Re: cryptoapi highmem bug

[Jean-Luc Cooke]

Not to be annoying...

Could you make this change against my patch at:
  http://jlcooke.ca/lkml/crypto_28feb2004.patch

I moved all the scatterwalk stuff into a scatterwalk.c file.

JLC

On Wed, Feb 25, 2004 at 04:51:22PM +0100, Christophe Saout wrote:
> On Wed, Feb 25, 2004 at 04:31:26PM +0100, Christophe Saout wrote:
> 
> > It's just a proof of concept though, it would be less complicated if we
> > would just pass the other walk struct to the functions that take one
> > and let them do the checking (no need to disable preemption and use
> > per cpu variables). Hmm.
> 
> Ok, this also works. It makes copy_chunks and crypt responsible for
> tracking the walk struct which might contain a page to reuse:
> 
> 
> --- linux-2.6.3/crypto/cipher.c	2004-02-25 13:49:53.000000000 +0100
> +++ linux-2.6.3.test/crypto/cipher.c	2004-02-25 16:46:58.430294600 +0100
> @@ -29,6 +29,7 @@
>  struct scatter_walk {
>  	struct scatterlist	*sg;
>  	struct page		*page;
> +	int			out;
>  	void			*data;
>  	unsigned int		len_this_page;
>  	unsigned int		len_this_segment;
> @@ -64,7 +65,7 @@
>  	return sg + 1;
>  }
>  
> -void *which_buf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)
> +static void *which_buf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)
>  {
>  	if (nbytes <= walk->len_this_page &&
>  	    (((unsigned long)walk->data) & (PAGE_CACHE_SIZE - 1)) + nbytes <=
> @@ -96,9 +97,23 @@
>  	walk->offset = sg->offset;
>  }
>  
> -static void scatterwalk_map(struct scatter_walk *walk, int out)
> +static void scatterwalk_map(struct scatter_walk *walk,
> +			    struct scatter_walk *other, int out)
>  {
> -	walk->data = crypto_kmap(walk->page, out) + walk->offset;
> +	if (other && other->page == walk->page) {
> +		walk->data = (other->data - other->offset) + walk->offset;
> +		walk->out = other->out;
> +	} else {
> +		walk->data = crypto_kmap(walk->page, out) + walk->offset;
> +		walk->out = out;
> +	}
> +}
> +
> +static void scatterwalk_unmap(struct scatter_walk *walk,
> +			      struct scatter_walk *other, int out)
> +{
> +	if (!other || other->page != walk->page)
> +		crypto_kunmap(walk->data, walk->out);
>  }
>  
>  static void scatter_page_done(struct scatter_walk *walk, int out,
> @@ -125,9 +140,10 @@
>  	}
>  }
>  
> -static void scatter_done(struct scatter_walk *walk, int out, int more)
> +static void scatter_done(struct scatter_walk *walk,
> +			 struct scatter_walk *other, int out, int more)
>  {
> -	crypto_kunmap(walk->data, out);
> +	scatterwalk_unmap(walk, other, out);
>  	if (walk->len_this_page == 0 || !more)
>  		scatter_page_done(walk, out, more);
>  }
> @@ -137,7 +153,7 @@
>   * has been verified as multiple of the block size.
>   */
>  static int copy_chunks(void *buf, struct scatter_walk *walk,
> -			size_t nbytes, int out)
> +		       struct scatter_walk *other, size_t nbytes, int out)
>  {
>  	if (buf != walk->data) {
>  		while (nbytes > walk->len_this_page) {
> @@ -145,9 +161,9 @@
>  			buf += walk->len_this_page;
>  			nbytes -= walk->len_this_page;
>  
> -			crypto_kunmap(walk->data, out);
> +			scatterwalk_unmap(walk, other, out);
>  			scatter_page_done(walk, out, 1);
> -			scatterwalk_map(walk, out);
> +			scatterwalk_map(walk, other, out);
>  		}
>  
>  		memcpy_dir(buf, walk->data, nbytes, out);
> @@ -189,21 +205,21 @@
>  	for(;;) {
>  		u8 *src_p, *dst_p;
>  
> -		scatterwalk_map(&walk_in, 0);
> -		scatterwalk_map(&walk_out, 1);
> +		scatterwalk_map(&walk_in, NULL, 0);
> +		scatterwalk_map(&walk_out, &walk_in, 1);
>  		src_p = which_buf(&walk_in, bsize, tmp_src);
>  		dst_p = which_buf(&walk_out, bsize, tmp_dst);
>  
>  		nbytes -= bsize;
>  
> -		copy_chunks(src_p, &walk_in, bsize, 0);
> +		copy_chunks(src_p, &walk_in, &walk_out, bsize, 0);
>  
>  		prfn(tfm, dst_p, src_p, crfn, enc, info);
>  
> -		scatter_done(&walk_in, 0, nbytes);
> +		scatter_done(&walk_in, &walk_out, 0, nbytes);
>  
> -		copy_chunks(dst_p, &walk_out, bsize, 1);
> -		scatter_done(&walk_out, 1, nbytes);
> +		copy_chunks(dst_p, &walk_out, NULL, bsize, 1);
> +		scatter_done(&walk_out, NULL, 1, nbytes);
>  
>  		if (!nbytes)
>  			return 0;

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