[PATCH V3] purgatory: fix up declarations

[Nicholas Mc Guire]

Add the missing declarations of basic purgatory functions and variables
to allow a clean build.

Fixes: commit 8fc5b4d4121c ("purgatory: core purgatory functionality")
Link: http://lkml.org/lkml/2017/1/4/25
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.

V3: move it all into purgatory.h as fixing up the declarations in the .c
    file as suggested by Dave Young <dyoung@xxxxxxxxxx>, fixes the sparse
    warnings but then triggers a batch of checkpatch warnings. So the only
    clear solution it seems is to move it to a dedicated .h file.

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 in a dedicated purgatory.h file.

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

Patch is against 4.10-rc2 (localversion-next is next-20170106)

 arch/x86/purgatory/purgatory.c |  6 +-----
 arch/x86/purgatory/purgatory.h | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 5 deletions(-)
 create mode 100644 arch/x86/purgatory/purgatory.h

diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
index 25e068b..9420fe5 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 "purgatory.h"
 
 unsigned long backup_dest = 0;
 unsigned long backup_src = 0;
diff --git a/arch/x86/purgatory/purgatory.h b/arch/x86/purgatory/purgatory.h
new file mode 100644
index 0000000..2754e83
--- /dev/null
+++ b/arch/x86/purgatory/purgatory.h
@@ -0,0 +1,24 @@
+#ifndef BOOT_PURGATORY_H
+#define BOOT_PURGATORY_H
+
+/* This is really just to make sparse happy.
+ * Declaring it all static as sparse suggests is not an option as,
+ * the symbol information is needed. see kexec_purgatory_get_set_symbol()
+ * Technically these prototype and extern declarations are unnecessary
+ */
+void purgatory(void);
+int verify_sha256_digest(void);
+
+extern unsigned long backup_dest;
+extern unsigned long backup_src;
+extern unsigned long backup_sz;
+
+struct sha_region {
+	unsigned long start;
+	unsigned long len;
+};
+
+extern u8 sha256_digest[];
+extern struct sha_region sha_regions[];
+
+#endif
-- 
2.1.4