tee: simplify shm pool handling

Replaces the shared memory pool based on two pools with a single pool.
The alloc() function pointer in struct tee_shm_pool_ops gets another
parameter, align. This makes it possible to make less than page aligned
allocations from the optional reserved shared memory pool while still
making user space allocations page aligned. With in practice unchanged
behaviour using only a single pool for bookkeeping.

The allocation algorithm in the static OP-TEE shared memory pool is
changed from best-fit to first-fit since only the latter supports an
alignment parameter. The best-fit algorithm was previously the default
choice and not a conscious one.

The optee and amdtee drivers are updated as needed to work with this
changed pool handling.

This also removes OPTEE_SHM_NUM_PRIV_PAGES which becomes obsolete with
this change as the private pages can be mixed with the payload pages.

The OP-TEE driver changes minimum alignment for argument struct from 8
bytes to 512 bytes. A typical OP-TEE private shm allocation is 224 bytes
(argument struct with 6 parameters, needed for open session). So with an
alignment of 512 well waste a bit more than 50%. Before this we had a
single page reserved for this so worst case usage compared to that would
be 3 pages instead of 1 page. However, this worst case only occurs if
there is a high pressure from multiple threads on secure world. All in
all this should scale up and down better than fixed boundaries.

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index 17a6f51d3089..f4bccb5f0e93 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -18,8 +18,8 @@
 #include <linux/workqueue.h>
 #include "optee_private.h"
 
-int optee_pool_op_alloc_helper(struct tee_shm_pool_mgr *poolm,
-			       struct tee_shm *shm, size_t size,
+int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
+			       size_t size, size_t align,
 			       int (*shm_register)(struct tee_context *ctx,
 						   struct tee_shm *shm,
 						   struct page **pages,
@@ -30,6 +30,10 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool_mgr *poolm,
 	struct page *page;
 	int rc = 0;
 
+	/*
+	 * Ignore alignment since this is already going to be page aligned
+	 * and there's no need for any larger alignment.
+	 */
 	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
 	if (!page)
 		return -ENOMEM;
@@ -51,7 +55,6 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool_mgr *poolm,
 		for (i = 0; i < nr_pages; i++)
 			pages[i] = page + i;
 
-		shm->flags |= TEE_SHM_REGISTER;
 		rc = shm_register(shm->ctx, shm, pages, nr_pages,
 				  (unsigned long)shm->kaddr);
 		kfree(pages);
@@ -62,7 +65,7 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool_mgr *poolm,
 	return 0;
 
 err:
-	__free_pages(page, order);
+	free_pages((unsigned long)shm->kaddr, order);
 	return rc;
 }