[tip: objtool/core] objtool: Rework allocating stack_ops on decode

From: tip-bot2 for Peter Zijlstra
Date: Fri May 01 2020 - 14:23:21 EST

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The following commit has been merged into the objtool/core branch of tip:

Commit-ID: 7d989fcadd6e225a61d6490dd15bdbdfc8a53d5c
Gitweb: https://git.kernel.org/tip/7d989fcadd6e225a61d6490dd15bdbdfc8a53d5c
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 23 Apr 2020 13:22:10 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 30 Apr 2020 20:14:32 +02:00

objtool: Rework allocating stack_ops on decode

Wrap each stack_op in a macro that allocates and adds it to the list.
This simplifies trying to figure out what to do with the pre-allocated
stack_op at the end.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200428191659.736151601@xxxxxxxxxxxxx
---
tools/objtool/arch/x86/decode.c | 251 ++++++++++++++++++-------------
1 file changed, 147 insertions(+), 104 deletions(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index c45a0b4..97e66c7 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -77,6 +77,11 @@ unsigned long arch_jump_destination(struct instruction *insn)
return insn->offset + insn->len + insn->immediate;
}

+#define ADD_OP(op) \
+ if (!(op = calloc(1, sizeof(*op)))) \
+ return -1; \
+ else for (list_add_tail(&op->list, ops_list); op; op = NULL)
+
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,
@@ -88,7 +93,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
unsigned char op1, op2, 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, sib = 0;
- struct stack_op *op;
+ struct stack_op *op = NULL;

x86_64 = is_x86_64(elf);
if (x86_64 == -1)
@@ -129,10 +134,6 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
if (insn.sib.nbytes)
sib = insn.sib.bytes[0];

- op = calloc(1, sizeof(*op));
- if (!op)
- return -1;
-
switch (op1) {

case 0x1:
@@ -141,10 +142,12 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* add/sub reg, %rsp */
*type = INSN_STACK;
- op->src.type = OP_SRC_ADD;
- op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
}
break;

@@ -152,9 +155,11 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* push reg */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG;
- op->src.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
- op->dest.type = OP_DEST_PUSH;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+ op->dest.type = OP_DEST_PUSH;
+ }

break;

@@ -162,9 +167,11 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* pop reg */
*type = INSN_STACK;
- op->src.type = OP_SRC_POP;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+ ADD_OP(op) {
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+ }

break;

@@ -172,8 +179,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
case 0x6a:
/* push immediate */
*type = INSN_STACK;
- op->src.type = OP_SRC_CONST;
- op->dest.type = OP_DEST_PUSH;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ }
break;

case 0x70 ... 0x7f:
@@ -188,11 +197,13 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
if (modrm == 0xe4) {
/* and imm, %rsp */
*type = INSN_STACK;
- op->src.type = OP_SRC_AND;
- op->src.reg = CFI_SP;
- op->src.offset = insn.immediate.value;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_AND;
+ op->src.reg = CFI_SP;
+ op->src.offset = insn.immediate.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
break;
}

@@ -205,11 +216,13 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* add/sub imm, %rsp */
*type = INSN_STACK;
- 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;
+ 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;

case 0x89:
@@ -217,10 +230,12 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* mov %rsp, reg */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG;
- op->src.reg = CFI_SP;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG;
+ op->src.reg = CFI_SP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+ }
break;
}

@@ -228,10 +243,12 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* mov reg, %rsp */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG;
- op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
break;
}

@@ -242,21 +259,25 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* mov reg, disp(%rbp) */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG;
- op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
- op->dest.type = OP_DEST_REG_INDIRECT;
- op->dest.reg = CFI_BP;
- op->dest.offset = insn.displacement.value;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG_INDIRECT;
+ op->dest.reg = CFI_BP;
+ op->dest.offset = insn.displacement.value;
+ }

} else if (rex_w && !rex_b && modrm_rm == 4 && sib == 0x24) {

/* mov reg, disp(%rsp) */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG;
- op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
- op->dest.type = OP_DEST_REG_INDIRECT;
- op->dest.reg = CFI_SP;
- op->dest.offset = insn.displacement.value;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG_INDIRECT;
+ op->dest.reg = CFI_SP;
+ op->dest.offset = insn.displacement.value;
+ }
}

break;
@@ -266,22 +287,26 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* mov disp(%rbp), reg */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG_INDIRECT;
- op->src.reg = CFI_BP;
- op->src.offset = insn.displacement.value;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG_INDIRECT;
+ op->src.reg = CFI_BP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ }

} else if (rex_w && !rex_b && sib == 0x24 &&
modrm_mod != 3 && modrm_rm == 4) {

/* mov disp(%rsp), reg */
*type = INSN_STACK;
- op->src.type = OP_SRC_REG_INDIRECT;
- op->src.reg = CFI_SP;
- op->src.offset = insn.displacement.value;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ ADD_OP(op) {
+ op->src.type = OP_SRC_REG_INDIRECT;
+ op->src.reg = CFI_SP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ }
}

break;
@@ -290,27 +315,31 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
if (sib == 0x24 && rex_w && !rex_b && !rex_x) {

*type = INSN_STACK;
- if (!insn.displacement.value) {
- /* lea (%rsp), reg */
- op->src.type = OP_SRC_REG;
- } else {
- /* lea disp(%rsp), reg */
- op->src.type = OP_SRC_ADD;
- op->src.offset = insn.displacement.value;
+ ADD_OP(op) {
+ if (!insn.displacement.value) {
+ /* lea (%rsp), reg */
+ op->src.type = OP_SRC_REG;
+ } else {
+ /* lea disp(%rsp), reg */
+ op->src.type = OP_SRC_ADD;
+ op->src.offset = insn.displacement.value;
+ }
+ op->src.reg = CFI_SP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
}
- op->src.reg = CFI_SP;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];

} else if (rex == 0x48 && modrm == 0x65) {

/* lea disp(%rbp), %rsp */
*type = INSN_STACK;
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_BP;
- op->src.offset = insn.displacement.value;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_BP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }

} else if (rex == 0x49 && modrm == 0x62 &&
insn.displacement.value == -8) {
@@ -322,11 +351,13 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
* stack realignment.
*/
*type = INSN_STACK;
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_R10;
- op->src.offset = -8;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_R10;
+ op->src.offset = -8;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }

} else if (rex == 0x49 && modrm == 0x65 &&
insn.displacement.value == -16) {
@@ -338,11 +369,13 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
* stack realignment.
*/
*type = INSN_STACK;
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_R13;
- op->src.offset = -16;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_R13;
+ op->src.offset = -16;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
}

break;
@@ -350,8 +383,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
case 0x8f:
/* pop to mem */
*type = INSN_STACK;
- op->src.type = OP_SRC_POP;
- op->dest.type = OP_DEST_MEM;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_MEM;
+ }
break;

case 0x90:
@@ -361,15 +396,19 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
case 0x9c:
/* pushf */
*type = INSN_STACK;
- op->src.type = OP_SRC_CONST;
- op->dest.type = OP_DEST_PUSHF;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSHF;
+ }
break;

case 0x9d:
/* popf */
*type = INSN_STACK;
- op->src.type = OP_SRC_POPF;
- op->dest.type = OP_DEST_MEM;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_POPF;
+ op->dest.type = OP_DEST_MEM;
+ }
break;

case 0x0f:
@@ -405,15 +444,19 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* push fs/gs */
*type = INSN_STACK;
- op->src.type = OP_SRC_CONST;
- op->dest.type = OP_DEST_PUSH;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ }

} else if (op2 == 0xa1 || op2 == 0xa9) {

/* pop fs/gs */
*type = INSN_STACK;
- op->src.type = OP_SRC_POP;
- op->dest.type = OP_DEST_MEM;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_MEM;
+ }
}

break;
@@ -427,7 +470,8 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
* pop bp
*/
*type = INSN_STACK;
- op->dest.type = OP_DEST_LEAVE;
+ ADD_OP(op)
+ op->dest.type = OP_DEST_LEAVE;

break;

@@ -449,12 +493,14 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
case 0xcf: /* iret */
*type = INSN_EXCEPTION_RETURN;

- /* add $40, %rsp */
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_SP;
- op->src.offset = 5*8;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
+ ADD_OP(op) {
+ /* add $40, %rsp */
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_SP;
+ op->src.offset = 5*8;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
break;

case 0xca: /* retf */
@@ -492,8 +538,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

/* push from mem */
*type = INSN_STACK;
- op->src.type = OP_SRC_CONST;
- op->dest.type = OP_DEST_PUSH;
+ ADD_OP(op) {
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ }
}

break;
@@ -504,11 +552,6 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,

*immediate = insn.immediate.nbytes ? insn.immediate.value : 0;

- if (*type == INSN_STACK || *type == INSN_EXCEPTION_RETURN)
- list_add_tail(&op->list, ops_list);
- else
- free(op);
-
return 0;
}

Next message: tip-bot2 for Peter Zijlstra: "[tip: objtool/core] x86/retpoline: Fix retpoline unwind"
Previous message: tip-bot2 for Alexandre Chartre: "[tip: objtool/core] objtool: UNWIND_HINT_RET_OFFSET should not check registers"
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