[dpdk-dev] [PATCH v2 10/16] eal/arm: cpu flag checks for ARM

[Jan Viktorin <viktorin@rehivetech.com>]

From: Vlastimil Kosar <kosar@rehivetech.com>

This implementation is based on IBM POWER version of
rte_cpuflags. We use software emulation of HW capability
registers, because those are usually not directly accessible
from userspace on ARM.

Signed-off-by: Vlastimil Kosar <kosar@rehivetech.com>
Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
---
v1 -> v2: check whether AT_HWCAP and AT_HWCAP2 exists
---
 app/test/test_cpuflags.c                           |   5 +
 .../common/include/arch/arm/rte_cpuflags.h         | 177 +++++++++++++++++++++
 mk/rte.cpuflags.mk                                 |   6 +
 3 files changed, 188 insertions(+)
 create mode 100644 lib/librte_eal/common/include/arch/arm/rte_cpuflags.h

diff --git a/app/test/test_cpuflags.c b/app/test/test_cpuflags.c
index 5b92061..557458f 100644
--- a/app/test/test_cpuflags.c
+++ b/app/test/test_cpuflags.c
@@ -115,6 +115,11 @@ test_cpuflags(void)
 	CHECK_FOR_FLAG(RTE_CPUFLAG_ICACHE_SNOOP);
 #endif
 
+#if defined(RTE_ARCH_ARM)
+	printf("Check for NEON:\t\t");
+	CHECK_FOR_FLAG(RTE_CPUFLAG_NEON);
+#endif
+
 #if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686)
 	printf("Check for SSE:\t\t");
 	CHECK_FOR_FLAG(RTE_CPUFLAG_SSE);
diff --git a/lib/librte_eal/common/include/arch/arm/rte_cpuflags.h b/lib/librte_eal/common/include/arch/arm/rte_cpuflags.h
new file mode 100644
index 0000000..1eadb33
--- /dev/null
+++ b/lib/librte_eal/common/include/arch/arm/rte_cpuflags.h
@@ -0,0 +1,177 @@
+/*
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2015 RehiveTech. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of RehiveTech nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _RTE_CPUFLAGS_ARM_H_
+#define _RTE_CPUFLAGS_ARM_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <elf.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <unistd.h>
+
+#include "generic/rte_cpuflags.h"
+
+#ifndef AT_HWCAP
+#define AT_HWCAP 16
+#endif
+
+#ifndef AT_HWCAP2
+#define AT_HWCAP2 26
+#endif
+
+/* software based registers */
+enum cpu_register_t {
+	REG_HWCAP = 0,
+	REG_HWCAP2,
+};
+
+/**
+ * Enumeration of all CPU features supported
+ */
+enum rte_cpu_flag_t {
+	RTE_CPUFLAG_SWP = 0,
+	RTE_CPUFLAG_HALF,
+	RTE_CPUFLAG_THUMB,
+	RTE_CPUFLAG_A26BIT,
+	RTE_CPUFLAG_FAST_MULT,
+	RTE_CPUFLAG_FPA,
+	RTE_CPUFLAG_VFP,
+	RTE_CPUFLAG_EDSP,
+	RTE_CPUFLAG_JAVA,
+	RTE_CPUFLAG_IWMMXT,
+	RTE_CPUFLAG_CRUNCH,
+	RTE_CPUFLAG_THUMBEE,
+	RTE_CPUFLAG_NEON,
+	RTE_CPUFLAG_VFPv3,
+	RTE_CPUFLAG_VFPv3D16,
+	RTE_CPUFLAG_TLS,
+	RTE_CPUFLAG_VFPv4,
+	RTE_CPUFLAG_IDIVA,
+	RTE_CPUFLAG_IDIVT,
+	RTE_CPUFLAG_VFPD32,
+	RTE_CPUFLAG_LPAE,
+	RTE_CPUFLAG_EVTSTRM,
+	RTE_CPUFLAG_AES,
+	RTE_CPUFLAG_PMULL,
+	RTE_CPUFLAG_SHA1,
+	RTE_CPUFLAG_SHA2,
+	RTE_CPUFLAG_CRC32,
+	/* The last item */
+	RTE_CPUFLAG_NUMFLAGS,/**< This should always be the last! */
+};
+
+static const struct feature_entry cpu_feature_table[] = {
+	FEAT_DEF(SWP,       0x00000001, 0, REG_HWCAP,  0)
+	FEAT_DEF(HALF,      0x00000001, 0, REG_HWCAP,  1)
+	FEAT_DEF(THUMB,     0x00000001, 0, REG_HWCAP,  2)
+	FEAT_DEF(A26BIT,    0x00000001, 0, REG_HWCAP,  3)
+	FEAT_DEF(FAST_MULT, 0x00000001, 0, REG_HWCAP,  4)
+	FEAT_DEF(FPA,       0x00000001, 0, REG_HWCAP,  5)
+	FEAT_DEF(VFP,       0x00000001, 0, REG_HWCAP,  6)
+	FEAT_DEF(EDSP,      0x00000001, 0, REG_HWCAP,  7)
+	FEAT_DEF(JAVA,      0x00000001, 0, REG_HWCAP,  8)
+	FEAT_DEF(IWMMXT,    0x00000001, 0, REG_HWCAP,  9)
+	FEAT_DEF(CRUNCH,    0x00000001, 0, REG_HWCAP,  10)
+	FEAT_DEF(THUMBEE,   0x00000001, 0, REG_HWCAP,  11)
+	FEAT_DEF(NEON,      0x00000001, 0, REG_HWCAP,  12)
+	FEAT_DEF(VFPv3,     0x00000001, 0, REG_HWCAP,  13)
+	FEAT_DEF(VFPv3D16,  0x00000001, 0, REG_HWCAP,  14)
+	FEAT_DEF(TLS,       0x00000001, 0, REG_HWCAP,  15)
+	FEAT_DEF(VFPv4,     0x00000001, 0, REG_HWCAP,  16)
+	FEAT_DEF(IDIVA,     0x00000001, 0, REG_HWCAP,  17)
+	FEAT_DEF(IDIVT,     0x00000001, 0, REG_HWCAP,  18)
+	FEAT_DEF(VFPD32,    0x00000001, 0, REG_HWCAP,  19)
+	FEAT_DEF(LPAE,      0x00000001, 0, REG_HWCAP,  20)
+	FEAT_DEF(EVTSTRM,   0x00000001, 0, REG_HWCAP,  21)
+	FEAT_DEF(AES,       0x00000001, 0, REG_HWCAP2,  0)
+	FEAT_DEF(PMULL,     0x00000001, 0, REG_HWCAP2,  1)
+	FEAT_DEF(SHA1,      0x00000001, 0, REG_HWCAP2,  2)
+	FEAT_DEF(SHA2,      0x00000001, 0, REG_HWCAP2,  3)
+	FEAT_DEF(CRC32,     0x00000001, 0, REG_HWCAP2,  4)
+};
+
+/*
+ * Read AUXV software register and get cpu features for ARM
+ */
+static inline void
+rte_cpu_get_features(__attribute__((unused)) uint32_t leaf,
+	__attribute__((unused)) uint32_t subleaf, cpuid_registers_t out)
+{
+	int auxv_fd;
+	Elf32_auxv_t auxv;
+
+	auxv_fd = open("/proc/self/auxv", O_RDONLY);
+	assert(auxv_fd);
+	while (read(auxv_fd, &auxv,
+		sizeof(Elf32_auxv_t)) == sizeof(Elf32_auxv_t)) {
+		if (auxv.a_type == AT_HWCAP)
+			out[REG_HWCAP] = auxv.a_un.a_val;
+		else if (auxv.a_type == AT_HWCAP2)
+			out[REG_HWCAP2] = auxv.a_un.a_val;
+	}
+}
+
+/*
+ * Checks if a particular flag is available on current machine.
+ */
+static inline int
+rte_cpu_get_flag_enabled(enum rte_cpu_flag_t feature)
+{
+	const struct feature_entry *feat;
+	cpuid_registers_t regs = {0};
+
+	if (feature >= RTE_CPUFLAG_NUMFLAGS)
+		/* Flag does not match anything in the feature tables */
+		return -ENOENT;
+
+	feat = &cpu_feature_table[feature];
+
+	if (!feat->leaf)
+		/* This entry in the table wasn't filled out! */
+		return -EFAULT;
+
+	/* get the cpuid leaf containing the desired feature */
+	rte_cpu_get_features(feat->leaf, feat->subleaf, regs);
+
+	/* check if the feature is enabled */
+	return (regs[feat->reg] >> feat->bit) & 1;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_CPUFLAGS_ARM_H_ */
diff --git a/mk/rte.cpuflags.mk b/mk/rte.cpuflags.mk
index f595cd0..bec7bdd 100644
--- a/mk/rte.cpuflags.mk
+++ b/mk/rte.cpuflags.mk
@@ -106,6 +106,12 @@ ifneq ($(filter $(AUTO_CPUFLAGS),__builtin_vsx_xvnmaddadp),)
 CPUFLAGS += VSX
 endif
 
+# ARM flags
+ifneq ($(filter $(AUTO_CPUFLAGS),__ARM_NEON_FP),)
+CPUFLAGS += NEON
+endif
+
+
 MACHINE_CFLAGS += $(addprefix -DRTE_MACHINE_CPUFLAG_,$(CPUFLAGS))
 
 # To strip whitespace
-- 
2.6.1