Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * usage: insmod data_breakpoint.ko ksym=<ksym_name>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  * This file is a kernel module that places a breakpoint over ksym_name kernel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  * variable using Hardware Breakpoint register. The corresponding handler which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  * prints a backtrace is invoked every time a write operation is performed on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)  * that variable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)  * Copyright (C) IBM Corporation, 2009
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)  * Author: K.Prasad <prasad@linux.vnet.ibm.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <linux/module.h>	/* Needed by all modules */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <linux/kernel.h>	/* Needed for KERN_INFO */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <linux/init.h>		/* Needed for the macros */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include <linux/kallsyms.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) #include <linux/perf_event.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) #include <linux/hw_breakpoint.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) struct perf_event * __percpu *sample_hbp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) static char ksym_name[KSYM_NAME_LEN] = "jiffies";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 			" write operations on the kernel symbol");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) static void sample_hbp_handler(struct perf_event *bp,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 			       struct perf_sample_data *data,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 			       struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 	printk(KERN_INFO "%s value is changed\n", ksym_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 	dump_stack();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 	printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) static int __init hw_break_module_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 	int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 	struct perf_event_attr attr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	void *addr = __symbol_get(ksym_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	if (!addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 		return -ENXIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	hw_breakpoint_init(&attr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 	attr.bp_addr = (unsigned long)addr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	attr.bp_len = HW_BREAKPOINT_LEN_4;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 	attr.bp_type = HW_BREAKPOINT_W;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	if (IS_ERR((void __force *)sample_hbp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 		ret = PTR_ERR((void __force *)sample_hbp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 		goto fail;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 	printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) fail:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) 	printk(KERN_INFO "Breakpoint registration failed\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) 	return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) static void __exit hw_break_module_exit(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) 	unregister_wide_hw_breakpoint(sample_hbp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) 	symbol_put(ksym_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) 	printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) module_init(hw_break_module_init);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) module_exit(hw_break_module_exit);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) MODULE_LICENSE("GPL");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) MODULE_AUTHOR("K.Prasad");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) MODULE_DESCRIPTION("ksym breakpoint");