csky: Add jump-label implementation

Add jump-label implementation for static branch

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

2 files changed, 55 insertions, 0 deletions

diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index 4eb41421ca5b..6f14c924b20d 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_STACKTRACE)		+= stacktrace.o
 obj-$(CONFIG_CSKY_PMU_V1)		+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)		+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)            += perf_regs.o
+obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
diff --git a/arch/csky/kernel/jump_label.c b/arch/csky/kernel/jump_label.c
new file mode 100644
index 000000000000..d0e8b21447e1
--- /dev/null
+++ b/arch/csky/kernel/jump_label.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/jump_label.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/mutex.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#define NOP32_HI	0xc400
+#define NOP32_LO	0x4820
+#define BSR_LINK	0xe000
+
+void arch_jump_label_transform(struct jump_entry *entry,
+			       enum jump_label_type type)
+{
+	unsigned long addr = jump_entry_code(entry);
+	u16 insn[2];
+	int ret = 0;
+
+	if (type == JUMP_LABEL_JMP) {
+		long offset = jump_entry_target(entry) - jump_entry_code(entry);
+
+		if (WARN_ON(offset & 1 || offset < -67108864 || offset >= 67108864))
+			return;
+
+		offset = offset >> 1;
+
+		insn[0] = BSR_LINK |
+			((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
+		insn[1] = (uint16_t)((unsigned long) offset & 0xffff);
+	} else {
+		insn[0] = NOP32_HI;
+		insn[1] = NOP32_LO;
+	}
+
+	ret = copy_to_kernel_nofault((void *)addr, insn, 4);
+	WARN_ON(ret);
+
+	flush_icache_range(addr, addr + 4);
+}
+
+void arch_jump_label_transform_static(struct jump_entry *entry,
+				      enum jump_label_type type)
+{
+	/*
+	 * We use the same instructions in the arch_static_branch and
+	 * arch_static_branch_jump inline functions, so there's no
+	 * need to patch them up here.
+	 * The core will call arch_jump_label_transform  when those
+	 * instructions need to be replaced.
+	 */
+	arch_jump_label_transform(entry, type);
+}