* [PATCH RT] crypto: Reduce preempt disabled regions, more algos
[not found] ` <CABB1KXpPB+zsEZZxwUWkKLA8OifCi6Qf1Q86x6o-bcLgKe8ysg@mail.gmail.com>
@ 2014-02-21 16:36 ` Sebastian Andrzej Siewior
0 siblings, 0 replies; only message in thread
From: Sebastian Andrzej Siewior @ 2014-02-21 16:36 UTC (permalink / raw)
To: Don Estabrook; +Cc: Thomas Gleixner, linux-rt-users, linux-kernel
Don Estabrook reported
| kernel: WARNING: CPU: 2 PID: 858 at kernel/sched/core.c:2428 migrate_disable+0xed/0x100()
| kernel: WARNING: CPU: 2 PID: 858 at kernel/sched/core.c:2462 migrate_enable+0x17b/0x200()
| kernel: WARNING: CPU: 3 PID: 865 at kernel/sched/core.c:2428 migrate_disable+0xed/0x100()
and his backtrace showed some crypto functions which looked fine.
The problem is the following sequence:
glue_xts_crypt_128bit()
{
blkcipher_walk_virt(); /* normal migrate_disable() */
glue_fpu_begin(); /* get atomic */
while (nbytes) {
__glue_xts_crypt_128bit();
blkcipher_walk_done(); /* with nbytes = 0, migrate_enable()
* while we are atomic */
};
glue_fpu_end() /* no longer atomic */
}
and this is why the counter get out of sync and the warning is printed.
The other problem is that we are non-preemptible between
glue_fpu_begin() and glue_fpu_end() and the latency grows. To fix this,
I shorten the FPU off region and ensure blkcipher_walk_done() is called
with preemption enabled. This might hurt the performance because we now
enable/disable the FPU state more often but we gain lower latency and
the bug is gone.
Reported-by: Don Estabrook <don.estabrook@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/crypto/cast5_avx_glue.c | 21 +++++++++------------
arch/x86/crypto/glue_helper.c | 31 +++++++++++++++----------------
2 files changed, 24 insertions(+), 28 deletions(-)
diff --git a/arch/x86/crypto/cast5_avx_glue.c b/arch/x86/crypto/cast5_avx_glue.c
index c663181..2d48e83 100644
--- a/arch/x86/crypto/cast5_avx_glue.c
+++ b/arch/x86/crypto/cast5_avx_glue.c
@@ -60,7 +60,7 @@ static inline void cast5_fpu_end(bool fpu_enabled)
static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
bool enc)
{
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct cast5_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
const unsigned int bsize = CAST5_BLOCK_SIZE;
unsigned int nbytes;
@@ -76,7 +76,7 @@ static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
u8 *wsrc = walk->src.virt.addr;
u8 *wdst = walk->dst.virt.addr;
- fpu_enabled = cast5_fpu_begin(fpu_enabled, nbytes);
+ fpu_enabled = cast5_fpu_begin(false, nbytes);
/* Process multi-block batch */
if (nbytes >= bsize * CAST5_PARALLEL_BLOCKS) {
@@ -104,10 +104,9 @@ static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
} while (nbytes >= bsize);
done:
+ cast5_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, walk, nbytes);
}
-
- cast5_fpu_end(fpu_enabled);
return err;
}
@@ -231,7 +230,7 @@ static unsigned int __cbc_decrypt(struct blkcipher_desc *desc,
static int cbc_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct blkcipher_walk walk;
int err;
@@ -240,12 +239,11 @@ static int cbc_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
while ((nbytes = walk.nbytes)) {
- fpu_enabled = cast5_fpu_begin(fpu_enabled, nbytes);
+ fpu_enabled = cast5_fpu_begin(false, nbytes);
nbytes = __cbc_decrypt(desc, &walk);
+ cast5_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, &walk, nbytes);
}
-
- cast5_fpu_end(fpu_enabled);
return err;
}
@@ -315,7 +313,7 @@ static unsigned int __ctr_crypt(struct blkcipher_desc *desc,
static int ctr_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct blkcipher_walk walk;
int err;
@@ -324,13 +322,12 @@ static int ctr_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
while ((nbytes = walk.nbytes) >= CAST5_BLOCK_SIZE) {
- fpu_enabled = cast5_fpu_begin(fpu_enabled, nbytes);
+ fpu_enabled = cast5_fpu_begin(false, nbytes);
nbytes = __ctr_crypt(desc, &walk);
+ cast5_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, &walk, nbytes);
}
- cast5_fpu_end(fpu_enabled);
-
if (walk.nbytes) {
ctr_crypt_final(desc, &walk);
err = blkcipher_walk_done(desc, &walk, 0);
diff --git a/arch/x86/crypto/glue_helper.c b/arch/x86/crypto/glue_helper.c
index 432f1d76..4a2bd21 100644
--- a/arch/x86/crypto/glue_helper.c
+++ b/arch/x86/crypto/glue_helper.c
@@ -39,7 +39,7 @@ static int __glue_ecb_crypt_128bit(const struct common_glue_ctx *gctx,
void *ctx = crypto_blkcipher_ctx(desc->tfm);
const unsigned int bsize = 128 / 8;
unsigned int nbytes, i, func_bytes;
- bool fpu_enabled = false;
+ bool fpu_enabled;
int err;
err = blkcipher_walk_virt(desc, walk);
@@ -49,7 +49,7 @@ static int __glue_ecb_crypt_128bit(const struct common_glue_ctx *gctx,
u8 *wdst = walk->dst.virt.addr;
fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
- desc, fpu_enabled, nbytes);
+ desc, false, nbytes);
for (i = 0; i < gctx->num_funcs; i++) {
func_bytes = bsize * gctx->funcs[i].num_blocks;
@@ -71,10 +71,10 @@ static int __glue_ecb_crypt_128bit(const struct common_glue_ctx *gctx,
}
done:
+ glue_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, walk, nbytes);
}
- glue_fpu_end(fpu_enabled);
return err;
}
@@ -194,7 +194,7 @@ int glue_cbc_decrypt_128bit(const struct common_glue_ctx *gctx,
struct scatterlist *src, unsigned int nbytes)
{
const unsigned int bsize = 128 / 8;
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct blkcipher_walk walk;
int err;
@@ -203,12 +203,12 @@ int glue_cbc_decrypt_128bit(const struct common_glue_ctx *gctx,
while ((nbytes = walk.nbytes)) {
fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
- desc, fpu_enabled, nbytes);
+ desc, false, nbytes);
nbytes = __glue_cbc_decrypt_128bit(gctx, desc, &walk);
+ glue_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, &walk, nbytes);
}
- glue_fpu_end(fpu_enabled);
return err;
}
EXPORT_SYMBOL_GPL(glue_cbc_decrypt_128bit);
@@ -278,7 +278,7 @@ int glue_ctr_crypt_128bit(const struct common_glue_ctx *gctx,
struct scatterlist *src, unsigned int nbytes)
{
const unsigned int bsize = 128 / 8;
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct blkcipher_walk walk;
int err;
@@ -287,13 +287,12 @@ int glue_ctr_crypt_128bit(const struct common_glue_ctx *gctx,
while ((nbytes = walk.nbytes) >= bsize) {
fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
- desc, fpu_enabled, nbytes);
+ desc, false, nbytes);
nbytes = __glue_ctr_crypt_128bit(gctx, desc, &walk);
+ glue_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, &walk, nbytes);
}
- glue_fpu_end(fpu_enabled);
-
if (walk.nbytes) {
glue_ctr_crypt_final_128bit(
gctx->funcs[gctx->num_funcs - 1].fn_u.ctr, desc, &walk);
@@ -348,7 +347,7 @@ int glue_xts_crypt_128bit(const struct common_glue_ctx *gctx,
void *tweak_ctx, void *crypt_ctx)
{
const unsigned int bsize = 128 / 8;
- bool fpu_enabled = false;
+ bool fpu_enabled;
struct blkcipher_walk walk;
int err;
@@ -361,21 +360,21 @@ int glue_xts_crypt_128bit(const struct common_glue_ctx *gctx,
/* set minimum length to bsize, for tweak_fn */
fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
- desc, fpu_enabled,
+ desc, false,
nbytes < bsize ? bsize : nbytes);
-
/* calculate first value of T */
tweak_fn(tweak_ctx, walk.iv, walk.iv);
+ glue_fpu_end(fpu_enabled);
while (nbytes) {
+ fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
+ desc, false, nbytes);
nbytes = __glue_xts_crypt_128bit(gctx, crypt_ctx, desc, &walk);
+ glue_fpu_end(fpu_enabled);
err = blkcipher_walk_done(desc, &walk, nbytes);
nbytes = walk.nbytes;
}
-
- glue_fpu_end(fpu_enabled);
-
return err;
}
EXPORT_SYMBOL_GPL(glue_xts_crypt_128bit);
--
1.9.0.rc3
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