On Wed, Apr 03, 2019 at 11:56:24AM +0100, Andrew Murray wrote:
> The introduction of AT_HWCAP2 introduced accessors which ensure that
> hwcap features are set and tested appropriately.
>
> Let's now mandate access to elf_hwcap via these accessors by making
> elf_hwcap static within cpufeature.c.
>
> Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
Reviewed-by: Dave Martin <Dave.Martin@xxxxxxx>
> ---
> arch/arm64/include/asm/cpufeature.h | 15 ++++---------
> arch/arm64/include/asm/hwcap.h | 7 +++---
> arch/arm64/kernel/cpufeature.c | 33 +++++++++++++++++++++++++++--
> 3 files changed, 38 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 347c17046668..a3f028f82def 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -392,19 +392,12 @@ extern DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE);
> for_each_set_bit(cap, cpu_hwcaps, ARM64_NCAPS)
>
> bool this_cpu_has_cap(unsigned int cap);
> +void cpu_set_feature(unsigned int num);
> +bool cpu_have_feature(unsigned int num);
> +unsigned long cpu_get_elf_hwcap(void);
> +unsigned long cpu_get_elf_hwcap2(void);
>
> -static inline void cpu_set_feature(unsigned int num)
> -{
> - WARN_ON(num >= MAX_CPU_FEATURES);
> - elf_hwcap |= BIT(num);
> -}
> #define cpu_set_named_feature(name) cpu_set_feature(cpu_feature(name))
> -
> -static inline bool cpu_have_feature(unsigned int num)
> -{
> - WARN_ON(num >= MAX_CPU_FEATURES);
> - return elf_hwcap & BIT(num);
> -}
> #define cpu_have_named_feature(name) cpu_have_feature(cpu_feature(name))
>
> /* System capability check for constant caps */
> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
> index 1f38a2740f7a..509ee0d2fa0f 100644
> --- a/arch/arm64/include/asm/hwcap.h
> +++ b/arch/arm64/include/asm/hwcap.h
> @@ -17,6 +17,7 @@
> #define __ASM_HWCAP_H
>
> #include <uapi/asm/hwcap.h>
> +#include <asm/cpufeature.h>
>
> #define COMPAT_HWCAP_HALF (1 << 1)
> #define COMPAT_HWCAP_THUMB (1 << 2)
> @@ -86,14 +87,13 @@
> #define __khwcap2_feature(x) (ilog2(HWCAP2_ ## x) + 32)
>
> #ifndef __ASSEMBLY__
> -#include <linux/kernel.h>
>
> /*
> * This yields a mask that user programs can use to figure out what
> * instruction set this cpu supports.
> */
> -#define ELF_HWCAP lower_32_bits(elf_hwcap)
> -#define ELF_HWCAP2 upper_32_bits(elf_hwcap)
> +#define ELF_HWCAP cpu_get_elf_hwcap()
> +#define ELF_HWCAP2 cpu_get_elf_hwcap2()
>
> #ifdef CONFIG_COMPAT
> #define COMPAT_ELF_HWCAP (compat_elf_hwcap)
> @@ -109,6 +109,5 @@ enum {
> #endif
> };
>
> -extern unsigned long elf_hwcap;
> #endif
> #endif
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 986ceeacd19f..a655d1bb1186 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -35,8 +35,8 @@
> #include <asm/traps.h>
> #include <asm/virt.h>
>
> -unsigned long elf_hwcap __read_mostly;
> -EXPORT_SYMBOL_GPL(elf_hwcap);
> +/* Kernel representation of AT_HWCAP and AT_HWCAP2 */
> +static unsigned long elf_hwcap __read_mostly;
>
> #ifdef CONFIG_COMPAT
> #define COMPAT_ELF_HWCAP_DEFAULT \
> @@ -1947,6 +1947,35 @@ bool this_cpu_has_cap(unsigned int n)
> return false;
> }
>
> +void cpu_set_feature(unsigned int num)
> +{
> + WARN_ON(num >= MAX_CPU_FEATURES);
> + elf_hwcap |= BIT(num);
> +}
> +EXPORT_SYMBOL_GPL(cpu_set_feature);
> +
> +bool cpu_have_feature(unsigned int num)
> +{
> + WARN_ON(num >= MAX_CPU_FEATURES);
> + return elf_hwcap & BIT(num);
> +}
> +EXPORT_SYMBOL_GPL(cpu_have_feature);
> +
> +unsigned long cpu_get_elf_hwcap(void)
> +{
> + /*
> + * We currently only populate the first 32 bits of AT_HWCAP. Please
> + * note that for userspace compatibility we guarantee that bits 62
> + * and 63 will always be returned as 0.
> + */
> + return lower_32_bits(elf_hwcap);
> +}
> +
> +unsigned long cpu_get_elf_hwcap2(void)
> +{
> + return upper_32_bits(elf_hwcap);
> +}
> +
> static void __init setup_system_capabilities(void)
> {
> /*
> --
> 2.21.0
>
