diff options
| -rw-r--r-- | samples/Kconfig | 6 | ||||
| -rw-r--r-- | samples/Makefile | 3 | ||||
| -rw-r--r-- | samples/hw_breakpoint/Makefile | 1 | ||||
| -rw-r--r-- | samples/hw_breakpoint/data_breakpoint.c | 83 |
4 files changed, 92 insertions, 1 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index b75d28c..8458516 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -45,5 +45,11 @@ config SAMPLE_KRETPROBES default m depends on SAMPLE_KPROBES && KRETPROBES +config SAMPLE_HW_BREAKPOINT + tristate "Build kernel hardware breakpoint examples -- loadable module only" + depends on HAVE_HW_BREAKPOINT && m + help + This builds kernel hardware breakpoint example modules. + endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile index 13e4b47..42e1755 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -1,3 +1,4 @@ # Makefile for Linux samples code -obj-$(CONFIG_SAMPLES) += markers/ kobject/ kprobes/ tracepoints/ trace_events/ +obj-$(CONFIG_SAMPLES) += markers/ kobject/ kprobes/ tracepoints/ \ + trace_events/ hw_breakpoint/ diff --git a/samples/hw_breakpoint/Makefile b/samples/hw_breakpoint/Makefile new file mode 100644 index 0000000..0f5c31c --- /dev/null +++ b/samples/hw_breakpoint/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SAMPLE_HW_BREAKPOINT) += data_breakpoint.o diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c new file mode 100644 index 0000000..9cbdbb8 --- /dev/null +++ b/samples/hw_breakpoint/data_breakpoint.c @@ -0,0 +1,83 @@ +/* + * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * usage: insmod data_breakpoint.ko ksym=<ksym_name> + * + * This file is a kernel module that places a breakpoint over ksym_name kernel + * variable using Hardware Breakpoint register. The corresponding handler which + * prints a backtrace is invoked everytime a write operation is performed on + * that variable. + * + * Copyright (C) IBM Corporation, 2009 + */ +#include <linux/module.h> /* Needed by all modules */ +#include <linux/kernel.h> /* Needed for KERN_INFO */ +#include <linux/init.h> /* Needed for the macros */ + +#include <asm/hw_breakpoint.h> + +struct hw_breakpoint sample_hbp; + +static char ksym_name[KSYM_NAME_LEN] = "pid_max"; +module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO); +MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any" + " write operations on the kernel symbol"); + +void sample_hbp_handler(struct hw_breakpoint *temp, struct pt_regs + *temp_regs) +{ + printk(KERN_INFO "%s value is changed\n", ksym_name); + dump_stack(); + printk(KERN_INFO "Dump stack from sample_hbp_handler\n"); +} + +static int __init hw_break_module_init(void) +{ + int ret; + +#ifdef CONFIG_X86 + sample_hbp.info.name = ksym_name; + sample_hbp.info.type = HW_BREAKPOINT_WRITE; + sample_hbp.info.len = HW_BREAKPOINT_LEN_4; +#endif /* CONFIG_X86 */ + + sample_hbp.triggered = (void *)sample_hbp_handler; + + ret = register_kernel_hw_breakpoint(&sample_hbp); + + if (ret < 0) { + printk(KERN_INFO "Breakpoint registration failed\n"); + return ret; + } else + printk(KERN_INFO "HW Breakpoint for %s write installed\n", + ksym_name); + + return 0; +} + +static void __exit hw_break_module_exit(void) +{ + unregister_kernel_hw_breakpoint(&sample_hbp); + printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name); +} + +module_init(hw_break_module_init); +module_exit(hw_break_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("K.Prasad"); +MODULE_DESCRIPTION("ksym breakpoint"); |
