mirror of https://gitee.com/openkylin/linux.git
500 lines
12 KiB
C
500 lines
12 KiB
C
// 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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if (!instruction_pointer(regs))
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BUG();
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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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* We increment the nmissed count for accounting,
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* we can also use npre/npostfault count for accounting
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* these specific fault cases.
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*/
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kprobes_inc_nmissed_count(cur);
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/*
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* We come here because instructions in the pre/post
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* handler caused the page_fault, this could happen
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* if handler tries to access user space by
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* copy_from_user(), get_user() etc. Let the
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* user-specified handler try to fix it first.
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*/
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if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
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return 1;
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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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struct kretprobe_instance *ri = NULL;
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struct hlist_head *head, empty_rp;
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struct hlist_node *tmp;
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unsigned long flags, orig_ret_address = 0;
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unsigned long trampoline_address =
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(unsigned long)&kretprobe_trampoline;
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kprobe_opcode_t *correct_ret_addr = NULL;
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INIT_HLIST_HEAD(&empty_rp);
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kretprobe_hash_lock(current, &head, &flags);
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/*
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* It is possible to have multiple instances associated with a given
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* task either because multiple functions in the call path have
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* return probes installed on them, and/or more than one
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* return probe was registered for a target function.
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*
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* We can handle this because:
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* - instances are always pushed into the head of the list
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* - when multiple return probes are registered for the same
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* function, the (chronologically) first instance's ret_addr
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* will be the real return address, and all the rest will
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* point to kretprobe_trampoline.
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*/
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hlist_for_each_entry_safe(ri, tmp, head, hlist) {
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if (ri->task != current)
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/* another task is sharing our hash bucket */
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continue;
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orig_ret_address = (unsigned long)ri->ret_addr;
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if (orig_ret_address != trampoline_address)
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/*
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* This is the real return address. Any other
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* instances associated with this task are for
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* other calls deeper on the call stack
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*/
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break;
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}
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kretprobe_assert(ri, orig_ret_address, trampoline_address);
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correct_ret_addr = ri->ret_addr;
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hlist_for_each_entry_safe(ri, tmp, head, hlist) {
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if (ri->task != current)
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/* another task is sharing our hash bucket */
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continue;
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orig_ret_address = (unsigned long)ri->ret_addr;
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if (ri->rp && ri->rp->handler) {
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__this_cpu_write(current_kprobe, &ri->rp->kp);
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get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
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ri->ret_addr = correct_ret_addr;
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ri->rp->handler(ri, regs);
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__this_cpu_write(current_kprobe, NULL);
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}
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recycle_rp_inst(ri, &empty_rp);
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if (orig_ret_address != trampoline_address)
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/*
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* This is the real return address. Any other
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* instances associated with this task are for
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* other calls deeper on the call stack
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*/
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break;
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}
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kretprobe_hash_unlock(current, &flags);
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hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
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hlist_del(&ri->hlist);
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kfree(ri);
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}
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return (void *)orig_ret_address;
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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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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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