src/arm/linux/arm32-isa.c

#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(
	const struct cpuinfo_arm_linux_processor processor[restrict static 1],
	struct cpuinfo_arm_isa isa[restrict static 1])
{
	const uint32_t midr = processor->midr;
	uint32_t architecture_version = processor->architecture_version;
	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;
		}

		const uint32_t features = processor->features;
		const uint32_t architecture_flags = processor->architecture_flags;
		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;
		}
	}

	const uint32_t features2 = processor->features2;
	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;
	}
}