kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

Since commit d1bcae833b32f1 ("ELF: Don't generate unused section
symbols") [1], binutils (v2.36+) started dropping section symbols that
it thought were unused.  This isn't an issue in general, but with
kexec_file.c, gcc is placing kexec_arch_apply_relocations[_add] into a
separate .text.unlikely section and the section symbol ".text.unlikely"
is being dropped. Due to this, recordmcount is unable to find a non-weak
symbol in .text.unlikely to generate a relocation record against.

Address this by dropping the weak attribute from these functions.
Instead, follow the existing pattern of having architectures #define the
name of the function they want to override in their headers.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1

[akpm@linux-foundation.org: arch/s390/include/asm/kexec.h needs linux/module.h]
Link: https://lkml.kernel.org/r/20220519091237.676736-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: rnav

arch/s390/include/asm/kexec.h

@@ -9,6 +9,8 @@
 #ifndef _S390_KEXEC_H
 #define _S390_KEXEC_H
 
+#include <linux/module.h>
+
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/setup.h>
@@ -83,4 +85,12 @@ struct kimage_arch {
 extern const struct kexec_file_ops s390_kexec_image_ops;
 extern const struct kexec_file_ops s390_kexec_elf_ops;
 
+#ifdef CONFIG_KEXEC_FILE
+struct purgatory_info;
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+				     Elf_Shdr *section,
+				     const Elf_Shdr *relsec,
+				     const Elf_Shdr *symtab);
+#define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
+#endif
 #endif /*_S390_KEXEC_H */

arch/x86/include/asm/kexec.h

@@ -186,6 +186,14 @@ extern int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages,
 extern void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages);
 #define arch_kexec_pre_free_pages arch_kexec_pre_free_pages
 
+#ifdef CONFIG_KEXEC_FILE
+struct purgatory_info;
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+				     Elf_Shdr *section,
+				     const Elf_Shdr *relsec,
+				     const Elf_Shdr *symtab);
+#define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
+#endif
 #endif
 
 typedef void crash_vmclear_fn(void);

include/linux/kexec.h

@@ -193,14 +193,6 @@ void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name);
 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
 				  unsigned long buf_len);
 void *arch_kexec_kernel_image_load(struct kimage *image);
-int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
-				     Elf_Shdr *section,
-				     const Elf_Shdr *relsec,
-				     const Elf_Shdr *symtab);
-int arch_kexec_apply_relocations(struct purgatory_info *pi,
-				 Elf_Shdr *section,
-				 const Elf_Shdr *relsec,
-				 const Elf_Shdr *symtab);
 int arch_kimage_file_post_load_cleanup(struct kimage *image);
 #ifdef CONFIG_KEXEC_SIG
 int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
@@ -229,6 +221,44 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
 				   unsigned long long mend);
 extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
 				       void **addr, unsigned long *sz);
+
+#ifndef arch_kexec_apply_relocations_add
+/*
+ * arch_kexec_apply_relocations_add - apply relocations of type RELA
+ * @pi:		Purgatory to be relocated.
+ * @section:	Section relocations applying to.
+ * @relsec:	Section containing RELAs.
+ * @symtab:	Corresponding symtab.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+static inline int
+arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
+				 const Elf_Shdr *relsec, const Elf_Shdr *symtab)
+{
+	pr_err("RELA relocation unsupported.\n");
+	return -ENOEXEC;
+}
+#endif
+
+#ifndef arch_kexec_apply_relocations
+/*
+ * arch_kexec_apply_relocations - apply relocations of type REL
+ * @pi:		Purgatory to be relocated.
+ * @section:	Section relocations applying to.
+ * @relsec:	Section containing RELs.
+ * @symtab:	Corresponding symtab.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+static inline int
+arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
+			     const Elf_Shdr *relsec, const Elf_Shdr *symtab)
+{
+	pr_err("REL relocation unsupported.\n");
+	return -ENOEXEC;
+}
+#endif
 #endif /* CONFIG_KEXEC_FILE */
 
 #ifdef CONFIG_KEXEC_ELF

kernel/kexec_file.c

@@ -108,40 +108,6 @@ int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
 }
 #endif
 
-/*
- * arch_kexec_apply_relocations_add - apply relocations of type RELA
- * @pi:		Purgatory to be relocated.
- * @section:	Section relocations applying to.
- * @relsec:	Section containing RELAs.
- * @symtab:	Corresponding symtab.
- *
- * Return: 0 on success, negative errno on error.
- */
-int __weak
-arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
-				 const Elf_Shdr *relsec, const Elf_Shdr *symtab)
-{
-	pr_err("RELA relocation unsupported.\n");
-	return -ENOEXEC;
-}
-
-/*
- * arch_kexec_apply_relocations - apply relocations of type REL
- * @pi:		Purgatory to be relocated.
- * @section:	Section relocations applying to.
- * @relsec:	Section containing RELs.
- * @symtab:	Corresponding symtab.
- *
- * Return: 0 on success, negative errno on error.
- */
-int __weak
-arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
-			     const Elf_Shdr *relsec, const Elf_Shdr *symtab)
-{
-	pr_err("REL relocation unsupported.\n");
-	return -ENOEXEC;
-}
-
 /*
  * Free up memory used by kernel, initrd, and command line. This is temporary
  * memory allocation which is not needed any more after these buffers have