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kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add] 

commit 3e35142ef9 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Naveen N. Rao 2022-05-19 14:42:37 +05:30 committed by Greg Kroah-Hartman
parent 2d83b6548a
commit 6af88cc6e4
3 changed files with 28 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/kexec.h
View File

@ -21,6 +21,7 @@
#ifndef __ASSEMBLY__
#include <linux/string.h>
#include <linux/module.h>
#include <asm/page.h>
#include <asm/ptrace.h>
@ -217,6 +218,11 @@ 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
int arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
Elf_Shdr *sechdrs, unsigned int relsec);
#define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
#endif
#endif
typedef void crash_vmclear_fn(void);

26
include/linux/kexec.h
View File

@ -163,6 +163,28 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
int (*func)(u64, u64, void *));
extern int kexec_add_buffer(struct kexec_buf *kbuf);
int kexec_locate_mem_hole(struct kexec_buf *kbuf);
#ifndef arch_kexec_apply_relocations_add
/* Apply relocations of type RELA */
static inline int
arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
Elf_Shdr *sechdrs, unsigned int relsec)
{
pr_err("RELA relocation unsupported.\n");
return -ENOEXEC;
}
#endif
#ifndef arch_kexec_apply_relocations
/* Apply relocations of type REL */
static inline int
arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
{
pr_err("REL relocation unsupported.\n");
return -ENOEXEC;
}
#endif
#endif /* CONFIG_KEXEC_FILE */
struct kimage {
@ -288,10 +310,6 @@ void * __weak arch_kexec_kernel_image_load(struct kimage *image);
int __weak arch_kimage_file_post_load_cleanup(struct kimage *image);
int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
unsigned long buf_len);
int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
Elf_Shdr *sechdrs, unsigned int relsec);
int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec);
void arch_kexec_protect_crashkres(void);
void arch_kexec_unprotect_crashkres(void);

18
kernel/kexec_file.c
View File

@ -53,24 +53,6 @@ int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
}
#endif
/* Apply relocations of type RELA */
int __weak
arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
{
pr_err("RELA relocation unsupported.\n");
return -ENOEXEC;
}
/* Apply relocations of type REL */
int __weak
arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
{
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