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

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Message-Id: <20221002002326.946620-3-ira.weiny@intel.com>
Date:   Sat,  1 Oct 2022 17:23:24 -0700
From:   ira.weiny@...el.com
To:     Jens Wiklander <jens.wiklander@...aro.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Ira Weiny <ira.weiny@...el.com>, Al Viro <viro@...iv.linux.org.uk>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Christoph Hellwig <hch@....de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH 2/4] tee: Remove vmalloc page support

From: Ira Weiny <ira.weiny@...el.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@...aro.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@...el.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