx->csa.class_0_pending)
77 		return 1;
78 
79 	return 0;
80 }
81 
82 static int spu_setup_isolated(struct spu_context *ctx)
83 {
84 	int ret;
85 	u64 __iomem *mfc_cntl;
86 	u64 sr1;
87 	u32 status;
88 	unsigned long timeout;
89 	const u32 status_loading = SPU_STATUS_RUNNING
90 		| SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
91 
92 	ret = -ENODEV;
93 	if (!isolated_loader)
94 		goto out;
95 
96 	/*
97 	 * We need to exclude userspace access to the context.
98 	 *
99 	 * To protect against memory access we invalidate all ptes
100 	 * and make sure the pagefault handlers block on the mutex.
101 	 */
102 	spu_unmap_mappings(ctx);
103 
104 	mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
105 
106 	/* purge the MFC DMA queue to ensure no spurious accesses before we
107 	 * enter kernel mode */
108 	timeout = jiffies + HZ;
109 	out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
110 	while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
111 			!= MFC_CNTL_PURGE_DMA_COMPLETE) {
112 		if (time_after(jiffies, timeout)) {
113 			printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
114 					__func__);
115 			ret = -EIO;
116 			goto out;
117 		}
118 		cond_resched();
119 	}
120 
121 	/* clear purge status */
122 	out_be64(mfc_cntl, 0);
123 
124 	/* put the SPE in kernel mode to allow access to the loader */
125 	sr1 = spu_mfc_sr1_get(ctx->spu);
126 	sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
127 	spu_mfc_sr1_set(ctx->spu, sr1);
128 
129 	/* start the loader */
130 	ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
131 	ctx->ops->signal2_write(ctx,
132 			(unsigned long)isolated_loader & 0xffffffff);
133 
134 	ctx->ops->runcntl_write(ctx,
135 			SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
136 
137 	ret = 0;
138 	timeout = jiffies + HZ;
139 	while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
140 				status_loading) {
141 		if (time_after(jiffies, timeout)) {
142 			printk(KERN_ERR "%s: timeout waiting for loader\n",
143 					__func__);
144 			ret = -EIO;
145 			goto out_drop_priv;
146 		}
147 		cond_resched();
148 	}
149 
150 	if (!(status & SPU_STATUS_RUNNING)) {
151 		/* If isolated LOAD has failed: run SPU, we will get a stop-and
152 		 * signal later. */
153 		pr_debug("%s: isolated LOAD failed\n", __func__);
154 		ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
155 		ret = -EACCES;
156 		goto out_drop_priv;
157 	}
158 
159 	if (!(status & SPU_STATUS_ISOLATED_STATE)) {
160 		/* This isn't allowed by the CBEA, but check anyway */
161 		pr_debug("%s: SPU fell out of isolated mode?\n", __func__);
162 		ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
163 		ret = -EINVAL;
164 		goto out_drop_priv;
165 	}
166 
167 out_drop_priv:
168 	/* Finished accessing the loader. Drop kernel mode */
169 	sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
170 	spu_mfc_sr1_set(ctx->spu, sr1);
171 
172 out:
173 	return ret;
174 }
175 
176 static int spu_run_init(struct spu_context *ctx, u32 *npc)
177 {
178 	unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
179 	int ret;
180 
181 	spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
182 
183 	/*
184 	 * NOSCHED is synchronous scheduling with respect to the caller.
185 	 * The caller waits for the context to be loaded.
186 	 */
187 	if (ctx->flags & SPU_CREATE_NOSCHED) {
188 		if (ctx->state == SPU_STATE_SAVED) {
189 			ret = spu_activate(ctx, 0);
190 			if (ret)
191 				return ret;
192 		}
193 	}
194 
195 	/*
196 	 * Apply special setup as required.
197 	 */
198 	if (ctx->flags & SPU_CREATE_ISOLATE) {
199 		if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
200 			ret = spu_setup_isolated(ctx);
201 			if (ret)
202 				return ret;
203 		}
204 
205 		/*
206 		 * If userspace has set the runcntrl register (eg, to
207 		 * issue an isolated exit), we need to re-set it here
208 		 */
209 		runcntl = ctx->ops->runcntl_read(ctx) &
210 			(SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
211 		if (runcntl == 0)
212 			runcntl = SPU_RUNCNTL_RUNNABLE;
213 	} else {
214 		unsigned long privcntl;
215 
216 		if (test_thread_flag(TIF_SINGLESTEP))
217 			privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
218 		else
219 			privcntl = SPU_PRIVCNTL_MODE_NORMAL;
220 
221 		ctx->ops->privcntl_write(ctx, privcntl);
222 		ctx->ops->npc_write(ctx, *npc);
223 	}
224 
225 	ctx->ops->runcntl_write(ctx, runcntl);
226 
227 	if (ctx->flags & SPU_CREATE_NOSCHED) {
228 		spuctx_switch_state(ctx, SPU_UTIL_USER);
229 	} else {
230 
231 		if (ctx->state == SPU_STATE_SAVED) {
232 			ret = spu_activate(ctx, 0);
233 			if (ret)
234 				return ret;
235 		} else {
236 			spuctx_switch_state(ctx, SPU_UTIL_USER);
237 		}
238 	}
239 
240 	set_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
241 	return 0;
242 }
243 
244 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
245 			       u32 *status)
246 {
247 	int ret = 0;
248 
249 	spu_del_from_rq(ctx);
250 
251 	*status = ctx->ops->status_read(ctx);
252 	*npc = ctx->ops->npc_read(ctx);
253 
254 	spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
255 	clear_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
256 	spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, *status);
257 	spu_release(ctx);
258 
259 	if (signal_pending(current))
260 		ret = -ERESTARTSYS;
261 
262 	return ret;
263 }
264 
265 /*
266  * SPU syscall restarting is tricky because we violate the basic
267  * assumption that the signal handler is running on the interrupted
268  * thread. Here instead, the handler runs on PowerPC user space code,
269  * while the syscall was called from the SPU.
270  * This means we can only do a very rough approximation of POSIX
271  * signal semantics.
272  */
273 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
274 			  unsigned int *npc)
275 {
276 	int ret;
277 
278 	switch (*spu_ret) {
279 	case -ERESTARTSYS:
280 	case -ERESTARTNOINTR:
281 		/*
282 		 * Enter the regular syscall restarting for
283 		 * sys_spu_run, then restart the SPU syscall
284 		 * callback.
285 		 */
286 		*npc -= 8;
287 		ret = -ERESTARTSYS;
288 		break;
289 	case -ERESTARTNOHAND:
290 	case -ERESTART_RESTARTBLOCK:
291 		/*
292 		 * Restart block is too hard for now, just return -EINTR
293 		 * to the SPU.
294 		 * ERESTARTNOHAND comes from sys_pause, we also return
295 		 * -EINTR from there.
296 		 * Assume that we need to be restarted ourselves though.
297 		 */
298 		*spu_ret = -EINTR;
299 		ret = -ERESTARTSYS;
300 		break;
301 	default:
302 		printk(KERN_WARNING "%s: unexpected return code %ld\n",
303 			__func__, *spu_ret);
304 		ret = 0;
305 	}
306 	return ret;
307 }
308 
309 static int spu_process_callback(struct spu_context *ctx)
310 {
311 	struct spu_syscall_block s;
312 	u32 ls_pointer, npc;
313 	void __iomem *ls;
314 	long spu_ret;
315 	int ret;
316 
317 	/* get syscall block from local store */
318 	npc = ctx->ops->npc_read(ctx) & ~3;
319 	ls = (void __iomem *)ctx->ops->get_ls(ctx);
320 	ls_pointer = in_be32(ls + npc);
321 	if (ls_pointer > (LS_SIZE - sizeof(s)))
322 		return -EFAULT;
323 	memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
324 
325 	/* do actual syscall without pinning the spu */
326 	ret = 0;
327 	spu_ret = -ENOSYS;
328 	npc += 4;
329 
330 	if (s.nr_ret < NR_syscalls) {
331 		spu_release(ctx);
332 		/* do actual system call from here */
333 		spu_ret = spu_sys_callback(&s);
334 		if (spu_ret <= -ERESTARTSYS) {
335 			ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
336 		}
337 		mutex_lock(&ctx->state_mutex);
338 		if (ret == -ERESTARTSYS)
339 			return ret;
340 	}
341 
342 	/* need to re-get the ls, as it may have changed when we released the
343 	 * spu */
344 	ls = (void __iomem *)ctx->ops->get_ls(ctx);
345 
346 	/* write result, jump over indirect pointer */
347 	memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
348 	ctx->ops->npc_write(ctx, npc);
349 	ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
350 	return ret;
351 }
352 
353 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
354 {
355 	int ret;
356 	u32 status;
357 
358 	if (mutex_lock_interruptible(&ctx->run_mutex))
359 		return -ERESTARTSYS;
360 
361 	ctx->event_return = 0;
362 
363 	ret = spu_acquire(ctx);
364 	if (ret)
365 		goto out_unlock;
366 
367 	spu_enable_spu(ctx);
368 
369 	spu_update_sched_info(ctx);
370 
371 	ret = spu_run_init(ctx, npc);
372 	if (ret) {
373 		spu_release(ctx);
374 		goto out;
375 	}
376 
377 	do {
378 		ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
379 		if (unlikely(ret)) {
380 			/*
381 			 * This is nasty: we need the state_mutex for all the
382 			 * bookkeeping even if the syscall was interrupted by
383 			 * a signal. ewww.
384 			 */
385 			mutex_lock(&ctx->state_mutex);
386 			break;
387 		}
388 		if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
389 						&ctx->sched_flags))) {
390 			if (!(status & SPU_STATUS_STOPPED_BY_STOP))
391 				continue;
392 		}
393 
394 		spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
395 
396 		if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
397 		    (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
398 			ret = spu_process_callback(ctx);
399 			if (ret)
400 				break;
401 			status &= ~SPU_STATUS_STOPPED_BY_STOP;
402 		}
403 		ret = spufs_handle_class1(ctx);
404 		if (ret)
405 			break;
406 
407 		ret = spufs_handle_class0(ctx);
408 		if (ret)
409 			break;
410 
411 		if (signal_pending(current))
412 			ret = -ERESTARTSYS;
413 	} while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
414 				      SPU_STATUS_STOPPED_BY_HALT |
415 				       SPU_STATUS_SINGLE_STEP)));
416 
417 	spu_disable_spu(ctx);
418 	ret = spu_run_fini(ctx, npc, &status);
419 	spu_yield(ctx);
420 
421 	if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
422 	    (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100))
423 		ctx->stats.libassist++;
424 
425 	if ((ret == 0) ||
426 	    ((ret == -ERESTARTSYS) &&
427 	     ((status & SPU_STATUS_STOPPED_BY_HALT) ||
428 	      (status & SPU_STATUS_SINGLE_STEP) ||
429 	      ((status & SPU_STATUS_STOPPED_BY_STOP) &&
430 	       (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
431 		ret = status;
432 
433 	/* Note: we don't need to force_sig SIGTRAP on single-step
434 	 * since we have TIF_SINGLESTEP set, thus the kernel will do
435 	 * it upon return from the syscall anyway.
436 	 */
437 	if (unlikely(status & SPU_STATUS_SINGLE_STEP))
438 		ret = -ERESTARTSYS;
439 
440 	else if (unlikely((status & SPU_STATUS_STOPPED_BY_STOP)
441 	    && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff)) {
442 		force_sig(SIGTRAP);
443 		ret = -ERESTARTSYS;
444 	}
445 
446 out:
447 	*event = ctx->event_return;
448 out_unlock:
449 	mutex_unlock(&ctx->run_mutex);
450 	return ret;
451 }
452