[PATCH 2/4] tee: Remove vmalloc page support

ira.weiny
2022-10-02T00:23:40Z

From: Ira Weiny <ira.weiny@intel.com>

The kernel pages used by shm_get_kernel_pages() are allocated using
GFP_KERNEL through the following call stack:

trusted_instantiate()
trusted_payload_alloc() -> GFP_KERNEL
<trusted key op>
tee_shm_register_kernel_buf()
register_shm_helper()
shm_get_kernel_pages()

Where <trusted key op> is one of:

trusted_key_unseal()
trusted_key_get_random()
trusted_key_seal()

Remove the vmalloc page support from shm_get_kernel_pages(). Replace
with a warn on once.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Jens I went with the suggestion from Linus and Christoph and rejected
vmalloc addresses. I did not hear back from you regarding Linus'
question if the vmalloc page support was required by an up coming patch
set or not. So I assumed it was something out of tree.
---
drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 27295bda3e0b..527a6eabc03e 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -24,37 +24,25 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
static int shm_get_kernel_pages(unsigned long start, size_t page_count,
struct page **pages)
{
+ struct kvec *kiov;
size_t n;
int rc;

- if (is_vmalloc_addr((void *)start)) {
- struct page *page;
-
- for (n = 0; n < page_count; n++) {
- page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
- if (!page)
- return -ENOMEM;
-
- get_page(page);
- pages[n] = page;
- }
- rc = page_count;
- } else {
- struct kvec *kiov;
-
- kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
- if (!kiov)
- return -ENOMEM;
+ if (WARN_ON_ONCE(is_vmalloc_addr((void *)start)))
+ return -EINVAL;

- for (n = 0; n < page_count; n++) {
- kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
- kiov[n].iov_len = PAGE_SIZE;
- }
+ kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
+ if (!kiov)
+ return -ENOMEM;

- rc = get_kernel_pages(kiov, page_count, 0, pages);
- kfree(kiov);
+ for (n = 0; n < page_count; n++) {
+ kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
+ kiov[n].iov_len = PAGE_SIZE;
}

+ rc = get_kernel_pages(kiov, page_count, 0, pages);
+ kfree(kiov);
+
return rc;
}

--
2.37.2