linux-kernel - Re: [PATCH v2 2/4] tee: Remove vmalloc page support

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Date:   Mon, 13 Feb 2023 16:54:23 +0100
From:   Jens Wiklander <jens.wiklander@...aro.org>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Sumit Garg <sumit.garg@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org,
        op-tee@...ts.trustedfirmware.org, linux-mm@...ck.org,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        John Hubbard <jhubbard@...dia.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 2/4] tee: Remove vmalloc page support

On Fri, Feb 03, 2023 at 08:06:33PM -0800, Ira Weiny wrote:
> 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: 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>
> Reviewed-by: Jens Wiklander <jens.wiklander@...aro.org>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
>  drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> 
> 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;
>  }
>  
> 
> -- 
> 2.39.1