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arm64: add cpu_capabilities bitmap

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For taking note if at least one CPU in the system needs a bug
workaround or would benefit from a code optimization, we create a new
bitmap to hold (artificial) feature bits.
Since elf_hwcap is part of the userland ABI, we keep it alone and
introduce a new data structure for that (along with some accessors).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Andre Przywara 2014-11-14 15:54:07 +00:00 committed by Will Deacon
parent 909633957d
commit 930da09f5e
2 changed files with 23 additions and 0 deletions
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20
arch/arm64/include/asm/cpufeature.h
View File

@ -21,9 +21,29 @@
#define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap))
#define cpu_feature(x) ilog2(HWCAP_ ## x)
#define NCAPS 0
extern DECLARE_BITMAP(cpu_hwcaps, NCAPS);
static inline bool cpu_have_feature(unsigned int num)
{
return elf_hwcap & (1UL << num);
}
static inline bool cpus_have_cap(unsigned int num)
{
if (num >= NCAPS)
return false;
return test_bit(num, cpu_hwcaps);
}
static inline void cpus_set_cap(unsigned int num)
{
if (num >= NCAPS)
pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n",
num, NCAPS);
else
__set_bit(num, cpu_hwcaps);
}
#endif

3
arch/arm64/kernel/setup.c
View File

@ -50,6 +50,7 @@
#include <asm/cputype.h>
#include <asm/elf.h>
#include <asm/cputable.h>
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/sections.h>
#include <asm/setup.h>
@ -79,6 +80,8 @@ unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
unsigned int compat_elf_hwcap2 __read_mostly;
#endif
DECLARE_BITMAP(cpu_hwcaps, NCAPS);
static const char *cpu_name;
phys_addr_t __fdt_pointer __initdata;