| Message ID | 1472145992-10660-3-git-send-email-catalin.marinas@arm.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Aug 26, 2016 at 10:22:13AM +0100, Suzuki K. Poulose wrote: > On 25/08/16 18:26, Catalin Marinas wrote: > > static inline int __attribute_const__ > >diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > >index 62272eac1352..919b2d0d68ae 100644 > >--- a/arch/arm64/kernel/cpufeature.c > >+++ b/arch/arm64/kernel/cpufeature.c > >@@ -46,6 +46,9 @@ unsigned int compat_elf_hwcap2 __read_mostly; > > > > DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); > > > >+DEFINE_STATIC_KEY_ARRAY_FALSE(cpu_hwcap_keys, ARM64_NCAPS); > >+EXPORT_SYMBOL(cpu_hwcap_keys); > >+ > > #define __ARM64_FTR_BITS(SIGNED, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \ > > { \ > > .sign = SIGNED, \ > >diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c > >index ed1b84fe6925..6a141e399daf 100644 > >--- a/arch/arm64/kernel/cpuinfo.c > >+++ b/arch/arm64/kernel/cpuinfo.c > >@@ -377,6 +377,12 @@ void cpuinfo_store_cpu(void) > > void __init cpuinfo_store_boot_cpu(void) > > { > > struct cpuinfo_arm64 *info = &per_cpu(cpu_data, 0); > >+ > >+ /* > >+ * Initialise the static keys early as they may be enabled by > >+ * check_local_cpu_errata() -> update_cpu_capabilities(). > >+ */ > >+ jump_label_init(); > > __cpuinfo_store_cpu(info); > > Just a heads up. I have a patch [1] which moves the "check_local_cpu_errata()" > around to smp_prepare_boot_cpu(). This patch should still work fine with that > case. Only that may be we could move the jump_lable_init() to smp_prepare_boot_cpu(), > before we call "update_cpu_errata_work_arounds()" for Boot CPU. IIUC, we wouldn't call update_cpu_errata_work_arounds() until the CPU feature infrastructure is initialised via cpuinfo_store_boot_cpu(). So I don't think moving the jump_label_init() call above is necessary. > [1] https://lkml.kernel.org/r/1471525832-21209-4-git-send-email-suzuki.poulose@arm.com -- Catalin
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 7099f26e3702..c9dfb1e4c435 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -9,6 +9,8 @@ #ifndef __ASM_CPUFEATURE_H #define __ASM_CPUFEATURE_H +#include <linux/jump_label.h> + #include <asm/hwcap.h> #include <asm/sysreg.h> @@ -109,6 +111,7 @@ struct arm64_cpu_capabilities { }; extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); +extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS]; bool this_cpu_has_cap(unsigned int cap); @@ -121,16 +124,21 @@ static inline bool cpus_have_cap(unsigned int num) { if (num >= ARM64_NCAPS) return false; - return test_bit(num, cpu_hwcaps); + if (__builtin_constant_p(num)) + return static_branch_unlikely(&cpu_hwcap_keys[num]); + else + return test_bit(num, cpu_hwcaps); } static inline void cpus_set_cap(unsigned int num) { - if (num >= ARM64_NCAPS) + if (num >= ARM64_NCAPS) { pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n", num, ARM64_NCAPS); - else + } else { __set_bit(num, cpu_hwcaps); + static_branch_enable(&cpu_hwcap_keys[num]); + } } static inline int __attribute_const__ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 62272eac1352..919b2d0d68ae 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -46,6 +46,9 @@ unsigned int compat_elf_hwcap2 __read_mostly; DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); +DEFINE_STATIC_KEY_ARRAY_FALSE(cpu_hwcap_keys, ARM64_NCAPS); +EXPORT_SYMBOL(cpu_hwcap_keys); + #define __ARM64_FTR_BITS(SIGNED, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \ { \ .sign = SIGNED, \ diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index ed1b84fe6925..6a141e399daf 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -377,6 +377,12 @@ void cpuinfo_store_cpu(void) void __init cpuinfo_store_boot_cpu(void) { struct cpuinfo_arm64 *info = &per_cpu(cpu_data, 0); + + /* + * Initialise the static keys early as they may be enabled by + * check_local_cpu_errata() -> update_cpu_capabilities(). + */ + jump_label_init(); __cpuinfo_store_cpu(info); boot_cpu_data = *info;
This patch adds static keys transparently for all the cpu_hwcaps features by implementing an array of default-false static keys and enabling them when detected. The cpus_have_cap() check uses the static keys if the feature being checked is a constant, otherwise the compiler generates the bitmap test. Because of the early call to static_branch_enable() via check_local_cpu_errata() -> update_cpu_capabilities(), the jump labels are initialised in cpuinfo_store_boot_cpu(). Cc: Will Deacon <will.deacon@arm.com> Cc: Suzuki K. Poulose <Suzuki.Poulose@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/include/asm/cpufeature.h | 14 +++++++++++--- arch/arm64/kernel/cpufeature.c | 3 +++ arch/arm64/kernel/cpuinfo.c | 6 ++++++ 3 files changed, 20 insertions(+), 3 deletions(-)