linux-kernel - [PATCH v5 03/10] objtool: Handle PC relative relocation type

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Message-ID: <20241207015915.1159-4-yangtiezhu@loongson.cn>
Date: Sat,  7 Dec 2024 09:59:08 +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 v5 03/10] objtool: Handle PC relative relocation type

When compiling on LoongArch, there exists PC relative relocation type,
it needs to get the symbol offset with "S + A - PC" according to the
spec of "ELF for the LoongArch Architecture".

Add an arch-specific function arch_adjust_offset() to assign the symbol
offset, the default value is "reloc->sym->offset + reloc_addend(reloc)"
in the weak definition, it can be overridden by archs that have different
requirements.

Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 tools/objtool/arch/loongarch/decode.c         | 20 +++++++++++++++----
 .../objtool/arch/loongarch/include/arch/elf.h |  7 +++++++
 tools/objtool/check.c                         |  7 ++++++-
 tools/objtool/include/objtool/arch.h          |  1 +
 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index b64205b89f6b..431eb4757458 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -5,10 +5,7 @@
 #include <asm/inst.h>
 #include <asm/orc_types.h>
 #include <linux/objtool_types.h>
-
-#ifndef EM_LOONGARCH
-#define EM_LOONGARCH	258
-#endif
+#include <arch/elf.h>
 
 int arch_ftrace_match(char *name)
 {
@@ -374,3 +371,18 @@ unsigned int arch_reloc_size(struct reloc *reloc)
 		return 8;
 	}
 }
+
+unsigned long arch_adjust_offset(struct reloc *reloc, struct reloc *table)
+{
+	switch (reloc_type(reloc)) {
+	case R_LARCH_32_PCREL:
+	case R_LARCH_64_PCREL:
+		if (reloc->sym->type == STT_SECTION)
+			return reloc->sym->offset + reloc_addend(reloc) -
+			       (reloc_offset(reloc) - reloc_offset(table));
+		else
+			return reloc->sym->offset;
+	default:
+		return reloc->sym->offset + reloc_addend(reloc);
+	}
+}
diff --git a/tools/objtool/arch/loongarch/include/arch/elf.h b/tools/objtool/arch/loongarch/include/arch/elf.h
index 9623d663220e..ec79062c9554 100644
--- a/tools/objtool/arch/loongarch/include/arch/elf.h
+++ b/tools/objtool/arch/loongarch/include/arch/elf.h
@@ -18,6 +18,13 @@
 #ifndef R_LARCH_32_PCREL
 #define R_LARCH_32_PCREL	99
 #endif
+#ifndef R_LARCH_64_PCREL
+#define R_LARCH_64_PCREL	109
+#endif
+
+#ifndef EM_LOONGARCH
+#define EM_LOONGARCH		258
+#endif
 
 #define R_NONE			R_LARCH_NONE
 #define R_ABS32			R_LARCH_32
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7271e959520e..4a23aae40c03 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1948,6 +1948,11 @@ __weak unsigned int arch_reloc_size(struct reloc *reloc)
 	return 8;
 }
 
+__weak unsigned long arch_adjust_offset(struct reloc *reloc, struct reloc *table)
+{
+	return reloc->sym->offset + reloc_addend(reloc);
+}
+
 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 			  struct reloc *next_table)
 {
@@ -1979,7 +1984,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 		if (prev_offset && reloc_offset(reloc) != prev_offset + entry_size)
 			break;
 
-		sym_offset = reloc->sym->offset + reloc_addend(reloc);
+		sym_offset = arch_adjust_offset(reloc, table);
 
 		/* Detect function pointers from contiguous objects: */
 		if (reloc->sym->sec == pfunc->sec && sym_offset == pfunc->offset)
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 396f7c6c81c0..34f41ba6d910 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -98,5 +98,6 @@ int arch_rewrite_retpolines(struct objtool_file *file);
 bool arch_pc_relative_reloc(struct reloc *reloc);
 
 unsigned int arch_reloc_size(struct reloc *reloc);
+unsigned long arch_adjust_offset(struct reloc *reloc, struct reloc *table);
 
 #endif /* _ARCH_H */
-- 
2.42.0