Fix: Handle recent SLE major version codes

Starting in early 2022, the SLE linux version codes changed from the
previous style `5.3.18-59.40.1` to a new convention in which the major
version is a compound number consisting of the major release version,
the service pack version, and the auxillary version (currently unused
from my understanding) similar to the following `5.3.18-150300.59.43.1`[1].

The newer values used in the SLE major version causes the integer
value to "overflow" the expected number of digits and the comparisons
may fail. The `LTTNG_SLE_KERNEL_VERSION` macro also multiplies the
`LTTNG_KERNEL_VERSION` by `100000000ULL` which doesn't work in all
situations, as the resulting value is too large to be stored fully in
an `unsigned long long`.

Example of previous results:

```
// Example range comparison. True or false depending on the value of
// `LTTNG_SLE_VERSION_CODE` and `LTTNG_LINUX_VERSION_CODE`.
LTTNG_SLE_KERNEL_RANGE(5,15,21,150400,24,46, 5,15,0,0,0,0);

// Note: values printed with `%ull`
LTTNG_SLE_KERNEL_VERSION(5,15,21,24,26,1); // 6106486698364570153
LTTNG_SLE_KERNEL_VERSION(5,15,0,0,0,0);    // 0
LTTNG_KERNEL_VERSION(5,15,0);              // 84869120

// Corrected SLE version codes
LTTNG_SLE_KERNEL_VERSION(5,14,21,150400,24,26); // 14918348902249793914
LTTNG_SLE_KERNEL_VERSION(5,14,21,150400,24,46); // 14918348902249793934
LTTNG_SLE_KERNEL_VERSION(5,15,0,150400,0,0));   // 6971507145825058816
```

`LTTNG_KERNEL_VERSION` packs the kernel version into a 32-bit integer;
however, using that type of packing on the SLE kernel version will not
work well:

* Major: `150400` needs 18 bits
* Minor: may exceed 127, requires 8 bits (eg. `4.12.14-150100.197.148.1`)
* Patch: may exceed 127, requires 8 bits (eg. `5.3.18-150300.59.124.1`)

In this patch, the SLE version is packed into a 64-bit integer
with 48 bits for the major version, 8 bits for each of the minor and
patch versions.

As a result of packing the SLE version into a 64-bit integer,
it is not possible to coherently combine an `LTTNG_KERNEL_VERSION` and
an `LTTNG_SLE_KERNEL_VERSION`. Doing so would require an integer
larger than 64-bits. Therefore, the `LTTNG_SLE_KERNEL_RANGE` macro has
been adjusted to perform the range comparisons using the two values
separately. The usage of the `LTTNG_SLE_KERNEL_RANGE` remains
unchanged, as `LTTNG_SLE_VERSION` is only used inside that macro.

Using the adjusted macros:

```
// Example range comparison. True or false depending on the value of
// `LTTNG_SLE_VERSION_CODE` and `LTTNG_LINUX_VERSION_CODE`.
LTTNG_SLE_KERNEL_RANGE(5,15,21,150400,24,46, 5,15,0,0,0,0);

// Note: values printed with `%ull`
LTTNG_SLE_VERSION(24,26,1); // 1579521
LTTNG_SLE_VERSION(0,0,0);   // 0
LTTNG_KERNEL_VERSION(5,15,0);      // 84869120

// Corrected SLE version codes
LTTNG_SLE_VERSION(150400,24,26); // 9856620570
LTTNG_SLE_VERSION(150400,24,46); // 9856620590
LTTNG_SLE_VERSION(150400,0,0));  // 9863168000
```

Known drawbacks
===============

It's possible that future releases of SLE kernels have minor or patch
values that exceed 255 (SLE15SP1 has a release using `197`, for example),
requiring an adjustment to using more bits for those fields when
packing into a 64-bit integer.

The schema of multiplying an `LTTNG_KERNEL_VERSION` by a large value
is used for other distributions. RHEL in particular uses
`100000000ULL`, which could lead to overflow issues with certain
comparisons similar to the previous behaviour of
`LTTNG_SLE_KERNEL_VERSION(5,15,0,0,0,0);`.

[1]: https://www.suse.com/support/kb/doc/?id=000019587#SLE15SP4

Change-Id: Iaa90bfa422e47213a13829cdf008ab20d7484cab
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/lttng/kernel-version.h b/include/lttng/kernel-version.h
index 5b4e1a6481c3fb7094c80b9cb5af9baa1725baba..b5791fa7b60dc8a1ef131ea318d86b4c7ef416ae 100644 (file)
--- a/include/lttng/kernel-version.h
+++ b/include/lttng/kernel-version.h
@@ -127,22 +127,48 @@
 
 /* SUSE Linux enterprise */
 
-#define LTTNG_SLE_KERNEL_VERSION(a, b, c, d, e, f) \
-       (((LTTNG_KERNEL_VERSION(a, b, c)) * 100000000ULL) + ((d) * 100000) + ((e) * 100) + (f))
+/*
+ * SLE major version codes may be large, eg. 150400, and require more than
+ * 32 bits to store. Multiplying `a` by `1ULL` avoids compiler warnings, eg:
+ *
+ * `warning: result of ‘150400 << 16’ requires 35 bits to represent, but ‘int’ only has 32 bits`
+ *
+ */
+#define LTTNG_SLE_VERSION(a, b, c) \
+   ((((a * 1ULL) << 16) + (b << 8) + c) * 1ULL)
 
-#ifdef SLE_API_VERSION
+#if defined(SLE_API_VERSION_MAJOR) && defined(SLE_API_VERSION_MINOR) && defined(SLE_API_VERSION_PATCH)
 #define LTTNG_SLE_VERSION_CODE \
-       ((LTTNG_LINUX_VERSION_CODE * 100000000ULL) + SLE_API_VERSION)
+       (LTTNG_SLE_VERSION(SLE_API_VERSION_MAJOR, SLE_API_VERSION_MINOR, SLE_API_VERSION_PATCH))
 #else
-#define LTTNG_SLE_VERSION_CODE         0
+#define LTTNG_SLE_VERSION_CODE 0
 #endif
 
 #define LTTNG_SLE_KERNEL_RANGE(a_low, b_low, c_low, d_low, e_low, f_low, \
                a_high, b_high, c_high, d_high, e_high, f_high) \
-       (LTTNG_SLE_VERSION_CODE >= \
-               LTTNG_SLE_KERNEL_VERSION(a_low, b_low, c_low, d_low, e_low, f_low) && \
-               LTTNG_SLE_VERSION_CODE < \
-               LTTNG_SLE_KERNEL_VERSION(a_high, b_high, c_high, d_high, e_high, f_high))
+       ( \
+               LTTNG_SLE_VERSION_CODE != 0 && \
+               ( \
+                       /* Linux kernel version code exclusive inside range */ \
+                       (LTTNG_LINUX_VERSION_CODE > LTTNG_KERNEL_VERSION(a_low, b_low, c_low) && \
+                       LTTNG_LINUX_VERSION_CODE < LTTNG_KERNEL_VERSION(a_high, b_high, c_high)) || \
+                       \
+                       /* Linux kernel version code is at lower and upper limit */ \
+                       (LTTNG_LINUX_VERSION_CODE == LTTNG_KERNEL_VERSION(a_low, b_low, c_low) && \
+                       LTTNG_LINUX_VERSION_CODE == LTTNG_KERNEL_VERSION(a_high, b_high, c_high) && \
+                       LTTNG_SLE_VERSION_CODE >= LTTNG_SLE_VERSION(d_low, e_low, f_low) && \
+                       LTTNG_SLE_VERSION_CODE < LTTNG_SLE_VERSION(d_high, e_high, f_high)) || \
+                       \
+                       /* Linux kernel version code is at lower limit */ \
+                       (LTTNG_LINUX_VERSION_CODE == LTTNG_KERNEL_VERSION(a_low, b_low, c_low) && \
+                       LTTNG_KERNEL_VERSION(a_low, b_low, c_low) != LTTNG_KERNEL_VERSION(a_high, b_high, c_high) && \
+                       LTTNG_SLE_VERSION_CODE >= LTTNG_SLE_VERSION(d_low, e_low, f_low)) || \
+                       \
+                       /* Linux kernel version code is at upper limit */ \
+                       (LTTNG_LINUX_VERSION_CODE == LTTNG_KERNEL_VERSION(a_high, b_high, c_high) && \
+                       LTTNG_KERNEL_VERSION(a_low, b_low, c_low) != LTTNG_KERNEL_VERSION(a_high, b_high, c_high) && \
+                       LTTNG_SLE_VERSION_CODE < LTTNG_SLE_VERSION(d_high, e_high, f_high)) \
+               ))
 
 /* Fedora */
 

diff --git a/scripts/abi-sle-version.sh b/scripts/abi-sle-version.sh
index e079e0657e812c45980e801cdd9dc16702bced3f..9b7da92d407c99562c2c800fdd02932158fb349c 100755 (executable)
--- a/scripts/abi-sle-version.sh
+++ b/scripts/abi-sle-version.sh
@@ -37,7 +37,4 @@ if [ "x$SLE_RELEASE_PATCH" = "x" ]; then
        SLE_RELEASE_PATCH=0
 fi
 
-# Combine all update numbers into one
-SLE_API_VERSION="$((SLE_RELEASE_MAJOR * 100000 + SLE_RELEASE_MINOR * 100 + SLE_RELEASE_PATCH))"
-
-echo ${SLE_API_VERSION}
+echo "${SLE_RELEASE_MAJOR} ${SLE_RELEASE_MINOR} ${SLE_RELEASE_PATCH}"

diff --git a/src/Kbuild.common b/src/Kbuild.common
index f64cb09d5ff0c5a83bdf22d9e75b2e74d9aa1f89..78afa21ec9d9551f119402c52f9742ca0ff4dffc 100644 (file)
--- a/src/Kbuild.common
+++ b/src/Kbuild.common
@@ -25,7 +25,9 @@ endif
 SLE_API_VERSION:=$(shell $(TOP_LTTNG_MODULES_DIR)/scripts/abi-sle-version.sh $(CURDIR))
 
 ifneq ($(SLE_API_VERSION), 0)
-  ccflags-y += -DSLE_API_VERSION=$(SLE_API_VERSION)
+  ccflags-y += -DSLE_API_VERSION_MAJOR=$(word 1, $(SLE_API_VERSION))
+  ccflags-y += -DSLE_API_VERSION_MINOR=$(word 2, $(SLE_API_VERSION))
+  ccflags-y += -DSLE_API_VERSION_PATCH=$(word 3, $(SLE_API_VERSION))
 endif
 
 FEDORA_REVISION_VERSION:=$(shell $(TOP_LTTNG_MODULES_DIR)/scripts/abi-fedora-version.sh $(CURDIR))