kernel/kexec_file.c: make purgatory_info->ehdr const
The kexec_purgatory buffer is read-only. Thus all pointers into
kexec_purgatory are read-only, too. Point this out by explicitly
marking purgatory_info->ehdr as 'const' and update the comments in
purgatory_info.
Link: http://lkml.kernel.org/r/20180321112751.22196-4-prudo@linux.vnet.ibm.com
Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 08b8b9d..8c5819d 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -99,14 +99,19 @@ struct compat_kexec_segment {
#ifdef CONFIG_KEXEC_FILE
struct purgatory_info {
- /* Pointer to elf header of read only purgatory */
- Elf_Ehdr *ehdr;
-
- /* Pointer to purgatory sechdrs which are modifiable */
+ /*
+ * Pointer to elf header at the beginning of kexec_purgatory.
+ * Note: kexec_purgatory is read only
+ */
+ const Elf_Ehdr *ehdr;
+ /*
+ * Temporary, modifiable buffer for sechdrs used for relocation.
+ * This memory can be freed post image load.
+ */
Elf_Shdr *sechdrs;
/*
- * Temporary buffer location where purgatory is loaded and relocated
- * This memory can be freed post image load
+ * Temporary, modifiable buffer for stripped purgatory used for
+ * relocation. This memory can be freed post image load.
*/
void *purgatory_buf;