| Message ID | 18a6df64615a10be64c3c902f8b1f36e472548d7.1741318360.git.herbert@gondor.apana.org.au |
|---|---|
| State | Accepted |
| Commit | 131bdceca1f0a2d9381270dc40f898458e5e184b |
| Headers | show |
| Series | crypto: scatterwalk - scatterwalk_next and memcpy_sglist | expand |
On Fri, Mar 07, 2025 at 11:36:19AM +0800, Herbert Xu wrote: > Add memcpy_sglist which copies one SG list to another. > > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> There's no user of this yet, but presumably this is going to be used to replace some of the bizarre code that is using the "null skcipher" to copy between two scatterlists? For example the code in crypto/seqiv.c. - Eric
On Fri, Mar 07, 2025 at 01:37:49PM -0800, Eric Biggers wrote: > > There's no user of this yet, but presumably this is going to be used to replace > some of the bizarre code that is using the "null skcipher" to copy between two > scatterlists? For example the code in crypto/seqiv.c. It was actually for zram: https://lore.kernel.org/all/Z8kiRym1hS9fB2mE@gondor.apana.org.au/ But yes we could definitely replace the null skcipher with this. Do you want to have a go at that? Thanks,
On Sat, Mar 08, 2025 at 06:52:35PM +0800, Herbert Xu wrote: > On Fri, Mar 07, 2025 at 01:37:49PM -0800, Eric Biggers wrote: > > > > There's no user of this yet, but presumably this is going to be used to replace > > some of the bizarre code that is using the "null skcipher" to copy between two > > scatterlists? For example the code in crypto/seqiv.c. > > It was actually for zram: > > https://lore.kernel.org/all/Z8kiRym1hS9fB2mE@gondor.apana.org.au/ > > But yes we could definitely replace the null skcipher with this. > Do you want to have a go at that? > Yes, I'll do that. - Eric
On Fri, Mar 07, 2025 at 11:36:19AM +0800, Herbert Xu wrote: > Add memcpy_sglist which copies one SG list to another. > > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> > --- > crypto/scatterwalk.c | 27 +++++++++++++++++++++++++++ > include/crypto/scatterwalk.h | 3 +++ > 2 files changed, 30 insertions(+) > > diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c > index 20a28c6d94da..8225801488d5 100644 > --- a/crypto/scatterwalk.c > +++ b/crypto/scatterwalk.c > @@ -86,6 +86,33 @@ void memcpy_to_sglist(struct scatterlist *sg, unsigned int start, > } > EXPORT_SYMBOL_GPL(memcpy_to_sglist); > > +void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src, > + unsigned int nbytes) > +{ > + struct scatter_walk swalk; > + struct scatter_walk dwalk; > + > + if (unlikely(nbytes == 0)) /* in case sg == NULL */ > + return; > + > + scatterwalk_start(&swalk, src); > + scatterwalk_start(&dwalk, dst); > + > + do { > + unsigned int slen, dlen; > + unsigned int len; > + > + slen = scatterwalk_next(&swalk, nbytes); > + dlen = scatterwalk_next(&dwalk, nbytes); > + len = min(slen, dlen); > + memcpy(dwalk.addr, swalk.addr, len); > + scatterwalk_done_dst(&dwalk, len); > + scatterwalk_done_src(&swalk, len); > + nbytes -= len; > + } while (nbytes); > +} > +EXPORT_SYMBOL_GPL(memcpy_sglist); Actually this new function is useless as-is, since it invokes undefined behavior when the source and destination coincide (which can happen even when src == dst), and all the potential callers need to handle that case. I'm working on a fixed version. - Eric
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index 20a28c6d94da..8225801488d5 100644 --- a/crypto/scatterwalk.c +++ b/crypto/scatterwalk.c @@ -86,6 +86,33 @@ void memcpy_to_sglist(struct scatterlist *sg, unsigned int start, } EXPORT_SYMBOL_GPL(memcpy_to_sglist); +void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct scatter_walk swalk; + struct scatter_walk dwalk; + + if (unlikely(nbytes == 0)) /* in case sg == NULL */ + return; + + scatterwalk_start(&swalk, src); + scatterwalk_start(&dwalk, dst); + + do { + unsigned int slen, dlen; + unsigned int len; + + slen = scatterwalk_next(&swalk, nbytes); + dlen = scatterwalk_next(&dwalk, nbytes); + len = min(slen, dlen); + memcpy(dwalk.addr, swalk.addr, len); + scatterwalk_done_dst(&dwalk, len); + scatterwalk_done_src(&swalk, len); + nbytes -= len; + } while (nbytes); +} +EXPORT_SYMBOL_GPL(memcpy_sglist); + struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], struct scatterlist *src, unsigned int len) diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h index 791100054f7c..533e52dd7e0f 100644 --- a/include/crypto/scatterwalk.h +++ b/include/crypto/scatterwalk.h @@ -210,6 +210,9 @@ void memcpy_from_sglist(void *buf, struct scatterlist *sg, void memcpy_to_sglist(struct scatterlist *sg, unsigned int start, const void *buf, unsigned int nbytes); +void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes); + /* In new code, please use memcpy_{from,to}_sglist() directly instead. */ static inline void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, unsigned int start,
Add memcpy_sglist which copies one SG list to another. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> --- crypto/scatterwalk.c | 27 +++++++++++++++++++++++++++ include/crypto/scatterwalk.h | 3 +++ 2 files changed, 30 insertions(+)