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408 lines
9.6 KiB
408 lines
9.6 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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#include <linux/kprobes.h> |
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#include <linux/extable.h> |
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#include <linux/slab.h> |
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#include <linux/stop_machine.h> |
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#include <asm/ptrace.h> |
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#include <linux/uaccess.h> |
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#include <asm/sections.h> |
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#include <asm/cacheflush.h> |
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#include "decode-insn.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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static void __kprobes |
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post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); |
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struct csky_insn_patch { |
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kprobe_opcode_t *addr; |
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u32 opcode; |
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atomic_t cpu_count; |
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}; |
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static int __kprobes patch_text_cb(void *priv) |
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{ |
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struct csky_insn_patch *param = priv; |
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unsigned int addr = (unsigned int)param->addr; |
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if (atomic_inc_return(¶m->cpu_count) == 1) { |
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*(u16 *) addr = cpu_to_le16(param->opcode); |
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dcache_wb_range(addr, addr + 2); |
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atomic_inc(¶m->cpu_count); |
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} else { |
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while (atomic_read(¶m->cpu_count) <= num_online_cpus()) |
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cpu_relax(); |
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} |
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icache_inv_range(addr, addr + 2); |
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return 0; |
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} |
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static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) |
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{ |
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struct csky_insn_patch param = { addr, opcode, ATOMIC_INIT(0) }; |
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return stop_machine_cpuslocked(patch_text_cb, ¶m, cpu_online_mask); |
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} |
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static void __kprobes arch_prepare_ss_slot(struct kprobe *p) |
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{ |
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unsigned long offset = is_insn32(p->opcode) ? 4 : 2; |
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p->ainsn.api.restore = (unsigned long)p->addr + offset; |
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patch_text(p->ainsn.api.insn, p->opcode); |
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} |
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static void __kprobes arch_prepare_simulate(struct kprobe *p) |
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{ |
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p->ainsn.api.restore = 0; |
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} |
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static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) |
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{ |
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
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if (p->ainsn.api.handler) |
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p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs); |
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post_kprobe_handler(kcb, regs); |
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} |
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int __kprobes arch_prepare_kprobe(struct kprobe *p) |
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{ |
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unsigned long probe_addr = (unsigned long)p->addr; |
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if (probe_addr & 0x1) { |
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pr_warn("Address not aligned.\n"); |
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return -EINVAL; |
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} |
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/* copy instruction */ |
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p->opcode = le32_to_cpu(*p->addr); |
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/* decode instruction */ |
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switch (csky_probe_decode_insn(p->addr, &p->ainsn.api)) { |
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case INSN_REJECTED: /* insn not supported */ |
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return -EINVAL; |
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case INSN_GOOD_NO_SLOT: /* insn need simulation */ |
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p->ainsn.api.insn = NULL; |
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break; |
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case INSN_GOOD: /* instruction uses slot */ |
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p->ainsn.api.insn = get_insn_slot(); |
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if (!p->ainsn.api.insn) |
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return -ENOMEM; |
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break; |
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} |
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/* prepare the instruction */ |
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if (p->ainsn.api.insn) |
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arch_prepare_ss_slot(p); |
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else |
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arch_prepare_simulate(p); |
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return 0; |
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} |
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/* install breakpoint in text */ |
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void __kprobes arch_arm_kprobe(struct kprobe *p) |
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{ |
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patch_text(p->addr, USR_BKPT); |
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} |
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/* remove breakpoint from text */ |
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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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void __kprobes arch_remove_kprobe(struct kprobe *p) |
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{ |
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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 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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/* |
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* Interrupts need to be disabled before single-step mode is set, and not |
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* reenabled until after single-step mode ends. |
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* Without disabling interrupt on local CPU, there is a chance of |
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* interrupt occurrence in the period of exception return and start of |
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* out-of-line single-step, that result in wrongly single stepping |
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* into the interrupt handler. |
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*/ |
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static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, |
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struct pt_regs *regs) |
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{ |
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kcb->saved_sr = regs->sr; |
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regs->sr &= ~BIT(6); |
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} |
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static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, |
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struct pt_regs *regs) |
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{ |
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regs->sr = kcb->saved_sr; |
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} |
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static void __kprobes |
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set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr, struct kprobe *p) |
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{ |
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unsigned long offset = is_insn32(p->opcode) ? 4 : 2; |
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kcb->ss_ctx.ss_pending = true; |
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kcb->ss_ctx.match_addr = addr + offset; |
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} |
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static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) |
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{ |
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kcb->ss_ctx.ss_pending = false; |
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kcb->ss_ctx.match_addr = 0; |
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} |
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#define TRACE_MODE_SI BIT(14) |
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#define TRACE_MODE_MASK ~(0x3 << 14) |
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#define TRACE_MODE_RUN 0 |
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static void __kprobes setup_singlestep(struct kprobe *p, |
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struct pt_regs *regs, |
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struct kprobe_ctlblk *kcb, int reenter) |
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{ |
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unsigned long slot; |
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if (reenter) { |
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save_previous_kprobe(kcb); |
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set_current_kprobe(p); |
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kcb->kprobe_status = KPROBE_REENTER; |
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} else { |
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kcb->kprobe_status = KPROBE_HIT_SS; |
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} |
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if (p->ainsn.api.insn) { |
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/* prepare for single stepping */ |
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slot = (unsigned long)p->ainsn.api.insn; |
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set_ss_context(kcb, slot, p); /* mark pending ss */ |
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/* IRQs and single stepping do not mix well. */ |
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kprobes_save_local_irqflag(kcb, regs); |
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regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_SI; |
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instruction_pointer_set(regs, slot); |
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} else { |
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/* insn simulation */ |
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arch_simulate_insn(p, regs); |
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} |
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} |
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static int __kprobes reenter_kprobe(struct kprobe *p, |
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struct pt_regs *regs, |
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struct kprobe_ctlblk *kcb) |
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{ |
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switch (kcb->kprobe_status) { |
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case KPROBE_HIT_SSDONE: |
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case KPROBE_HIT_ACTIVE: |
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kprobes_inc_nmissed_count(p); |
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setup_singlestep(p, regs, kcb, 1); |
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break; |
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case KPROBE_HIT_SS: |
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case KPROBE_REENTER: |
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pr_warn("Unrecoverable kprobe detected.\n"); |
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dump_kprobe(p); |
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BUG(); |
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break; |
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default: |
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WARN_ON(1); |
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return 0; |
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} |
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return 1; |
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} |
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static void __kprobes |
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post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) |
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{ |
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struct kprobe *cur = kprobe_running(); |
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if (!cur) |
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return; |
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/* return addr restore if non-branching insn */ |
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if (cur->ainsn.api.restore != 0) |
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regs->pc = cur->ainsn.api.restore; |
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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; |
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} |
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/* call post handler */ |
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kcb->kprobe_status = KPROBE_HIT_SSDONE; |
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if (cur->post_handler) { |
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/* post_handler can hit breakpoint and single step |
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* again, so we enable D-flag for recursive exception. |
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*/ |
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cur->post_handler(cur, regs, 0); |
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} |
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reset_current_kprobe(); |
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} |
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int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned 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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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 ip 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->pc = (unsigned long) cur->addr; |
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BUG_ON(!instruction_pointer(regs)); |
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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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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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if (fixup_exception(regs)) |
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return 1; |
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} |
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return 0; |
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} |
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int __kprobes |
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kprobe_breakpoint_handler(struct pt_regs *regs) |
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{ |
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struct kprobe *p, *cur_kprobe; |
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struct kprobe_ctlblk *kcb; |
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unsigned long addr = instruction_pointer(regs); |
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kcb = get_kprobe_ctlblk(); |
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cur_kprobe = kprobe_running(); |
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p = get_kprobe((kprobe_opcode_t *) addr); |
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if (p) { |
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if (cur_kprobe) { |
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if (reenter_kprobe(p, regs, kcb)) |
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return 1; |
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} else { |
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/* Probe hit */ |
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set_current_kprobe(p); |
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kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
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/* |
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* If we have no pre-handler or it returned 0, we |
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* continue with normal processing. If we have a |
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* pre-handler and it returned non-zero, it will |
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* modify the execution path and no need to single |
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* stepping. Let's just reset current kprobe and exit. |
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* |
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* pre_handler can hit a breakpoint and can step thru |
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* before return. |
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*/ |
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if (!p->pre_handler || !p->pre_handler(p, regs)) |
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setup_singlestep(p, regs, kcb, 0); |
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else |
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reset_current_kprobe(); |
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} |
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return 1; |
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} |
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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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* Return back to original instruction, and continue. |
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*/ |
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return 0; |
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} |
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int __kprobes |
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kprobe_single_step_handler(struct pt_regs *regs) |
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{ |
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
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if ((kcb->ss_ctx.ss_pending) |
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&& (kcb->ss_ctx.match_addr == instruction_pointer(regs))) { |
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clear_ss_context(kcb); /* clear pending ss */ |
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kprobes_restore_local_irqflag(kcb, regs); |
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regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_RUN; |
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post_kprobe_handler(kcb, regs); |
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return 1; |
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} |
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return 0; |
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} |
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/* |
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* Provide a blacklist of symbols identifying ranges which cannot be kprobed. |
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* This blacklist is exposed to userspace via debugfs (kprobes/blacklist). |
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*/ |
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int __init arch_populate_kprobe_blacklist(void) |
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{ |
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int ret; |
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ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start, |
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(unsigned long)__irqentry_text_end); |
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return ret; |
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} |
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void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) |
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{ |
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return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL); |
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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->lr; |
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ri->fp = NULL; |
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regs->lr = (unsigned long) &kretprobe_trampoline; |
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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 0; |
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} |
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int __init arch_init_kprobes(void) |
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{ |
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return 0; |
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}
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