[POWERPC] spufs: Add isolated-mode SPE recycling support

When in isolated mode, SPEs have access to an area of persistent
storage, which is per-SPE. In order for isolated-mode apps to
communicate arbitrary data through this storage, we need to ensure that
isolated physical SPEs can be reused for subsequent applications.

Add a file ("recycle") in a spethread dir to enable isolated-mode
recycling. By writing to this file, the kernel will reload the
isolated-mode loader kernel, allowing a new app to be run on the same
physical SPE.

This requires the spu_acquire_exclusive function to enforce exclusive
access to the SPE while the loader is initialised.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index 034cf6a..48eb050 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -120,6 +120,33 @@ void spu_unmap_mappings(struct spu_context *ctx)
 		unmap_mapping_range(ctx->signal2, 0, 0x4000, 1);
 }
 
+int spu_acquire_exclusive(struct spu_context *ctx)
+{
+       int ret = 0;
+
+       down_write(&ctx->state_sema);
+       /* ctx is about to be freed, can't acquire any more */
+       if (!ctx->owner) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       if (ctx->state == SPU_STATE_SAVED) {
+               ret = spu_activate(ctx, 0);
+               if (ret)
+                       goto out;
+               ctx->state = SPU_STATE_RUNNABLE;
+       } else {
+               /* We need to exclude userspace access to the context. */
+               spu_unmap_mappings(ctx);
+       }
+
+out:
+       if (ret)
+               up_write(&ctx->state_sema);
+       return ret;
+}
+
 int spu_acquire_runnable(struct spu_context *ctx)
 {
 	int ret = 0;