1 files changed, 69 insertions, 0 deletions
diff --git a/arch/arm/kernel/opcodes.c b/arch/arm/kernel/opcodes.c
new file mode 100644
index 000000000..651914947
--- /dev/null
+++ b/arch/arm/kernel/opcodes.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/kernel/opcodes.c
+ *
+ *  A32 condition code lookup feature moved from nwfpe/fpopcode.c
+ */
+
+#include <linux/module.h>
+#include <asm/opcodes.h>
+
+#define ARM_OPCODE_CONDITION_UNCOND 0xf
+
+/*
+ * condition code lookup table
+ * index into the table is test code: EQ, NE, ... LT, GT, AL, NV
+ *
+ * bit position in short is condition code: NZCV
+ */
+static const unsigned short cc_map[16] = {
+	0xF0F0,			/* EQ == Z set            */
+	0x0F0F,			/* NE                     */
+	0xCCCC,			/* CS == C set            */
+	0x3333,			/* CC                     */
+	0xFF00,			/* MI == N set            */
+	0x00FF,			/* PL                     */
+	0xAAAA,			/* VS == V set            */
+	0x5555,			/* VC                     */
+	0x0C0C,			/* HI == C set && Z clear */
+	0xF3F3,			/* LS == C clear || Z set */
+	0xAA55,			/* GE == (N==V)           */
+	0x55AA,			/* LT == (N!=V)           */
+	0x0A05,			/* GT == (!Z && (N==V))   */
+	0xF5FA,			/* LE == (Z || (N!=V))    */
+	0xFFFF,			/* AL always              */
+	0			/* NV                     */
+};
+
+/*
+ * Returns:
+ * ARM_OPCODE_CONDTEST_FAIL   - if condition fails
+ * ARM_OPCODE_CONDTEST_PASS   - if condition passes (including AL)
+ * ARM_OPCODE_CONDTEST_UNCOND - if NV condition, or separate unconditional
+ *                              opcode space from v5 onwards
+ *
+ * Code that tests whether a conditional instruction would pass its condition
+ * check should check that return value == ARM_OPCODE_CONDTEST_PASS.
+ *
+ * Code that tests if a condition means that the instruction would be executed
+ * (regardless of conditional or unconditional) should instead check that the
+ * return value != ARM_OPCODE_CONDTEST_FAIL.
+ */
+asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr)
+{
+	u32 cc_bits  = opcode >> 28;
+	u32 psr_cond = psr >> 28;
+	unsigned int ret;
+
+	if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) {
+		if ((cc_map[cc_bits] >> (psr_cond)) & 1)
+			ret = ARM_OPCODE_CONDTEST_PASS;
+		else
+			ret = ARM_OPCODE_CONDTEST_FAIL;
+	} else {
+		ret = ARM_OPCODE_CONDTEST_UNCOND;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(arm_check_condition);