From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux@arm.linux.org.uk,
herbert@gondor.apana.org.au
Cc: steve.capper@linaro.org, Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: [PATCH 1/5] ARM: wire up HWCAP2 feature bits to the CPU modalias
Date: Tue, 18 Oct 2016 11:52:15 +0100 [thread overview]
Message-ID: <1476787939-21889-2-git-send-email-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <1476787939-21889-1-git-send-email-ard.biesheuvel@linaro.org>
Wire up the generic support for exposing CPU feature bits via the
modalias in /sys/device/system/cpu. This allows udev to automatically
load modules for things like crypto algorithms that are implemented
using optional instructions.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/cpufeature.h | 32 ++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b5d529fdffab..1a0c6a486a9c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -21,6 +21,7 @@ config ARM
select GENERIC_ALLOCATOR
select GENERIC_ATOMIC64 if (CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI)
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+ select GENERIC_CPU_AUTOPROBE
select GENERIC_EARLY_IOREMAP
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_PROBE
diff --git a/arch/arm/include/asm/cpufeature.h b/arch/arm/include/asm/cpufeature.h
new file mode 100644
index 000000000000..19c3dddd901a
--- /dev/null
+++ b/arch/arm/include/asm/cpufeature.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.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.
+ */
+
+#ifndef __ASM_CPUFEATURE_H
+#define __ASM_CPUFEATURE_H
+
+#include <asm/hwcap.h>
+
+/*
+ * Due to the fact that ELF_HWCAP is a 32-bit type on ARM, and given the number
+ * of optional CPU features it defines, ARM's CPU capability bits have been
+ * divided across separate elf_hwcap and elf_hwcap2 variables, each of which
+ * covers a subset of the available CPU features.
+ *
+ * Currently, only a few of those are suitable for automatic module loading
+ * (which is the primary use case of this facility) and those happen to be all
+ * covered by HWCAP2. So let's only expose those via the CPU modalias for now.
+ */
+#define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap2))
+#define cpu_feature(x) ilog2(HWCAP2_ ## x)
+
+static inline bool cpu_have_feature(unsigned int num)
+{
+ return elf_hwcap2 & (1UL << num);
+}
+
+#endif
--
2.7.4
next prev parent reply other threads:[~2016-10-18 10:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-18 10:52 [PATCH 0/5] ARM: add module autoloading support for crypto modules Ard Biesheuvel
2016-10-18 10:52 ` Ard Biesheuvel [this message]
2016-10-29 10:08 ` [PATCH 1/5] ARM: wire up HWCAP2 feature bits to the CPU modalias Ard Biesheuvel
2016-10-31 16:13 ` Russell King - ARM Linux
2017-01-02 21:06 ` Ard Biesheuvel
2017-01-02 23:40 ` Russell King - ARM Linux
2017-01-04 16:42 ` Ard Biesheuvel
2016-10-18 10:52 ` [PATCH 2/5] crypto: arm/aes-ce - enable module autoloading based on CPU feature bits Ard Biesheuvel
2016-10-18 10:52 ` [PATCH 3/5] crypto: arm/ghash-ce " Ard Biesheuvel
2016-10-18 10:52 ` [PATCH 4/5] crypto: arm/sha1-ce " Ard Biesheuvel
2016-10-18 10:52 ` [PATCH 5/5] crypto: arm/sha2-ce " Ard Biesheuvel
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