407 lines
9.9 KiB
C
407 lines
9.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kdebug.h>
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#include <linux/kprobes.h>
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#include <linux/preempt.h>
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#include <asm/break.h>
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static const union loongarch_instruction breakpoint_insn = {
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.reg0i15_format = {
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.opcode = break_op,
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.immediate = BRK_KPROBE_BP,
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}
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};
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static const union loongarch_instruction singlestep_insn = {
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.reg0i15_format = {
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.opcode = break_op,
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.immediate = BRK_KPROBE_SSTEPBP,
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}
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};
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DEFINE_PER_CPU(struct kprobe *, current_kprobe);
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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static bool insns_not_supported(union loongarch_instruction insn)
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{
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switch (insn.reg2i14_format.opcode) {
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case llw_op:
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case lld_op:
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case scw_op:
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case scd_op:
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pr_notice("kprobe: ll and sc instructions are not supported\n");
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return true;
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}
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switch (insn.reg1i21_format.opcode) {
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case bceqz_op:
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pr_notice("kprobe: bceqz and bcnez instructions are not supported\n");
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return true;
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}
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return false;
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}
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NOKPROBE_SYMBOL(insns_not_supported);
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static bool insns_need_simulation(struct kprobe *p)
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{
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if (is_pc_ins(&p->opcode))
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return true;
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if (is_branch_ins(&p->opcode))
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return true;
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return false;
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}
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NOKPROBE_SYMBOL(insns_need_simulation);
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static void arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
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{
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if (is_pc_ins(&p->opcode))
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simu_pc(regs, p->opcode);
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else if (is_branch_ins(&p->opcode))
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simu_branch(regs, p->opcode);
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}
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NOKPROBE_SYMBOL(arch_simulate_insn);
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static void arch_prepare_ss_slot(struct kprobe *p)
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{
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p->ainsn.insn[0] = *p->addr;
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p->ainsn.insn[1] = singlestep_insn;
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p->ainsn.restore = (unsigned long)p->addr + LOONGARCH_INSN_SIZE;
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}
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NOKPROBE_SYMBOL(arch_prepare_ss_slot);
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static void arch_prepare_simulate(struct kprobe *p)
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{
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p->ainsn.restore = 0;
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}
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NOKPROBE_SYMBOL(arch_prepare_simulate);
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int arch_prepare_kprobe(struct kprobe *p)
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{
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if ((unsigned long)p->addr & 0x3)
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return -EILSEQ;
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/* copy instruction */
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p->opcode = *p->addr;
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/* decode instruction */
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if (insns_not_supported(p->opcode))
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return -EINVAL;
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if (insns_need_simulation(p)) {
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p->ainsn.insn = NULL;
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} else {
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p->ainsn.insn = get_insn_slot();
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if (!p->ainsn.insn)
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return -ENOMEM;
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}
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/* prepare the instruction */
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if (p->ainsn.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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NOKPROBE_SYMBOL(arch_prepare_kprobe);
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/* Install breakpoint in text */
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void arch_arm_kprobe(struct kprobe *p)
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{
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*p->addr = breakpoint_insn;
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flush_insn_slot(p);
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}
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NOKPROBE_SYMBOL(arch_arm_kprobe);
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/* Remove breakpoint from text */
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void arch_disarm_kprobe(struct kprobe *p)
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{
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*p->addr = p->opcode;
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flush_insn_slot(p);
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}
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NOKPROBE_SYMBOL(arch_disarm_kprobe);
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void arch_remove_kprobe(struct kprobe *p)
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{
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if (p->ainsn.insn) {
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free_insn_slot(p->ainsn.insn, 0);
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p->ainsn.insn = NULL;
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}
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}
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NOKPROBE_SYMBOL(arch_remove_kprobe);
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static void 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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NOKPROBE_SYMBOL(save_previous_kprobe);
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static void 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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NOKPROBE_SYMBOL(restore_previous_kprobe);
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static void 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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NOKPROBE_SYMBOL(set_current_kprobe);
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/*
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* Interrupts need to be disabled before single-step mode is set,
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* and not 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
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* of 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 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_status = regs->csr_prmd;
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regs->csr_prmd &= ~CSR_PRMD_PIE;
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}
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NOKPROBE_SYMBOL(save_local_irqflag);
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static void restore_local_irqflag(struct kprobe_ctlblk *kcb,
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struct pt_regs *regs)
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{
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regs->csr_prmd = kcb->saved_status;
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}
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NOKPROBE_SYMBOL(restore_local_irqflag);
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static void post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb,
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struct pt_regs *regs)
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{
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/* return addr restore if non-branching insn */
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if (cur->ainsn.restore != 0)
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instruction_pointer_set(regs, cur->ainsn.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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preempt_enable_no_resched();
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return;
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}
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/*
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* update the kcb status even if the cur->post_handler is
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* not set because reset_curent_kprobe() doesn't update kcb.
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*/
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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if (cur->post_handler)
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cur->post_handler(cur, regs, 0);
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reset_current_kprobe();
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preempt_enable_no_resched();
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}
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NOKPROBE_SYMBOL(post_kprobe_handler);
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static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
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struct kprobe_ctlblk *kcb, int reenter)
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{
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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.insn) {
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/* IRQs and single stepping do not mix well */
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save_local_irqflag(kcb, regs);
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/* set ip register to prepare for single stepping */
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regs->csr_era = (unsigned long)p->ainsn.insn;
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} else {
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/* simulate single steping */
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arch_simulate_insn(p, regs);
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/* now go for post processing */
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post_kprobe_handler(p, kcb, regs);
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}
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}
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NOKPROBE_SYMBOL(setup_singlestep);
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static bool reenter_kprobe(struct kprobe *p, 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_SS:
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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_REENTER:
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pr_warn("Failed to recover from reentered kprobes.\n");
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dump_kprobe(p);
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WARN_ON_ONCE(1);
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break;
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default:
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WARN_ON(1);
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return false;
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}
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return true;
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}
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NOKPROBE_SYMBOL(reenter_kprobe);
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bool kprobe_breakpoint_handler(struct pt_regs *regs)
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{
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struct kprobe_ctlblk *kcb;
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struct kprobe *p, *cur_kprobe;
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kprobe_opcode_t *addr = (kprobe_opcode_t *)regs->csr_era;
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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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cur_kprobe = kprobe_running();
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p = get_kprobe(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 true;
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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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preempt_enable_no_resched();
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}
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return true;
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}
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}
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if (addr->word != breakpoint_insn.word) {
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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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regs->csr_era = (unsigned long)addr;
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preempt_enable_no_resched();
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return true;
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}
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preempt_enable_no_resched();
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return false;
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}
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NOKPROBE_SYMBOL(kprobe_breakpoint_handler);
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bool kprobe_singlestep_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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unsigned long addr = instruction_pointer(regs);
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if (cur && (kcb->kprobe_status & (KPROBE_HIT_SS | KPROBE_REENTER)) &&
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((unsigned long)&cur->ainsn.insn[1] == addr)) {
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restore_local_irqflag(kcb, regs);
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post_kprobe_handler(cur, kcb, regs);
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return true;
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}
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preempt_enable_no_resched();
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return false;
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}
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NOKPROBE_SYMBOL(kprobe_singlestep_handler);
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bool 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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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->csr_era = (unsigned long)cur->addr;
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WARN_ON_ONCE(!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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restore_local_irqflag(kcb, regs);
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reset_current_kprobe();
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}
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preempt_enable_no_resched();
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break;
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}
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return false;
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}
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NOKPROBE_SYMBOL(kprobe_fault_handler);
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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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return kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
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(unsigned long)__irqentry_text_end);
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}
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int __init arch_init_kprobes(void)
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{
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* ASM function that handles the kretprobes must not be probed */
|
||
|
|
NOKPROBE_SYMBOL(__kretprobe_trampoline);
|
||
|
|
|
||
|
|
/* Called from __kretprobe_trampoline */
|
||
|
|
void __used *trampoline_probe_handler(struct pt_regs *regs)
|
||
|
|
{
|
||
|
|
return (void *)kretprobe_trampoline_handler(regs, NULL);
|
||
|
|
}
|
||
|
|
NOKPROBE_SYMBOL(trampoline_probe_handler);
|
||
|
|
|
||
|
|
void arch_prepare_kretprobe(struct kretprobe_instance *ri,
|
||
|
|
struct pt_regs *regs)
|
||
|
|
{
|
||
|
|
ri->ret_addr = (kprobe_opcode_t *)regs->regs[1];
|
||
|
|
ri->fp = NULL;
|
||
|
|
|
||
|
|
/* Replace the return addr with trampoline addr */
|
||
|
|
regs->regs[1] = (unsigned long)&__kretprobe_trampoline;
|
||
|
|
}
|
||
|
|
NOKPROBE_SYMBOL(arch_prepare_kretprobe);
|
||
|
|
|
||
|
|
int arch_trampoline_kprobe(struct kprobe *p)
|
||
|
|
{
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
NOKPROBE_SYMBOL(arch_trampoline_kprobe);
|