From: Julien Thierry <jthierry@redhat.com>
Date: Fri, 27 Mar 2020 15:28:47 +0000
Subject: objtool: Support multiple stack_op per instruction
Git-commit: 65ea47dcf4f936987a5fbf839c97acea00f4f196
Patch-mainline: v5.8-rc1
References: bsc#1202396

Instruction sets can include more or less complex operations which might
not fit the currently defined set of stack_ops.

Combining more than one stack_op provides more flexibility to describe
the behaviour of an instruction. This also reduces the need to define
new stack_ops specific to a single instruction set.

Allow instruction decoders to generate multiple stack_op per
instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
 tools/objtool/arch.h            |    4 +++-
 tools/objtool/arch/x86/decode.c |   13 ++++++++++++-
 tools/objtool/check.c           |   32 +++++++++++++++++++++++++-------
 tools/objtool/check.h           |    2 +-
 4 files changed, 41 insertions(+), 10 deletions(-)

--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -70,6 +70,7 @@ struct op_src {
 struct stack_op {
 	struct op_dest dest;
 	struct op_src src;
+	struct list_head list;
 };
 
 void arch_initial_func_cfi_state(struct cfi_state *state);
@@ -77,7 +78,8 @@ void arch_initial_func_cfi_state(struct
 int arch_decode_instruction(struct elf *elf, struct section *sec,
 			    unsigned long offset, unsigned int maxlen,
 			    unsigned int *len, enum insn_type *type,
-			    unsigned long *immediate, struct stack_op *op);
+			    unsigned long *immediate,
+			    struct list_head *ops_list);
 
 bool arch_callee_saved_reg(unsigned char reg);
 
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -81,13 +81,15 @@ bool arch_callee_saved_reg(unsigned char
 int arch_decode_instruction(struct elf *elf, struct section *sec,
 			    unsigned long offset, unsigned int maxlen,
 			    unsigned int *len, enum insn_type *type,
-			    unsigned long *immediate, struct stack_op *op)
+			    unsigned long *immediate,
+			    struct list_head *ops_list)
 {
 	struct insn insn;
 	int x86_64, sign;
 	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;
 
 	x86_64 = is_x86_64(elf);
 	if (x86_64 == -1)
@@ -128,6 +130,10 @@ int arch_decode_instruction(struct elf *
 	if (insn.sib.nbytes)
 		sib = insn.sib.bytes[0];
 
+	op = calloc(1, sizeof(*op));
+	if (!op)
+		return -1;
+
 	switch (op1) {
 
 	case 0x1:
@@ -474,6 +480,11 @@ int arch_decode_instruction(struct elf *
 
 	*immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
 
+	if (*type == INSN_STACK)
+		list_add_tail(&op->list, ops_list);
+	else
+		free(op);
+
 	return 0;
 }
 
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -282,6 +282,7 @@ static int decode_instructions(struct ob
 			}
 			memset(insn, 0, sizeof(*insn));
 			INIT_LIST_HEAD(&insn->alts);
+			INIT_LIST_HEAD(&insn->stack_ops);
 			clear_insn_state(&insn->state);
 
 			insn->sec = sec;
@@ -291,7 +292,7 @@ static int decode_instructions(struct ob
 						      sec->len - offset,
 						      &insn->len, &insn->type,
 						      &insn->immediate,
-						      &insn->stack_op);
+						      &insn->stack_ops);
 			if (ret)
 				goto err;
 
@@ -673,6 +674,7 @@ static int handle_group_alt(struct objto
 		}
 		memset(fake_jump, 0, sizeof(*fake_jump));
 		INIT_LIST_HEAD(&fake_jump->alts);
+		INIT_LIST_HEAD(&fake_jump->stack_ops);
 		clear_insn_state(&fake_jump->state);
 
 		fake_jump->sec = special_alt->new_sec;
@@ -1317,10 +1319,11 @@ static bool has_valid_stack_frame(struct
 	return false;
 }
 
-static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
+static int update_insn_state_regs(struct instruction *insn,
+				  struct insn_state *state,
+				  struct stack_op *op)
 {
 	struct cfi_reg *cfa = &state->cfa;
-	struct stack_op *op = &insn->stack_op;
 
 	if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
 		return 0;
@@ -1410,9 +1413,9 @@ static void restore_reg(struct insn_stat
  *   41 5d			pop    %r13
  *   c3				retq
  */
-static int update_insn_state(struct instruction *insn, struct insn_state *state)
+static int update_insn_state(struct instruction *insn, struct insn_state *state,
+			     struct stack_op *op)
 {
-	struct stack_op *op = &insn->stack_op;
 	struct cfi_reg *cfa = &state->cfa;
 	struct cfi_reg *regs = state->regs;
 
@@ -1426,7 +1429,7 @@ static int update_insn_state(struct inst
 	}
 
 	if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
-		return update_insn_state_regs(insn, state);
+		return update_insn_state_regs(insn, state, op);
 
 	switch (op->dest.type) {
 
@@ -1752,6 +1755,21 @@ static int update_insn_state(struct inst
 	return 0;
 }
 
+static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
+{
+	struct stack_op *op;
+
+	list_for_each_entry(op, &insn->stack_ops, list) {
+		int res;
+
+		res = update_insn_state(insn, state, op);
+		if (res)
+			return res;
+	}
+
+	return 0;
+}
+
 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
 {
 	struct insn_state *state1 = &insn->state, *state2 = state;
@@ -1996,7 +2014,7 @@ static int validate_branch(struct objtoo
 			return 0;
 
 		case INSN_STACK:
-			if (update_insn_state(insn, &state))
+			if (handle_insn_ops(insn, &state))
 				return 1;
 
 			break;
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -51,7 +51,7 @@ struct instruction {
 	struct instruction *first_jump_src;
 	struct list_head alts;
 	struct symbol *func;
-	struct stack_op stack_op;
+	struct list_head stack_ops;
 	struct insn_state state;
 	struct orc_entry orc;
 };