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