Re: [PATCH] util/cpuinfo: Make use of elf_aux_info(3) on OpenBSD

[Richard Henderson]

On 7/28/24 13:58, Brad Smith wrote:
> util/cpuinfo: Make use of elf_aux_info(3) on OpenBSD
>
> Signed-off-by: Brad Smith <brad@comstyle.com>
> ---
>   meson.build            | 8 ++++++++
>   util/cpuinfo-aarch64.c | 9 ++++++---
>   util/cpuinfo-ppc.c     | 5 +++--
>   util/getauxval.c       | 2 +-
>   4 files changed, 18 insertions(+), 6 deletions(-)

Is this specifically better than sysctl for cpuinfo-aarch64.c?
Otherwise, I'm happy with the getauxval.c and cpuinfo-ppc.c changes.


r~

> diff --git a/meson.build b/meson.build
> index 5613b62a4f..97f63aa86c 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2835,6 +2835,14 @@ config_host_data.set('CONFIG_GETAUXVAL', 
> cc.links(gnu_source_prefix + '''
>       return getauxval(AT_HWCAP) == 0;
>     }'''))
>   
> +config_host_data.set('CONFIG_ELF_AUX_INFO', cc.links(gnu_source_prefix + '''
> +  #include <sys/auxv.h>
> +  int main(void) {
> +    unsigned long hwcap = 0;
> +    elf_aux_info(AT_HWCAP, &hwcap, sizeof(hwcap));
> +    return hwcap;
> +  }'''))
> +
>   config_host_data.set('CONFIG_USBFS', have_linux_user and cc.compiles('''
>     #include <linux/usbdevice_fs.h>
>   
> diff --git a/util/cpuinfo-aarch64.c b/util/cpuinfo-aarch64.c
> index 8ca775a14b..57468890c3 100644
> --- a/util/cpuinfo-aarch64.c
> +++ b/util/cpuinfo-aarch64.c
> @@ -17,10 +17,13 @@
>   #  define HWCAP2_BTI 0  /* added in glibc 2.32 */
>   # endif
>   #endif
> +#ifdef CONFIG_ELF_AUX_INFO
> +#include <sys/auxv.h>
> +#endif
>   #ifdef CONFIG_DARWIN
>   # include <sys/sysctl.h>
>   #endif
> -#ifdef __OpenBSD__
> +#if defined(__OpenBSD__) && !defined(CONFIG_ELF_AUX_INFO)
>   # include <machine/armreg.h>
>   # include <machine/cpu.h>
>   # include <sys/types.h>
> @@ -61,7 +64,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>   
>       info = CPUINFO_ALWAYS;
>   
> -#ifdef CONFIG_LINUX
> +#if defined(CONFIG_LINUX) || defined(CONFIG_ELF_AUX_INFO)
>       unsigned long hwcap = qemu_getauxval(AT_HWCAP);
>       info |= (hwcap & HWCAP_ATOMICS ? CPUINFO_LSE : 0);
>       info |= (hwcap & HWCAP_USCAT ? CPUINFO_LSE2 : 0);
> @@ -78,7 +81,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_PMULL") * CPUINFO_PMULL;
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_BTI") * CPUINFO_BTI;
>   #endif
> -#ifdef __OpenBSD__
> +#if defined(__OpenBSD__) && !defined(CONFIG_ELF_AUX_INFO)
>       int mib[2];
>       uint64_t isar0;
>       uint64_t pfr1;
> diff --git a/util/cpuinfo-ppc.c b/util/cpuinfo-ppc.c
> index 1304f9aa80..ccfcaa0754 100644
> --- a/util/cpuinfo-ppc.c
> +++ b/util/cpuinfo-ppc.c
> @@ -14,7 +14,8 @@
>   #  include "elf.h"
>   # endif
>   #endif
> -#ifdef __FreeBSD__
> +#if defined(CONFIG_ELF_AUX_INFO)
> +# include <sys/auxv.h>
>   # include <machine/cpu.h>
>   # ifndef PPC_FEATURE2_ARCH_3_1
>   #  define PPC_FEATURE2_ARCH_3_1   0
> @@ -35,7 +36,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>   
>       info = CPUINFO_ALWAYS;
>   
> -#if defined(CONFIG_LINUX) || defined(__FreeBSD__)
> +#if defined(CONFIG_LINUX) || deinfed(CONFIG_ELF_AUX_INFO)
>       unsigned long hwcap = qemu_getauxval(AT_HWCAP);
>       unsigned long hwcap2 = qemu_getauxval(AT_HWCAP2);
>   
> diff --git a/util/getauxval.c b/util/getauxval.c
> index b124107d61..5bdbb04f8f 100644
> --- a/util/getauxval.c
> +++ b/util/getauxval.c
> @@ -98,7 +98,7 @@ unsigned long qemu_getauxval(unsigned long type)
>       return 0;
>   }
>   
> -#elif defined(__FreeBSD__)
> +#elif deinfed(CONFIG_ELF_AUX_INFO)
>   #include <sys/auxv.h>
>   
>   unsigned long qemu_getauxval(unsigned long type)