1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/kprobes.h> 4 5 int arch_check_ftrace_location(struct kprobe *p) 6 { 7 if (ftrace_location((unsigned long)p->addr)) 8 p->flags |= KPROBE_FLAG_FTRACE; 9 return 0; 10 } 11 12 /* Ftrace callback handler for kprobes -- called under preepmt disabled */ 13 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 14 struct ftrace_ops *ops, struct ftrace_regs *fregs) 15 { 16 int bit; 17 bool lr_saver = false; 18 struct kprobe *p; 19 struct kprobe_ctlblk *kcb; 20 struct pt_regs *regs; 21 22 bit = ftrace_test_recursion_trylock(ip, parent_ip); 23 if (bit < 0) 24 return; 25 26 regs = ftrace_get_regs(fregs); 27 preempt_disable_notrace(); 28 p = get_kprobe((kprobe_opcode_t *)ip); 29 if (!p) { 30 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE)); 31 if (unlikely(!p) || kprobe_disabled(p)) 32 goto out; 33 lr_saver = true; 34 } 35 36 kcb = get_kprobe_ctlblk(); 37 if (kprobe_running()) { 38 kprobes_inc_nmissed_count(p); 39 } else { 40 unsigned long orig_ip = instruction_pointer(regs); 41 42 if (lr_saver) 43 ip -= MCOUNT_INSN_SIZE; 44 instruction_pointer_set(regs, ip); 45 __this_cpu_write(current_kprobe, p); 46 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 47 if (!p->pre_handler || !p->pre_handler(p, regs)) { 48 /* 49 * Emulate singlestep (and also recover regs->pc) 50 * as if there is a nop 51 */ 52 instruction_pointer_set(regs, 53 (unsigned long)p->addr + MCOUNT_INSN_SIZE); 54 if (unlikely(p->post_handler)) { 55 kcb->kprobe_status = KPROBE_HIT_SSDONE; 56 p->post_handler(p, regs, 0); 57 } 58 instruction_pointer_set(regs, orig_ip); 59 } 60 /* 61 * If pre_handler returns !0, it changes regs->pc. We have to 62 * skip emulating post_handler. 63 */ 64 __this_cpu_write(current_kprobe, NULL); 65 } 66 out: 67 preempt_enable_notrace(); 68 ftrace_test_recursion_unlock(bit); 69 } 70 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 71 72 int arch_prepare_kprobe_ftrace(struct kprobe *p) 73 { 74 p->ainsn.api.insn = NULL; 75 return 0; 76 } 77