Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/Documentation/fault-injection/provoke-crashes.rst b/Documentation/fault-injection/provoke-crashes.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+============================================================
+Provoking crashes with Linux Kernel Dump Test Module (LKDTM)
+============================================================
+
+The lkdtm module provides an interface to disrupt (and usually crash)
+the kernel at predefined code locations to evaluate the reliability of
+the kernel's exception handling and to test crash dumps obtained using
+different dumping solutions. The module uses KPROBEs to instrument the
+trigger location, but can also trigger the kernel directly without KPROBE
+support via debugfs.
+
+You can select the location of the trigger ("crash point name") and the
+type of action ("crash point type") either through module arguments when
+inserting the module, or through the debugfs interface.
+
+Usage::
+
+	insmod lkdtm.ko [recur_count={>0}] cpoint_name=<> cpoint_type=<>
+			[cpoint_count={>0}]
+
+recur_count
+	Recursion level for the stack overflow test. By default this is
+	dynamically calculated based on kernel configuration, with the
+	goal of being just large enough to exhaust the kernel stack. The
+	value can be seen at `/sys/module/lkdtm/parameters/recur_count`.
+
+cpoint_name
+	Where in the kernel to trigger the action. It can be
+	one of INT_HARDWARE_ENTRY, INT_HW_IRQ_EN, INT_TASKLET_ENTRY,
+	FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_QUEUE_RQ,
+	IDE_CORE_CP, or DIRECT
+
+cpoint_type
+	Indicates the action to be taken on hitting the crash point.
+	These are numerous, and best queried directly from debugfs. Some
+	of the common ones are PANIC, BUG, EXCEPTION, LOOP, and OVERFLOW.
+	See the contents of `/sys/kernel/debug/provoke-crash/DIRECT` for
+	a complete list.
+
+cpoint_count
+	Indicates the number of times the crash point is to be hit
+	before triggering the action. The default is 10 (except for
+	DIRECT, which always fires immediately).
+
+You can also induce failures by mounting debugfs and writing the type to
+<debugfs>/provoke-crash/<crashpoint>. E.g.::
+
+  mount -t debugfs debugfs /sys/kernel/debug
+  echo EXCEPTION > /sys/kernel/debug/provoke-crash/INT_HARDWARE_ENTRY
+
+The special file `DIRECT` will induce the action directly without KPROBE
+instrumentation. This mode is the only one available when the module is
+built for a kernel without KPROBEs support::
+
+  # Instead of having a BUG kill your shell, have it kill "cat":
+  cat <(echo WRITE_RO) >/sys/kernel/debug/provoke-crash/DIRECT