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authorMasami Hiramatsu <mhiramat@redhat.com>2009-04-06 19:01:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-07 08:31:08 -0700
commitde5bd88d5a5cce3cacea904d3503e5ebdb3852a2 (patch)
treeda24ac8b38d371ee03a21ed0f3647c518689ebd3 /Documentation/kprobes.txt
parente579abeb58eb4b8d7321c6eb44dd9e2d0cbaebaa (diff)
downloadlinux-linaro-android-de5bd88d5a5cce3cacea904d3503e5ebdb3852a2.tar.gz
kprobes: support per-kprobe disabling
Add disable_kprobe() and enable_kprobe() to disable/enable kprobes temporarily. disable_kprobe() asynchronously disables probe handlers of specified kprobe. So, after calling it, some handlers can be called at a while. enable_kprobe() enables specified kprobe. aggr_pre_handler and aggr_post_handler check disabled probes. On the other hand aggr_break_handler and aggr_fault_handler don't check it because these handlers will be called while executing pre or post handlers and usually those help error handling. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/kprobes.txt')
-rw-r--r--Documentation/kprobes.txt34
1 files changed, 28 insertions, 6 deletions
diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 48b3de90eb1..f609af242d6 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -212,7 +212,9 @@ hit, Kprobes calls kp->pre_handler. After the probed instruction
is single-stepped, Kprobe calls kp->post_handler. If a fault
occurs during execution of kp->pre_handler or kp->post_handler,
or during single-stepping of the probed instruction, Kprobes calls
-kp->fault_handler. Any or all handlers can be NULL.
+kp->fault_handler. Any or all handlers can be NULL. If kp->flags
+is set KPROBE_FLAG_DISABLED, that kp will be registered but disabled,
+so, it's handlers aren't hit until calling enable_kprobe(kp).
NOTE:
1. With the introduction of the "symbol_name" field to struct kprobe,
@@ -363,6 +365,22 @@ probes) in the specified array, they clear the addr field of those
incorrect probes. However, other probes in the array are
unregistered correctly.
+4.7 disable_kprobe
+
+#include <linux/kprobes.h>
+int disable_kprobe(struct kprobe *kp);
+
+Temporarily disables the specified kprobe. You can enable it again by using
+enable_kprobe(). You must specify the kprobe which has been registered.
+
+4.8 enable_kprobe
+
+#include <linux/kprobes.h>
+int enable_kprobe(struct kprobe *kp);
+
+Enables kprobe which has been disabled by disable_kprobe(). You must specify
+the kprobe which has been registered.
+
5. Kprobes Features and Limitations
Kprobes allows multiple probes at the same address. Currently,
@@ -500,10 +518,14 @@ the probe. If the probed function belongs to a module, the module name
is also specified. Following columns show probe status. If the probe is on
a virtual address that is no longer valid (module init sections, module
virtual addresses that correspond to modules that've been unloaded),
-such probes are marked with [GONE].
+such probes are marked with [GONE]. If the probe is temporarily disabled,
+such probes are marked with [DISABLED].
-/debug/kprobes/enabled: Turn kprobes ON/OFF
+/debug/kprobes/enabled: Turn kprobes ON/OFF forcibly.
-Provides a knob to globally turn registered kprobes ON or OFF. By default,
-all kprobes are enabled. By echoing "0" to this file, all registered probes
-will be disarmed, till such time a "1" is echoed to this file.
+Provides a knob to globally and forcibly turn registered kprobes ON or OFF.
+By default, all kprobes are enabled. By echoing "0" to this file, all
+registered probes will be disarmed, till such time a "1" is echoed to this
+file. Note that this knob just disarms and arms all kprobes and doesn't
+change each probe's disabling state. This means that disabled kprobes (marked
+[DISABLED]) will be not enabled if you turn ON all kprobes by this knob.