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arm64: elf: advertise 8.1 atomic instructions as new hwcap

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The ARM v8.1 architecture introduces new atomic instructions to the A64
instruction set for things like cmpxchg, so advertise their availability
to userspace using a hwcap.

Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2015-01-26 18:46:19 +00:00
parent c275f76bb4
commit 40a1db2434
2 changed files with 15 additions and 0 deletions
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1
arch/arm64/include/uapi/asm/hwcap.h
View File

@ -27,5 +27,6 @@
#define HWCAP_SHA1 (1 << 5)
#define HWCAP_SHA2 (1 << 6)
#define HWCAP_CRC32 (1 << 7)
#define HWCAP_ATOMICS (1 << 8)
#endif /* _UAPI__ASM_HWCAP_H */

14
arch/arm64/kernel/setup.c
View File

@ -278,6 +278,19 @@ static void __init setup_processor(void)
if (block && !(block & 0x8))
elf_hwcap |= HWCAP_CRC32;
block = (features >> 20) & 0xf;
if (!(block & 0x8)) {
switch (block) {
default:
case 2:
elf_hwcap |= HWCAP_ATOMICS;
case 1:
/* RESERVED */
case 0:
break;
}
}
#ifdef CONFIG_COMPAT
/*
* ID_ISAR5_EL1 carries similar information as above, but pertaining to
@ -457,6 +470,7 @@ static const char *hwcap_str[] = {
"sha1",
"sha2",
"crc32",
"atomics",
NULL
};