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 int bit; 10 bool lr_saver = false; 11 struct kprobe *p; 12 struct kprobe_ctlblk *kcb; 13 struct pt_regs *regs; 14 15 bit = ftrace_test_recursion_trylock(ip, parent_ip); 16 if (bit < 0) 17 return; 18 19 regs = ftrace_get_regs(fregs); 20 preempt_disable_notrace(); 21 p = get_kprobe((kprobe_opcode_t *)ip); 22 if (!p) { 23 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE)); 24 if (unlikely(!p) || kprobe_disabled(p)) 25 goto out; 26 lr_saver = true; 27 } 28 29 kcb = get_kprobe_ctlblk(); 30 if (kprobe_running()) { 31 kprobes_inc_nmissed_count(p); 32 } else { 33 unsigned long orig_ip = instruction_pointer(regs); 34 35 if (lr_saver) 36 ip -= MCOUNT_INSN_SIZE; 37 instruction_pointer_set(regs, ip); 38 __this_cpu_write(current_kprobe, p); 39 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 40 if (!p->pre_handler || !p->pre_handler(p, regs)) { 41 /* 42 * Emulate singlestep (and also recover regs->pc) 43 * as if there is a nop 44 */ 45 instruction_pointer_set(regs, 46 (unsigned long)p->addr + MCOUNT_INSN_SIZE); 47 if (unlikely(p->post_handler)) { 48 kcb->kprobe_status = KPROBE_HIT_SSDONE; 49 p->post_handler(p, regs, 0); 50 } 51 instruction_pointer_set(regs, orig_ip); 52 } 53 /* 54 * If pre_handler returns !0, it changes regs->pc. We have to 55 * skip emulating post_handler. 56 */ 57 __this_cpu_write(current_kprobe, NULL); 58 } 59 out: 60 preempt_enable_notrace(); 61 ftrace_test_recursion_unlock(bit); 62 } 63 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 64 65 int arch_prepare_kprobe_ftrace(struct kprobe *p) 66 { 67 p->ainsn.api.insn = NULL; 68 return 0; 69 } 70