Fix the Linux kernel version number calculation

The Linux compatibility code was converting the version number (e.g.
2.6.32) in two different ways and then comparing the results.

The linux_map_osrel() function converted MAJOR.MINOR.PATCH similar to
what FreeBSD does natively. I.e. where major=v0, minor=v1, and patch=v2
    v = v0 * 1000000 + v1 * 1000 + v2;

The LINUX_KERNVER() macro, on the other hand, converted the value with
bit shifts. I.e. where major=a, minor=b, and patch=c
    v = (((a) << 16) + ((b) << 8) + (c))

The Linux kernel uses the later format via the KERNEL_VERSION() macro in
include/generated/uapi/linux/version.h

Fix is to use the LINUX_KERNVER() macro in linux_map_osrel() as well as
in the .trans_osrel functions.

PR: 229209
Reviewed by: emaste, cem, imp (mentor)
Approved by: imp (mentor)
Differential Revision: https://reviews.freebsd.org/D15952

1 files changed, 4 insertions, 3 deletions

diff --git a/sys/amd64/linux32/linux32_sysvec.c b/sys/amd64/linux32/linux32_sysvec.c
index 648456dc718d..66d441e96c68 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -993,10 +993,11 @@ linux32_trans_osrel(const Elf_Note *note, int32_t *osrel)
 		return (false);
 
 	/*
-	 * For Linux we encode osrel as follows (see linux_mib.c):
-	 * VVVMMMIII (version, major, minor), see linux_mib.c.
+	 * For Linux we encode osrel using the Linux convention of
+	 * 	(version << 16) | (major << 8) | (minor)
+	 * See macro in linux_mib.h
 	 */
-	*osrel = desc[1] * 1000000 + desc[2] * 1000 + desc[3];
+	*osrel = LINUX_KERNVER(desc[1], desc[2], desc[3]);
 
 	return (true);
 }