More robust ISA detection on ARM/Linux

1 files changed, 200 insertions, 0 deletions

diff --git a/src/arm/linux/aarch32-isa.c b/src/arm/linux/aarch32-isa.c
new file mode 100644
index 0000000..2d36182
--- /dev/null
+++ b/src/arm/linux/aarch32-isa.c
@@ -0,0 +1,200 @@
+#include <stdint.h>
+
+#if CPUINFO_MOCK
+	#include <cpuinfo-mock.h>
+#endif
+#include <arm/linux/api.h>
+#include <arm/linux/cp.h>
+#include <arm/midr.h>
+#include <log.h>
+
+
+#if CPUINFO_MOCK
+	uint32_t cpuinfo_arm_fpsid = 0;
+	uint32_t cpuinfo_arm_mvfr0 = 0;
+	uint32_t cpuinfo_arm_wcid = 0;
+
+	void cpuinfo_set_fpsid(uint32_t fpsid) {
+		cpuinfo_arm_fpsid = fpsid;
+	}
+
+	void cpuinfo_set_wcid(uint32_t wcid) {
+		cpuinfo_arm_wcid = wcid;
+	}
+#endif
+
+
+void cpuinfo_arm_linux_decode_isa_from_proc_cpuinfo(
+	uint32_t features,
+	uint32_t features2,
+	uint32_t midr,
+	uint32_t architecture_version,
+	uint32_t architecture_flags,
+	struct cpuinfo_arm_isa isa[restrict static 1])
+{
+	if (architecture_version >= 8) {
+		/*
+		 * ARMv7 code running on ARMv8: IDIV, VFP, NEON are always supported,
+		 * but may be not reported in /proc/cpuinfo features.
+		 */
+		isa->armv5e  = true;
+		isa->armv6   = true;
+		isa->armv6k  = true;
+		isa->armv7   = true;
+		isa->armv7mp = true;
+		isa->thumb  = true;
+		isa->thumb2 = true;
+		isa->idiv = true;
+		isa->vfpv3 = true;
+		isa->d32 = true;
+		isa->fp16 = true;
+		isa->fma = true;
+		isa->neon = true;
+	} else {
+		/* ARMv7 or lower: use feature flags to detect optional features */
+
+		/*
+		 * ARM11 (ARM 1136/1156/1176/11 MPCore) processors can report v7 architecture
+		 * even though they support only ARMv6 instruction set.
+		 */
+		if (architecture_version == 7 && midr_is_arm11(midr)) {
+			cpuinfo_log_warning("kernel-reported architecture ARMv7 ignored due to mismatch with processor microarchitecture (ARM11)");
+			architecture_version = 6;
+		}
+
+		if (architecture_version < 7) {
+			const uint32_t armv7_features_mask = CPUINFO_ARM_LINUX_FEATURE_VFPV3 | CPUINFO_ARM_LINUX_FEATURE_VFPV3D16 | CPUINFO_ARM_LINUX_FEATURE_VFPD32 |
+				CPUINFO_ARM_LINUX_FEATURE_VFPV4 | CPUINFO_ARM_LINUX_FEATURE_NEON | CPUINFO_ARM_LINUX_FEATURE_IDIVT | CPUINFO_ARM_LINUX_FEATURE_IDIVA;
+			if (features & armv7_features_mask) {
+				architecture_version = 7;
+			}
+		}
+		if ((architecture_version >= 6) || (features & CPUINFO_ARM_LINUX_FEATURE_EDSP) || (architecture_flags & CPUINFO_ARM_LINUX_ARCH_E)) {
+			isa->armv5e = true;
+		}
+		if (architecture_version >= 6) {
+			isa->armv6 = true;
+		}
+		if (architecture_version >= 7) {
+			isa->armv6k = true;
+			isa->armv7 = true;
+
+			/*
+			 * ARMv7 MP extension (PLDW instruction) is not indicated in /proc/cpuinfo.
+			 * Use heuristic list of supporting processors:
+			 * - Processors supporting UDIV/SDIV instructions ("idiva" + "idivt" features in /proc/cpuinfo)
+			 * - Cortex-A5
+			 * - Cortex-A9
+			 * - Krait (supports UDIV/SDIV, but kernels may not report it in /proc/cpuinfo)
+			 *
+			 * TODO: check Qualcomm Scorpion.
+			 */
+			switch (midr & (CPUINFO_ARM_MIDR_IMPLEMENTER_MASK | CPUINFO_ARM_MIDR_PART_MASK)) {
+				case UINT32_C(0x4100C050): /* Cortex-A5 */
+				case UINT32_C(0x4100C0A0): /* Cortex-A9 */
+				case UINT32_C(0x510004D0): /* Krait (dual-core) */
+				case UINT32_C(0x510006F0): /* Krait (quad-core) */
+					isa->armv7mp = true;
+					break;
+				default:
+					/* In practice IDIV instruction implies ARMv7+MP ISA */
+					isa->armv7mp = (features & CPUINFO_ARM_LINUX_FEATURE_IDIV) == CPUINFO_ARM_LINUX_FEATURE_IDIV;
+					break;
+			}
+		}
+
+		if (features & CPUINFO_ARM_LINUX_FEATURE_IWMMXT) {
+			const uint32_t wcid = read_wcid();
+			cpuinfo_log_debug("WCID = 0x%08"PRIx32, wcid);
+			const uint32_t coprocessor_type = (wcid >> 8) & UINT32_C(0xFF);
+			if (coprocessor_type >= 0x10) {
+				isa->wmmx = true;
+				if (coprocessor_type >= 0x20) {
+					isa->wmmx2 = true;
+				}
+			} else {
+				cpuinfo_log_warning("WMMX ISA disabled: OS reported iwmmxt feature, "
+					"but WCID coprocessor type 0x%"PRIx32" indicates no WMMX support",
+					coprocessor_type);
+			}
+		}
+
+		if ((features & CPUINFO_ARM_LINUX_FEATURE_THUMB) || (architecture_flags & CPUINFO_ARM_LINUX_ARCH_T)) {
+			isa->thumb = true;
+
+			/*
+			 * There is no separate feature flag for Thumb 2.
+			 * All ARMv7 processors and ARM 1156 support Thumb 2.
+			 */
+			if (architecture_version >= 7 || midr_is_arm1156(midr)) {
+				isa->thumb2 = true;
+			}
+		}
+		if (features & CPUINFO_ARM_LINUX_FEATURE_THUMBEE) {
+			isa->thumbee = true;
+		}
+		if ((features & CPUINFO_ARM_LINUX_FEATURE_JAVA) || (architecture_flags & CPUINFO_ARM_LINUX_ARCH_J)) {
+			isa->jazelle = true;
+		}
+
+		/* Qualcomm Krait may have buggy kernel configuration that doesn't report IDIV */
+		if ((features & CPUINFO_ARM_LINUX_FEATURE_IDIV) == CPUINFO_ARM_LINUX_FEATURE_IDIV || midr_is_krait(midr)) {
+			isa->idiv = true;
+		}
+
+		const uint32_t vfp_mask = \
+			CPUINFO_ARM_LINUX_FEATURE_VFP | CPUINFO_ARM_LINUX_FEATURE_VFPV3 | CPUINFO_ARM_LINUX_FEATURE_VFPV3D16 | \
+			CPUINFO_ARM_LINUX_FEATURE_VFPD32 | CPUINFO_ARM_LINUX_FEATURE_VFPV4 | CPUINFO_ARM_LINUX_FEATURE_NEON;
+		if (features & vfp_mask) {
+			const uint32_t vfpv3_mask = CPUINFO_ARM_LINUX_FEATURE_VFPV3 | CPUINFO_ARM_LINUX_FEATURE_VFPV3D16 | \
+				CPUINFO_ARM_LINUX_FEATURE_VFPD32 | CPUINFO_ARM_LINUX_FEATURE_VFPV4 | CPUINFO_ARM_LINUX_FEATURE_NEON;
+			if ((architecture_version >= 7) | (features & vfpv3_mask)) {
+				isa->vfpv3 = true;
+			
+				const uint32_t d32_mask = CPUINFO_ARM_LINUX_FEATURE_VFPD32 | CPUINFO_ARM_LINUX_FEATURE_NEON;
+				if (features & d32_mask) {
+					isa->d32 = true;
+				}
+			} else {
+				const uint32_t fpsid = read_fpsid();
+				cpuinfo_log_debug("FPSID = 0x%08"PRIx32, fpsid);
+				const uint32_t subarchitecture = (fpsid >> 16) & UINT32_C(0x7F);
+				if (subarchitecture >= 0x01) {
+					isa->vfpv2 = true;
+				}
+			}
+		}
+		if (features & CPUINFO_ARM_LINUX_FEATURE_NEON) {
+			isa->neon = true;
+		}
+
+		/*
+		 * There is no separate feature flag for FP16 support.
+		 * VFPv4 implies VFPv3-FP16 support (and in practice, NEON-HP as well).
+		 * Additionally, ARM Cortex-A9 supports FP16.
+		 */
+		if ((features & CPUINFO_ARM_LINUX_FEATURE_VFPV4) || midr_is_cortex_a9(midr)) {
+			isa->fp16 = true;
+		}
+
+		if (features & CPUINFO_ARM_LINUX_FEATURE_VFPV4) {
+			isa->fma = true;
+		}
+	}
+
+	if (features2 & CPUINFO_ARM_LINUX_FEATURE2_AES) {
+		isa->aes = true;
+	}
+	if (features2 & CPUINFO_ARM_LINUX_FEATURE2_PMULL) {
+		isa->pmull = true;
+	}
+	if (features2 & CPUINFO_ARM_LINUX_FEATURE2_SHA1) {
+		isa->sha1 = true;
+	}
+	if (features2 & CPUINFO_ARM_LINUX_FEATURE2_SHA2) {
+		isa->sha2 = true;
+	}
+	if (features2 & CPUINFO_ARM_LINUX_FEATURE2_CRC32) {
+		isa->crc32 = true;
+	}
+}