/* * Kernel probes (kprobes) for SuperH * * Copyright (C) 2007 Chris Smith * Copyright (C) 2006 Lineo Solutions, Inc. * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. */ #include #include #include #include #include #include #include DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); static struct kprobe saved_current_opcode; static struct kprobe saved_next_opcode; static struct kprobe saved_next_opcode2; #define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b) #define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b) #define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000) #define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023) #define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000) #define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003) #define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00) #define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00) #define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00) #define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900) #define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b) #define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b) int __kprobes arch_prepare_kprobe(struct kprobe *p) { kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr); if (OPCODE_RTE(opcode)) return -EFAULT; /* Bad breakpoint */ p->opcode = opcode; return 0; } void __kprobes arch_copy_kprobe(struct kprobe *p) { memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); p->opcode = *p->addr; } void __kprobes arch_arm_kprobe(struct kprobe *p) { *p->addr = BREAKPOINT_INSTRUCTION; flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t)); } void __kprobes arch_disarm_kprobe(struct kprobe *p) { *p->addr = p->opcode; flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t)); } int __kprobes arch_trampoline_kprobe(struct kprobe *p) { if (*p->addr == BREAKPOINT_INSTRUCTION) return 1; return 0; } /** * If an illegal slot instruction exception occurs for an address * containing a kprobe, remove the probe. * * Returns 0 if the exception was handled successfully, 1 otherwise. */ int __kprobes kprobe_handle_illslot(unsigned long pc) { struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1); if (p != NULL) { printk("Warning: removing kprobe from delay slot: 0x%.8x\n", (unsigned int)pc + 2); unregister_kprobe(p); return 0; } return 1; } void __kprobes arch_remove_kprobe(struct kprobe *p) { if (saved_next_opcode.addr != 0x0) { arch_disarm_kprobe(p); arch_disarm_kprobe(&saved_next_opcode); saved_next_opcode.addr = 0x0; saved_next_opcode.opcode = 0x0; if (saved_next_opcode2.addr != 0x0) { arch_disarm_kprobe(&saved_next_opcode2); saved_next_opcode2.addr = 0x0; saved_next_opcode2.opcode = 0x0; } } } 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) { __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; kcb->kprobe_status = kcb->prev_kprobe.status; } static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { __get_cpu_var(current_kprobe) = p; } /* * Singlestep is implemented by disabling the current kprobe and setting one * on the next instruction, following branches. Two probes are set if the * branch is conditional. */ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { kprobe_opcode_t *addr = NULL; saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc); addr = saved_current_opcode.addr; if (p != NULL) { arch_disarm_kprobe(p); if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) { unsigned int reg_nr = ((p->opcode >> 8) & 0x000F); saved_next_opcode.addr = (kprobe_opcode_t *) regs->regs[reg_nr]; } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) { unsigned long disp = (p->opcode & 0x0FFF); saved_next_opcode.addr = (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) { unsigned int reg_nr = ((p->opcode >> 8) & 0x000F); saved_next_opcode.addr = (kprobe_opcode_t *) (regs->pc + 4 + regs->regs[reg_nr]); } else if (OPCODE_RTS(p->opcode)) { saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr; } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) { unsigned long disp = (p->opcode & 0x00FF); /* case 1 */ saved_next_opcode.addr = p->addr + 1; /* case 2 */ saved_next_opcode2.addr = (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); saved_next_opcode2.opcode = *(saved_next_opcode2.addr); arch_arm_kprobe(&saved_next_opcode2); } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) { unsigned long disp = (p->opcode & 0x00FF); /* case 1 */ saved_next_opcode.addr = p->addr + 2; /* case 2 */ saved_next_opcode2.addr = (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); saved_next_opcode2.opcode = *(saved_next_opcode2.addr); arch_arm_kprobe(&saved_next_opcode2); } else { saved_next_opcode.addr = p->addr + 1; } saved_next_opcode.opcode = *(saved_next_opcode.addr); arch_arm_kprobe(&saved_next_opcode); } } /* Called with kretprobe_lock held */ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { ri->ret_addr = (kprobe_opcode_t *) regs->pr; /* Replace the return addr with trampoline addr */ regs->pr = (unsigned long)kretprobe_trampoline; } static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); kcb = get_kprobe_ctlblk(); addr = (kprobe_opcode_t *) (regs->pc); /* Check we're not actually recursing */ if (kprobe_running()) { p = get_kprobe(addr); if (p) { if (kcb->kprobe_status == KPROBE_HIT_SS && *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { goto no_kprobe; } /* We have reentered the kprobe_handler(), since * another probe was hit while within the handler. * We here save the original kprobes variables and * just single step on the instruction of the new probe * without calling any user handlers. */ save_previous_kprobe(kcb); set_current_kprobe(p, regs, kcb); kprobes_inc_nmissed_count(p); prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_REENTER; return 1; } else { p = __get_cpu_var(current_kprobe); if (p->break_handler && p->break_handler(p, regs)) { goto ss_probe; } } goto no_kprobe; } p = get_kprobe(addr); if (!p) { /* Not one of ours: let kernel handle it */ if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) { /* * 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. */ ret = 1; } goto no_kprobe; } set_current_kprobe(p, regs, kcb); kcb->kprobe_status = KPROBE_HIT_ACTIVE; if (p->pre_handler && p->pre_handler(p, regs)) /* handler has already set things up, so skip ss setup */ return 1; ss_probe: prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_HIT_SS; return 1; no_kprobe: preempt_enable_no_resched(); return ret; } /* * For function-return probes, init_kprobes() establishes a probepoint * here. When a retprobed function returns, this probe is hit and * trampoline_probe_handler() runs, calling the kretprobe's handler. */ static void __used kretprobe_trampoline_holder(void) { asm volatile (".globl kretprobe_trampoline\n" "kretprobe_trampoline:\n\t" "nop\n"); } /* * Called when we hit the probe point at kretprobe_trampoline */ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) { struct kretprobe_instance *ri = NULL; struct hlist_head *head, empty_rp; struct hlist_node *node, *tmp; unsigned long flags, orig_ret_address = 0; unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; INIT_HLIST_HEAD(&empty_rp); kretprobe_hash_lock(current, &head, &flags); /* * It is possible to have multiple instances associated with a given * task either because an multiple functions in the call path * have a return probe installed on them, and/or more then one return * return probe was registered for a target function. * * We can handle this because: * - instances are always inserted at the head of the list * - when multiple return probes are registered for the same * function, the first instance's ret_addr will point to the * real return address, and all the rest will point to * kretprobe_trampoline */ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { if (ri->task != current) /* another task is sharing our hash bucket */ continue; if (ri->rp && ri->rp->handler) { __get_cpu_var(current_kprobe) = &ri->rp->kp; ri->rp->handler(ri, regs); __get_cpu_var(current_kprobe) = NULL; } orig_ret_address = (unsigned long)ri->ret_addr; recycle_rp_inst(ri, &empty_rp); if (orig_ret_address != trampoline_address) /* * This is the real return address. Any other * instances associated with this task are for * other calls deeper on the call stack */ break; } kretprobe_assert(ri, orig_ret_address, trampoline_address); regs->pc = orig_ret_address; kretprobe_hash_unlock(current, &flags); preempt_enable_no_resched(); hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri); } return orig_ret_address; } static int __kprobes post_kprobe_handler(struct pt_regs *regs) { struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); kprobe_opcode_t *addr = NULL; struct kprobe *p = NULL; if (!cur) return 0; if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { kcb->kprobe_status = KPROBE_HIT_SSDONE; cur->post_handler(cur, regs, 0); } if (saved_next_opcode.addr != 0x0) { arch_disarm_kprobe(&saved_next_opcode); saved_next_opcode.addr = 0x0; saved_next_opcode.opcode = 0x0; addr = saved_current_opcode.addr; saved_current_opcode.addr = 0x0; p = get_kprobe(addr); arch_arm_kprobe(p); if (saved_next_opcode2.addr != 0x0) { arch_disarm_kprobe(&saved_next_opcode2); saved_next_opcode2.addr = 0x0; saved_next_opcode2.opcode = 0x0; } } /* Restore back the original saved kprobes variables and continue. */ if (kcb->kprobe_status == KPROBE_REENTER) { restore_previous_kprobe(kcb); goto out; } reset_current_kprobe(); out: preempt_enable_no_resched(); return 1; } int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) { struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); const struct exception_table_entry *entry; 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, point the pc 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 (kcb->kprobe_status == KPROBE_REENTER) restore_previous_kprobe(kcb); else reset_current_kprobe(); preempt_enable_no_resched(); break; case KPROBE_HIT_ACTIVE: case KPROBE_HIT_SSDONE: /* * We increment the nmissed count for accounting, * we can also use npre/npostfault count for accounting * these specific fault cases. */ kprobes_inc_nmissed_count(cur); /* * We come here because instructions in the pre/post * handler caused the page_fault, this could happen * if handler tries to access user space by * copy_from_user(), get_user() etc. Let the * user-specified handler try to fix it first. */ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) return 1; /* * In case the user-specified fault handler returned * zero, try to fix up. */ if ((entry = search_exception_tables(regs->pc)) != NULL) { regs->pc = entry->fixup; return 1; } /* * fixup_exception() could not handle it, * Let do_page_fault() fix it. */ break; default: break; } return 0; } /* * Wrapper routine to for handling exceptions. */ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data) { struct kprobe *p = NULL; struct die_args *args = (struct die_args *)data; int ret = NOTIFY_DONE; kprobe_opcode_t *addr = NULL; struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); addr = (kprobe_opcode_t *) (args->regs->pc); if (val == DIE_TRAP) { if (!kprobe_running()) { if (kprobe_handler(args->regs)) { ret = NOTIFY_STOP; } else { /* Not a kprobe trap */ ret = NOTIFY_DONE; } } else { p = get_kprobe(addr); if ((kcb->kprobe_status == KPROBE_HIT_SS) || (kcb->kprobe_status == KPROBE_REENTER)) { if (post_kprobe_handler(args->regs)) ret = NOTIFY_STOP; } else { if (kprobe_handler(args->regs)) { ret = NOTIFY_STOP; } else { p = __get_cpu_var(current_kprobe); if (p->break_handler && p->break_handler(p, args->regs)) ret = NOTIFY_STOP; } } } } return ret; } int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct jprobe *jp = container_of(p, struct jprobe, kp); unsigned long addr; struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); kcb->jprobe_saved_regs = *regs; kcb->jprobe_saved_r15 = regs->regs[15]; addr = kcb->jprobe_saved_r15; /* * TBD: As Linus pointed out, gcc assumes that the callee * owns the argument space and could overwrite it, e.g. * tailcall optimization. So, to be absolutely safe * we also save and restore enough stack bytes to cover * the argument area. */ memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr)); regs->pc = (unsigned long)(jp->entry); return 1; } void __kprobes jprobe_return(void) { asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t"); } int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); unsigned long stack_addr = kcb->jprobe_saved_r15; u8 *addr = (u8 *)regs->pc; if ((addr >= (u8 *)jprobe_return) && (addr <= (u8 *)jprobe_return_end)) { *regs = kcb->jprobe_saved_regs; memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack, MIN_STACK_SIZE(stack_addr)); kcb->kprobe_status = KPROBE_HIT_SS; preempt_enable_no_resched(); return 1; } return 0; } static struct kprobe trampoline_p = { .addr = (kprobe_opcode_t *)&kretprobe_trampoline, .pre_handler = trampoline_probe_handler }; int __init arch_init_kprobes(void) { saved_next_opcode.addr = 0x0; saved_next_opcode.opcode = 0x0; saved_current_opcode.addr = 0x0; saved_current_opcode.opcode = 0x0; saved_next_opcode2.addr = 0x0; saved_next_opcode2.opcode = 0x0; return register_kprobe(&trampoline_p); }