kernel/kexec_file.c: use read-only sections in arch_kexec_apply_relocations*

When the relocations are applied to the purgatory only the section the
relocations are applied to is writable.  The other sections, i.e.  the
symtab and .rel/.rela, are in read-only kexec_purgatory.  Highlight this
by marking the corresponding variables as 'const'.

While at it also change the signatures of arch_kexec_apply_relocations* to
take section pointers instead of just the index of the relocation section.
This removes the second lookup and sanity check of the sections in arch
code.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Philipp Rudo <[email protected]>
Acked-by: Dave Young <[email protected]>
Cc: AKASHI Takahiro <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Thiago Jung Bauermann <[email protected]>
Cc: Vivek Goyal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 9 insertions, 4 deletions

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 8c5819d1a808..0e389b9b7722 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -171,6 +171,15 @@ struct kexec_buf {
 	bool top_down;
 };
 
+int __weak arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+					    Elf_Shdr *section,
+					    const Elf_Shdr *relsec,
+					    const Elf_Shdr *symtab);
+int __weak arch_kexec_apply_relocations(struct purgatory_info *pi,
+					Elf_Shdr *section,
+					const Elf_Shdr *relsec,
+					const Elf_Shdr *symtab);
+
 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 			       int (*func)(struct resource *, void *));
 extern int kexec_add_buffer(struct kexec_buf *kbuf);
@@ -304,10 +313,6 @@ int crash_shrink_memory(unsigned long new_size);
 size_t crash_get_memory_size(void);
 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
 
-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);