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