linux-kernel - [PATCH v2 03/10] objtool: check: Clean instruction state before each function validation

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Date:   Fri, 27 Mar 2020 15:28:40 +0000
From:   Julien Thierry <jthierry@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     jpoimboe@...hat.com, peterz@...radead.org, raphael.gault@....com,
        Julien Thierry <jthierry@...hat.com>
Subject: [PATCH v2 03/10] objtool: check: Clean instruction state before each function validation

When a function fails its validation, it might leave a stale state
that will be used for the validation of other functions. That would
cause false warnings on potentially valid functions.

Reset the instruction state before the validation of each individual
function.

Signed-off-by: Julien Thierry <jthierry@...hat.com>
---
 tools/objtool/check.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3ab87e3aa750..74353b2c39ce 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2400,13 +2400,6 @@ static int validate_section(struct objtool_file *file, struct section *sec)
 	struct insn_state state;
 	int ret, warnings = 0;
 
-	clear_insn_state(&state);
-
-	state.cfa = initial_func_cfi.cfa;
-	memcpy(&state.regs, &initial_func_cfi.regs,
-	       CFI_NUM_REGS * sizeof(struct cfi_reg));
-	state.stack_size = initial_func_cfi.cfa.offset;
-
 	list_for_each_entry(func, &sec->symbol_list, list) {
 		if (func->type != STT_FUNC)
 			continue;
@@ -2424,6 +2417,12 @@ static int validate_section(struct objtool_file *file, struct section *sec)
 		if (!insn || insn->ignore || insn->visited)
 			continue;
 
+		clear_insn_state(&state);
+		state.cfa = initial_func_cfi.cfa;
+		memcpy(&state.regs, &initial_func_cfi.regs,
+		       CFI_NUM_REGS * sizeof(struct cfi_reg));
+		state.stack_size = initial_func_cfi.cfa.offset;
+
 		state.uaccess = func->uaccess_safe;
 
 		ret = validate_branch(file, func, insn, state);
-- 
2.21.1