fix: RT_PATCH_VERSION is close to overflow

[lttng-modules.git] / lttng-kernel-version.h

diff --git a/lttng-kernel-version.h b/lttng-kernel-version.h
index 65281b2e8e2912f876143f155ac30e4ee8e7d692..9ce339b19b0d4a1a45b8e5f8b0f2641715848352 100644 (file)
--- a/lttng-kernel-version.h
+++ b/lttng-kernel-version.h
@@ -12,8 +12,51 @@
 
 #include <linux/version.h>
 
-#define LTTNG_KERNEL_VERSION(a, b, c) KERNEL_VERSION(a, b, c)
-#define LTTNG_LINUX_VERSION_CODE LINUX_VERSION_CODE
+/*
+ * The following defines are extracted from the toplevel Linux Makefile and
+ * passed on the command line -with '-D'.
+ */
+
+#ifndef LTTNG_LINUX_MAJOR
+#define LTTNG_LINUX_MAJOR 0
+#endif
+
+#ifndef LTTNG_LINUX_MINOR
+#define LTTNG_LINUX_MINOR 0
+#endif
+
+#ifndef LTTNG_LINUX_PATCH
+#define LTTNG_LINUX_PATCH 0
+#endif
+
+/*
+ * Some stable releases have overflowed the 8bits allocated to the sublevel in
+ * the version code. To determine if the current kernel is affected, use the
+ * sublevel version from the Makefile. This is currently true for the 4.4.256
+ * and 4.9.256 stable releases.
+ *
+ * When the sublevel has overflowed, use the values from the Makefile instead
+ * of LINUX_VERSION_CODE from the kernel headers and allocate 16bits.
+ * Otherwise, keep using the version code from the headers to minimise the
+ * behavior change and avoid regressions.
+ *
+ * Cast the result to uint64_t to prevent overflowing when we append distro
+ * specific version information.
+ */
+#if (LTTNG_LINUX_PATCH >= 256)
+
+#define LTTNG_KERNEL_VERSION(a, b, c) \
+       ((((a) << 24) + ((b) << 16) + (c)) * 1ULL)
+
+#define LTTNG_LINUX_VERSION_CODE \
+       LTTNG_KERNEL_VERSION(LTTNG_LINUX_MAJOR, LTTNG_LINUX_MINOR, LTTNG_LINUX_PATCH)
+
+#else
+
+#define LTTNG_KERNEL_VERSION(a, b, c) (KERNEL_VERSION(a, b, c) * 1ULL)
+#define LTTNG_LINUX_VERSION_CODE (LINUX_VERSION_CODE * 1ULL)
+
+#endif
 
 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(2,6,33))
 #include <generated/utsrelease.h>
@@ -32,11 +75,11 @@
 /* Ubuntu */
 
 #define LTTNG_UBUNTU_KERNEL_VERSION(a, b, c, d) \
-       (((LTTNG_KERNEL_VERSION(a, b, c)) << 8) + (d))
+       (((LTTNG_KERNEL_VERSION(a, b, c)) << 16) + (d))
 
 #ifdef UTS_UBUNTU_RELEASE_ABI
 #define LTTNG_UBUNTU_VERSION_CODE \
-       ((LTTNG_LINUX_VERSION_CODE << 8) + UTS_UBUNTU_RELEASE_ABI)
+       ((LTTNG_LINUX_VERSION_CODE << 16) + UTS_UBUNTU_RELEASE_ABI)
 #else
 #define LTTNG_UBUNTU_VERSION_CODE      0
 #endif
@@ -127,11 +170,11 @@
 /* RT patch */
 
 #define LTTNG_RT_KERNEL_VERSION(a, b, c, d) \
-       (((LTTNG_KERNEL_VERSION(a, b, c)) << 8) + (d))
+       (((LTTNG_KERNEL_VERSION(a, b, c)) << 16) + (d))
 
 #ifdef RT_PATCH_VERSION
 #define LTTNG_RT_VERSION_CODE \
-       ((LTTNG_LINUX_VERSION_CODE << 8) + RT_PATCH_VERSION)
+       ((LTTNG_LINUX_VERSION_CODE << 16) + RT_PATCH_VERSION)
 #else
 #define LTTNG_RT_VERSION_CODE  0
 #endif