Support static branches depending on the value of misaligned accesses.
This will be used by a later patch in the series. All cpus must be
considered "fast" for this static branch to be flipped.
Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
---
arch/riscv/include/asm/cpufeature.h | 3 +++
arch/riscv/kernel/cpufeature.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index b139796392d0..febd9de4373e 100644
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -7,6 +7,7 @@
#define _ASM_CPUFEATURE_H
#include <linux/bitmap.h>
+#include <linux/jump_label.h>
#include <asm/hwcap.h>
/*
@@ -32,4 +33,6 @@ extern struct riscv_isainfo hart_isa[NR_CPUS];
int check_unaligned_access(void *unused);
+DECLARE_STATIC_KEY_FALSE(fast_misaligned_access_speed_key);
+
#endif
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 40bb854fcb96..8935481d32da 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -9,6 +9,7 @@
#include <linux/acpi.h>
#include <linux/bitmap.h>
#include <linux/ctype.h>
+#include <linux/jump_label.h>
#include <linux/log2.h>
#include <linux/memory.h>
#include <linux/module.h>
@@ -665,6 +666,35 @@ static int check_unaligned_access_all_cpus(void)
arch_initcall(check_unaligned_access_all_cpus);
+DEFINE_STATIC_KEY_FALSE(fast_misaligned_access_speed_key);
+
+static int set_unaligned_access_static_branches(void)
+{
+ /*
+ * This will be called after check_unaligned_access_all_cpus so the
+ * result of unaligned access speed for all cpus will be available.
+ */
+
+ int cpu;
+ bool fast_misaligned_access_speed = true;
+
+ for_each_online_cpu(cpu) {
+ int this_perf = per_cpu(misaligned_access_speed, cpu);
+
+ if (this_perf != RISCV_HWPROBE_MISALIGNED_FAST) {
+ fast_misaligned_access_speed = false;
+ break;
+ }
+ }
+
+ if (fast_misaligned_access_speed)
+ static_branch_enable(&fast_misaligned_access_speed_key);
+
+ return 0;
+}
+
+arch_initcall_sync(set_unaligned_access_static_branches);
+
#ifdef CONFIG_RISCV_ALTERNATIVE
/*
* Alternative patch sites consider 48 bits when determining when to patch
--
2.34.1
