objtool: Support multiple stack_op per instruction

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>

1 files changed, 46 insertions, 28 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e06a891a4a3b..9e854fd128d4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -260,6 +260,7 @@ static int decode_instructions(struct objtool_file *file)
 			}
 			memset(insn, 0, sizeof(*insn));
 			INIT_LIST_HEAD(&insn->alts);
+			INIT_LIST_HEAD(&insn->stack_ops);
 			clear_insn_state(&insn->state);
 
 			insn->sec = sec;
@@ -269,7 +270,7 @@ static int decode_instructions(struct objtool_file *file)
 						      sec->len - offset,
 						      &insn->len, &insn->type,
 						      &insn->immediate,
-						      &insn->stack_op);
+						      &insn->stack_ops);
 			if (ret)
 				goto err;
 
@@ -754,6 +755,7 @@ static int handle_group_alt(struct objtool_file *file,
 		}
 		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;
@@ -1452,10 +1454,11 @@ static bool has_valid_stack_frame(struct insn_state *state)
 	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)
 		return 0;
@@ -1545,9 +1548,9 @@ static void restore_reg(struct insn_state *state, unsigned char reg)
  *   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;
 
@@ -1561,7 +1564,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
 	}
 
 	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) {
 
@@ -1898,6 +1901,42 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
 	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;
+
+		if (op->dest.type == OP_DEST_PUSHF) {
+			if (!state->uaccess_stack) {
+				state->uaccess_stack = 1;
+			} else if (state->uaccess_stack >> 31) {
+				WARN_FUNC("PUSHF stack exhausted",
+					  insn->sec, insn->offset);
+				return 1;
+			}
+			state->uaccess_stack <<= 1;
+			state->uaccess_stack  |= state->uaccess;
+		}
+
+		if (op->src.type == OP_SRC_POPF) {
+			if (state->uaccess_stack) {
+				state->uaccess = state->uaccess_stack & 1;
+				state->uaccess_stack >>= 1;
+				if (state->uaccess_stack == 1)
+					state->uaccess_stack = 0;
+			}
+		}
+	}
+
+	return 0;
+}
+
 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
 {
 	struct insn_state *state1 = &insn->state, *state2 = state;
@@ -2198,29 +2237,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			return 0;
 
 		case INSN_STACK:
-			if (update_insn_state(insn, &state))
+			if (handle_insn_ops(insn, &state))
 				return 1;
-
-			if (insn->stack_op.dest.type == OP_DEST_PUSHF) {
-				if (!state.uaccess_stack) {
-					state.uaccess_stack = 1;
-				} else if (state.uaccess_stack >> 31) {
-					WARN_FUNC("PUSHF stack exhausted", sec, insn->offset);
-					return 1;
-				}
-				state.uaccess_stack <<= 1;
-				state.uaccess_stack  |= state.uaccess;
-			}
-
-			if (insn->stack_op.src.type == OP_SRC_POPF) {
-				if (state.uaccess_stack) {
-					state.uaccess = state.uaccess_stack & 1;
-					state.uaccess_stack >>= 1;
-					if (state.uaccess_stack == 1)
-						state.uaccess_stack = 0;
-				}
-			}
-
 			break;
 
 		case INSN_STAC: