linux-kernel - [PATCH v4 03/10] objtool: Handle different entry size of rodata

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Message-ID: <20241122045005.14617-4-yangtiezhu@loongson.cn>
Date: Fri, 22 Nov 2024 12:49:58 +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 03/10] objtool: Handle different entry size of rodata

In the most cases, the entry size of rodata is 8 bytes because the
relocation type is 64 bit, but when compling with Clang on LoongArch,
there exists 32 bit relocation type, the entry size of rodata should
be 4 bytes in this case.

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 | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 191950551352..19d1263e64e4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -26,6 +26,10 @@
 #define EM_LOONGARCH		258
 #endif
 
+#ifndef R_LARCH_32_PCREL
+#define R_LARCH_32_PCREL	99
+#endif
+
 struct alternative {
 	struct alternative *next;
 	struct instruction *insn;
@@ -2096,6 +2100,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 	struct reloc *reloc = table;
 	struct alternative *alt;
 	unsigned long offset;
+	unsigned long rodata_entry_size;
 
 	/*
 	 * Each @reloc is a switch table relocation which points to the target
@@ -2107,8 +2112,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 		if (reloc != table && reloc == next_table)
 			break;
 
+		/* Handle the special cases compiled with Clang on LoongArch */
+		if (file->elf->ehdr.e_machine == EM_LOONGARCH &&
+		    reloc_type(reloc) == R_LARCH_32_PCREL)
+			rodata_entry_size = 4;
+		else
+			rodata_entry_size = 8;
+
 		/* Make sure the table entries are consecutive: */
-		if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
+		if (prev_offset && reloc_offset(reloc) != prev_offset + rodata_entry_size)
 			break;
 
 		if (reloc->sym->type == STT_SECTION) {
-- 
2.42.0