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kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

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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>
This commit is contained in:
Naveen N. Rao 2022-05-19 14:42:37 +05:30 committed by akpm
parent c572e4888a
commit 3e35142ef9
4 changed files with 56 additions and 42 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
arch/s390/include/asm/kexec.h
View file

@ -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 */

8
arch/x86/include/asm/kexec.h
View file

@ -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);

46
include/linux/kexec.h
View file

@ -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

34
kernel/kexec_file.c
View file

@ -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