1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/kprobes.h> 4 5 /* Ftrace callback handler for kprobes -- called under preepmt disabled */ 6 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 7 struct ftrace_ops *ops, struct ftrace_regs *fregs) 8 { 9 struct kprobe *p; 10 struct pt_regs *regs; 11 struct kprobe_ctlblk *kcb; 12 int bit; 13 14 bit = ftrace_test_recursion_trylock(ip, parent_ip); 15 if (bit < 0) 16 return; 17 18 preempt_disable_notrace(); 19 p = get_kprobe((kprobe_opcode_t *)ip); 20 if (unlikely(!p) || kprobe_disabled(p)) 21 goto out; 22 23 regs = ftrace_get_regs(fregs); 24 kcb = get_kprobe_ctlblk(); 25 if (kprobe_running()) { 26 kprobes_inc_nmissed_count(p); 27 } else { 28 unsigned long orig_ip = instruction_pointer(regs); 29 30 instruction_pointer_set(regs, ip); 31 32 __this_cpu_write(current_kprobe, p); 33 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 34 if (!p->pre_handler || !p->pre_handler(p, regs)) { 35 /* 36 * Emulate singlestep (and also recover regs->pc) 37 * as if there is a nop 38 */ 39 instruction_pointer_set(regs, 40 (unsigned long)p->addr + MCOUNT_INSN_SIZE); 41 if (unlikely(p->post_handler)) { 42 kcb->kprobe_status = KPROBE_HIT_SSDONE; 43 p->post_handler(p, regs, 0); 44 } 45 instruction_pointer_set(regs, orig_ip); 46 } 47 48 /* 49 * If pre_handler returns !0, it changes regs->pc. We have to 50 * skip emulating post_handler. 51 */ 52 __this_cpu_write(current_kprobe, NULL); 53 } 54 out: 55 preempt_enable_notrace(); 56 ftrace_test_recursion_unlock(bit); 57 } 58 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 59 60 int arch_prepare_kprobe_ftrace(struct kprobe *p) 61 { 62 p->ainsn.api.insn = NULL; 63 return 0; 64 } 65