[POWERPC] spufs: implement error event delivery to user space

This tries to fix spufs so we have an interface closer to what is
specified in the man page for events returned in the third argument of
spu_run.

Fortunately, libspe has never been using the returned contents of that
register, as they were the same as the return code of spu_run (duh!).

Unlike the specification that we never implemented correctly, we now
require a SPU_CREATE_EVENTS_ENABLED flag passed to spu_create, in
order to get the new behavior. When this flag is not passed, spu_run
will simply ignore the third argument now.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/platforms/cell/spu_base.c

···
 static int __spu_trap_invalid_dma(struct spu *spu)
 {
 	pr_debug("%s\n", __FUNCTION__);
-	force_sig(SIGBUS, /* info, */ current);
+	spu->dma_callback(spu, SPE_EVENT_INVALID_DMA);
 	return 0;
 }
 
 static int __spu_trap_dma_align(struct spu *spu)
 {
 	pr_debug("%s\n", __FUNCTION__);
-	force_sig(SIGBUS, /* info, */ current);
+	spu->dma_callback(spu, SPE_EVENT_DMA_ALIGNMENT);
 	return 0;
 }
 
 static int __spu_trap_error(struct spu *spu)
 {
 	pr_debug("%s\n", __FUNCTION__);
-	force_sig(SIGILL, /* info, */ current);
+	spu->dma_callback(spu, SPE_EVENT_SPE_ERROR);
 	return 0;
 }
 

arch/powerpc/platforms/cell/spufs/inode.c

···
 };
 
 static int
-spufs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+spufs_mkdir(struct inode *dir, struct dentry *dentry, unsigned int flags,
+		int mode)
 {
 	int ret;
 	struct inode *inode;
···
 	SPUFS_I(inode)->i_ctx = ctx;
 	if (!ctx)
 		goto out_iput;
+
+	ctx->flags = flags;
 
 	inode->i_op = &spufs_dir_inode_operations;
 	inode->i_fop = &simple_dir_operations;
···
 		goto out;
 
 	/* all flags are reserved */
-	if (flags)
+	if (flags & (~SPU_CREATE_FLAG_ALL))
 		goto out;
 
 	dentry = lookup_create(nd, 1);
···
 		goto out_dput;
 
 	mode &= ~current->fs->umask;
-	ret = spufs_mkdir(nd->dentry->d_inode, dentry, mode & S_IRWXUGO);
+	ret = spufs_mkdir(nd->dentry->d_inode, dentry, flags, mode & S_IRWXUGO);
 	if (ret)
 		goto out_dput;
 

arch/powerpc/platforms/cell/spufs/run.c

···
 	wake_up_all(&ctx->stop_wq);
 }
 
+void spufs_dma_callback(struct spu *spu, int type)
+{
+	struct spu_context *ctx = spu->ctx;
+
+	if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
+		ctx->event_return |= type;
+		wake_up_all(&ctx->stop_wq);
+	} else {
+		switch (type) {
+		case SPE_EVENT_DMA_ALIGNMENT:
+		case SPE_EVENT_INVALID_DMA:
+			force_sig(SIGBUS, /* info, */ current);
+			break;
+		case SPE_EVENT_SPE_ERROR:
+			force_sig(SIGILL, /* info */ current);
+			break;
+		}
+	}
+}
+
 static inline int spu_stopped(struct spu_context *ctx, u32 * stat)
 {
 	struct spu *spu;
···
 	return (!(*stat & 0x1) || pte_fault || spu->class_0_pending) ? 1 : 0;
 }
 
-static inline int spu_run_init(struct spu_context *ctx, u32 * npc,
-			       u32 * status)
+static inline int spu_run_init(struct spu_context *ctx, u32 * npc)
 {
 	int ret;
 
···
 		       SPU_STATUS_STOPPED_BY_HALT)) {
 		return *status;
 	}
-	if ((ret = spu_run_init(ctx, npc, status)) != 0)
+	if ((ret = spu_run_init(ctx, npc)) != 0)
 		return ret;
 	return 0;
 }
···
 }
 
 long spufs_run_spu(struct file *file, struct spu_context *ctx,
-		   u32 * npc, u32 * status)
+		   u32 *npc, u32 *event)
 {
 	int ret;
+	u32 status;
 
 	if (down_interruptible(&ctx->run_sema))
 		return -ERESTARTSYS;
 
-	ret = spu_run_init(ctx, npc, status);
+	ctx->event_return = 0;
+	ret = spu_run_init(ctx, npc);
 	if (ret)
 		goto out;
 
 	do {
-		ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, status));
+		ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 		if (unlikely(ret))
 			break;
-		if ((*status & SPU_STATUS_STOPPED_BY_STOP) &&
-		    (*status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
+		if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
+		    (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) {
 			ret = spu_process_callback(ctx);
 			if (ret)
 				break;
-			*status &= ~SPU_STATUS_STOPPED_BY_STOP;
+			status &= ~SPU_STATUS_STOPPED_BY_STOP;
 		}
 		if (unlikely(ctx->state != SPU_STATE_RUNNABLE)) {
-			ret = spu_reacquire_runnable(ctx, npc, status);
+			ret = spu_reacquire_runnable(ctx, npc, &status);
 			if (ret)
 				goto out;
 			continue;
 		}
 		ret = spu_process_events(ctx);
 
-	} while (!ret && !(*status & (SPU_STATUS_STOPPED_BY_STOP |
+	} while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
 				      SPU_STATUS_STOPPED_BY_HALT)));
 
 	ctx->ops->runcntl_stop(ctx);
-	ret = spu_run_fini(ctx, npc, status);
+	ret = spu_run_fini(ctx, npc, &status);
 	if (!ret)
-		ret = *status;
+		ret = status;
 	spu_yield(ctx);
 
 out:
+	*event = ctx->event_return;
 	up(&ctx->run_sema);
 	return ret;
 }

arch/powerpc/platforms/cell/spufs/sched.c

···
 		 spu->number, spu->node);
 	spu->ctx = ctx;
 	spu->flags = 0;
-	ctx->flags = 0;
 	ctx->spu = spu;
 	ctx->ops = &spu_hw_ops;
 	spu->pid = current->pid;
···
 	spu->wbox_callback = spufs_wbox_callback;
 	spu->stop_callback = spufs_stop_callback;
 	spu->mfc_callback = spufs_mfc_callback;
+	spu->dma_callback = spufs_dma_callback;
 	mb();
 	spu_unmap_mappings(ctx);
 	spu_restore(&ctx->csa, spu);
···
 	spu->wbox_callback = NULL;
 	spu->stop_callback = NULL;
 	spu->mfc_callback = NULL;
+	spu->dma_callback = NULL;
 	spu->mm = NULL;
 	spu->pid = 0;
 	spu->prio = MAX_PRIO;
 	ctx->ops = &spu_backing_ops;
 	ctx->spu = NULL;
-	ctx->flags = 0;
 	spu->flags = 0;
 	spu->ctx = NULL;
 }

arch/powerpc/platforms/cell/spufs/spufs.h

···
 	u32 tagwait;
 	struct spu_context_ops *ops;
 	struct work_struct reap_work;
-	u64 flags;
+	unsigned long flags;
+	unsigned long event_return;
 };
 
 struct mfc_dma_command {
···
 void spufs_wbox_callback(struct spu *spu);
 void spufs_stop_callback(struct spu *spu);
 void spufs_mfc_callback(struct spu *spu);
+void spufs_dma_callback(struct spu *spu, int type);
 
 #endif

arch/powerpc/platforms/cell/spufs/syscalls.c

···
 	u32 npc, status;
 
 	ret = -EFAULT;
-	if (get_user(npc, unpc) || get_user(status, ustatus))
+	if (get_user(npc, unpc))
 		goto out;
 
 	/* check if this file was created by spu_create */
···
 	i = SPUFS_I(filp->f_dentry->d_inode);
 	ret = spufs_run_spu(filp, i->i_ctx, &npc, &status);
 
-	if (put_user(npc, unpc) || put_user(status, ustatus))
+	if (put_user(npc, unpc))
+		ret = -EFAULT;
+
+	if (ustatus && put_user(status, ustatus))
 		ret = -EFAULT;
 out:
 	return ret;

include/asm-powerpc/spu.h

···
 	void (* ibox_callback)(struct spu *spu);
 	void (* stop_callback)(struct spu *spu);
 	void (* mfc_callback)(struct spu *spu);
+	void (* dma_callback)(struct spu *spu, int type);
 
 	char irq_c0[8];
 	char irq_c1[8];
···
 						__u32 __user *ustatus);
 	struct module *owner;
 } spufs_calls;
+
+/* return status from spu_run, same as in libspe */
+#define SPE_EVENT_DMA_ALIGNMENT		0x0008	/*A DMA alignment error */
+#define SPE_EVENT_SPE_ERROR		0x0010	/*An illegal instruction error*/
+#define SPE_EVENT_SPE_DATA_SEGMENT	0x0020	/*A DMA segmentation error    */
+#define SPE_EVENT_SPE_DATA_STORAGE	0x0040	/*A DMA storage error */
+#define SPE_EVENT_INVALID_DMA		0x0800	/* Invalid MFC DMA */
+
+/*
+ * Flags for sys_spu_create.
+ */
+#define SPU_CREATE_EVENTS_ENABLED	0x0001
+#define SPU_CREATE_FLAG_ALL		0x0001 /* mask of all valid flags */
 
 #ifdef CONFIG_SPU_FS_MODULE
 int register_spu_syscalls(struct spufs_calls *calls);