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489 lines
13 KiB
489 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* arch/sparc64/kernel/kprobes.c |
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* |
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* Copyright (C) 2004 David S. Miller <[email protected]> |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/kprobes.h> |
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#include <linux/extable.h> |
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#include <linux/kdebug.h> |
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#include <linux/slab.h> |
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#include <linux/context_tracking.h> |
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#include <asm/signal.h> |
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#include <asm/cacheflush.h> |
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#include <linux/uaccess.h> |
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/* We do not have hardware single-stepping on sparc64. |
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* So we implement software single-stepping with breakpoint |
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* traps. The top-level scheme is similar to that used |
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* in the x86 kprobes implementation. |
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* |
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* In the kprobe->ainsn.insn[] array we store the original |
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* instruction at index zero and a break instruction at |
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* index one. |
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* |
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* When we hit a kprobe we: |
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* - Run the pre-handler |
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* - Remember "regs->tnpc" and interrupt level stored in |
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* "regs->tstate" so we can restore them later |
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* - Disable PIL interrupts |
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* - Set regs->tpc to point to kprobe->ainsn.insn[0] |
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* - Set regs->tnpc to point to kprobe->ainsn.insn[1] |
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* - Mark that we are actively in a kprobe |
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* |
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* At this point we wait for the second breakpoint at |
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* kprobe->ainsn.insn[1] to hit. When it does we: |
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* - Run the post-handler |
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* - Set regs->tpc to "remembered" regs->tnpc stored above, |
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* restore the PIL interrupt level in "regs->tstate" as well |
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* - Make any adjustments necessary to regs->tnpc in order |
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* to handle relative branches correctly. See below. |
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* - Mark that we are no longer actively in a kprobe. |
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*/ |
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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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struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; |
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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 & 0x3UL) |
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return -EILSEQ; |
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p->ainsn.insn[0] = *p->addr; |
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flushi(&p->ainsn.insn[0]); |
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p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2; |
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flushi(&p->ainsn.insn[1]); |
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p->opcode = *p->addr; |
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return 0; |
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} |
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void __kprobes arch_arm_kprobe(struct kprobe *p) |
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{ |
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*p->addr = BREAKPOINT_INSTRUCTION; |
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flushi(p->addr); |
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} |
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void __kprobes arch_disarm_kprobe(struct kprobe *p) |
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{ |
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*p->addr = p->opcode; |
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flushi(p->addr); |
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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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kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc; |
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kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil; |
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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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kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc; |
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kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil; |
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} |
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static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
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struct kprobe_ctlblk *kcb) |
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{ |
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__this_cpu_write(current_kprobe, p); |
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kcb->kprobe_orig_tnpc = regs->tnpc; |
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kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL); |
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} |
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static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs, |
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struct kprobe_ctlblk *kcb) |
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{ |
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regs->tstate |= TSTATE_PIL; |
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/*single step inline, if it a breakpoint instruction*/ |
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if (p->opcode == BREAKPOINT_INSTRUCTION) { |
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regs->tpc = (unsigned long) p->addr; |
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regs->tnpc = kcb->kprobe_orig_tnpc; |
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} else { |
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regs->tpc = (unsigned long) &p->ainsn.insn[0]; |
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regs->tnpc = (unsigned long) &p->ainsn.insn[1]; |
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} |
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} |
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static int __kprobes kprobe_handler(struct pt_regs *regs) |
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{ |
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struct kprobe *p; |
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void *addr = (void *) regs->tpc; |
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int ret = 0; |
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struct kprobe_ctlblk *kcb; |
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/* |
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* We don't want to be preempted for the entire |
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* duration of kprobe processing |
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*/ |
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preempt_disable(); |
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kcb = get_kprobe_ctlblk(); |
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if (kprobe_running()) { |
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p = get_kprobe(addr); |
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if (p) { |
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if (kcb->kprobe_status == KPROBE_HIT_SS) { |
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regs->tstate = ((regs->tstate & ~TSTATE_PIL) | |
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kcb->kprobe_orig_tstate_pil); |
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goto no_kprobe; |
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} |
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/* We have reentered the kprobe_handler(), since |
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* another probe was hit while within the handler. |
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* We here save the original kprobes variables and |
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* just single step on the instruction of the new probe |
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* without calling any user handlers. |
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*/ |
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save_previous_kprobe(kcb); |
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set_current_kprobe(p, regs, kcb); |
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kprobes_inc_nmissed_count(p); |
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kcb->kprobe_status = KPROBE_REENTER; |
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prepare_singlestep(p, regs, kcb); |
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return 1; |
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} else if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { |
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/* The breakpoint instruction was removed by |
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* another cpu right after we hit, no further |
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* handling of this interrupt is appropriate |
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*/ |
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ret = 1; |
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} |
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goto no_kprobe; |
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} |
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p = get_kprobe(addr); |
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if (!p) { |
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if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { |
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/* |
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* The breakpoint instruction was removed right |
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* after we hit it. Another cpu has removed |
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* either a probepoint or a debugger breakpoint |
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* at this address. In either case, no further |
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* handling of this interrupt is appropriate. |
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*/ |
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ret = 1; |
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} |
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/* Not one of ours: let kernel handle it */ |
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goto no_kprobe; |
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} |
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set_current_kprobe(p, regs, kcb); |
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kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
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if (p->pre_handler && p->pre_handler(p, regs)) { |
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reset_current_kprobe(); |
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preempt_enable_no_resched(); |
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return 1; |
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} |
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prepare_singlestep(p, regs, kcb); |
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kcb->kprobe_status = KPROBE_HIT_SS; |
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return 1; |
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no_kprobe: |
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preempt_enable_no_resched(); |
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return ret; |
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} |
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/* If INSN is a relative control transfer instruction, |
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* return the corrected branch destination value. |
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* |
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* regs->tpc and regs->tnpc still hold the values of the |
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* program counters at the time of trap due to the execution |
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* of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1] |
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* |
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*/ |
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static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p, |
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struct pt_regs *regs) |
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{ |
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unsigned long real_pc = (unsigned long) p->addr; |
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/* Branch not taken, no mods necessary. */ |
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if (regs->tnpc == regs->tpc + 0x4UL) |
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return real_pc + 0x8UL; |
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/* The three cases are call, branch w/prediction, |
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* and traditional branch. |
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*/ |
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if ((insn & 0xc0000000) == 0x40000000 || |
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(insn & 0xc1c00000) == 0x00400000 || |
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(insn & 0xc1c00000) == 0x00800000) { |
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unsigned long ainsn_addr; |
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ainsn_addr = (unsigned long) &p->ainsn.insn[0]; |
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/* The instruction did all the work for us |
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* already, just apply the offset to the correct |
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* instruction location. |
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*/ |
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return (real_pc + (regs->tnpc - ainsn_addr)); |
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} |
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/* It is jmpl or some other absolute PC modification instruction, |
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* leave NPC as-is. |
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*/ |
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return regs->tnpc; |
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} |
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/* If INSN is an instruction which writes it's PC location |
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* into a destination register, fix that up. |
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*/ |
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static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn, |
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unsigned long real_pc) |
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{ |
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unsigned long *slot = NULL; |
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/* Simplest case is 'call', which always uses %o7 */ |
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if ((insn & 0xc0000000) == 0x40000000) { |
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slot = ®s->u_regs[UREG_I7]; |
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} |
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/* 'jmpl' encodes the register inside of the opcode */ |
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if ((insn & 0xc1f80000) == 0x81c00000) { |
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unsigned long rd = ((insn >> 25) & 0x1f); |
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if (rd <= 15) { |
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slot = ®s->u_regs[rd]; |
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} else { |
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/* Hard case, it goes onto the stack. */ |
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flushw_all(); |
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rd -= 16; |
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slot = (unsigned long *) |
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(regs->u_regs[UREG_FP] + STACK_BIAS); |
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slot += rd; |
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} |
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} |
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if (slot != NULL) |
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*slot = real_pc; |
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} |
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/* |
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* Called after single-stepping. p->addr is the address of the |
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* instruction which has been replaced by the breakpoint |
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* instruction. To avoid the SMP problems that can occur when we |
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* temporarily put back the original opcode to single-step, we |
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* single-stepped a copy of the instruction. The address of this |
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* copy is &p->ainsn.insn[0]. |
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* |
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* This function prepares to return from the post-single-step |
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* breakpoint trap. |
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*/ |
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static void __kprobes resume_execution(struct kprobe *p, |
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struct pt_regs *regs, struct kprobe_ctlblk *kcb) |
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{ |
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u32 insn = p->ainsn.insn[0]; |
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regs->tnpc = relbranch_fixup(insn, p, regs); |
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/* This assignment must occur after relbranch_fixup() */ |
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regs->tpc = kcb->kprobe_orig_tnpc; |
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retpc_fixup(regs, insn, (unsigned long) p->addr); |
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regs->tstate = ((regs->tstate & ~TSTATE_PIL) | |
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kcb->kprobe_orig_tstate_pil); |
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} |
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static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
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{ |
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struct kprobe *cur = kprobe_running(); |
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
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if (!cur) |
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return 0; |
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if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
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kcb->kprobe_status = KPROBE_HIT_SSDONE; |
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cur->post_handler(cur, regs, 0); |
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} |
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resume_execution(cur, regs, kcb); |
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/*Restore back the original saved kprobes 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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goto out; |
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} |
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reset_current_kprobe(); |
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out: |
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preempt_enable_no_resched(); |
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return 1; |
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} |
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int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
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{ |
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struct kprobe *cur = kprobe_running(); |
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
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const struct exception_table_entry *entry; |
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switch(kcb->kprobe_status) { |
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case KPROBE_HIT_SS: |
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case KPROBE_REENTER: |
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/* |
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* We are here because the instruction being single |
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* stepped caused a page fault. We reset the current |
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* kprobe and the tpc points back to the probe address |
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* and allow the page fault handler to continue as a |
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* normal page fault. |
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*/ |
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regs->tpc = (unsigned long)cur->addr; |
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regs->tnpc = kcb->kprobe_orig_tnpc; |
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regs->tstate = ((regs->tstate & ~TSTATE_PIL) | |
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kcb->kprobe_orig_tstate_pil); |
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if (kcb->kprobe_status == KPROBE_REENTER) |
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restore_previous_kprobe(kcb); |
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else |
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reset_current_kprobe(); |
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preempt_enable_no_resched(); |
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break; |
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case KPROBE_HIT_ACTIVE: |
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case KPROBE_HIT_SSDONE: |
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/* |
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* In case the user-specified fault handler returned |
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* zero, try to fix up. |
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*/ |
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entry = search_exception_tables(regs->tpc); |
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if (entry) { |
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regs->tpc = entry->fixup; |
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regs->tnpc = regs->tpc + 4; |
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return 1; |
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} |
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/* |
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* fixup_exception() could not handle it, |
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* Let do_page_fault() fix it. |
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*/ |
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break; |
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default: |
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break; |
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} |
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return 0; |
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} |
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/* |
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* Wrapper routine to for handling exceptions. |
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*/ |
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int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
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unsigned long val, void *data) |
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{ |
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struct die_args *args = (struct die_args *)data; |
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int ret = NOTIFY_DONE; |
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if (args->regs && user_mode(args->regs)) |
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return ret; |
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switch (val) { |
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case DIE_DEBUG: |
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if (kprobe_handler(args->regs)) |
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ret = NOTIFY_STOP; |
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break; |
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case DIE_DEBUG_2: |
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if (post_kprobe_handler(args->regs)) |
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ret = NOTIFY_STOP; |
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break; |
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default: |
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break; |
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} |
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return ret; |
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} |
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asmlinkage void __kprobes kprobe_trap(unsigned long trap_level, |
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struct pt_regs *regs) |
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{ |
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enum ctx_state prev_state = exception_enter(); |
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BUG_ON(trap_level != 0x170 && trap_level != 0x171); |
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if (user_mode(regs)) { |
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local_irq_enable(); |
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bad_trap(regs, trap_level); |
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goto out; |
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} |
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/* trap_level == 0x170 --> ta 0x70 |
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* trap_level == 0x171 --> ta 0x71 |
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*/ |
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if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2, |
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(trap_level == 0x170) ? "debug" : "debug_2", |
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regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP) |
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bad_trap(regs, trap_level); |
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out: |
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exception_exit(prev_state); |
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} |
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/* The value stored in the return address register is actually 2 |
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* instructions before where the callee will return to. |
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* Sequences usually look something like this |
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* |
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* call some_function <--- return register points here |
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* nop <--- call delay slot |
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* whatever <--- where callee returns to |
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* |
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* To keep trampoline_probe_handler logic simpler, we normalize the |
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* value kept in ri->ret_addr so we don't need to keep adjusting it |
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* back and forth. |
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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->u_regs[UREG_RETPC] + 8); |
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ri->fp = NULL; |
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/* Replace the return addr with trampoline addr */ |
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regs->u_regs[UREG_RETPC] = |
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((unsigned long)kretprobe_trampoline) - 8; |
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} |
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/* |
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* Called when the probe at kretprobe trampoline is hit |
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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 = 0; |
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orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL); |
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regs->tpc = orig_ret_address; |
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regs->tnpc = orig_ret_address + 4; |
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/* |
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* By returning a non-zero value, we are telling |
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* kprobe_handler() that we don't want the post_handler |
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* to run (and have re-enabled preemption) |
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*/ |
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return 1; |
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} |
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static void __used kretprobe_trampoline_holder(void) |
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{ |
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asm volatile(".global kretprobe_trampoline\n" |
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"kretprobe_trampoline:\n" |
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"\tnop\n" |
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"\tnop\n"); |
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} |
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static struct kprobe trampoline_p = { |
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.addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
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.pre_handler = trampoline_probe_handler |
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}; |
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int __init arch_init_kprobes(void) |
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{ |
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return register_kprobe(&trampoline_p); |
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} |
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int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
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{ |
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if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) |
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return 1; |
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return 0; |
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}
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