diff options
| author | Suzuki K Poulose <suzuki.poulose@arm.com> | 2016-11-08 16:56:20 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-16 20:50:51 +0300 |
| commit | a4023f682739439b434165b54af7cb3676a4766e (patch) | |
| tree | ef2638d37291c56d972f20b69c59a6dee9292c18 /arch/arm64 | |
| parent | c02433dd6de32f042cf3ffe476746b1115b8c096 (diff) | |
| download | linux-a4023f682739439b434165b54af7cb3676a4766e.tar.xz | |
arm64: Add hypervisor safe helper for checking constant capabilities
The hypervisor may not have full access to the kernel data structures
and hence cannot safely use cpus_have_cap() helper for checking the
system capability. Add a safe helper for hypervisors to check a constant
system capability, which *doesn't* fall back to checking the bitmap
maintained by the kernel. With this, make the cpus_have_cap() only
check the bitmask and force constant cap checks to use the new API
for quicker checks.
Cc: Robert Ritcher <rritcher@cavium.com>
Cc: Tirumalesh Chalamarla <tchalamarla@cavium.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/include/asm/cpufeature.h | 19 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/process.c | 2 |
3 files changed, 14 insertions, 9 deletions
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index a27c3245ba21..8b63adb148e7 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -9,8 +9,6 @@ #ifndef __ASM_CPUFEATURE_H #define __ASM_CPUFEATURE_H -#include <linux/jump_label.h> - #include <asm/hwcap.h> #include <asm/sysreg.h> @@ -45,6 +43,8 @@ #ifndef __ASSEMBLY__ +#include <linux/bug.h> +#include <linux/jump_label.h> #include <linux/kernel.h> /* CPU feature register tracking */ @@ -122,14 +122,19 @@ static inline bool cpu_have_feature(unsigned int num) return elf_hwcap & (1UL << num); } +/* System capability check for constant caps */ +static inline bool cpus_have_const_cap(int num) +{ + if (num >= ARM64_NCAPS) + return false; + return static_branch_unlikely(&cpu_hwcap_keys[num]); +} + static inline bool cpus_have_cap(unsigned int num) { if (num >= ARM64_NCAPS) return false; - if (__builtin_constant_p(num)) - return static_branch_unlikely(&cpu_hwcap_keys[num]); - else - return test_bit(num, cpu_hwcaps); + return test_bit(num, cpu_hwcaps); } static inline void cpus_set_cap(unsigned int num) @@ -218,7 +223,7 @@ static inline bool cpu_supports_mixed_endian_el0(void) static inline bool system_supports_32bit_el0(void) { - return cpus_have_cap(ARM64_HAS_32BIT_EL0); + return cpus_have_const_cap(ARM64_HAS_32BIT_EL0); } static inline bool system_supports_mixed_endian_el0(void) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index c02504ea304b..fc2bd1926607 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1102,5 +1102,5 @@ void __init setup_cpu_features(void) static bool __maybe_unused cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) { - return (cpus_have_cap(ARM64_HAS_PAN) && !cpus_have_cap(ARM64_HAS_UAO)); + return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO)); } diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index a98b743631c5..a3a2816ba73a 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -283,7 +283,7 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, memset(childregs, 0, sizeof(struct pt_regs)); childregs->pstate = PSR_MODE_EL1h; if (IS_ENABLED(CONFIG_ARM64_UAO) && - cpus_have_cap(ARM64_HAS_UAO)) + cpus_have_const_cap(ARM64_HAS_UAO)) childregs->pstate |= PSR_UAO_BIT; p->thread.cpu_context.x19 = stack_start; p->thread.cpu_context.x20 = stk_sz; |