Quellcode-Bibliothek kprobe_example.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Here's a sample kernel module showing the use of kprobes to dump a
 * stack trace and selected registers when kernel_clone() is called.
 *
 * For more information on theory of operation of kprobes, see
 * Documentation/trace/kprobes.rst
 *
 * You will see the trace data in /var/log/messages and on the console
 * whenever kernel_clone() is invoked to create a new process.
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>

static char symbol[KSYM_NAME_LEN] = "kernel_clone";
module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644);

/* For each probe you need to allocate a kprobe structure */
static struct kprobe kp = {
 .symbol_name = symbol,
};

/* kprobe pre_handler: called just before the probed instruction is executed */
static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
{
#ifdef CONFIG_X86
 pr_info("<%s> p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
  p->symbol_name, p->addr, regs->ip, regs->flags);
#endif
#ifdef CONFIG_PPC
 pr_info("<%s> p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
  p->symbol_name, p->addr, regs->nip, regs->msr);
#endif
#ifdef CONFIG_MIPS
 pr_info("<%s> p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
  p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
#endif
#ifdef CONFIG_ARM64
 pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",
  p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
#endif
#ifdef CONFIG_ARM
 pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
  p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);
#endif
#ifdef CONFIG_RISCV
 pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
  p->symbol_name, p->addr, regs->epc, regs->status);
#endif
#ifdef CONFIG_S390
 pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
  p->symbol_name, p->addr, regs->psw.addr, regs->flags);
#endif
#ifdef CONFIG_LOONGARCH
 pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",
  p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);
#endif

 /* A dump_stack() here will give a stack backtrace */
 return 0;
}

/* kprobe post_handler: called after the probed instruction is executed */
static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
    unsigned long flags)
{
#ifdef CONFIG_X86
 pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",
  p->symbol_name, p->addr, regs->flags);
#endif
#ifdef CONFIG_PPC
 pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",
  p->symbol_name, p->addr, regs->msr);
#endif
#ifdef CONFIG_MIPS
 pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
  p->symbol_name, p->addr, regs->cp0_status);
#endif
#ifdef CONFIG_ARM64
 pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",
  p->symbol_name, p->addr, (long)regs->pstate);
#endif
#ifdef CONFIG_ARM
 pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",
  p->symbol_name, p->addr, (long)regs->ARM_cpsr);
#endif
#ifdef CONFIG_RISCV
 pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
  p->symbol_name, p->addr, regs->status);
#endif
#ifdef CONFIG_S390
 pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
  p->symbol_name, p->addr, regs->flags);
#endif
#ifdef CONFIG_LOONGARCH
 pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",
  p->symbol_name, p->addr, regs->csr_estat);
#endif
}

static int __init kprobe_init(void)
{
 int ret;
 kp.pre_handler = handler_pre;
 kp.post_handler = handler_post;

 ret = register_kprobe(&kp);
 if (ret < 0) {
  pr_err("register_kprobe failed, returned %d\n", ret);
  return ret;
 }
 pr_info("Planted kprobe at %p\n", kp.addr);
 return 0;
}

static void __exit kprobe_exit(void)
{
 unregister_kprobe(&kp);
 pr_info("kprobe at %p unregistered\n", kp.addr);
}

module_init(kprobe_init)
module_exit(kprobe_exit)
MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");
MODULE_LICENSE("GPL");