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Date: Fri, 22 Mar 2019 12:21:51 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: "Jason A. Donenfeld" <Jason@...c4.com>
cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, Samuel Neves <sneves@....uc.pt>,
Andy Lutomirski <luto@...nel.org>,
Greg KH <gregkh@...uxfoundation.org>,
linux-arch@...r.kernel.org
Subject: Re: [PATCH net-next v9 01/19] asm: simd context helper API
Jason,
On Fri, 22 Mar 2019, Jason A. Donenfeld wrote:
> index 000000000000..264ed84b41d8
> --- /dev/null
> +++ b/arch/arm/include/asm/simd.h
> @@ -0,0 +1,63 @@
> +/* SPDX-License-Identifier: GPL-2.0
The SPDX identifier has to be in a separate comment line.
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2015-2018 Jason....
*/
Yes, it looks odd, but it's defined that way.
> +static __must_check inline bool simd_use(simd_context_t *ctx)
> +{
> + if (!(*ctx & HAVE_FULL_SIMD))
> + return false;
> + if (*ctx & HAVE_SIMD_IN_USE)
> + return true;
> + kernel_neon_begin();
> + *ctx |= HAVE_SIMD_IN_USE;
> + return true;
> +}
> +static __must_check inline bool simd_use(simd_context_t *ctx)
> +{
> + if (!(*ctx & HAVE_FULL_SIMD))
> + return false;
> + if (*ctx & HAVE_SIMD_IN_USE)
> + return true;
> + kernel_neon_begin();
> + *ctx |= HAVE_SIMD_IN_USE;
> + return true;
> +}
> +static __must_check inline bool simd_use(simd_context_t *ctx)
> +{
> +#if !defined(CONFIG_UML)
> + if (!(*ctx & HAVE_FULL_SIMD))
> + return false;
> + if (*ctx & HAVE_SIMD_IN_USE)
> + return true;
> + kernel_fpu_begin();
> + *ctx |= HAVE_SIMD_IN_USE;
> + return true;
> +#else
> + return false;
> +#endif
> +}
So now we have 3 almost identical copies of the same thing and x86/UM
handling it differently than the ARM(64) ones.
That can be completely avoided. Untested patch below.
Thanks,
tglx
8<-------------
--- /dev/null
+++ b/arch/arm/include/asm/simd.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
+ */
+#ifndef _ASM_SIMD_H
+#define _ASM_SIMD_H
+
+#ifdef CONFIG_KERNEL_MODE_NEON
+#include <asm/neon.h>
+
+static __must_check inline bool may_use_simd(void)
+{
+ return !in_nmi() && !in_irq() && !in_serving_softirq();
+}
+
+static inline void arch_simd_end(void)
+{
+ kernel_neon_end();
+}
+
+static inline void arch_simd_begin(void)
+{
+ kernel_neon_begin();
+}
+
+#else
+#include <asm-generic/simd.h>
+#endif
+
+#endif /* _ASM_SIMD_H */
--- a/arch/arm64/include/asm/simd.h
+++ b/arch/arm64/include/asm/simd.h
@@ -1,11 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@...aro.org>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation.
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
*/
+#include <linux/simd.h>
#ifndef __ASM_SIMD_H
#define __ASM_SIMD_H
@@ -16,6 +15,8 @@
#include <linux/types.h>
#ifdef CONFIG_KERNEL_MODE_NEON
+#include <asm/neon.h>
+#include <asm/simd.h>
DECLARE_PER_CPU(bool, kernel_neon_busy);
@@ -40,12 +41,18 @@ static __must_check inline bool may_use_
!this_cpu_read(kernel_neon_busy);
}
-#else /* ! CONFIG_KERNEL_MODE_NEON */
+static inline void arch_simd_end(void)
+{
+ kernel_neon_end();
+}
-static __must_check inline bool may_use_simd(void) {
- return false;
+static inline void arch_simd_begin(void)
+{
+ kernel_neon_begin();
}
-#endif /* ! CONFIG_KERNEL_MODE_NEON */
+#else
+#include <asm-generic/simd.h>
+#endif
#endif
--- a/arch/x86/include/asm/simd.h
+++ b/arch/x86/include/asm/simd.h
@@ -1,4 +1,12 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
+ */
+
+#ifndef _ASM_SIMD_H
+#define _ASM_SIMD_H
+
+#ifndef CONFIG_UML
#include <asm/fpu/api.h>
@@ -10,3 +18,21 @@ static __must_check inline bool may_use_
{
return irq_fpu_usable();
}
+
+static inline void arch_simd_begin(void)
+{
+ kernel_fpu_begin();
+}
+
+static inline void arch_simd_end(void)
+{
+ kernel_fpu_end();
+}
+
+#else
+#include <asm-generic/simd.h>
+#endif
+
+#include <linux/simd.h>
+
+#endif /* _ASM_SIMD_H */
--- a/include/asm-generic/simd.h
+++ b/include/asm-generic/simd.h
@@ -1,7 +1,12 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_SIMD_H
+#define _ASM_SIMD_H
+
#include <linux/hardirq.h>
+#define SIMD_GENERIC 1
+
/*
* may_use_simd - whether it is allowable at this time to issue SIMD
* instructions or access the SIMD register file
@@ -13,3 +18,10 @@ static __must_check inline bool may_use_
{
return !in_interrupt();
}
+
+static inline void arch_simd_begin(void) { }
+static inline void arch_simd_end(void) { }
+
+#include <linux/simd.h>
+
+#endif /* _ASM_SIMD_H */
--- /dev/null
+++ b/include/linux/simd.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
+ */
+
+#ifndef _SIMD_H
+#define _SIMD_H
+
+typedef enum {
+ HAVE_NO_SIMD = 1 << 0,
+ HAVE_FULL_SIMD = 1 << 1,
+ HAVE_SIMD_IN_USE = 1 << 31
+} simd_context_t;
+
+#define DONT_USE_SIMD ((simd_context_t []){ HAVE_NO_SIMD })
+
+#include <asm/simd.h>
+
+#ifndef SIMD_GENERIC
+
+#include <linux/sched.h>
+
+static inline bool simd_relax(simd_context_t *ctx)
+{
+#ifdef CONFIG_PREEMPT
+ if ((*ctx & HAVE_SIMD_IN_USE) && need_resched()) {
+ simd_put(ctx);
+ simd_get(ctx);
+ return true;
+ }
+#endif
+ return false;
+}
+
+static inline void simd_get(simd_context_t *ctx)
+{
+ *ctx = may_use_simd() ? HAVE_FULL_SIMD : HAVE_NO_SIMD;
+}
+
+static inline void simd_put(simd_context_t *ctx)
+{
+ if (*ctx & HAVE_SIMD_IN_USE)
+ arch_simd_end();
+
+ *ctx = HAVE_NO_SIMD;
+}
+
+static __must_check inline bool simd_use(simd_context_t *ctx)
+{
+ if (!(*ctx & HAVE_FULL_SIMD))
+ return false;
+ if (*ctx & HAVE_SIMD_IN_USE)
+ return true;
+ arch_simd_begin();
+ *ctx |= HAVE_SIMD_IN_USE;
+ return true;
+}
+
+#else /* !SIMD_GENERIC */
+
+static inline bool simd_relax(simd_context_t *ctx)
+{
+ return false;
+}
+
+static inline void simd_get(simd_context_t *ctx)
+{
+ *ctx = HAVE_NO_SIMD;
+}
+
+static inline void simd_put(simd_context_t *ctx)
+{
+}
+
+static __must_check inline bool simd_use(simd_context_t *ctx)
+{
+ return false;
+}
+
+#endif /* SIMD_GENERIC */
+
+#endif /* _SIMD_H */
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