1 #define DEBUG
2 
3 #include <linux/wait.h>
4 #include <linux/ptrace.h>
5 
6 #include <asm/spu.h>
7 #include <asm/spu_priv1.h>
8 #include <asm/io.h>
9 #include <asm/unistd.h>
10 
11 #include "spufs.h"
12 
13 /* interrupt-level stop callback function. */
14 void spufs_stop_callback(struct spu *spu)
15 {
16 	struct spu_context *ctx = spu->ctx;
17 
18 	/*
19 	 * It should be impossible to preempt a context while an exception
20 	 * is being processed, since the context switch code is specially
21 	 * coded to deal with interrupts ... But, just in case, sanity check
22 	 * the context pointer.  It is OK to return doing nothing since
23 	 * the exception will be regenerated when the context is resumed.
24 	 */
25 	if (ctx) {
26 		/* Copy exception arguments into module specific structure */
27 		ctx->csa.class_0_pending = spu->class_0_pending;
28 		ctx->csa.dsisr = spu->dsisr;
29 		ctx->csa.dar = spu->dar;
30 
31 		/* ensure that the exception status has hit memory before a
32 		 * thread waiting on the context's stop queue is woken */
33 		smp_wmb();
34 
35 		wake_up_all(&ctx->stop_wq);
36 	}
37 
38 	/* Clear callback arguments from spu structure */
39 	spu->class_0_pending = 0;
40 	spu->dsisr = 0;
41 	spu->dar = 0;
42 }
43 
44 int spu_stopped(struct spu_context *ctx, u32 *stat)
45 {
46 	u64 dsisr;
47 	u32 stopped;
48 
49 	*stat = ctx->ops->status_read(ctx);
50 
51 	if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
52 		return 1;
53 
54 	stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
55 		SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
56 	if (*stat & stopped)
57 		return 1;
58 
59 	dsisr = ctx->csa.dsisr;
60 	if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
61 		return 1;
62 
63 	if (ctx->csa.class_0_pending)
64 		return 1;
65 
66 	return 0;
67 }
68 
69 static int spu_setup_isolated(struct spu_context *ctx)
70 {
71 	int ret;
72 	u64 __iomem *mfc_cntl;
73 	u64 sr1;
74 	u32 status;
75 	unsigned long timeout;
76 	const u32 status_loading = SPU_STATUS_RUNNING
77 		| SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
78 
79 	ret = -ENODEV;
80 	if (!isolated_loader)
81 		goto out;
82 
83 	/*
84 	 * We need to exclude userspace access to the context.
85 	 *
86 	 * To protect against memory access we invalidate all ptes
87 	 * and make sure the pagefault handlers block on the mutex.
88 	 */
89 	spu_unmap_mappings(ctx);
90 
91 	mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
92 
93 	/* purge the MFC DMA queue to ensure no spurious accesses before we
94 	 * enter kernel mode */
95 	timeout = jiffies + HZ;
96 	out_be64(mfc_cntl, MFC_CNTL_PURGE_DMA_REQUEST);
97 	while ((in_be64(mfc_cntl) & MFC_CNTL_PURGE_DMA_STATUS_MASK)
98 			!= MFC_CNTL_PURGE_DMA_COMPLETE) {
99 		if (time_after(jiffies, timeout)) {
100 			printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
101 					__FUNCTION__);
102 			ret = -EIO;
103 			goto out;
104 		}
105 		cond_resched();
106 	}
107 
108 	/* put the SPE in kernel mode to allow access to the loader */
109 	sr1 = spu_mfc_sr1_get(ctx->spu);
110 	sr1 &= ~MFC_STATE1_PROBLEM_STATE_MASK;
111 	spu_mfc_sr1_set(ctx->spu, sr1);
112 
113 	/* start the loader */
114 	ctx->ops->signal1_write(ctx, (unsigned long)isolated_loader >> 32);
115 	ctx->ops->signal2_write(ctx,
116 			(unsigned long)isolated_loader & 0xffffffff);
117 
118 	ctx->ops->runcntl_write(ctx,
119 			SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
120 
121 	ret = 0;
122 	timeout = jiffies + HZ;
123 	while (((status = ctx->ops->status_read(ctx)) & status_loading) ==
124 				status_loading) {
125 		if (time_after(jiffies, timeout)) {
126 			printk(KERN_ERR "%s: timeout waiting for loader\n",
127 					__FUNCTION__);
128 			ret = -EIO;
129 			goto out_drop_priv;
130 		}
131 		cond_resched();
132 	}
133 
134 	if (!(status & SPU_STATUS_RUNNING)) {
135 		/* If isolated LOAD has failed: run SPU, we will get a stop-and
136 		 * signal later. */
137 		pr_debug("%s: isolated LOAD failed\n", __FUNCTION__);
138 		ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
139 		ret = -EACCES;
140 		goto out_drop_priv;
141 	}
142 
143 	if (!(status & SPU_STATUS_ISOLATED_STATE)) {
144 		/* This isn't allowed by the CBEA, but check anyway */
145 		pr_debug("%s: SPU fell out of isolated mode?\n", __FUNCTION__);
146 		ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
147 		ret = -EINVAL;
148 		goto out_drop_priv;
149 	}
150 
151 out_drop_priv:
152 	/* Finished accessing the loader. Drop kernel mode */
153 	sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
154 	spu_mfc_sr1_set(ctx->spu, sr1);
155 
156 out:
157 	return ret;
158 }
159 
160 static int spu_run_init(struct spu_context *ctx, u32 *npc)
161 {
162 	unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
163 	int ret;
164 
165 	spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
166 
167 	/*
168 	 * NOSCHED is synchronous scheduling with respect to the caller.
169 	 * The caller waits for the context to be loaded.
170 	 */
171 	if (ctx->flags & SPU_CREATE_NOSCHED) {
172 		if (ctx->state == SPU_STATE_SAVED) {
173 			ret = spu_activate(ctx, 0);
174 			if (ret)
175 				return ret;
176 		}
177 	}
178 
179 	/*
180 	 * Apply special setup as required.
181 	 */
182 	if (ctx->flags & SPU_CREATE_ISOLATE) {
183 		if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
184 			ret = spu_setup_isolated(ctx);
185 			if (ret)
186 				return ret;
187 		}
188 
189 		/*
190 		 * If userspace has set the runcntrl register (eg, to
191 		 * issue an isolated exit), we need to re-set it here
192 		 */
193 		runcntl = ctx->ops->runcntl_read(ctx) &
194 			(SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
195 		if (runcntl == 0)
196 			runcntl = SPU_RUNCNTL_RUNNABLE;
197 	}
198 
199 	if (ctx->flags & SPU_CREATE_NOSCHED) {
200 		spuctx_switch_state(ctx, SPU_UTIL_USER);
201 		ctx->ops->runcntl_write(ctx, runcntl);
202 	} else {
203 		unsigned long privcntl;
204 
205 		if (test_thread_flag(TIF_SINGLESTEP))
206 			privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
207 		else
208 			privcntl = SPU_PRIVCNTL_MODE_NORMAL;
209 
210 		ctx->ops->npc_write(ctx, *npc);
211 		ctx->ops->privcntl_write(ctx, privcntl);
212 		ctx->ops->runcntl_write(ctx, runcntl);
213 
214 		if (ctx->state == SPU_STATE_SAVED) {
215 			ret = spu_activate(ctx, 0);
216 			if (ret)
217 				return ret;
218 		} else {
219 			spuctx_switch_state(ctx, SPU_UTIL_USER);
220 		}
221 	}
222 
223 	return 0;
224 }
225 
226 static int spu_run_fini(struct spu_context *ctx, u32 *npc,
227 			       u32 *status)
228 {
229 	int ret = 0;
230 
231 	spu_del_from_rq(ctx);
232 
233 	*status = ctx->ops->status_read(ctx);
234 	*npc = ctx->ops->npc_read(ctx);
235 
236 	spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
237 	spu_release(ctx);
238 
239 	if (signal_pending(current))
240 		ret = -ERESTARTSYS;
241 
242 	return ret;
243 }
244 
245 /*
246  * SPU syscall restarting is tricky because we violate the basic
247  * assumption that the signal handler is running on the interrupted
248  * thread. Here instead, the handler runs on PowerPC user space code,
249  * while the syscall was called from the SPU.
250  * This means we can only do a very rough approximation of POSIX
251  * signal semantics.
252  */
253 static int spu_handle_restartsys(struct spu_context *ctx, long *spu_ret,
254 			  unsigned int *npc)
255 {
256 	int ret;
257 
258 	switch (*spu_ret) {
259 	case -ERESTARTSYS:
260 	case -ERESTARTNOINTR:
261 		/*
262 		 * Enter the regular syscall restarting for
263 		 * sys_spu_run, then restart the SPU syscall
264 		 * callback.
265 		 */
266 		*npc -= 8;
267 		ret = -ERESTARTSYS;
268 		break;
269 	case -ERESTARTNOHAND:
270 	case -ERESTART_RESTARTBLOCK:
271 		/*
272 		 * Restart block is too hard for now, just return -EINTR
273 		 * to the SPU.
274 		 * ERESTARTNOHAND comes from sys_pause, we also return
275 		 * -EINTR from there.
276 		 * Assume that we need to be restarted ourselves though.
277 		 */
278 		*spu_ret = -EINTR;
279 		ret = -ERESTARTSYS;
280 		break;
281 	default:
282 		printk(KERN_WARNING "%s: unexpected return code %ld\n",
283 			__FUNCTION__, *spu_ret);
284 		ret = 0;
285 	}
286 	return ret;
287 }
288 
289 static int spu_process_callback(struct spu_context *ctx)
290 {
291 	struct spu_syscall_block s;
292 	u32 ls_pointer, npc;
293 	void __iomem *ls;
294 	long spu_ret;
295 	int ret, ret2;
296 
297 	/* get syscall block from local store */
298 	npc = ctx->ops->npc_read(ctx) & ~3;
299 	ls = (void __iomem *)ctx->ops->get_ls(ctx);
300 	ls_pointer = in_be32(ls + npc);
301 	if (ls_pointer > (LS_SIZE - sizeof(s)))
302 		return -EFAULT;
303 	memcpy_fromio(&s, ls + ls_pointer, sizeof(s));
304 
305 	/* do actual syscall without pinning the spu */
306 	ret = 0;
307 	spu_ret = -ENOSYS;
308 	npc += 4;
309 
310 	if (s.nr_ret < __NR_syscalls) {
311 		spu_release(ctx);
312 		/* do actual system call from here */
313 		spu_ret = spu_sys_callback(&s);
314 		if (spu_ret <= -ERESTARTSYS) {
315 			ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
316 		}
317 		ret2 = spu_acquire(ctx);
318 		if (ret == -ERESTARTSYS)
319 			return ret;
320 		if (ret2)
321 			return -EINTR;
322 	}
323 
324 	/* write result, jump over indirect pointer */
325 	memcpy_toio(ls + ls_pointer, &spu_ret, sizeof(spu_ret));
326 	ctx->ops->npc_write(ctx, npc);
327 	ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
328 	return ret;
329 }
330 
331 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
332 {
333 	int ret;
334 	struct spu *spu;
335 	u32 status;
336 
337 	if (mutex_lock_interruptible(&ctx->run_mutex))
338 		return -ERESTARTSYS;
339 
340 	spu_enable_spu(ctx);
341 	ctx->event_return = 0;
342 
343 	ret = spu_acquire(ctx);
344 	if (ret)
345 		goto out_unlock;
346 
347 	spu_update_sched_info(ctx);
348 
349 	ret = spu_run_init(ctx, npc);
350 	if (ret) {
351 		spu_release(ctx);
352 		goto out;
353 	}
354 
355 	do {
356 		ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
357 		if (unlikely(ret))
358 			break;
359 		spu = ctx->spu;
360 		if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
361 						&ctx->sched_flags))) {
362 			if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
363 				spu_switch_notify(spu, ctx);
364 				continue;
365 			}
366 		}
367 
368 		spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
369 
370 		if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
371 		    (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
372 			ret = spu_process_callback(ctx);
373 			if (ret)
374 				break;
375 			status &= ~SPU_STATUS_STOPPED_BY_STOP;
376 		}
377 		ret = spufs_handle_class1(ctx);
378 		if (ret)
379 			break;
380 
381 		ret = spufs_handle_class0(ctx);
382 		if (ret)
383 			break;
384 
385 		if (signal_pending(current))
386 			ret = -ERESTARTSYS;
387 	} while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
388 				      SPU_STATUS_STOPPED_BY_HALT |
389 				       SPU_STATUS_SINGLE_STEP)));
390 
391 	if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
392 	    (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100) &&
393 	    (ctx->state == SPU_STATE_RUNNABLE))
394 		ctx->stats.libassist++;
395 
396 
397 	spu_disable_spu(ctx);
398 	ret = spu_run_fini(ctx, npc, &status);
399 	spu_yield(ctx);
400 
401 	if ((ret == 0) ||
402 	    ((ret == -ERESTARTSYS) &&
403 	     ((status & SPU_STATUS_STOPPED_BY_HALT) ||
404 	      (status & SPU_STATUS_SINGLE_STEP) ||
405 	      ((status & SPU_STATUS_STOPPED_BY_STOP) &&
406 	       (status >> SPU_STOP_STATUS_SHIFT != 0x2104)))))
407 		ret = status;
408 
409 	/* Note: we don't need to force_sig SIGTRAP on single-step
410 	 * since we have TIF_SINGLESTEP set, thus the kernel will do
411 	 * it upon return from the syscall anyawy
412 	 */
413 	if ((status & SPU_STATUS_STOPPED_BY_STOP)
414 	    && (status >> SPU_STOP_STATUS_SHIFT) == 0x3fff) {
415 		force_sig(SIGTRAP, current);
416 		ret = -ERESTARTSYS;
417 	}
418 
419 out:
420 	*event = ctx->event_return;
421 out_unlock:
422 	mutex_unlock(&ctx->run_mutex);
423 	return ret;
424 }
425