diff mbox series

[07/13] crypto: x86/ghash - restructure FPU context saving

Message ID 20221219220223.3982176-8-elliott@hpe.com
State New
Headers
Series crypto: x86 - yield FPU context during long loops |

Commit Message

Elliott, Robert (Servers) Dec. 19, 2022, 10:02 p.m. UTC 
  Wrap each of the calls to clmul_hash_update and clmul_ghash__mul
in its own set of kernel_fpu_begin and kernel_fpu_end calls, preparing
to limit the amount of data processed by each _update call to avoid
RCU stalls.

This is more like how polyval-clmulni_glue is structured.

Fixes: 0e1227d356e9 ("crypto: ghash - Add PCLMULQDQ accelerated implementation")
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Robert Elliott <elliott@hpe.com>
---
 arch/x86/crypto/ghash-clmulni-intel_glue.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Herbert Xu Dec. 30, 2022, 9:04 a.m. UTC | #1 
On Mon, Dec 19, 2022 at 04:02:17PM -0600, Robert Elliott wrote:
> Wrap each of the calls to clmul_hash_update and clmul_ghash__mul
> in its own set of kernel_fpu_begin and kernel_fpu_end calls, preparing
> to limit the amount of data processed by each _update call to avoid
> RCU stalls.
> 
> This is more like how polyval-clmulni_glue is structured.
> 
> Fixes: 0e1227d356e9 ("crypto: ghash - Add PCLMULQDQ accelerated implementation")
> Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
> Signed-off-by: Robert Elliott <elliott@hpe.com>
> ---
>  arch/x86/crypto/ghash-clmulni-intel_glue.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/crypto/ghash-clmulni-intel_glue.c b/arch/x86/crypto/ghash-clmulni-intel_glue.c
> index beac4b2eddf6..1bfde099de0f 100644
> --- a/arch/x86/crypto/ghash-clmulni-intel_glue.c
> +++ b/arch/x86/crypto/ghash-clmulni-intel_glue.c
> @@ -80,7 +80,6 @@ static int ghash_update(struct shash_desc *desc,
>  	struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
>  	u8 *dst = dctx->buffer;
>  
> -	kernel_fpu_begin();
>  	if (dctx->bytes) {
>  		int n = min(srclen, dctx->bytes);
>  		u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
> @@ -91,10 +90,14 @@ static int ghash_update(struct shash_desc *desc,
>  		while (n--)
>  			*pos++ ^= *src++;
>  
> -		if (!dctx->bytes)
> +		if (!dctx->bytes) {
> +			kernel_fpu_begin();
>  			clmul_ghash_mul(dst, &ctx->shash);
> +			kernel_fpu_end();
> +		}
>  	}
>  
> +	kernel_fpu_begin();
>  	clmul_ghash_update(dst, src, srclen, &ctx->shash);
>  	kernel_fpu_end();

Why is this necessary? Couldn't you just add the kernel_fpu_yield
calls even without this patch?

This just seems to be adding some unnecessary begin/end calls.

Cheers,
diff mbox series

Patch

diff --git a/arch/x86/crypto/ghash-clmulni-intel_glue.c b/arch/x86/crypto/ghash-clmulni-intel_glue.c
index beac4b2eddf6..1bfde099de0f 100644
--- a/arch/x86/crypto/ghash-clmulni-intel_glue.c
+++ b/arch/x86/crypto/ghash-clmulni-intel_glue.c
@@ -80,7 +80,6 @@  static int ghash_update(struct shash_desc *desc,
 	struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 	u8 *dst = dctx->buffer;
 
-	kernel_fpu_begin();
 	if (dctx->bytes) {
 		int n = min(srclen, dctx->bytes);
 		u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
@@ -91,10 +90,14 @@  static int ghash_update(struct shash_desc *desc,
 		while (n--)
 			*pos++ ^= *src++;
 
-		if (!dctx->bytes)
+		if (!dctx->bytes) {
+			kernel_fpu_begin();
 			clmul_ghash_mul(dst, &ctx->shash);
+			kernel_fpu_end();
+		}
 	}
 
+	kernel_fpu_begin();
 	clmul_ghash_update(dst, src, srclen, &ctx->shash);
 	kernel_fpu_end();