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objtool,x86: Rewrite ADD/SUB/AND 

Support sign extending and imm8 forms.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.588366777@infradead.org
This commit is contained in:
Peter Zijlstra 2021-02-10 14:11:30 +01:00 committed by Ingo Molnar
parent 78df6245c3
commit 961d83b907
1 changed files with 51 additions and 19 deletions
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70
tools/objtool/arch/x86/decode.c
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@ -98,13 +98,14 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
struct list_head *ops_list) struct list_head *ops_list)
{ {
struct insn insn; struct insn insn;
int x86_64, sign; int x86_64;
unsigned char op1, op2, unsigned char op1, op2,
rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0,
modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0,
sib = 0, /* sib_scale = 0, */ sib_index = 0, sib_base = 0; sib = 0, /* sib_scale = 0, */ sib_index = 0, sib_base = 0;
struct stack_op *op = NULL; struct stack_op *op = NULL;
struct symbol *sym; struct symbol *sym;
u64 imm;
x86_64 = is_x86_64(elf); x86_64 = is_x86_64(elf);
if (x86_64 == -1) if (x86_64 == -1)
@ -200,12 +201,54 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
*type = INSN_JUMP_CONDITIONAL; *type = INSN_JUMP_CONDITIONAL;
break; break;
case 0x81: case 0x80 ... 0x83:
case 0x83: /*
if (rex != 0x48) * 1000 00sw : mod OP r/m : immediate
*
* s - sign extend immediate
* w - imm8 / imm32
*
* OP: 000 ADD 100 AND
* 001 OR 101 SUB
* 010 ADC 110 XOR
* 011 SBB 111 CMP
*/
/* 64bit only */
if (!rex_w)
break; break;
if (modrm == 0xe4) { /* %rsp target only */
if (!(modrm_mod == 3 && modrm_rm == CFI_SP))
break;
imm = insn.immediate.value;
if (op1 & 2) { /* sign extend */
if (op1 & 1) { /* imm32 */
imm <<= 32;
imm = (s64)imm >> 32;
} else { /* imm8 */
imm <<= 56;
imm = (s64)imm >> 56;
}
}
switch (modrm_reg & 7) {
case 5:
imm = -imm;
/* fallthrough */
case 0:
/* add/sub imm, %rsp */
ADD_OP(op) {
op->src.type = OP_SRC_ADD;
op->src.reg = CFI_SP;
op->src.offset = imm;
op->dest.type = OP_DEST_REG;
op->dest.reg = CFI_SP;
}
break;
case 4:
/* and imm, %rsp */ /* and imm, %rsp */
ADD_OP(op) { ADD_OP(op) {
op->src.type = OP_SRC_AND; op->src.type = OP_SRC_AND;
@ -215,23 +258,12 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
op->dest.reg = CFI_SP; op->dest.reg = CFI_SP;
} }
break; break;
}
if (modrm == 0xc4) default:
sign = 1; /* WARN ? */
else if (modrm == 0xec)
sign = -1;
else
break; break;
/* add/sub imm, %rsp */
ADD_OP(op) {
op->src.type = OP_SRC_ADD;
op->src.reg = CFI_SP;
op->src.offset = insn.immediate.value * sign;
op->dest.type = OP_DEST_REG;
op->dest.reg = CFI_SP;
} }
break; break;
case 0x89: case 0x89: