[LTP] [PATCH v4 1/3] Add library support for /proc/sys/kernel/tainted
Michael Moese
mmoese@suse.de
Mon Feb 12 11:03:39 CET 2018
Sometimes, it is important to detect if the kernel has issued a
warning, died, or is tainted in another way. Linux provides this
information in /proc/sys/kernel/tainted in the form of a bitfield.
This patch provides library functions for testcases to detect, if
it has tainted the kernel.
The following functions will be introduced:
- int tst_taint_init(unsigned int mask)
check if the flags supplied as mask are supported by the running
kernel, and if so, if they are not yet set.
- int tst_taint_check()
check if one or more of the bits specified in the mask provided
to tst_taint_init() before are set.
Returns 0 if those flags are not set, or the bitmask of set flags
These can be used in the following way:
First, during testcase setup:
void setup(void)
{
...
tst_taint_init(TST_TAINT_W | TST_TAINT_D);
}
Second, check if the test triggered a bug:
void run(void)
{
...
. test code here
...
if (tst_taint_check() != 0)
tst_res(TFAIL, "kernel has issues");
else
tst_res(TPASS, "kernel seems to be fine");
}
Signed-off-by: Michael Moese <mmoese@suse.de>
---
doc/test-writing-guidelines.txt | 42 ++++++++++++++++
include/tst_taint.h | 104 +++++++++++++++++++++++++++++++++++++++
lib/tst_taint.c | 106 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 252 insertions(+)
create mode 100644 include/tst_taint.h
create mode 100644 lib/tst_taint.c
diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index 739b295b8..f12386485 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1312,6 +1312,48 @@ common.h:9: FAIL: check failed
test.c:8: INFO: do_action(arg) failed
-------------------------------------------------------------------------------
+2.2.24 Tainted kernels
+^^^^^^^^^^^^^^^^^^^^^^
+
+If you need to detect, if a testcase triggers a kernel warning, bug or oops,
+the following can be used to detect TAINT_W or TAINT_D:
+
+[source,c]
+-------------------------------------------------------------------------------
+#include "tst_test.h"
+#include "tst_taint.h"
+
+void setup(void)
+{
+ ...
+ tst_taint_init(TST_TAINT_W | TST_TAINT_D);
+ ...
+}
+...
+void run(void)
+{
+ ...
+ if (tst_taint_check() == 0)
+ tst_res(TPASS, "kernel is not tainted");
+ else
+ tst_res(TFAIL, "kernel is tainted");
+}
+-------------------------------------------------------------------------------
+
+You have to call tst_taint_init() with non-zero flags first, preferably during
+setup(). The function will generate a TCONF if the requested flags are not
+fully supported on the running kernel, and TBROK if either a zero mask was
+supplied or if the kernel is already tainted before executing the test.
+
+Then you can call tst_taint_check() during run(), which returns 0 or the
+tainted flags set in /proc/sys/kernel/tainted as specified earlier.
+
+Depending on your kernel version, not all tainted-flags will be supported.
+
+For reference to tainted kernels, see kernel documentation:
+Documentation/admin-guide/tainted-kernels.rst or
+https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html
+
2.3 Writing a testcase in shell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/include/tst_taint.h b/include/tst_taint.h
new file mode 100644
index 000000000..1039e2ddc
--- /dev/null
+++ b/include/tst_taint.h
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2018 Michael Moese <mmoese@suse.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Usage example
+ *
+ * ...
+ * #include "tst_test.h"
+ * #include "tst_taint.h"
+ * ..
+ * void setup(void)
+ * {
+ * ...
+ * tst_taint_init(TST_TAINT_W | TST_TAINT_D));
+ * ...
+ * }
+ *
+ * void run(void)
+ * {
+ * ...
+ * . test code here
+ * ...
+ * if (tst_taint_check() != 0)
+ * tst_res(TFAIL, "kernel has issues");
+ * else
+ * tst_res(TPASS, "kernel seems to be fine");
+ * }
+ *
+ *
+ *
+ * The above code checks, if the kernel issued a warning (TST_TAINT_W)
+ * or even died (TST_TAINT_D) during test execution.
+ * If these are set after running a test case, we most likely
+ * triggered a kernel bug.
+ */
+
+#ifndef TST_TAINTED_H__
+#define TST_TAINTED_H__
+
+/*
+ * This are all 17 flags that are present in kernel 4.15
+ * see kernel/panic.c in kernel sources
+ *
+ * Not all of them are valid in all kernel versions.
+ */
+#define TST_TAINT_G (1 << 0) /* a module with non-GPL license loaded */
+#define TST_TAINT_F (1 << 1) /* a module was force-loaded */
+#define TST_TAINT_S (1 << 2) /* SMP with Non-SMP kernel */
+#define TST_TAINT_R (1 << 3) /* module force unloaded */
+#define TST_TAINT_M (1 << 4) /* machine check error occurred */
+#define TST_TAINT_B (1 << 5) /* page-release function found bad page */
+#define TST_TAINT_U (1 << 6) /* user requested taint flag */
+#define TST_TAINT_D (1 << 7) /* kernel died recently - OOPS or BUG */
+#define TST_TAINT_A (1 << 8) /* ACPI table has been overwritten */
+#define TST_TAINT_W (1 << 9) /* a warning has been issued by kernel */
+#define TST_TAINT_C (1 << 10) /* driver from drivers/staging was loaded */
+#define TST_TAINT_I (1 << 11) /* working around BIOS/Firmware bug */
+#define TST_TAINT_O (1 << 12) /* out of tree module loaded */
+#define TST_TAINT_E (1 << 13) /* unsigned module was loaded */
+#define TST_TAINT_L (1 << 14) /* A soft lock-up has previously occurred */
+#define TST_TAINT_K (1 << 15) /* kernel has been live-patched */
+#define TST_TAINT_X (1 << 16) /* auxiliary taint, for distro's use */
+
+/*
+ * Initialize and prepare support for checking tainted kernel.
+ *
+ * supply the mask of TAINT-flags you want to check, for example
+ * (TST_TAINT_W | TST_TAINT_D) when you want to check if the kernel issued
+ * a warning or even reported it died.
+ *
+ * This function tests if the requested flags are supported on the
+ * locally running kernel. In case the tainted-flags are already set by
+ * the kernel, there is no reason to continue and TCONF is generated.
+ *
+ * The mask must not be zero.
+ */
+void tst_taint_init(unsigned int mask);
+
+
+/*
+ * check if the tainted flags handed to tst_taint_init() are still not set
+ * during or after running the test.
+ * Calling this function is only allowed after tst_taint_init() was called,
+ * otherwise TBROK will be generated.
+ *
+ * returns 0 or a bitmask of the flags that currently tainted the kernel.
+ */
+unsigned int tst_taint_check(void);
+
+
+#endif /* TST_TAINTED_H__ */
diff --git a/lib/tst_taint.c b/lib/tst_taint.c
new file mode 100644
index 000000000..8d7a37b47
--- /dev/null
+++ b/lib/tst_taint.c
@@ -0,0 +1,106 @@
+#define TST_NO_DEFAULT_MAIN
+
+#include "tst_test.h"
+#include "tst_taint.h"
+#include "tst_safe_stdio.h"
+
+#define TAINT_FILE "/proc/sys/kernel/tainted"
+
+static unsigned int taint_mask = -1;
+
+static unsigned int tst_taint_read(void)
+{
+ unsigned int val;
+
+ if (taint_mask == (unsigned int) -1)
+ tst_brk(TBROK, "need to call tst_taint_init() first");
+
+ SAFE_FILE_SCANF(TAINT_FILE, "%u", &val);
+
+ return val;
+}
+
+static int tst_taint_check_kver(unsigned int mask)
+{
+ int r1;
+ int r2;
+ int r3 = 0;
+
+ if (mask & TST_TAINT_X) {
+ r1 = 4;
+ r2 = 15;
+ } else if (mask & TST_TAINT_K) {
+ r1 = 4;
+ r2 = 0;
+ } else if (mask & TST_TAINT_L) {
+ r1 = 3;
+ r2 = 17;
+ } else if (mask & TST_TAINT_E) {
+ r1 = 3;
+ r2 = 15;
+ } else if (mask & TST_TAINT_O) {
+ r1 = 3;
+ r2 = 2;
+ } else if (mask & TST_TAINT_I) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 35;
+ } else if (mask & TST_TAINT_C) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 28;
+ } else if (mask & TST_TAINT_W) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 26;
+ } else if (mask & TST_TAINT_A) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 25;
+ } else if (mask & TST_TAINT_D) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 23;
+ } else if (mask & TST_TAINT_U) {
+ r1 = 2;
+ r2 = 6;
+ r3 = 21;
+ } else {
+ r1 = 2;
+ r2 = 6;
+ r3 = 16;
+ }
+
+ return tst_kvercmp(r1, r2, r3);
+}
+
+void tst_taint_init(unsigned int mask)
+{
+ unsigned int taint = -1;
+
+ if (mask == 0)
+ tst_brk(TBROK, "mask is not allowed to be 0");
+
+ if (tst_taint_check_kver(mask) < 0)
+ tst_res(TCONF, "Kernel is too old for requested mask");
+
+ taint_mask = mask;
+
+ taint = tst_taint_read();
+ if ((taint & mask) != 0)
+ tst_brk(TBROK, "Kernel is already tainted: %u", taint);
+}
+
+
+unsigned int tst_taint_check(void)
+{
+ unsigned int taint = -1;
+
+ if (taint_mask == (unsigned int) -1)
+ tst_brk(TBROK, "need to call tst_taint_init() first");
+
+ taint = tst_taint_read();
+
+ return (taint & taint_mask);
+}
+
--
2.13.6
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