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Subject[RFC v5 21/57] objtool: arm64: Decode simple data processing instructions
Date
Decode data processing instructions that do not constitute stack
operations.

Suggested-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
tools/objtool/arch/arm64/decode.c | 104 ++++++++++++++++++
.../objtool/arch/arm64/include/insn_decode.h | 18 +++
2 files changed, 122 insertions(+)

diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index 04358f41ef1d..6c8db9335fc9 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -81,6 +81,7 @@ static arm_decode_class aarch64_insn_class_decode_table[NR_INSN_CLASS] = {
[INSN_RESERVED] = arm_decode_unknown,
[INSN_UNKNOWN] = arm_decode_unknown,
[INSN_UNALLOC] = arm_decode_unknown,
+ [0b1000 ... INSN_DP_IMM] = arm_decode_dp_imm,
};

/*
@@ -145,3 +146,106 @@ int arm_decode_unknown(u32 instr, enum insn_type *type,

return 0;
}
+
+#define NR_DP_IMM_SUBCLASS 8
+#define INSN_DP_IMM_SUBCLASS(opcode) \
+ (((opcode) >> 23) & (NR_DP_IMM_SUBCLASS - 1))
+
+static arm_decode_class aarch64_insn_dp_imm_decode_table[NR_DP_IMM_SUBCLASS] = {
+ [0 ... INSN_PCREL] = arm_decode_pcrel,
+ [INSN_MOVE_WIDE] = arm_decode_move_wide,
+ [INSN_BITFIELD] = arm_decode_bitfield,
+ [INSN_EXTRACT] = arm_decode_extract,
+};
+
+int arm_decode_dp_imm(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ arm_decode_class decode_fun;
+
+ decode_fun = aarch64_insn_dp_imm_decode_table[INSN_DP_IMM_SUBCLASS(instr)];
+ if (!decode_fun)
+ return -1;
+ return decode_fun(instr, type, immediate, ops_list);
+}
+
+int arm_decode_pcrel(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ unsigned char page = 0;
+ u32 immhi = 0, immlo = 0;
+
+ page = EXTRACT_BIT(instr, 31);
+ immhi = (instr >> 5) & ONES(19);
+ immlo = (instr >> 29) & ONES(2);
+
+ *immediate = SIGN_EXTEND((immhi << 2) | immlo, 21);
+
+ if (page)
+ *immediate = SIGN_EXTEND(*immediate << 12, 33);
+
+ *type = INSN_OTHER;
+
+ return 0;
+}
+
+int arm_decode_move_wide(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ u32 imm16 = 0;
+ unsigned char hw = 0, opc = 0, sf = 0;
+
+ sf = EXTRACT_BIT(instr, 31);
+ opc = (instr >> 29) & ONES(2);
+ hw = (instr >> 21) & ONES(2);
+ imm16 = (instr >> 5) & ONES(16);
+
+ if ((sf == 0 && (hw & 0x2)) || opc == 0x1)
+ return arm_decode_unknown(instr, type, immediate, ops_list);
+
+ *type = INSN_OTHER;
+ *immediate = imm16;
+
+ return 0;
+}
+
+int arm_decode_bitfield(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ unsigned char sf = 0, opc = 0, N = 0;
+
+ sf = EXTRACT_BIT(instr, 31);
+ opc = (instr >> 29) & ONES(2);
+ N = EXTRACT_BIT(instr, 22);
+
+ if (opc == 0x3 || sf != N)
+ return arm_decode_unknown(instr, type, immediate, ops_list);
+
+ *type = INSN_OTHER;
+
+ return 0;
+}
+
+int arm_decode_extract(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ unsigned char sf = 0, op21 = 0, N = 0, o0 = 0;
+ unsigned char imms = 0;
+ unsigned char decode_field = 0;
+
+ sf = EXTRACT_BIT(instr, 31);
+ op21 = (instr >> 29) & ONES(2);
+ N = EXTRACT_BIT(instr, 22);
+ o0 = EXTRACT_BIT(instr, 21);
+ imms = (instr >> 10) & ONES(6);
+
+ decode_field = (sf << 4) | (op21 << 2) | (N << 1) | o0;
+ *type = INSN_OTHER;
+ *immediate = imms;
+
+ if ((decode_field == 0 && !EXTRACT_BIT(imms, 5)) ||
+ decode_field == 0b10010)
+ return 0;
+
+ return arm_decode_unknown(instr, type, immediate, ops_list);
+}
diff --git a/tools/objtool/arch/arm64/include/insn_decode.h b/tools/objtool/arch/arm64/include/insn_decode.h
index 16066f8fca0d..06235d81300c 100644
--- a/tools/objtool/arch/arm64/include/insn_decode.h
+++ b/tools/objtool/arch/arm64/include/insn_decode.h
@@ -8,15 +8,33 @@
#define INSN_RESERVED 0b0000
#define INSN_UNKNOWN 0b0001
#define INSN_UNALLOC 0b0011
+#define INSN_DP_IMM 0b1001 //0x100x

#define NR_INSN_CLASS 16
#define INSN_CLASS(opcode) (((opcode) >> 25) & (NR_INSN_CLASS - 1))

+#define INSN_PCREL 0b001 //0b00x
+#define INSN_MOVE_WIDE 0b101
+#define INSN_BITFIELD 0b110
+#define INSN_EXTRACT 0b111
+
typedef int (*arm_decode_class)(u32 instr, enum insn_type *type,
unsigned long *immediate,
struct list_head *ops_list);

/* arm64 instruction classes */
+int arm_decode_dp_imm(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
int arm_decode_unknown(u32 instr, enum insn_type *type,
unsigned long *immediate, struct list_head *ops_list);
+
+/* arm64 data processing -- immediate subclasses */
+int arm_decode_pcrel(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_move_wide(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_bitfield(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_extract(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
#endif /* _ARM_INSN_DECODE_H */
--
2.21.0
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