[PATCH RFC V2] purgatory: fix up declarations

[Nicholas Mc Guire]

Add the missing declarations of basic purgatory functions and variables
used with kexec_purgatory_get_set_symbol() to allow a clean build.

Fixes: commit 8fc5b4d4121c ("purgatory: core purgatory functionality")
Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
---

V2: after kbuild test robot <lkp@xxxxxxxxx> reported a build failure
    removed incorrect declaration of copy_backup_region which is static
    anyway.

sparse complained about:
  CHECK   arch/x86/purgatory/purgatory.c
arch/x86/purgatory/purgatory.c:21:15: warning: symbol 'backup_dest' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:22:15: warning: symbol 'backup_src' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:23:15: warning: symbol 'backup_sz' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:25:4: warning: symbol 'sha256_digest' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:27:19: warning: symbol 'sha_regions' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:42:5: warning: symbol 'verify_sha256_digest' was not declared. Should it be static?
arch/x86/purgatory/purgatory.c:61:6: warning: symbol 'purgatory' was not declared. Should it be static?
  CC      arch/x86/purgatory/purgatory.o

Numerous sparse messages regarding functions not being declared, these
functions are resolved via kexec_purgatory_get_set_symbol() and not
directly called anywhere. To resolve the sparse issues appropriate
declarations were added to asm/kexec-bzimage64.h and the appropriate
reference included in purgatory.c. Adding this to kexec-bzimage64.h
was done as setup_purgatory() from machine_kexec_file_64.c uses
these symbols - not sure if this is the proper place to add this.

While at it the initialization of sha_regions to {{0,0}} was added.

Patch was compile tested with: x86_64_defconfig (implies CONFIG_KEXEC=y)

Patch is against 4.9.0 (localversion-next is next-20161223)

 arch/x86/include/asm/kexec-bzimage64.h | 16 ++++++++++++++++
 arch/x86/purgatory/purgatory.c         |  8 ++------
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kexec-bzimage64.h b/arch/x86/include/asm/kexec-bzimage64.h
index d1b5d19..fd7f776 100644
--- a/arch/x86/include/asm/kexec-bzimage64.h
+++ b/arch/x86/include/asm/kexec-bzimage64.h
@@ -1,6 +1,21 @@
 #ifndef _ASM_KEXEC_BZIMAGE64_H
 #define _ASM_KEXEC_BZIMAGE64_H
 
+struct sha_region {
+	unsigned long start;
+	unsigned long len;
+};
+
 extern struct kexec_file_ops kexec_bzImage64_ops;
 
+/* needed for kexec_purgatory_get_set_symbol() */
+extern unsigned long backup_dest;
+extern unsigned long backup_src;
+extern unsigned long backup_sz;
+extern u8 sha256_digest[];
+extern struct sha_region sha_regions[];
+
+void purgatory(void);
+int verify_sha256_digest(void);
+
 #endif  /* _ASM_KEXE_BZIMAGE64_H */
diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
index 25e068b..26c8367 100644
--- a/arch/x86/purgatory/purgatory.c
+++ b/arch/x86/purgatory/purgatory.c
@@ -12,11 +12,7 @@
 
 #include "sha256.h"
 #include "../boot/string.h"
-
-struct sha_region {
-	unsigned long start;
-	unsigned long len;
-};
+#include <asm/kexec-bzimage64.h>
 
 unsigned long backup_dest = 0;
 unsigned long backup_src = 0;
@@ -24,7 +20,7 @@ unsigned long backup_sz = 0;
 
 u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 };
 
-struct sha_region sha_regions[16] = {};
+struct sha_region sha_regions[16] = { { 0, 0 } };
 
 /*
  * On x86, second kernel requries first 640K of memory to boot. Copy
-- 
2.1.4