From dd9ced1c6d7ae7956b1b667b6289c143c2070255 Mon Sep 17 00:00:00 2001 From: Xi Ruoyao Date: Sat, 19 Jul 2025 14:36:11 +0800 Subject: [PATCH] loong64: Use HWCAP instead of CPUCFG to detect LSX/LASX MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Per the Software Development and Build Convention for LoongArch™ Architectures manual, on Linux we should use HWCAP instead of CPUCFG to detect if LSX/LASX is available. The reason is the kernel may be configured to disable them, and CPUCFG cannot provide info about the kernel support. Change-Id: I3f1b23e6d4c91c7da81311fbbe294e36ff178121 Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/6772567 Reviewed-by: Frank Barchard Reviewed-by: Wan-Teh Chang --- source/cpu_id.cc | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/source/cpu_id.cc b/source/cpu_id.cc index 0e0740b41..95a658661 100644 --- a/source/cpu_id.cc +++ b/source/cpu_id.cc @@ -23,7 +23,7 @@ #include // For fopen() #include -#if defined(__linux__) && defined(__aarch64__) +#if defined(__linux__) && (defined(__aarch64__) || defined(__loongarch__)) #include // For getauxval() #endif @@ -388,21 +388,20 @@ LIBYUV_API SAFEBUFFERS int MipsCpuCaps(const char* cpuinfo_name) { return flag; } -#define LOONGARCH_CFG2 0x2 -#define LOONGARCH_CFG2_LSX (1 << 6) -#define LOONGARCH_CFG2_LASX (1 << 7) +#if defined(__loongarch__) && defined(__linux__) +// Define hwcap values ourselves: building with an old auxv header where these +// hwcap values are not defined should not prevent features from being enabled. +#define YUV_LOONGARCH_HWCAP_LSX (1 << 4) +#define YUV_LOONGARCH_HWCAP_LASX (1 << 5) -#if defined(__loongarch__) LIBYUV_API SAFEBUFFERS int LoongarchCpuCaps(void) { int flag = 0; - uint32_t cfg2 = 0; + unsigned long hwcap = getauxval(AT_HWCAP); - __asm__ volatile("cpucfg %0, %1 \n\t" : "+&r"(cfg2) : "r"(LOONGARCH_CFG2)); - - if (cfg2 & LOONGARCH_CFG2_LSX) + if (hwcap & YUV_LOONGARCH_HWCAP_LSX) flag |= kCpuHasLSX; - if (cfg2 & LOONGARCH_CFG2_LASX) + if (hwcap & YUV_LOONGARCH_HWCAP_LASX) flag |= kCpuHasLASX; return flag; }