From e57173085aab2dae3fb8b777ea9a4a252feb78a6 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 27 Jun 2024 17:36:43 +0000 Subject: [PATCH] util/cpuinfo-riscv: Use linux __riscv_hwprobe syscall With recent linux kernels, there is a syscall to probe for various ISA extensions. These bits were phased in over several kernel releases, so we still require checks for symbol availability. Acked-by: Alistair Francis Reviewed-by: Daniel Henrique Barboza Signed-off-by: Richard Henderson --- meson.build | 6 ++++++ util/cpuinfo-riscv.c | 26 ++++++++++++++++++++++++++ 2 files changed, 32 insertions(+) diff --git a/meson.build b/meson.build index 54e6b09f4f..2f981f936e 100644 --- a/meson.build +++ b/meson.build @@ -2862,6 +2862,12 @@ have_cpuid_h = cc.links(''' }''') config_host_data.set('CONFIG_CPUID_H', have_cpuid_h) +# Don't bother to advertise asm/hwprobe.h for old versions that do +# not contain RISCV_HWPROBE_EXT_ZBA. +config_host_data.set('CONFIG_ASM_HWPROBE_H', + cc.has_header_symbol('asm/hwprobe.h', + 'RISCV_HWPROBE_EXT_ZBA')) + config_host_data.set('CONFIG_AVX2_OPT', get_option('avx2') \ .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot enable AVX2') \ .require(cc.links(''' diff --git a/util/cpuinfo-riscv.c b/util/cpuinfo-riscv.c index 7dcfbee2ab..497ce12680 100644 --- a/util/cpuinfo-riscv.c +++ b/util/cpuinfo-riscv.c @@ -6,6 +6,11 @@ #include "qemu/osdep.h" #include "host/cpuinfo.h" +#ifdef CONFIG_ASM_HWPROBE_H +#include +#include +#endif + unsigned cpuinfo; static volatile sig_atomic_t got_sigill; @@ -47,6 +52,27 @@ unsigned __attribute__((constructor)) cpuinfo_init(void) #endif left &= ~info; +#ifdef CONFIG_ASM_HWPROBE_H + if (left) { + /* + * TODO: glibc 2.40 will introduce , which + * provides __riscv_hwprobe and __riscv_hwprobe_one, + * which is a slightly cleaner interface. + */ + struct riscv_hwprobe pair = { .key = RISCV_HWPROBE_KEY_IMA_EXT_0 }; + if (syscall(__NR_riscv_hwprobe, &pair, 1, 0, NULL, 0) == 0 + && pair.key >= 0) { + info |= pair.value & RISCV_HWPROBE_EXT_ZBA ? CPUINFO_ZBA : 0; + info |= pair.value & RISCV_HWPROBE_EXT_ZBB ? CPUINFO_ZBB : 0; + left &= ~(CPUINFO_ZBA | CPUINFO_ZBB); +#ifdef RISCV_HWPROBE_EXT_ZICOND + info |= pair.value & RISCV_HWPROBE_EXT_ZICOND ? CPUINFO_ZICOND : 0; + left &= ~CPUINFO_ZICOND; +#endif + } + } +#endif /* CONFIG_ASM_HWPROBE_H */ + if (left) { struct sigaction sa_old, sa_new; -- 2.39.5