1 files changed, 64 insertions, 0 deletions
diff --git a/arch/arm/kernel/insn.c b/arch/arm/kernel/insn.c
new file mode 100644
index 000000000..db0acbb7d
--- /dev/null
+++ b/arch/arm/kernel/insn.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <asm/opcodes.h>
+
+static unsigned long __arm_gen_branch_thumb2(unsigned long pc,
+					     unsigned long addr, bool link,
+					     bool warn)
+{
+	unsigned long s, j1, j2, i1, i2, imm10, imm11;
+	unsigned long first, second;
+	long offset;
+
+	offset = (long)addr - (long)(pc + 4);
+	if (offset < -16777216 || offset > 16777214) {
+		WARN_ON_ONCE(warn);
+		return 0;
+	}
+
+	s	= (offset >> 24) & 0x1;
+	i1	= (offset >> 23) & 0x1;
+	i2	= (offset >> 22) & 0x1;
+	imm10	= (offset >> 12) & 0x3ff;
+	imm11	= (offset >>  1) & 0x7ff;
+
+	j1 = (!i1) ^ s;
+	j2 = (!i2) ^ s;
+
+	first = 0xf000 | (s << 10) | imm10;
+	second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
+	if (link)
+		second |= 1 << 14;
+
+	return __opcode_thumb32_compose(first, second);
+}
+
+static unsigned long __arm_gen_branch_arm(unsigned long pc, unsigned long addr,
+					  bool link, bool warn)
+{
+	unsigned long opcode = 0xea000000;
+	long offset;
+
+	if (link)
+		opcode |= 1 << 24;
+
+	offset = (long)addr - (long)(pc + 8);
+	if (unlikely(offset < -33554432 || offset > 33554428)) {
+		WARN_ON_ONCE(warn);
+		return 0;
+	}
+
+	offset = (offset >> 2) & 0x00ffffff;
+
+	return opcode | offset;
+}
+
+unsigned long
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn)
+{
+	if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
+		return __arm_gen_branch_thumb2(pc, addr, link, warn);
+	else
+		return __arm_gen_branch_arm(pc, addr, link, warn);
+}