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