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Diffstat (limited to 'Documentation/kprobes.txt')
| -rw-r--r-- | Documentation/kprobes.txt | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 0cfb00fd86ff..4bbeca8483ed 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -22,8 +22,9 @@ Appendix B: The kprobes sysctl interface Kprobes enables you to dynamically break into any kernel routine and collect debugging and performance information non-disruptively. You -can trap at almost any kernel code address, specifying a handler +can trap at almost any kernel code address(*), specifying a handler routine to be invoked when the breakpoint is hit. +(*: some parts of the kernel code can not be trapped, see 1.5 Blacklist) There are currently three types of probes: kprobes, jprobes, and kretprobes (also called return probes). A kprobe can be inserted @@ -273,6 +274,19 @@ using one of the following techniques: or - Execute 'sysctl -w debug.kprobes_optimization=n' +1.5 Blacklist + +Kprobes can probe most of the kernel except itself. This means +that there are some functions where kprobes cannot probe. Probing +(trapping) such functions can cause a recursive trap (e.g. double +fault) or the nested probe handler may never be called. +Kprobes manages such functions as a blacklist. +If you want to add a function into the blacklist, you just need +to (1) include linux/kprobes.h and (2) use NOKPROBE_SYMBOL() macro +to specify a blacklisted function. +Kprobes checks the given probe address against the blacklist and +rejects registering it, if the given address is in the blacklist. + 2. Architectures Supported Kprobes, jprobes, and return probes are implemented on the following |