From b8c9592b4a6c93211c8163888a97880d608503b5 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 19 Mar 2015 19:03:25 +0100 Subject: ARM: 8318/1: treat CPU feature register fields as signed quantities The various CPU feature registers consist of 4-bit blocks that represent signed quantities, whose positive values represent incremental features, and whose negative values are reserved. To improve forward compatibility, update the feature detection code to take possible future higher values into account, but ignore negative values. Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King --- arch/arm/kernel/setup.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) (limited to 'arch/arm/kernel/setup.c') diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index e55408e96559..637c449e6060 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -375,30 +375,26 @@ void __init early_print(const char *str, ...) static void __init cpuid_init_hwcaps(void) { - unsigned int divide_instrs, vmsa; + int block; if (cpu_architecture() < CPU_ARCH_ARMv7) return; - divide_instrs = (read_cpuid_ext(CPUID_EXT_ISAR0) & 0x0f000000) >> 24; - - switch (divide_instrs) { - case 2: + block = cpuid_feature_extract(CPUID_EXT_ISAR0, 24); + if (block >= 2) elf_hwcap |= HWCAP_IDIVA; - case 1: + if (block >= 1) elf_hwcap |= HWCAP_IDIVT; - } /* LPAE implies atomic ldrd/strd instructions */ - vmsa = (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xf) >> 0; - if (vmsa >= 5) + block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0); + if (block >= 5) elf_hwcap |= HWCAP_LPAE; } static void __init elf_hwcap_fixup(void) { unsigned id = read_cpuid_id(); - unsigned sync_prim; /* * HWCAP_TLS is available only on 1136 r1p0 and later, @@ -419,9 +415,9 @@ static void __init elf_hwcap_fixup(void) * avoid advertising SWP; it may not be atomic with * multiprocessing cores. */ - sync_prim = ((read_cpuid_ext(CPUID_EXT_ISAR3) >> 8) & 0xf0) | - ((read_cpuid_ext(CPUID_EXT_ISAR4) >> 20) & 0x0f); - if (sync_prim >= 0x13) + if (cpuid_feature_extract(CPUID_EXT_ISAR3, 12) > 1 || + (cpuid_feature_extract(CPUID_EXT_ISAR3, 12) == 1 && + cpuid_feature_extract(CPUID_EXT_ISAR3, 20) >= 3)) elf_hwcap &= ~HWCAP_SWP; } -- cgit v1.2.3