1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==============================================
4 Provoking crashes with Linux Kernel Dump Test
5 ==============================================
6
7 The lkdtm module provides an interface to disr
8 the kernel at predefined code locations to eva
9 the kernel's exception handling and to test cr
10 different dumping solutions. The module uses K
11 trigger location, but can also trigger the ker
12 support via debugfs.
13
14 You can select the location of the trigger ("c
15 type of action ("crash point type") either thr
16 inserting the module, or through the debugfs i
17
18 Usage::
19
20 insmod lkdtm.ko [recur_count={>0}] cpo
21 [cpoint_count={>0}]
22
23 recur_count
24 Recursion level for the stack overflow
25 dynamically calculated based on kernel
26 goal of being just large enough to exh
27 value can be seen at `/sys/module/lkdt
28
29 cpoint_name
30 Where in the kernel to trigger the act
31 one of INT_HARDWARE_ENTRY, INT_HW_IRQ_
32 FS_SUBMIT_BH, MEM_SWAPOUT, TIMERADD, S
33
34 cpoint_type
35 Indicates the action to be taken on hi
36 These are numerous, and best queried d
37 of the common ones are PANIC, BUG, EXC
38 See the contents of `/sys/kernel/debug
39 a complete list.
40
41 cpoint_count
42 Indicates the number of times the cras
43 before triggering the action. The defa
44 DIRECT, which always fires immediately
45
46 You can also induce failures by mounting debug
47 <debugfs>/provoke-crash/<crashpoint>. E.g.::
48
49 mount -t debugfs debugfs /sys/kernel/debug
50 echo EXCEPTION > /sys/kernel/debug/provoke-c
51
52 The special file `DIRECT` will induce the acti
53 instrumentation. This mode is the only one ava
54 built for a kernel without KPROBEs support::
55
56 # Instead of having a BUG kill your shell, h
57 cat <(echo WRITE_RO) >/sys/kernel/debug/prov
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