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Subject[PATCH v1 06/14] tee: optee: add page list manipulation functions
Date
From: Volodymyr Babchuk <vlad.babchuk@gmail.com>

These functions will be used to pass information about shared
buffers to OP-TEE. ABI between Linux and OP-TEE is defined
in optee_msg.h and optee_smc.h.

optee_msg.h defines OPTEE_MSG_ATTR_NONCONTIG attribute
for shared memory references and describes how such references
should be passed. Note that it uses 64-bit page addresses even
on 32 bit systems. This is done to support LPAE and to unify
interface.

Signed-off-by: Volodymyr Babchuk <vlad.babchuk@gmail.com>
---
* optee_allocate_pages_array() and friends were renamed to
optee_allocate_pages_list() (and friends) to make naming consistent.

* Reworked get_pages_list_size(). Now calculations are right. Thanks
to Mark Rutland for suggestion.

* Totaly reworked optee_fill_pages_list(). Now it support all possible
page sizes. It was tested on qemu with page sizes of 4k and 64k.

---
drivers/tee/optee/call.c | 91 +++++++++++++++++++++++++++++++++++++++
drivers/tee/optee/optee_private.h | 5 +++
2 files changed, 96 insertions(+)

diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
index f7b7b40..2366300 100644
--- a/drivers/tee/optee/call.c
+++ b/drivers/tee/optee/call.c
@@ -11,6 +11,7 @@
* GNU General Public License for more details.
*
*/
+#include <asm/pgtable.h>
#include <linux/arm-smccc.h>
#include <linux/device.h>
#include <linux/err.h>
@@ -442,3 +443,93 @@ void optee_disable_shm_cache(struct optee *optee)
}
optee_cq_wait_final(&optee->call_queue, &w);
}
+
+#define PAGELIST_ENTRIES_PER_PAGE \
+ ((OPTEE_MSG_NONCONTIG_PAGE_SIZE / sizeof(u64)) - 1)
+
+/**
+ * optee_fill_pages_list() - write list of user pages to given shared
+ * buffer.
+ *
+ * @dst: page-aligned buffer where list of pages will be stored
+ * @pages: array of pages that represents shared buffer
+ * @num_pages: number of entries in @pages
+ * @page_offset: offset of user buffer from page start
+ *
+ * @dst should be big enough to hold list of user page addresses and
+ * links to the next pages of buffer
+ */
+void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
+ size_t page_offset)
+{
+ int n = 0;
+ phys_addr_t optee_page;
+ /*
+ * Refer to OPTEE_MSG_ATTR_NONCONTIG description in optee_msg.h
+ * for details.
+ */
+ struct {
+ uint64_t pages_list[PAGELIST_ENTRIES_PER_PAGE];
+ uint64_t next_page_data;
+ } *pages_data;
+
+ /*
+ * Currently OP-TEE uses 4k page size and it does not looks
+ * like this will change in the future. On other hand, there are
+ * no know ARM architectures with page size < 4k.
+ * Thus the next built assert looks redundant. But the following
+ * code heavily relies on this assumption, so it is better be
+ * safe than sorry.
+ */
+ BUILD_BUG_ON(PAGE_SIZE < OPTEE_MSG_NONCONTIG_PAGE_SIZE);
+
+ pages_data = (void *)dst;
+ /*
+ * If linux page is bigger than 4k, and user buffer offset is
+ * larger than 4k/8k/12k/etc this will skip first 4k pages,
+ * because they bear no value data for OP-TEE.
+ */
+ optee_page = page_to_phys(*pages) +
+ round_down(page_offset, OPTEE_MSG_NONCONTIG_PAGE_SIZE);
+
+ while (true) {
+ pages_data->pages_list[n++] = optee_page;
+
+ if (n == PAGELIST_ENTRIES_PER_PAGE) {
+ pages_data->next_page_data =
+ virt_to_phys(pages_data + 1);
+ pages_data++;
+ n = 0;
+ }
+
+ optee_page += OPTEE_MSG_NONCONTIG_PAGE_SIZE;
+ if (!(optee_page & ~PAGE_MASK)) {
+ if (!--num_pages)
+ break;
+ pages++;
+ optee_page = page_to_phys(*pages);
+ }
+ }
+}
+
+/*
+ * The final entry in each pagelist page is a pointer to the next
+ * pagelist page.
+ */
+static size_t get_pages_list_size(size_t num_entries)
+{
+ int pages = DIV_ROUND_UP(num_entries, PAGELIST_ENTRIES_PER_PAGE);
+
+ return pages * OPTEE_MSG_NONCONTIG_PAGE_SIZE;
+}
+
+u64 *optee_allocate_pages_list(size_t num_entries)
+{
+ return alloc_pages_exact(get_pages_list_size(num_entries), GFP_KERNEL);
+}
+
+void optee_free_pages_list(void *list, size_t num_entries)
+{
+ free_pages_exact(list, get_pages_list_size(num_entries));
+}
+
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index c374cd5..b63213d 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -165,6 +165,11 @@ int optee_from_msg_param(struct tee_param *params, size_t num_params,
int optee_to_msg_param(struct optee_msg_param *msg_params, size_t num_params,
const struct tee_param *params);

+u64 *optee_allocate_pages_list(size_t num_entries);
+void optee_free_pages_list(void *array, size_t num_entries);
+void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
+ size_t page_offset);
+
/*
* Small helpers
*/
--
2.7.4
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