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arm64: HWCAP: encapsulate elf_hwcap

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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@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Andrew Murray 2019-04-09 10:52:41 +01:00 committed by Will Deacon
parent aaba098fe6
commit aec0bff757
3 changed files with 38 additions and 17 deletions
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15
arch/arm64/include/asm/cpufeature.h
View File

@ -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 */

7
arch/arm64/include/asm/hwcap.h
View File

@ -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)
@ -40,7 +41,6 @@
#define COMPAT_HWCAP2_CRC32 (1 << 4)
#ifndef __ASSEMBLY__
#include <linux/kernel.h>
#include <linux/log2.h>
/*
@ -93,8 +93,8 @@
* 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)
@ -110,6 +110,5 @@ enum {
#endif
};
extern unsigned long elf_hwcap;
#endif
#endif

33
arch/arm64/kernel/cpufeature.c
View File

@ -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)
{
/*