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Commit 3f860199 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Greg Kroah-Hartman
Browse files

kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add] 

commit 3e35142ef99fe6b4fe5d834ad43ee13cca10a2dc 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: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent eb581547

arch/x86/include/asm/kexec.h

+7 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#ifndef __ASSEMBLY__



#include <linux/string.h>

#include <linux/module.h>



#include <asm/page.h>

#include <asm/ptrace.h>
@@ -206,6 +207,12 @@ struct kexec_entry64_regs { 
	uint64_t r15;

	uint64_t rip;

};



#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);

include/linux/kexec.h

+22 −4
Original line number Diff line number Diff line
@@ -148,6 +148,28 @@ struct kexec_file_ops { 
	kexec_verify_sig_t *verify_sig;

#endif

};



#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



struct kimage {
@@ -320,10 +342,6 @@ 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);

kernel/kexec_file.c

+0 −18
Original line number Diff line number Diff line
@@ -59,24 +59,6 @@ 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