[RFC v5 38/57] objtool: arm64: Decode load/store with memory tag

[Julien Thierry]

Decode load/store instructions provided by the v8.5 memorty tagging
architecture extension.

Suggested-by: Raphael Gault <raphael.gault@xxxxxxx>
Signed-off-by: Julien Thierry <jthierry@xxxxxxxxxx>
---
 tools/objtool/arch/arm64/decode.c             | 87 +++++++++++++++++++
 .../objtool/arch/arm64/include/insn_decode.h  |  3 +
 2 files changed, 90 insertions(+)

diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index becc563345dd..bc4c62401012 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -830,6 +830,11 @@ static struct aarch64_insn_decoder ld_st_decoder[] = {
 		.value = 0b000011100000000,
 		.decode_func = arm_decode_adv_simd_single_post,
 	},
+	{
+		.mask = 0b111111010000000,
+		.value = 0b110101010000000,
+		.decode_func = arm_decode_ld_st_mem_tags,
+	},
 	{
 		.mask = 0b001111000000000,
 		.value = 0b000000000000000,
@@ -2100,3 +2105,85 @@ int arm_decode_ldapr_stlr_unsc_imm(u32 instr, enum insn_type *type,
 
 	return 0;
 }
+
+int arm_decode_ld_st_mem_tags(u32 instr, enum insn_type *type,
+			      unsigned long *immediate,
+			      struct list_head *ops_list)
+{
+	u32 imm9 = 0;
+	unsigned char opc = 0, op2 = 0, rn = 0, rt = 0, decode_field = 0;
+	struct stack_op *op;
+
+	imm9 = (instr >> 12) & ONES(9);
+	opc = (instr >> 22) & ONES(2);
+	op2 = (instr >> 10) & ONES(2);
+	rn = (instr >> 5) & ONES(5);
+	rt = instr & ONES(6);
+
+	decode_field = (opc << 2) | op2;
+
+	if (decode_field == 0x0 ||
+	    (decode_field == 0x8 && imm9 != 0) ||
+	    (decode_field == 0xC && imm9 != 0)) {
+		return arm_decode_unknown(instr, type, immediate, ops_list);
+	}
+
+	if (!stack_related_reg(rn)) {
+		*type = INSN_OTHER;
+		return 0;
+	}
+	*type = INSN_STACK;
+	*immediate = imm9;
+
+	op = calloc(1, sizeof(*op));
+	list_add_tail(&op->list, ops_list);
+
+	/*
+	 * Offset should normally be shifted to the
+	 * left of LOG2_TAG_GRANULE
+	 */
+	switch (decode_field) {
+	case 1:
+	case 5:
+	case 9:
+	case 13:
+		/* post index */
+	case 3:
+	case 7:
+	case 8:
+	case 11:
+	case 15:
+		/* pre index */
+		op->dest.reg = rn;
+		op->dest.type = OP_DEST_PUSH;
+		op->dest.offset = SIGN_EXTEND(imm9, 9);
+		op->src.reg = rt;
+		op->src.type = OP_SRC_REG;
+		op->src.offset = 0;
+		return 0;
+	case 2:
+	case 6:
+	case 10:
+	case 14:
+		/* store */
+		op->dest.reg = rn;
+		op->dest.type = OP_DEST_REG_INDIRECT;
+		op->dest.offset = SIGN_EXTEND(imm9, 9);
+		op->src.reg = rt;
+		op->src.type = OP_SRC_REG;
+		op->src.offset = 0;
+		return 0;
+	case 4:
+	case 12:
+		/* load */
+		op->src.reg = rn;
+		op->src.type = OP_SRC_REG_INDIRECT;
+		op->src.offset = SIGN_EXTEND(imm9, 9);
+		op->dest.reg = rt;
+		op->dest.type = OP_DEST_REG;
+		op->dest.offset = 0;
+		return 0;
+	}
+
+	return -1;
+}
diff --git a/tools/objtool/arch/arm64/include/insn_decode.h b/tools/objtool/arch/arm64/include/insn_decode.h
index 1721d9c487d0..e6a62691b487 100644
--- a/tools/objtool/arch/arm64/include/insn_decode.h
+++ b/tools/objtool/arch/arm64/include/insn_decode.h
@@ -106,6 +106,9 @@ int arm_decode_adv_simd_single(u32 instr, enum insn_type *type,
 int arm_decode_adv_simd_single_post(u32 instr, enum insn_type *type,
 				    unsigned long *immediate,
 				    struct list_head *ops_list);
+int arm_decode_ld_st_mem_tags(u32 instr, enum insn_type *type,
+			      unsigned long *immediate,
+			      struct list_head *ops_list);
 int arm_decode_ldapr_stlr_unsc_imm(u32 instr, enum insn_type *type,
 				   unsigned long *immediate,
 				   struct list_head *ops_list);
-- 
2.21.0