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 if (unlikely(kprobe_ftrace_disabled)) 16 return; 17 18 bit = ftrace_test_recursion_trylock(ip, parent_ip); 19 if (bit < 0) 20 return; 21 22 regs = ftrace_get_regs(fregs); 23 p = get_kprobe((kprobe_opcode_t *)ip); 24 if (!p) { 25 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE)); 26 if (unlikely(!p) || kprobe_disabled(p)) 27 goto out; 28 lr_saver = true; 29 } 30 31 kcb = get_kprobe_ctlblk(); 32 if (kprobe_running()) { 33 kprobes_inc_nmissed_count(p); 34 } else { 35 unsigned long orig_ip = instruction_pointer(regs); 36 37 if (lr_saver) 38 ip -= MCOUNT_INSN_SIZE; 39 instruction_pointer_set(regs, ip); 40 __this_cpu_write(current_kprobe, p); 41 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 42 if (!p->pre_handler || !p->pre_handler(p, regs)) { 43 /* 44 * Emulate singlestep (and also recover regs->pc) 45 * as if there is a nop 46 */ 47 instruction_pointer_set(regs, 48 (unsigned long)p->addr + MCOUNT_INSN_SIZE); 49 if (unlikely(p->post_handler)) { 50 kcb->kprobe_status = KPROBE_HIT_SSDONE; 51 p->post_handler(p, regs, 0); 52 } 53 instruction_pointer_set(regs, orig_ip); 54 } 55 /* 56 * If pre_handler returns !0, it changes regs->pc. We have to 57 * skip emulating post_handler. 58 */ 59 __this_cpu_write(current_kprobe, NULL); 60 } 61 out: 62 ftrace_test_recursion_unlock(bit); 63 } 64 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 65 66 int arch_prepare_kprobe_ftrace(struct kprobe *p) 67 { 68 p->ainsn.api.insn = NULL; 69 return 0; 70 } 71