linux-kernel - [tip: objtool/core] x86/module: Improve relocation error messages

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Message-ID: <176060839693.709179.17595631535499971067.tip-bot2@tip-bot2>
Date: Thu, 16 Oct 2025 09:53:16 -0000
From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Petr Mladek <pmladek@...e.com>, Joe Lawrence <joe.lawrence@...hat.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] x86/module: Improve relocation error messages

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     bf770d6d2097a52d87f4d9c88d0b05bd3998d7de
Gitweb:        https://git.kernel.org/tip/bf770d6d2097a52d87f4d9c88d0b05bd3998d7de
Author:        Josh Poimboeuf <jpoimboe@...nel.org>
AuthorDate:    Wed, 17 Sep 2025 09:03:11 -07:00
Committer:     Josh Poimboeuf <jpoimboe@...nel.org>
CommitterDate: Tue, 14 Oct 2025 14:45:21 -07:00

x86/module: Improve relocation error messages

Add the section number and reloc index to relocation error messages to
help find the faulty relocation.

Acked-by: Petr Mladek <pmladek@...e.com>
Tested-by: Joe Lawrence <joe.lawrence@...hat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/kernel/module.c | 15 +++++++++------
 kernel/livepatch/core.c  |  4 ++--
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 0ffbae9..11c45ce 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -97,6 +97,7 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 	DEBUGP("%s relocate section %u to %u\n",
 	       apply ? "Applying" : "Clearing",
 	       relsec, sechdrs[relsec].sh_info);
+
 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 		size_t size;
 
@@ -162,15 +163,17 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 
 		if (apply) {
 			if (memcmp(loc, &zero, size)) {
-				pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
-				       (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+				pr_err("x86/modules: Invalid relocation target, existing value is nonzero for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+				       relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+				       (unsigned long)loc, val);
 				return -ENOEXEC;
 			}
 			write(loc, &val, size);
 		} else {
 			if (memcmp(loc, &val, size)) {
-				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
-					(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+					relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+					(unsigned long)loc, val);
 				return -ENOEXEC;
 			}
 			write(loc, &zero, size);
@@ -179,8 +182,8 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 	return 0;
 
 overflow:
-	pr_err("overflow in relocation type %d val %Lx\n",
-	       (int)ELF64_R_TYPE(rel[i].r_info), val);
+	pr_err("overflow in relocation type %d val %llx sec %u idx %d\n",
+	       (int)ELF64_R_TYPE(rel[i].r_info), val, relsec, i);
 	pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
 	       me->name);
 	return -ENOEXEC;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0e73fac..7e443c2 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -217,8 +217,8 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
 	for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) {
 		sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info);
 		if (sym->st_shndx != SHN_LIVEPATCH) {
-			pr_err("symbol %s is not marked as a livepatch symbol\n",
-			       strtab + sym->st_name);
+			pr_err("symbol %s at rela sec %u idx %d is not marked as a livepatch symbol\n",
+			       strtab + sym->st_name, symndx, i);
 			return -EINVAL;
 		}