crypto: limit more FPU-enabled sections
Those crypto drivers use SSE/AVX/… for their crypto work and in order to
do so in kernel they need to enable the "FPU" in kernel mode which
disables preemption.
There are two problems with the way they are used:
- the while loop which processes X bytes may create latency spikes and
should be avoided or limited.
- the cipher-walk-next part may allocate/free memory and may use
kmap_atomic().
The whole kernel_fpu_begin()/end() processing isn't probably that cheap.
It most likely makes sense to process as much of those as possible in one
go. The new *_fpu_sched_rt() schedules only if a RT task is pending.
Probably we should measure the performance those ciphers in pure SW
mode and with this optimisations to see if it makes sense to keep them
for RT.
This kernel_fpu_resched() makes the code more preemptible which might hurt
performance.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
diff --git a/arch/x86/crypto/camellia_aesni_avx2_glue.c b/arch/x86/crypto/camellia_aesni_avx2_glue.c
index d844569..c54536d 100644
--- a/arch/x86/crypto/camellia_aesni_avx2_glue.c
+++ b/arch/x86/crypto/camellia_aesni_avx2_glue.c
@@ -206,6 +206,20 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void camellia_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ camellia_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+#else
+static void camellia_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = CAMELLIA_BLOCK_SIZE;
@@ -221,16 +235,19 @@
}
if (nbytes >= CAMELLIA_AESNI_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_ecb_enc_16way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_AESNI_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_AESNI_PARALLEL_BLOCKS;
}
while (nbytes >= CAMELLIA_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_enc_blk_2way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_PARALLEL_BLOCKS;
}
+ camellia_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
camellia_enc_blk(ctx->ctx, srcdst, srcdst);
@@ -251,16 +268,19 @@
}
if (nbytes >= CAMELLIA_AESNI_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_ecb_dec_16way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_AESNI_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_AESNI_PARALLEL_BLOCKS;
}
while (nbytes >= CAMELLIA_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_dec_blk_2way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_PARALLEL_BLOCKS;
}
+ camellia_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
camellia_dec_blk(ctx->ctx, srcdst, srcdst);
diff --git a/arch/x86/crypto/camellia_aesni_avx_glue.c b/arch/x86/crypto/camellia_aesni_avx_glue.c
index 93d8f29..a1666a5 100644
--- a/arch/x86/crypto/camellia_aesni_avx_glue.c
+++ b/arch/x86/crypto/camellia_aesni_avx_glue.c
@@ -210,6 +210,21 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void camellia_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ camellia_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void camellia_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = CAMELLIA_BLOCK_SIZE;
@@ -225,10 +240,12 @@
}
while (nbytes >= CAMELLIA_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_enc_blk_2way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_PARALLEL_BLOCKS;
}
+ camellia_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
camellia_enc_blk(ctx->ctx, srcdst, srcdst);
@@ -249,10 +266,12 @@
}
while (nbytes >= CAMELLIA_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
camellia_dec_blk_2way(ctx->ctx, srcdst, srcdst);
srcdst += bsize * CAMELLIA_PARALLEL_BLOCKS;
nbytes -= bsize * CAMELLIA_PARALLEL_BLOCKS;
}
+ camellia_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
camellia_dec_blk(ctx->ctx, srcdst, srcdst);
diff --git a/arch/x86/crypto/cast6_avx_glue.c b/arch/x86/crypto/cast6_avx_glue.c
index fca4595..9eb469b9 100644
--- a/arch/x86/crypto/cast6_avx_glue.c
+++ b/arch/x86/crypto/cast6_avx_glue.c
@@ -205,19 +205,33 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void cast6_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ cast6_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void cast6_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = CAST6_BLOCK_SIZE;
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = cast6_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * CAST6_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = cast6_fpu_begin(ctx->fpu_enabled, nbytes);
cast6_ecb_enc_8way(ctx->ctx, srcdst, srcdst);
+ cast6_fpu_end_rt(ctx);
return;
}
-
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
__cast6_encrypt(ctx->ctx, srcdst, srcdst);
}
@@ -228,10 +242,10 @@
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = cast6_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * CAST6_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = cast6_fpu_begin(ctx->fpu_enabled, nbytes);
cast6_ecb_dec_8way(ctx->ctx, srcdst, srcdst);
+ cast6_fpu_end_rt(ctx);
return;
}
diff --git a/arch/x86/crypto/chacha20_glue.c b/arch/x86/crypto/chacha20_glue.c
index 722bace..0e3eb53 100644
--- a/arch/x86/crypto/chacha20_glue.c
+++ b/arch/x86/crypto/chacha20_glue.c
@@ -80,22 +80,24 @@
crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
- kernel_fpu_begin();
-
while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
+ kernel_fpu_begin();
+
chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
+ kernel_fpu_end();
err = blkcipher_walk_done(desc, &walk,
walk.nbytes % CHACHA20_BLOCK_SIZE);
}
if (walk.nbytes) {
+ kernel_fpu_begin();
chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes);
+ kernel_fpu_end();
err = blkcipher_walk_done(desc, &walk, 0);
}
- kernel_fpu_end();
return err;
}
diff --git a/arch/x86/crypto/serpent_avx2_glue.c b/arch/x86/crypto/serpent_avx2_glue.c
index 6d19834..0954bae 100644
--- a/arch/x86/crypto/serpent_avx2_glue.c
+++ b/arch/x86/crypto/serpent_avx2_glue.c
@@ -184,6 +184,21 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void serpent_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ serpent_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void serpent_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = SERPENT_BLOCK_SIZE;
@@ -199,10 +214,12 @@
}
while (nbytes >= SERPENT_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
serpent_ecb_enc_8way_avx(ctx->ctx, srcdst, srcdst);
srcdst += bsize * SERPENT_PARALLEL_BLOCKS;
nbytes -= bsize * SERPENT_PARALLEL_BLOCKS;
}
+ serpent_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
__serpent_encrypt(ctx->ctx, srcdst, srcdst);
@@ -223,10 +240,12 @@
}
while (nbytes >= SERPENT_PARALLEL_BLOCKS * bsize) {
+ kernel_fpu_resched();
serpent_ecb_dec_8way_avx(ctx->ctx, srcdst, srcdst);
srcdst += bsize * SERPENT_PARALLEL_BLOCKS;
nbytes -= bsize * SERPENT_PARALLEL_BLOCKS;
}
+ serpent_fpu_end_rt(ctx);
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
__serpent_decrypt(ctx->ctx, srcdst, srcdst);
diff --git a/arch/x86/crypto/serpent_avx_glue.c b/arch/x86/crypto/serpent_avx_glue.c
index 5dc3702..8c812a0 100644
--- a/arch/x86/crypto/serpent_avx_glue.c
+++ b/arch/x86/crypto/serpent_avx_glue.c
@@ -218,16 +218,31 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void serpent_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ serpent_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void serpent_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = SERPENT_BLOCK_SIZE;
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
serpent_ecb_enc_8way_avx(ctx->ctx, srcdst, srcdst);
+ serpent_fpu_end_rt(ctx);
return;
}
@@ -241,10 +256,10 @@
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
serpent_ecb_dec_8way_avx(ctx->ctx, srcdst, srcdst);
+ serpent_fpu_end_rt(ctx);
return;
}
diff --git a/arch/x86/crypto/serpent_sse2_glue.c b/arch/x86/crypto/serpent_sse2_glue.c
index 3643dd5..1ef09f8 100644
--- a/arch/x86/crypto/serpent_sse2_glue.c
+++ b/arch/x86/crypto/serpent_sse2_glue.c
@@ -187,16 +187,31 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void serpent_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ serpent_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void serpent_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = SERPENT_BLOCK_SIZE;
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
serpent_enc_blk_xway(ctx->ctx, srcdst, srcdst);
+ serpent_fpu_end_rt(ctx);
return;
}
@@ -210,10 +225,10 @@
struct crypt_priv *ctx = priv;
int i;
- ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
-
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
+ ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
serpent_dec_blk_xway(ctx->ctx, srcdst, srcdst);
+ serpent_fpu_end_rt(ctx);
return;
}
diff --git a/arch/x86/crypto/twofish_avx_glue.c b/arch/x86/crypto/twofish_avx_glue.c
index b7a3904..de00fe2 100644
--- a/arch/x86/crypto/twofish_avx_glue.c
+++ b/arch/x86/crypto/twofish_avx_glue.c
@@ -218,6 +218,21 @@
bool fpu_enabled;
};
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void twofish_fpu_end_rt(struct crypt_priv *ctx)
+{
+ bool fpu_enabled = ctx->fpu_enabled;
+
+ if (!fpu_enabled)
+ return;
+ twofish_fpu_end(fpu_enabled);
+ ctx->fpu_enabled = false;
+}
+
+#else
+static void twofish_fpu_end_rt(struct crypt_priv *ctx) { }
+#endif
+
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = TF_BLOCK_SIZE;
@@ -228,12 +243,16 @@
if (nbytes == bsize * TWOFISH_PARALLEL_BLOCKS) {
twofish_ecb_enc_8way(ctx->ctx, srcdst, srcdst);
+ twofish_fpu_end_rt(ctx);
return;
}
- for (i = 0; i < nbytes / (bsize * 3); i++, srcdst += bsize * 3)
+ for (i = 0; i < nbytes / (bsize * 3); i++, srcdst += bsize * 3) {
+ kernel_fpu_resched();
twofish_enc_blk_3way(ctx->ctx, srcdst, srcdst);
+ }
+ twofish_fpu_end_rt(ctx);
nbytes %= bsize * 3;
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
@@ -250,11 +269,15 @@
if (nbytes == bsize * TWOFISH_PARALLEL_BLOCKS) {
twofish_ecb_dec_8way(ctx->ctx, srcdst, srcdst);
+ twofish_fpu_end_rt(ctx);
return;
}
- for (i = 0; i < nbytes / (bsize * 3); i++, srcdst += bsize * 3)
+ for (i = 0; i < nbytes / (bsize * 3); i++, srcdst += bsize * 3) {
+ kernel_fpu_resched();
twofish_dec_blk_3way(ctx->ctx, srcdst, srcdst);
+ }
+ twofish_fpu_end_rt(ctx);
nbytes %= bsize * 3;
diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index 1429a7c..85428df 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -24,6 +24,7 @@
extern void __kernel_fpu_end(void);
extern void kernel_fpu_begin(void);
extern void kernel_fpu_end(void);
+extern void kernel_fpu_resched(void);
extern bool irq_fpu_usable(void);
/*
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index d25097c..67ae18a 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -149,6 +149,18 @@
}
EXPORT_SYMBOL_GPL(kernel_fpu_end);
+void kernel_fpu_resched(void)
+{
+ WARN_ON_FPU(!this_cpu_read(in_kernel_fpu));
+
+ if (should_resched(PREEMPT_OFFSET)) {
+ kernel_fpu_end();
+ cond_resched();
+ kernel_fpu_begin();
+ }
+}
+EXPORT_SYMBOL_GPL(kernel_fpu_resched);
+
/*
* CR0::TS save/restore functions:
*/
