linux-kernel - [PATCH v4 05/10] objtool: Handle unreachable entry of rodata

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Message-ID: <20241122045005.14617-6-yangtiezhu@loongson.cn>
Date: Fri, 22 Nov 2024 12:50:00 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 05/10] objtool: Handle unreachable entry of rodata

When compling with Clang on LoongArch, there exists unreachable entry of
rodata which points to a position after the function return instruction,
this is generated by compiler to fill the non-existent switch case, just
skip the entry when parsing the relocation section of rodata.

This is preparation for later patch on LoongArch, there is no effect for
the other archs with this patch.

Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 tools/objtool/check.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8733ca620cca..b21e47d8d3d1 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2144,6 +2144,13 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 		if (!dest_insn)
 			break;
 
+		/* Handle the special cases compiled with Clang on LoongArch */
+		if (file->elf->ehdr.e_machine == EM_LOONGARCH && reloc->sym->type == STT_SECTION &&
+		    (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)) {
+			prev_offset = reloc_offset(reloc);
+			continue;
+		}
+
 		/* Make sure the destination is in the same function: */
 		if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
 			break;
-- 
2.42.0