i2c: the scheduled I2C RTC driver removal

[linux-2.6-omap-h63xx.git] / Documentation / kprobes.txt

diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index ba26201d50234ba3c78e2c0c9084b1d6d25d7110..cb12ae175aa2de80b3114434c20e64cac4857593 100644 (file)
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -14,6 +14,7 @@ CONTENTS
 8. Kprobes Example
 9. Jprobes Example
 10. Kretprobes Example
 8. Kprobes Example
 9. Jprobes Example
 10. Kretprobes Example

+Appendix A: The kprobes debugfs interface

 
 1. Concepts: Kprobes, Jprobes, Return Probes
 
 
 1. Concepts: Kprobes, Jprobes, Return Probes
 


@@ -246,12 +247,6 @@ control to Kprobes.)  If the probed function is declared asmlinkage,
 fastcall, or anything else that affects how args are passed, the
 handler's declaration must match.
 
 fastcall, or anything else that affects how args are passed, the
 handler's declaration must match.
 

-NOTE: A macro JPROBE_ENTRY is provided to handle architecture-specific
-aliasing of jp->entry. In the interest of portability, it is advised
-to use:
-
-       jp->entry = JPROBE_ENTRY(handler);
-

 register_jprobe() returns 0 on success, or a negative errno otherwise.
 
 4.3 register_kretprobe
 register_jprobe() returns 0 on success, or a negative errno otherwise.
 
 4.3 register_kretprobe


@@ -349,9 +344,12 @@ for instrumentation and error reporting.)
 
 If the number of times a function is called does not match the number
 of times it returns, registering a return probe on that function may
 
 If the number of times a function is called does not match the number
 of times it returns, registering a return probe on that function may

-produce undesirable results.  We have the do_exit() case covered.
-do_execve() and do_fork() are not an issue.  We're unaware of other
-specific cases where this could be a problem.
+produce undesirable results. In such a case, a line:
+kretprobe BUG!: Processing kretprobe d000000000041aa8 @ c00000000004f48c
+gets printed. With this information, one will be able to correlate the
+exact instance of the kretprobe that caused the problem. We have the
+do_exit() case covered. do_execve() and do_fork() are not an issue.
+We're unaware of other specific cases where this could be a problem.

 
 If, upon entry to or exit from a function, the CPU is running on
 a stack other than that of the current task, registering a return
 
 If, upon entry to or exit from a function, the CPU is running on
 a stack other than that of the current task, registering a return


@@ -442,9 +440,10 @@ static int __init kprobe_init(void)
        kp.fault_handler = handler_fault;
        kp.symbol_name = "do_fork";
 
        kp.fault_handler = handler_fault;
        kp.symbol_name = "do_fork";
 

-       if ((ret = register_kprobe(&kp) < 0)) {
+       ret = register_kprobe(&kp);
+       if (ret < 0) {

                printk("register_kprobe failed, returned %d\n", ret);
                printk("register_kprobe failed, returned %d\n", ret);

-               return -1;
+               return ret;

        }
        printk("kprobe registered\n");
        return 0;
        }
        printk("kprobe registered\n");
        return 0;


@@ -513,7 +512,7 @@ long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
 }
 
 static struct jprobe my_jprobe = {
 }
 
 static struct jprobe my_jprobe = {

-       .entry = JPROBE_ENTRY(jdo_fork)
+       .entry = jdo_fork

 };
 
 static int __init jprobe_init(void)
 };
 
 static int __init jprobe_init(void)


@@ -613,3 +612,27 @@ http://www-106.ibm.com/developerworks/library/l-kprobes.html?ca=dgr-lnxw42Kprobe
 http://www.redhat.com/magazine/005mar05/features/kprobes/
 http://www-users.cs.umn.edu/~boutcher/kprobes/
 http://www.linuxsymposium.org/2006/linuxsymposium_procv2.pdf (pages 101-115)
 http://www.redhat.com/magazine/005mar05/features/kprobes/
 http://www-users.cs.umn.edu/~boutcher/kprobes/
 http://www.linuxsymposium.org/2006/linuxsymposium_procv2.pdf (pages 101-115)

+
+
+Appendix A: The kprobes debugfs interface
+
+With recent kernels (> 2.6.20) the list of registered kprobes is visible
+under the /debug/kprobes/ directory (assuming debugfs is mounted at /debug).
+
+/debug/kprobes/list: Lists all registered probes on the system
+
+c015d71a  k  vfs_read+0x0
+c011a316  j  do_fork+0x0
+c03dedc5  r  tcp_v4_rcv+0x0
+
+The first column provides the kernel address where the probe is inserted.
+The second column identifies the type of probe (k - kprobe, r - kretprobe
+and j - jprobe), while the third column specifies the symbol+offset of
+the probe. If the probed function belongs to a module, the module name
+is also specified.
+
+/debug/kprobes/enabled: Turn kprobes ON/OFF
+
+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.