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222 lines
5.2 KiB
222 lines
5.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* arch/parisc/kernel/kprobes.c |
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* |
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* PA-RISC kprobes implementation |
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* |
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* Copyright (c) 2019 Sven Schnelle <[email protected]> |
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*/ |
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#include <linux/types.h> |
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#include <linux/kprobes.h> |
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#include <linux/slab.h> |
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#include <asm/cacheflush.h> |
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#include <asm/patch.h> |
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DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
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int __kprobes arch_prepare_kprobe(struct kprobe *p) |
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{ |
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if ((unsigned long)p->addr & 3UL) |
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return -EINVAL; |
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p->ainsn.insn = get_insn_slot(); |
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if (!p->ainsn.insn) |
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return -ENOMEM; |
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memcpy(p->ainsn.insn, p->addr, |
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MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
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p->opcode = *p->addr; |
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flush_insn_slot(p); |
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return 0; |
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} |
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void __kprobes arch_remove_kprobe(struct kprobe *p) |
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{ |
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if (!p->ainsn.insn) |
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return; |
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free_insn_slot(p->ainsn.insn, 0); |
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p->ainsn.insn = NULL; |
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} |
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void __kprobes arch_arm_kprobe(struct kprobe *p) |
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{ |
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patch_text(p->addr, PARISC_KPROBES_BREAK_INSN); |
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} |
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void __kprobes arch_disarm_kprobe(struct kprobe *p) |
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{ |
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patch_text(p->addr, p->opcode); |
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} |
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static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
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{ |
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kcb->prev_kprobe.kp = kprobe_running(); |
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kcb->prev_kprobe.status = kcb->kprobe_status; |
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} |
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static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
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{ |
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__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
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kcb->kprobe_status = kcb->prev_kprobe.status; |
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} |
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static inline void __kprobes set_current_kprobe(struct kprobe *p) |
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{ |
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__this_cpu_write(current_kprobe, p); |
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} |
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static void __kprobes setup_singlestep(struct kprobe *p, |
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struct kprobe_ctlblk *kcb, struct pt_regs *regs) |
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{ |
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kcb->iaoq[0] = regs->iaoq[0]; |
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kcb->iaoq[1] = regs->iaoq[1]; |
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regs->iaoq[0] = (unsigned long)p->ainsn.insn; |
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mtctl(0, 0); |
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regs->gr[0] |= PSW_R; |
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} |
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int __kprobes parisc_kprobe_break_handler(struct pt_regs *regs) |
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{ |
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struct kprobe *p; |
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struct kprobe_ctlblk *kcb; |
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preempt_disable(); |
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kcb = get_kprobe_ctlblk(); |
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p = get_kprobe((unsigned long *)regs->iaoq[0]); |
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if (!p) { |
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preempt_enable_no_resched(); |
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return 0; |
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} |
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if (kprobe_running()) { |
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/* |
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* We have reentered the kprobe_handler, since another kprobe |
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* was hit while within the handler, we save the original |
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* kprobes and single step on the instruction of the new probe |
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* without calling any user handlers to avoid recursive |
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* kprobes. |
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*/ |
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save_previous_kprobe(kcb); |
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set_current_kprobe(p); |
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kprobes_inc_nmissed_count(p); |
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setup_singlestep(p, kcb, regs); |
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kcb->kprobe_status = KPROBE_REENTER; |
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return 1; |
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} |
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set_current_kprobe(p); |
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kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
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/* If we have no pre-handler or it returned 0, we continue with |
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* normal processing. If we have a pre-handler and it returned |
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* non-zero - which means user handler setup registers to exit |
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* to another instruction, we must skip the single stepping. |
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*/ |
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if (!p->pre_handler || !p->pre_handler(p, regs)) { |
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setup_singlestep(p, kcb, regs); |
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kcb->kprobe_status = KPROBE_HIT_SS; |
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} else { |
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reset_current_kprobe(); |
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preempt_enable_no_resched(); |
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} |
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return 1; |
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} |
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int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs) |
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{ |
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
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struct kprobe *p = kprobe_running(); |
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if (!p) |
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return 0; |
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if (regs->iaoq[0] != (unsigned long)p->ainsn.insn+4) |
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return 0; |
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/* restore back original saved kprobe variables and continue */ |
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if (kcb->kprobe_status == KPROBE_REENTER) { |
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restore_previous_kprobe(kcb); |
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return 1; |
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} |
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/* for absolute branch instructions we can copy iaoq_b. for relative |
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* branch instructions we need to calculate the new address based on the |
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* difference between iaoq_f and iaoq_b. We cannot use iaoq_b without |
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* modificationt because it's based on our ainsn.insn address. |
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*/ |
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if (p->post_handler) |
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p->post_handler(p, regs, 0); |
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switch (regs->iir >> 26) { |
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case 0x38: /* BE */ |
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case 0x39: /* BE,L */ |
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case 0x3a: /* BV */ |
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case 0x3b: /* BVE */ |
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/* for absolute branches, regs->iaoq[1] has already the right |
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* address |
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*/ |
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regs->iaoq[0] = kcb->iaoq[1]; |
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break; |
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default: |
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regs->iaoq[1] = kcb->iaoq[0]; |
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regs->iaoq[1] += (regs->iaoq[1] - regs->iaoq[0]) + 4; |
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regs->iaoq[0] = kcb->iaoq[1]; |
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break; |
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} |
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kcb->kprobe_status = KPROBE_HIT_SSDONE; |
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reset_current_kprobe(); |
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return 1; |
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} |
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static inline void kretprobe_trampoline(void) |
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{ |
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asm volatile("nop"); |
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asm volatile("nop"); |
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} |
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static int __kprobes trampoline_probe_handler(struct kprobe *p, |
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struct pt_regs *regs); |
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static struct kprobe trampoline_p = { |
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.pre_handler = trampoline_probe_handler |
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}; |
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static int __kprobes trampoline_probe_handler(struct kprobe *p, |
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struct pt_regs *regs) |
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{ |
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unsigned long orig_ret_address; |
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orig_ret_address = __kretprobe_trampoline_handler(regs, trampoline_p.addr, NULL); |
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instruction_pointer_set(regs, orig_ret_address); |
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return 1; |
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} |
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
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struct pt_regs *regs) |
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{ |
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ri->ret_addr = (kprobe_opcode_t *)regs->gr[2]; |
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ri->fp = NULL; |
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/* Replace the return addr with trampoline addr. */ |
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regs->gr[2] = (unsigned long)trampoline_p.addr; |
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} |
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int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
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{ |
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return p->addr == trampoline_p.addr; |
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} |
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int __init arch_init_kprobes(void) |
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{ |
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trampoline_p.addr = (kprobe_opcode_t *) |
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dereference_function_descriptor(kretprobe_trampoline); |
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return register_kprobe(&trampoline_p); |
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}
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