Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751816AbXIYIn6 (ORCPT ); Tue, 25 Sep 2007 04:43:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750904AbXIYInt (ORCPT ); Tue, 25 Sep 2007 04:43:49 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:60204 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751423AbXIYInq (ORCPT ); Tue, 25 Sep 2007 04:43:46 -0400 Date: Tue, 25 Sep 2007 14:13:33 +0530 From: Ananth N Mavinakayanahalli To: Randy Dunlap Cc: lkml , prasanna@in.ibm.com, anil.s.keshavamurthy@intel.com, hch@infradead.org, mathieu.desnoyers@polymtl.ca, akpm , sam@ravnborg.org, davem@davemloft.net Subject: Re: [PATCH/RFC] samples/: move kprobes sources to samples Message-ID: <20070925084333.GA16077@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20070924145828.d279abac.randy.dunlap@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070924145828.d279abac.randy.dunlap@oracle.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16943 Lines: 564 On Mon, Sep 24, 2007 at 02:58:28PM -0700, Randy Dunlap wrote: > > This is RFC patch 2/2. > Patch 1/2 introduces the samples/ infrastructure: > http://lkml.org/lkml/2007/9/24/397 > > > --- > > From: Randy Dunlap > > Move kprobes source files from Documentation/kprobes.txt to > samples/kprobes/ and add them to the build system. > > Fix sparse warnings in all 3 kprobes samples source files. > > Although kprobe-example.c is x86-specific, make it build on any > platform by surrounding some code in ifdef/endif blocks. > > Signed-off-by: Randy Dunlap Thanks Randy for kicking this off. I've updated kprobe_example.c to work on powerpc also. In addition I have: o Removed samples/Kbuild so the build goes on fine o Modified examples slightly to display output better (cosmetic) o Changed the kretprobe_example.c to probe do_fork and log the new pid o Fixed code per roel's nitpicks o Renamed kretprobe-example.c to kretprobe_example.c for consistancy Signed-off-by: Randy Dunlap Signed-off-by: Ananth N Mavinakayanahalli --- samples/Kbuild | 2 Documentation/kprobes.txt | 206 ------------------------------------ samples/Kconfig | 5 samples/Makefile | 3 samples/kprobes/Makefile | 5 samples/kprobes/jprobe_example.c | 69 ++++++++++++ samples/kprobes/kprobe_example.c | 92 ++++++++++++++++ samples/kprobes/kretprobe_example.c | 61 ++++++++++ 8 files changed, 240 insertions(+), 203 deletions(-) Index: linux-2.6.23-rc7/samples/kprobes/Makefile =================================================================== --- /dev/null +++ linux-2.6.23-rc7/samples/kprobes/Makefile @@ -0,0 +1,5 @@ +# builds the kprobes example kernel modules; +# then to use one (as root): insmod + +obj-$(CONFIG_SAMPLE_KPROBES) += kprobe_example.o jprobe_example.o \ + kretprobe_example.o Index: linux-2.6.23-rc7/samples/Kconfig =================================================================== --- linux-2.6.23-rc7.orig/samples/Kconfig +++ linux-2.6.23-rc7/samples/Kconfig @@ -7,5 +7,10 @@ menuconfig SAMPLES if SAMPLES +config SAMPLE_KPROBES + tristate "Build kprobes examples -- loadable modules only" + depends on KPROBES && m + help + This builds several kprobes example modules. endif # SAMPLES Index: linux-2.6.23-rc7/samples/kprobes/jprobe_example.c =================================================================== --- /dev/null +++ linux-2.6.23-rc7/samples/kprobes/jprobe_example.c @@ -0,0 +1,69 @@ +/*jprobe-example.c */ +/* + * Here's a sample kernel module showing the use of jprobes to dump + * the arguments of do_fork(). + * + * Build and insert the kernel module as done in the kprobe example. + * You will see the trace data in /var/log/messages and on the + * console whenever do_fork() is invoked to create a new process. + * (Some messages may be suppressed if syslogd is configured to + * eliminate duplicate messages.) + */ + +#include +#include +#include +#include +#include +#include + +/* + * Jumper probe for do_fork. + * Mirror principle enables access to arguments of the probed routine + * from the probe handler. + */ +static const char *probed_func = "do_fork"; + +/* Proxy routine having the same arguments as actual do_fork() routine */ +static long jdo_fork(unsigned long clone_flags, unsigned long stack_start, + struct pt_regs *regs, unsigned long stack_size, + int __user * parent_tidptr, int __user * child_tidptr) +{ + printk("jprobe: clone_flags = 0x%lx, stack_size = 0x%lx, regs = 0x%p\n", + clone_flags, stack_size, regs); + + /* Always end with a call to jprobe_return(). */ + jprobe_return(); + + /*NOTREACHED*/ + return 0; +} + +static struct jprobe my_jprobe = { + .entry = jdo_fork +}; + +static int __init jprobe_init(void) +{ + int ret; + my_jprobe.kp.symbol_name = (char *)probed_func; + + ret = register_jprobe(&my_jprobe); + if (ret < 0) { + printk("register_jprobe failed, returned %d\n", ret); + return -1; + } + printk("Planted jprobe at %p, handler addr %p\n", + my_jprobe.kp.addr, my_jprobe.entry); + return 0; +} + +static void __exit jprobe_exit(void) +{ + unregister_jprobe(&my_jprobe); + printk("jprobe on %s unregistered\n", probed_func); +} + +module_init(jprobe_init) +module_exit(jprobe_exit) +MODULE_LICENSE("GPL"); Index: linux-2.6.23-rc7/samples/kprobes/kprobe_example.c =================================================================== --- /dev/null +++ linux-2.6.23-rc7/samples/kprobes/kprobe_example.c @@ -0,0 +1,92 @@ +/*kprobe_example.c*/ +/* + * NOTE: This example is works on x86 and powerpc. + * Here's a sample kernel module showing the use of kprobes to dump a + * stack trace and selected registers when do_fork() is called. + * + * You will see the trace data in /var/log/messages and on the console + * whenever do_fork() is invoked to create a new process. + */ + +#include +#include +#include +#include +#include + +/*For each probe you need to allocate a kprobe structure*/ +static struct kprobe kp; + +static const char *probed_func = "do_fork"; + +/*kprobe pre_handler: called just before the probed instruction is executed*/ +static int handler_pre(struct kprobe *p, struct pt_regs *regs) +{ +#ifdef CONFIG_X86_32 + printk("pre_handler: p->addr = 0x%p, eip = %lx, eflags = 0x%lx\n", + p->addr, regs->eip, regs->eflags); +#endif +#ifdef CONFIG_X86_64 + printk("pre_handler: p->addr = 0x%p, rip = %lx, eflags = 0x%lx\n", + p->addr, regs->rip, regs->eflags); +#endif +#ifdef CONFIG_PPC + printk("pre_handler: p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n", + p->addr, regs->nip, regs->msr); +#endif + + /* A dump_stack() here will give a stack backtrace */ + return 0; +} + +/*kprobe post_handler: called after the probed instruction is executed*/ +static void handler_post(struct kprobe *p, struct pt_regs *regs, unsigned long flags) +{ +#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64) + printk("post_handler: p->addr = 0x%p, eflags = 0x%lx\n", + p->addr, regs->eflags); +#endif +#ifdef CONFIG_PPC + printk("post_handler: p->addr = 0x%p, msr = 0x%lx\n", + p->addr, regs->msr); +#endif +} + +/* fault_handler: this is called if an exception is generated for any + * instruction within the pre- or post-handler, or when Kprobes + * single-steps the probed instruction. + */ +static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) +{ + printk("fault_handler: p->addr = 0x%p, trap #%dn", + p->addr, trapnr); + /* Return 0 because we don't handle the fault. */ + return 0; +} + +static int __init kprobe_init(void) +{ + int ret; + kp.pre_handler = handler_pre; + kp.post_handler = handler_post; + kp.fault_handler = handler_fault; + kp.symbol_name = (char *)probed_func; + + ret = register_kprobe(&kp); + if (ret < 0) { + printk("register_kprobe failed, returned %d\n", ret); + return ret; + } + printk("Planted kprobe at %p\n", kp.addr); + return 0; +} + +static void __exit kprobe_exit(void) +{ + unregister_kprobe(&kp); + printk("kprobe at %p unregistered\n", kp.addr); +} + +module_init(kprobe_init) +module_exit(kprobe_exit) +MODULE_LICENSE("GPL"); Index: linux-2.6.23-rc7/samples/kprobes/kretprobe_example.c =================================================================== --- /dev/null +++ linux-2.6.23-rc7/samples/kprobes/kretprobe_example.c @@ -0,0 +1,61 @@ +/*kretprobe_example.c*/ +/* + * Here's a sample kernel module showing the use of return probes to + * report failed calls to sys_open(). + * + * Build and insert the kernel module as done in the kprobe example. + * You will see the trace data in /var/log/messages and on the console + * whenever sys_open() returns a negative value. (Some messages + * may be suppressed if syslogd is configured to eliminate duplicate + * messages.) + */ + +#include +#include +#include +#include + +static const char *probed_func = "do_fork"; + +/* Return-probe handler: If the probed function fails, log the return value. */ +static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs) +{ + int retval = regs_return_value(regs); + + printk("%s returns %d\n", probed_func, retval); + return 0; +} + +static struct kretprobe my_kretprobe = { + .handler = ret_handler, + /* Probe up to 20 instances concurrently. */ + .maxactive = 20 +}; + +static int __init kretprobe_init(void) +{ + int ret; + my_kretprobe.kp.symbol_name = (char *)probed_func; + + ret = register_kretprobe(&my_kretprobe); + if (ret < 0) { + printk("register_kretprobe failed, returned %d\n", ret); + return -1; + } + printk("Planted return probe at %p\n", my_kretprobe.kp.addr); + return 0; +} + +static void __exit kretprobe_exit(void) +{ + unregister_kretprobe(&my_kretprobe); + printk("kretprobe on %s unregistered\n", probed_func); + + /* nmissed > 0 suggests that maxactive was set too low. */ + printk("Missed probing %d instances of %s\n", + my_kretprobe.nmissed, probed_func); +} + +module_init(kretprobe_init) +module_exit(kretprobe_exit) +MODULE_LICENSE("GPL"); Index: linux-2.6.23-rc7/Documentation/kprobes.txt =================================================================== --- linux-2.6.23-rc7.orig/Documentation/kprobes.txt +++ linux-2.6.23-rc7/Documentation/kprobes.txt @@ -166,7 +166,8 @@ code mapping. The Kprobes API includes a "register" function and an "unregister" function for each type of probe. Here are terse, mini-man-page specifications for these functions and the associated probe handlers -that you'll write. See the latter half of this document for examples. +that you'll write. See the files in the samples/kprobes/ sub-directory +for examples. 4.1 register_kprobe @@ -392,220 +393,15 @@ e. Watchpoint probes (which fire on data 8. Kprobes Example -Here's a sample kernel module showing the use of kprobes to dump a -stack trace and selected i386 registers when do_fork() is called. ------ cut here ----- -/*kprobe_example.c*/ -#include -#include -#include -#include - -/*For each probe you need to allocate a kprobe structure*/ -static struct kprobe kp; - -/*kprobe pre_handler: called just before the probed instruction is executed*/ -int handler_pre(struct kprobe *p, struct pt_regs *regs) -{ - printk("pre_handler: p->addr=0x%p, eip=%lx, eflags=0x%lx\n", - p->addr, regs->eip, regs->eflags); - dump_stack(); - return 0; -} - -/*kprobe post_handler: called after the probed instruction is executed*/ -void handler_post(struct kprobe *p, struct pt_regs *regs, unsigned long flags) -{ - printk("post_handler: p->addr=0x%p, eflags=0x%lx\n", - p->addr, regs->eflags); -} - -/* fault_handler: this is called if an exception is generated for any - * instruction within the pre- or post-handler, or when Kprobes - * single-steps the probed instruction. - */ -int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) -{ - printk("fault_handler: p->addr=0x%p, trap #%dn", - p->addr, trapnr); - /* Return 0 because we don't handle the fault. */ - return 0; -} - -static int __init kprobe_init(void) -{ - int ret; - kp.pre_handler = handler_pre; - kp.post_handler = handler_post; - kp.fault_handler = handler_fault; - kp.symbol_name = "do_fork"; - - ret = register_kprobe(&kp); - if (ret < 0) { - printk("register_kprobe failed, returned %d\n", ret); - return ret; - } - printk("kprobe registered\n"); - return 0; -} - -static void __exit kprobe_exit(void) -{ - unregister_kprobe(&kp); - printk("kprobe unregistered\n"); -} - -module_init(kprobe_init) -module_exit(kprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -You can build the kernel module, kprobe-example.ko, using the following -Makefile: ------ cut here ----- -obj-m := kprobe-example.o -KDIR := /lib/modules/$(shell uname -r)/build -PWD := $(shell pwd) -default: - $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules -clean: - rm -f *.mod.c *.ko *.o ------ cut here ----- - -$ make -$ su - -... -# insmod kprobe-example.ko - -You will see the trace data in /var/log/messages and on the console -whenever do_fork() is invoked to create a new process. +See samples/kprobes/kprobe_example.c. 9. Jprobes Example -Here's a sample kernel module showing the use of jprobes to dump -the arguments of do_fork(). ------ cut here ----- -/*jprobe-example.c */ -#include -#include -#include -#include -#include - -/* - * Jumper probe for do_fork. - * Mirror principle enables access to arguments of the probed routine - * from the probe handler. - */ - -/* Proxy routine having the same arguments as actual do_fork() routine */ -long jdo_fork(unsigned long clone_flags, unsigned long stack_start, - struct pt_regs *regs, unsigned long stack_size, - int __user * parent_tidptr, int __user * child_tidptr) -{ - printk("jprobe: clone_flags=0x%lx, stack_size=0x%lx, regs=0x%p\n", - clone_flags, stack_size, regs); - /* Always end with a call to jprobe_return(). */ - jprobe_return(); - /*NOTREACHED*/ - return 0; -} - -static struct jprobe my_jprobe = { - .entry = jdo_fork -}; - -static int __init jprobe_init(void) -{ - int ret; - my_jprobe.kp.symbol_name = "do_fork"; - - if ((ret = register_jprobe(&my_jprobe)) <0) { - printk("register_jprobe failed, returned %d\n", ret); - return -1; - } - printk("Planted jprobe at %p, handler addr %p\n", - my_jprobe.kp.addr, my_jprobe.entry); - return 0; -} - -static void __exit jprobe_exit(void) -{ - unregister_jprobe(&my_jprobe); - printk("jprobe unregistered\n"); -} - -module_init(jprobe_init) -module_exit(jprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -Build and insert the kernel module as shown in the above kprobe -example. You will see the trace data in /var/log/messages and on -the console whenever do_fork() is invoked to create a new process. -(Some messages may be suppressed if syslogd is configured to -eliminate duplicate messages.) +See samples/kprobes/jprobe_example.c. 10. Kretprobes Example -Here's a sample kernel module showing the use of return probes to -report failed calls to sys_open(). ------ cut here ----- -/*kretprobe-example.c*/ -#include -#include -#include - -static const char *probed_func = "sys_open"; - -/* Return-probe handler: If the probed function fails, log the return value. */ -static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs) -{ - int retval = regs_return_value(regs); - if (retval < 0) { - printk("%s returns %d\n", probed_func, retval); - } - return 0; -} - -static struct kretprobe my_kretprobe = { - .handler = ret_handler, - /* Probe up to 20 instances concurrently. */ - .maxactive = 20 -}; - -static int __init kretprobe_init(void) -{ - int ret; - my_kretprobe.kp.symbol_name = (char *)probed_func; - - if ((ret = register_kretprobe(&my_kretprobe)) < 0) { - printk("register_kretprobe failed, returned %d\n", ret); - return -1; - } - printk("Planted return probe at %p\n", my_kretprobe.kp.addr); - return 0; -} - -static void __exit kretprobe_exit(void) -{ - unregister_kretprobe(&my_kretprobe); - printk("kretprobe unregistered\n"); - /* nmissed > 0 suggests that maxactive was set too low. */ - printk("Missed probing %d instances of %s\n", - my_kretprobe.nmissed, probed_func); -} - -module_init(kretprobe_init) -module_exit(kretprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -Build and insert the kernel module as shown in the above kprobe -example. You will see the trace data in /var/log/messages and on the -console whenever sys_open() returns a negative value. (Some messages -may be suppressed if syslogd is configured to eliminate duplicate -messages.) +See samples/kprobes/kretprobe_example.c. For additional information on Kprobes, refer to the following URLs: http://www-106.ibm.com/developerworks/library/l-kprobes.html?ca=dgr-lnxw42Kprobe Index: linux-2.6.23-rc7/samples/Makefile =================================================================== --- /dev/null +++ linux-2.6.23-rc7/samples/Makefile @@ -0,0 +1,3 @@ +# Makefile for Linux samples code + +obj-$(CONFIG_SAMPLES) += kprobes/ Index: linux-2.6.23-rc7/samples/Kbuild =================================================================== --- linux-2.6.23-rc7.orig/samples/Kbuild +++ /dev/null @@ -1,2 +0,0 @@ -# Makefile for Linux samples code - - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/