From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- samples/kprobes/kprobe_example.c | 129 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 samples/kprobes/kprobe_example.c (limited to 'samples/kprobes/kprobe_example.c') diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c new file mode 100644 index 000000000..53ec6c8b8 --- /dev/null +++ b/samples/kprobes/kprobe_example.c @@ -0,0 +1,129 @@ +// 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 +#include +#include + +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"); -- cgit v1.3.1