linux-kernel - [PATCH v2 03/62] x86/module: Improve relocation error messages

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Message-ID: <9a93844560bef1c6c5aa3121c454fc32316bb120.1746821544.git.jpoimboe@kernel.org>
Date: Fri,  9 May 2025 13:16:27 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org,
	Song Liu <song@...nel.org>,
	laokz <laokz@...mail.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Weinan Liu <wnliu@...gle.com>,
	Fazla Mehrab <a.mehrab@...edance.com>,
	Chen Zhongjin <chenzhongjin@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>
Subject: [PATCH v2 03/62] x86/module: Improve relocation error messages

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

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 231d6326d1fd..ff64f3c6642b 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 0e73fac55f8e..7e443c2cf7d4 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;
 		}
 
-- 
2.49.0