linux-kernel - [RFC v5 02/57] objtool: check: Clean instruction state before each function validation

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Message-Id: <20200109160300.26150-3-jthierry@redhat.com>
Date:   Thu,  9 Jan 2020 16:02:05 +0000
From:   Julien Thierry <jthierry@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     jpoimboe@...hat.com, peterz@...radead.org, raphael.gault@....com,
        catalin.marinas@....com, will@...nel.org,
        Julien Thierry <jthierry@...hat.com>
Subject: [RFC v5 02/57] 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 a04778421144..4784f0f6a3ae 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2348,13 +2348,6 @@ static int validate_functions(struct objtool_file *file)
 	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;
-
 	for_each_sec(file, sec) {
 		list_for_each_entry(func, &sec->symbol_list, list) {
 			if (func->type != STT_FUNC)
@@ -2373,6 +2366,12 @@ static int validate_functions(struct objtool_file *file)
 			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);
--
2.21.0