[PATCH] kexec-tools: fix failure when kernel version patchlevel >255

[Joe Korty]

[PATCH] kexec-tools: fix kexec failure when kernel version patchlevel >255

[ 2nd try, to a larger cc: list, and this time submitted
  with a patch rather than just a bug report   ]

Kexec blows up when the kernel version patchlevel is >255.
This was first noticed when a 4.4.262 kernel was booted
on a CentOS 7 system.  The message on the console is of
the form:

  Unsupported utsname.release: 4.4.262

The attached patch should fix this.  Untested.  There might
be a few places where a hardcoded constant rather than
KERNEL_VERSION is used, but I did not see any.

Signed-off-by: Joe Korty <joe.korty at concurrent-rt.com

diff --git a/kexec/kernel_version.c b/kexec/kernel_version.c
index 21fb13adf095..36c06ffd603d 100644
--- a/kexec/kernel_version.c
+++ b/kexec/kernel_version.c
@@ -47,7 +47,7 @@ long kernel_version(void)
 		patch = 0;
 	}
 
-	if (major >= 256 || minor >= 256 || patch >= 256) {
+	if (major >= 256 || minor >= 256 || patch >= 65536) {
 		fprintf(stderr, "Unsupported utsname.release: %s\n",
 			utsname.release);
 		return -1;
diff --git a/kexec/kexec.h b/kexec/kexec.h
index f0f347d5e9e0..b388475ffa5a 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -180,7 +180,7 @@ extern const struct arch_map_entry arches[];
 long physical_arch(void);
 
 #define KERNEL_VERSION(major, minor, patch) \
-	(((major) << 16) | ((minor) << 8) | patch)
+	(((major) << 24) | ((minor) << 16) | patch)
 long kernel_version(void);
 
 void usage(void);