objtool,x86: More ModRM sugar

Better helpers to decode ModRM.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YCZB/ljatFXqQbm8@hirez.programming.kicks-ass.net

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index b42e5ec083a0d003df412aba4de991dbfc407a0f..431bafb881d443a82caaa221f4d4745a6d2daade 100644 (file)
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -82,15 +82,21 @@ unsigned long arch_jump_destination(struct instruction *insn)
  * 01 |  [r/m + d8]    |[S+d]|   [r/m + d8]  |
  * 10 |  [r/m + d32]   |[S+D]|   [r/m + d32] |
  * 11 |                   r/ m               |
- *
  */
+
+#define mod_is_mem()   (modrm_mod != 3)
+#define mod_is_reg()   (modrm_mod == 3)
+
 #define is_RIP()   ((modrm_rm & 7) == CFI_BP && modrm_mod == 0)
-#define have_SIB() ((modrm_rm & 7) == CFI_SP && modrm_mod != 3)
+#define have_SIB() ((modrm_rm & 7) == CFI_SP && mod_is_mem())
 
 #define rm_is(reg) (have_SIB() ? \
                    sib_base == (reg) && sib_index == CFI_SP : \
                    modrm_rm == (reg))
 
+#define rm_is_mem(reg) (mod_is_mem() && !is_RIP() && rm_is(reg))
+#define rm_is_reg(reg) (mod_is_reg() && modrm_rm == (reg))
+
 int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                            unsigned long offset, unsigned int maxlen,
                            unsigned int *len, enum insn_type *type,
@@ -154,7 +160,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
 
        case 0x1:
        case 0x29:
-               if (rex_w && modrm_mod == 3 && modrm_rm == CFI_SP) {
+               if (rex_w && rm_is_reg(CFI_SP)) {
 
                        /* add/sub reg, %rsp */
                        ADD_OP(op) {
@@ -219,7 +225,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                        break;
 
                /* %rsp target only */
-               if (!(modrm_mod == 3 && modrm_rm == CFI_SP))
+               if (!rm_is_reg(CFI_SP))
                        break;
 
                imm = insn.immediate.value;
@@ -272,7 +278,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
 
                if (modrm_reg == CFI_SP) {
 
-                       if (modrm_mod == 3) {
+                       if (mod_is_reg()) {
                                /* mov %rsp, reg */
                                ADD_OP(op) {
                                        op->src.type = OP_SRC_REG;
@@ -308,7 +314,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                        break;
                }
 
-               if (modrm_mod == 3 && modrm_rm == CFI_SP) {
+               if (rm_is_reg(CFI_SP)) {
 
                        /* mov reg, %rsp */
                        ADD_OP(op) {
@@ -325,7 +331,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                if (!rex_w)
                        break;
 
-               if ((modrm_mod == 1 || modrm_mod == 2) && modrm_rm == CFI_BP) {
+               if (rm_is_mem(CFI_BP)) {
 
                        /* mov reg, disp(%rbp) */
                        ADD_OP(op) {
@@ -338,7 +344,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                        break;
                }
 
-               if (modrm_mod != 3 && rm_is(CFI_SP)) {
+               if (rm_is_mem(CFI_SP)) {
 
                        /* mov reg, disp(%rsp) */
                        ADD_OP(op) {
@@ -357,7 +363,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                if (!rex_w)
                        break;
 
-               if ((modrm_mod == 1 || modrm_mod == 2) && modrm_rm == CFI_BP) {
+               if (rm_is_mem(CFI_BP)) {
 
                        /* mov disp(%rbp), reg */
                        ADD_OP(op) {
@@ -370,7 +376,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                        break;
                }
 
-               if (modrm_mod != 3 && rm_is(CFI_SP)) {
+               if (rm_is_mem(CFI_SP)) {
 
                        /* mov disp(%rsp), reg */
                        ADD_OP(op) {
@@ -386,7 +392,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
                break;
 
        case 0x8d:
-               if (modrm_mod == 3) {
+               if (mod_is_reg()) {
                        WARN("invalid LEA encoding at %s:0x%lx", sec->name, offset);
                        break;
                }