Commit aec0bff7 authored by Andrew Murray's avatar Andrew Murray Committed by Will Deacon
Browse files

arm64: HWCAP: encapsulate elf_hwcap 



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: default avatarAndrew Murray <andrew.murray@arm.com>
Reviewed-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent aaba098f

arch/arm64/include/asm/cpufeature.h

+4 −11
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/include/asm/hwcap.h

+3 −4
Original line number Diff line number Diff line
@@ -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

arch/arm64/kernel/cpufeature.c

+31 −2
Original line number Diff line number Diff line
@@ -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)

{

	/*

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