lkml.org 
[lkml]   [2020]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC v5 24/57] objtool: arm64: Decode system instructions not affecting the flow
Date
Decode basic system instructions that do not cause jumps or stack
pointer modifications.

Suggested-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
tools/objtool/arch/arm64/decode.c | 95 +++++++++++++++++++
.../objtool/arch/arm64/include/insn_decode.h | 23 +++++
2 files changed, 118 insertions(+)

diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index a30c3294cc21..c38d73fb57e1 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -87,6 +87,7 @@ static arm_decode_class aarch64_insn_class_decode_table[NR_INSN_CLASS] = {
[INSN_UNKNOWN] = arm_decode_unknown,
[INSN_UNALLOC] = arm_decode_unknown,
[0b1000 ... INSN_DP_IMM] = arm_decode_dp_imm,
+ [0b1010 ... INSN_SYS_BRANCH] = arm_decode_br_sys,
};

/*
@@ -391,3 +392,97 @@ int arm_decode_extract(u32 instr, enum insn_type *type,

return arm_decode_unknown(instr, type, immediate, ops_list);
}
+
+static struct aarch64_insn_decoder br_sys_decoder[] = {
+ {
+ .mask = 0b1111111111111111111111,
+ .value = 0b1100100000011001011111,
+ .decode_func = arm_decode_hints,
+ },
+ {
+ .mask = 0b1111111111111111100000,
+ .value = 0b1100100000011001100000,
+ .decode_func = arm_decode_barriers,
+ },
+ {
+ .mask = 0b1111111111000111100000,
+ .value = 0b1100100000000010000000,
+ .decode_func = arm_decode_pstate,
+ },
+ {
+ .mask = 0b1111111011000000000000,
+ .value = 0b1100100001000000000000,
+ .decode_func = arm_decode_system_insn,
+ },
+ {
+ .mask = 0b1111111010000000000000,
+ .value = 0b1100100010000000000000,
+ .decode_func = arm_decode_system_regs,
+ },
+};
+
+int arm_decode_br_sys(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ u32 decode_field = 0, op1 = 0;
+ unsigned char op0 = 0, op2 = 0;
+ int i = 0;
+
+ op0 = (instr >> 29) & ONES(3);
+ op1 = (instr >> 12) & ONES(14);
+ op2 = instr & ONES(5);
+
+ decode_field = op0;
+ decode_field = (decode_field << 19) | (op1 << 5) | op2;
+
+ for (i = 0; i < ARRAY_SIZE(br_sys_decoder); i++) {
+ if ((decode_field & br_sys_decoder[i].mask) ==
+ br_sys_decoder[i].value) {
+ return br_sys_decoder[i].decode_func(instr,
+ type,
+ immediate,
+ ops_list);
+ }
+ }
+
+ return arm_decode_unknown(instr, type, immediate, ops_list);
+}
+
+int arm_decode_hints(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ *type = INSN_NOP;
+ return 0;
+}
+
+int arm_decode_barriers(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ /* TODO:check unallocated */
+ *type = INSN_OTHER;
+ return 0;
+}
+
+int arm_decode_pstate(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ /* TODO:check unallocated */
+ *type = INSN_OTHER;
+ return 0;
+}
+
+int arm_decode_system_insn(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ /* TODO:check unallocated */
+ *type = INSN_OTHER;
+ return 0;
+}
+
+int arm_decode_system_regs(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list)
+{
+ /* TODO:check unallocated */
+ *type = INSN_OTHER;
+ return 0;
+}
diff --git a/tools/objtool/arch/arm64/include/insn_decode.h b/tools/objtool/arch/arm64/include/insn_decode.h
index 6f68e8887cdb..777a62f1a141 100644
--- a/tools/objtool/arch/arm64/include/insn_decode.h
+++ b/tools/objtool/arch/arm64/include/insn_decode.h
@@ -9,6 +9,7 @@
#define INSN_UNKNOWN 0b0001
#define INSN_UNALLOC 0b0011
#define INSN_DP_IMM 0b1001 //0x100x
+#define INSN_SYS_BRANCH 0b1011 //0x101x

#define NR_INSN_CLASS 16
#define INSN_CLASS(opcode) (((opcode) >> 25) & (NR_INSN_CLASS - 1))
@@ -25,9 +26,17 @@ typedef int (*arm_decode_class)(u32 instr, enum insn_type *type,
unsigned long *immediate,
struct list_head *ops_list);

+struct aarch64_insn_decoder {
+ u32 mask;
+ u32 value;
+ arm_decode_class decode_func;
+};
+
/* 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_br_sys(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);

@@ -47,4 +56,18 @@ 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);
+
+/* arm64 branch, exception generation, system insn subclasses */
+int arm_decode_hints(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_barriers(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_pstate(u32 instr, enum insn_type *type,
+ unsigned long *immediate, struct list_head *ops_list);
+int arm_decode_system_insn(u32 instr, enum insn_type *type,
+ unsigned long *immediate,
+ struct list_head *ops_list);
+int arm_decode_system_regs(u32 instr, enum insn_type *type,
+ unsigned long *immediate,
+ struct list_head *ops_list);
#endif /* _ARM_INSN_DECODE_H */
--
2.21.0
\
 
 \ /
  Last update: 2020-01-09 17:06    [W:0.507 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site