diff options
Diffstat (limited to 'arch/arm/kernel/kprobes.c')
| -rw-r--r-- | arch/arm/kernel/kprobes.c | 628 |
1 files changed, 0 insertions, 628 deletions
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c deleted file mode 100644 index 6d644202c8dc..000000000000 --- a/arch/arm/kernel/kprobes.c +++ /dev/null @@ -1,628 +0,0 @@ -/* - * arch/arm/kernel/kprobes.c - * - * Kprobes on ARM - * - * Abhishek Sagar <sagar.abhishek@gmail.com> - * Copyright (C) 2006, 2007 Motorola Inc. - * - * Nicolas Pitre <nico@marvell.com> - * Copyright (C) 2007 Marvell Ltd. - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - */ - -#include <linux/kernel.h> -#include <linux/kprobes.h> -#include <linux/module.h> -#include <linux/slab.h> -#include <linux/stop_machine.h> -#include <linux/stringify.h> -#include <asm/traps.h> -#include <asm/opcodes.h> -#include <asm/cacheflush.h> -#include <linux/percpu.h> -#include <linux/bug.h> - -#include "kprobes.h" -#include "probes-arm.h" -#include "probes-thumb.h" -#include "patch.h" - -#define MIN_STACK_SIZE(addr) \ - min((unsigned long)MAX_STACK_SIZE, \ - (unsigned long)current_thread_info() + THREAD_START_SP - (addr)) - -#define flush_insns(addr, size) \ - flush_icache_range((unsigned long)(addr), \ - (unsigned long)(addr) + \ - (size)) - -/* Used as a marker in ARM_pc to note when we're in a jprobe. */ -#define JPROBE_MAGIC_ADDR 0xffffffff - -DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; -DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); - - -int __kprobes arch_prepare_kprobe(struct kprobe *p) -{ - kprobe_opcode_t insn; - kprobe_opcode_t tmp_insn[MAX_INSN_SIZE]; - unsigned long addr = (unsigned long)p->addr; - bool thumb; - kprobe_decode_insn_t *decode_insn; - const union decode_action *actions; - int is; - - if (in_exception_text(addr)) - return -EINVAL; - -#ifdef CONFIG_THUMB2_KERNEL - thumb = true; - addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */ - insn = __mem_to_opcode_thumb16(((u16 *)addr)[0]); - if (is_wide_instruction(insn)) { - u16 inst2 = __mem_to_opcode_thumb16(((u16 *)addr)[1]); - insn = __opcode_thumb32_compose(insn, inst2); - decode_insn = thumb32_probes_decode_insn; - actions = kprobes_t32_actions; - } else { - decode_insn = thumb16_probes_decode_insn; - actions = kprobes_t16_actions; - } -#else /* !CONFIG_THUMB2_KERNEL */ - thumb = false; - if (addr & 0x3) - return -EINVAL; - insn = __mem_to_opcode_arm(*p->addr); - decode_insn = arm_probes_decode_insn; - actions = kprobes_arm_actions; -#endif - - p->opcode = insn; - p->ainsn.insn = tmp_insn; - - switch ((*decode_insn)(insn, &p->ainsn, true, actions)) { - case INSN_REJECTED: /* not supported */ - return -EINVAL; - - case INSN_GOOD: /* instruction uses slot */ - p->ainsn.insn = get_insn_slot(); - if (!p->ainsn.insn) - return -ENOMEM; - for (is = 0; is < MAX_INSN_SIZE; ++is) - p->ainsn.insn[is] = tmp_insn[is]; - flush_insns(p->ainsn.insn, - sizeof(p->ainsn.insn[0]) * MAX_INSN_SIZE); - p->ainsn.insn_fn = (probes_insn_fn_t *) - ((uintptr_t)p->ainsn.insn | thumb); - break; - - case INSN_GOOD_NO_SLOT: /* instruction doesn't need insn slot */ - p->ainsn.insn = NULL; - break; - } - - return 0; -} - -void __kprobes arch_arm_kprobe(struct kprobe *p) -{ - unsigned int brkp; - void *addr; - - if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) { - /* Remove any Thumb flag */ - addr = (void *)((uintptr_t)p->addr & ~1); - - if (is_wide_instruction(p->opcode)) - brkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION; - else - brkp = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION; - } else { - kprobe_opcode_t insn = p->opcode; - - addr = p->addr; - brkp = KPROBE_ARM_BREAKPOINT_INSTRUCTION; - - if (insn >= 0xe0000000) - brkp |= 0xe0000000; /* Unconditional instruction */ - else - brkp |= insn & 0xf0000000; /* Copy condition from insn */ - } - - patch_text(addr, brkp); -} - -/* - * The actual disarming is done here on each CPU and synchronized using - * stop_machine. This synchronization is necessary on SMP to avoid removing - * a probe between the moment the 'Undefined Instruction' exception is raised - * and the moment the exception handler reads the faulting instruction from - * memory. It is also needed to atomically set the two half-words of a 32-bit - * Thumb breakpoint. - */ -int __kprobes __arch_disarm_kprobe(void *p) -{ - struct kprobe *kp = p; - void *addr = (void *)((uintptr_t)kp->addr & ~1); - - __patch_text(addr, kp->opcode); - - return 0; -} - -void __kprobes arch_disarm_kprobe(struct kprobe *p) -{ - stop_machine(__arch_disarm_kprobe, p, cpu_online_mask); -} - -void __kprobes arch_remove_kprobe(struct kprobe *p) -{ - if (p->ainsn.insn) { - free_insn_slot(p->ainsn.insn, 0); - p->ainsn.insn = NULL; - } -} - -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); -} - -static void __kprobes -singlestep_skip(struct kprobe *p, struct pt_regs *regs) -{ -#ifdef CONFIG_THUMB2_KERNEL - regs->ARM_cpsr = it_advance(regs->ARM_cpsr); - if (is_wide_instruction(p->opcode)) - regs->ARM_pc += 4; - else - regs->ARM_pc += 2; -#else - regs->ARM_pc += 4; -#endif -} - -static inline void __kprobes -singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) -{ - p->ainsn.insn_singlestep(p->opcode, &p->ainsn, regs); -} - -/* - * Called with IRQs disabled. IRQs must remain disabled from that point - * all the way until processing this kprobe is complete. The current - * kprobes implementation cannot process more than one nested level of - * kprobe, and that level is reserved for user kprobe handlers, so we can't - * risk encountering a new kprobe in an interrupt handler. - */ -void __kprobes kprobe_handler(struct pt_regs *regs) -{ - struct kprobe *p, *cur; - struct kprobe_ctlblk *kcb; - - kcb = get_kprobe_ctlblk(); - cur = kprobe_running(); - -#ifdef CONFIG_THUMB2_KERNEL - /* - * First look for a probe which was registered using an address with - * bit 0 set, this is the usual situation for pointers to Thumb code. - * If not found, fallback to looking for one with bit 0 clear. - */ - p = get_kprobe((kprobe_opcode_t *)(regs->ARM_pc | 1)); - if (!p) - p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc); - -#else /* ! CONFIG_THUMB2_KERNEL */ - p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc); -#endif - - if (p) { - if (cur) { - /* Kprobe is pending, so we're recursing. */ - switch (kcb->kprobe_status) { - case KPROBE_HIT_ACTIVE: - case KPROBE_HIT_SSDONE: - /* A pre- or post-handler probe got us here. */ - kprobes_inc_nmissed_count(p); - save_previous_kprobe(kcb); - set_current_kprobe(p); - kcb->kprobe_status = KPROBE_REENTER; - singlestep(p, regs, kcb); - restore_previous_kprobe(kcb); - break; - default: - /* impossible cases */ - BUG(); - } - } else if (p->ainsn.insn_check_cc(regs->ARM_cpsr)) { - /* Probe hit and conditional execution check ok. */ - 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 prepped - * for calling the break_handler below on re-entry, - * so get out doing nothing more here. - */ - if (!p->pre_handler || !p->pre_handler(p, regs)) { - kcb->kprobe_status = KPROBE_HIT_SS; - singlestep(p, regs, kcb); - if (p->post_handler) { - kcb->kprobe_status = KPROBE_HIT_SSDONE; - p->post_handler(p, regs, 0); - } - reset_current_kprobe(); - } - } else { - /* - * Probe hit but conditional execution check failed, - * so just skip the instruction and continue as if - * nothing had happened. - */ - singlestep_skip(p, regs); - } - } else if (cur) { - /* We probably hit a jprobe. Call its break handler. */ - if (cur->break_handler && cur->break_handler(cur, regs)) { - kcb->kprobe_status = KPROBE_HIT_SS; - singlestep(cur, regs, kcb); - if (cur->post_handler) { - kcb->kprobe_status = KPROBE_HIT_SSDONE; - cur->post_handler(cur, regs, 0); - } - } - reset_current_kprobe(); - } else { - /* - * The probe was removed and a race is in progress. - * There is nothing we can do about it. Let's restart - * the instruction. By the time we can restart, the - * real instruction will be there. - */ - } -} - -static int __kprobes kprobe_trap_handler(struct pt_regs *regs, unsigned int instr) -{ - unsigned long flags; - local_irq_save(flags); - kprobe_handler(regs); - local_irq_restore(flags); - return 0; -} - -int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) -{ - 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 PC to point back to the probe address - * and allow the page fault handler to continue as a - * normal page fault. - */ - regs->ARM_pc = (long)cur->addr; - if (kcb->kprobe_status == KPROBE_REENTER) { - restore_previous_kprobe(kcb); - } else { - reset_current_kprobe(); - } - 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. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) - return 1; - break; - - default: - break; - } - - return 0; -} - -int __kprobes kprobe_exceptions_notify(struct notifier_block *self, - unsigned long val, void *data) -{ - /* - * notify_die() is currently never called on ARM, - * so this callback is currently empty. - */ - return NOTIFY_DONE; -} - -/* - * When a retprobed function returns, trampoline_handler() is called, - * calling the kretprobe's handler. We construct a struct pt_regs to - * give a view of registers r0-r11 to the user return-handler. This is - * not a complete pt_regs structure, but that should be plenty sufficient - * for kretprobe handlers which should normally be interested in r0 only - * anyway. - */ -void __naked __kprobes kretprobe_trampoline(void) -{ - __asm__ __volatile__ ( - "stmdb sp!, {r0 - r11} \n\t" - "mov r0, sp \n\t" - "bl trampoline_handler \n\t" - "mov lr, r0 \n\t" - "ldmia sp!, {r0 - r11} \n\t" -#ifdef CONFIG_THUMB2_KERNEL - "bx lr \n\t" -#else - "mov pc, lr \n\t" -#endif - : : : "memory"); -} - -/* Called from kretprobe_trampoline */ -static __used __kprobes void *trampoline_handler(struct pt_regs *regs) -{ - struct kretprobe_instance *ri = NULL; - struct hlist_head *head, empty_rp; - struct hlist_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 multiple functions in the call path have - * a return probe installed on them, and/or more than one 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, tmp, head, hlist) { - if (ri->task != current) - /* another task is sharing our hash bucket */ - continue; - - if (ri->rp && ri->rp->handler) { - __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; - ri->rp->handler(ri, regs); - __this_cpu_write(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); - kretprobe_hash_unlock(current, &flags); - - hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } - - return (void *)orig_ret_address; -} - -void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, - struct pt_regs *regs) -{ - ri->ret_addr = (kprobe_opcode_t *)regs->ARM_lr; - - /* Replace the return addr with trampoline addr. */ - regs->ARM_lr = (unsigned long)&kretprobe_trampoline; -} - -int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct jprobe *jp = container_of(p, struct jprobe, kp); - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - long sp_addr = regs->ARM_sp; - long cpsr; - - kcb->jprobe_saved_regs = *regs; - memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr)); - regs->ARM_pc = (long)jp->entry; - - cpsr = regs->ARM_cpsr | PSR_I_BIT; -#ifdef CONFIG_THUMB2_KERNEL - /* Set correct Thumb state in cpsr */ - if (regs->ARM_pc & 1) - cpsr |= PSR_T_BIT; - else - cpsr &= ~PSR_T_BIT; -#endif - regs->ARM_cpsr = cpsr; - - preempt_disable(); - return 1; -} - -void __kprobes jprobe_return(void) -{ - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - - __asm__ __volatile__ ( - /* - * Setup an empty pt_regs. Fill SP and PC fields as - * they're needed by longjmp_break_handler. - * - * We allocate some slack between the original SP and start of - * our fabricated regs. To be precise we want to have worst case - * covered which is STMFD with all 16 regs so we allocate 2 * - * sizeof(struct_pt_regs)). - * - * This is to prevent any simulated instruction from writing - * over the regs when they are accessing the stack. - */ -#ifdef CONFIG_THUMB2_KERNEL - "sub r0, %0, %1 \n\t" - "mov sp, r0 \n\t" -#else - "sub sp, %0, %1 \n\t" -#endif - "ldr r0, ="__stringify(JPROBE_MAGIC_ADDR)"\n\t" - "str %0, [sp, %2] \n\t" - "str r0, [sp, %3] \n\t" - "mov r0, sp \n\t" - "bl kprobe_handler \n\t" - - /* - * Return to the context saved by setjmp_pre_handler - * and restored by longjmp_break_handler. - */ -#ifdef CONFIG_THUMB2_KERNEL - "ldr lr, [sp, %2] \n\t" /* lr = saved sp */ - "ldrd r0, r1, [sp, %5] \n\t" /* r0,r1 = saved lr,pc */ - "ldr r2, [sp, %4] \n\t" /* r2 = saved psr */ - "stmdb lr!, {r0, r1, r2} \n\t" /* push saved lr and */ - /* rfe context */ - "ldmia sp, {r0 - r12} \n\t" - "mov sp, lr \n\t" - "ldr lr, [sp], #4 \n\t" - "rfeia sp! \n\t" -#else - "ldr r0, [sp, %4] \n\t" - "msr cpsr_cxsf, r0 \n\t" - "ldmia sp, {r0 - pc} \n\t" -#endif - : - : "r" (kcb->jprobe_saved_regs.ARM_sp), - "I" (sizeof(struct pt_regs) * 2), - "J" (offsetof(struct pt_regs, ARM_sp)), - "J" (offsetof(struct pt_regs, ARM_pc)), - "J" (offsetof(struct pt_regs, ARM_cpsr)), - "J" (offsetof(struct pt_regs, ARM_lr)) - : "memory", "cc"); -} - -int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - long stack_addr = kcb->jprobe_saved_regs.ARM_sp; - long orig_sp = regs->ARM_sp; - struct jprobe *jp = container_of(p, struct jprobe, kp); - - if (regs->ARM_pc == JPROBE_MAGIC_ADDR) { - if (orig_sp != stack_addr) { - struct pt_regs *saved_regs = - (struct pt_regs *)kcb->jprobe_saved_regs.ARM_sp; - printk("current sp %lx does not match saved sp %lx\n", - orig_sp, stack_addr); - printk("Saved registers for jprobe %p\n", jp); - show_regs(saved_regs); - printk("Current registers\n"); - show_regs(regs); - BUG(); - } - *regs = kcb->jprobe_saved_regs; - memcpy((void *)stack_addr, kcb->jprobes_stack, - MIN_STACK_SIZE(stack_addr)); - preempt_enable_no_resched(); - return 1; - } - return 0; -} - -int __kprobes arch_trampoline_kprobe(struct kprobe *p) -{ - return 0; -} - -#ifdef CONFIG_THUMB2_KERNEL - -static struct undef_hook kprobes_thumb16_break_hook = { - .instr_mask = 0xffff, - .instr_val = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION, - .cpsr_mask = MODE_MASK, - .cpsr_val = SVC_MODE, - .fn = kprobe_trap_handler, -}; - -static struct undef_hook kprobes_thumb32_break_hook = { - .instr_mask = 0xffffffff, - .instr_val = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION, - .cpsr_mask = MODE_MASK, - .cpsr_val = SVC_MODE, - .fn = kprobe_trap_handler, -}; - -#else /* !CONFIG_THUMB2_KERNEL */ - -static struct undef_hook kprobes_arm_break_hook = { - .instr_mask = 0x0fffffff, - .instr_val = KPROBE_ARM_BREAKPOINT_INSTRUCTION, - .cpsr_mask = MODE_MASK, - .cpsr_val = SVC_MODE, - .fn = kprobe_trap_handler, -}; - -#endif /* !CONFIG_THUMB2_KERNEL */ - -int __init arch_init_kprobes() -{ - arm_probes_decode_init(); -#ifdef CONFIG_THUMB2_KERNEL - register_undef_hook(&kprobes_thumb16_break_hook); - register_undef_hook(&kprobes_thumb32_break_hook); -#else - register_undef_hook(&kprobes_arm_break_hook); -#endif - return 0; -} |