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From:   Sathvika Vasireddy <sv@linux.ibm.com>
To:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc:     jpoimboe@redhat.com, peterz@infradead.org, aik@ozlabs.ru,
        mpe@ellerman.id.au, mingo@redhat.com, christophe.leroy@csgroup.eu,
        mbenes@suse.cz, npiggin@gmail.com, chenzhongjin@huawei.com,
        sfr@canb.auug.org.au, naveen.n.rao@linux.vnet.ibm.com,
        sv@linux.ibm.com
Subject: [PATCH] objtool: continue if find_insn() fails in decode_instructions()
Date:   Thu,  8 Dec 2022 12:58:13 +0530
Message-Id: <20221208072813.25799-1-sv@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Currently, decode_instructions() is failing if it is not able to find
instruction, and this is happening since commit dbcdbdfdf137b4
("objtool: Rework instruction -> symbol mapping") because it is
expecting instruction for STT_NOTYPE symbols.

Due to this, the following objtool warnings are seen:
 [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction
 [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: kvm_template_end(): can't find starting instruction
 [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction

The warnings are thrown because find_insn() is failing for symbols that
are at the end of the file, or at the end of the section. Given how
STT_NOTYPE symbols are currently handled in decode_instructions(),
continue if the instruction is not found, instead of throwing warning
and returning.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
---
 tools/objtool/check.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4350be739f4f..bce2be5ebf36 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -430,11 +430,8 @@ static int decode_instructions(struct objtool_file *file)
 			if (func->return_thunk || func->alias != func)
 				continue;
 
-			if (!find_insn(file, sec, func->offset)) {
-				WARN("%s(): can't find starting instruction",
-				     func->name);
-				return -1;
-			}
+			if (!find_insn(file, sec, func->offset))
+				continue;
 
 			sym_for_each_insn(file, func, insn) {
 				insn->sym = func;
-- 
2.31.1