On 25/08/16 18:26, Catalin Marinas wrote:
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.dea...@arm.com>
Cc: Suzuki K. Poulose <suzuki.poul...@arm.com>
Signed-off-by: Catalin Marinas <catalin.mari...@arm.com>
---
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);
Catalin,
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.
Either way, this will be useful for some of the other feature checks.
Thanks
Suzuki
[1]
https://lkml.kernel.org/r/1471525832-21209-4-git-send-email-suzuki.poul...@arm.com
