ARM kprobes: core code (24ba613c) · Commits · 戴 / test

arch/arm/kernel/Makefile

+1 −1

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		@@ -19,7 +19,7 @@ obj-$(CONFIG_ISA_DMA) += dma-isa.o
		obj-$(CONFIG_PCI) += bios32.o isa.o
		obj-$(CONFIG_SMP) += smp.o
		obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
		obj-$(CONFIG_KPROBES) += kprobes-decode.o
		obj-$(CONFIG_KPROBES) += kprobes.o kprobes-decode.o
		obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o

		obj-$(CONFIG_CRUNCH) += crunch.o crunch-bits.o

arch/arm/kernel/kprobes.c

0 → 100644

+453 −0

Original line number	Diff line number	Diff line
		/*
		* 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/stringify.h>
		#include <asm/traps.h>
		#include <asm/cacheflush.h>

		/*
		* This undefined instruction must be unique and
		* reserved solely for kprobes' use.
		*/
		#define KPROBE_BREAKPOINT_INSTRUCTION 0xe7f001f8

		#define MIN_STACK_SIZE(addr) \
		min((unsigned long)MAX_STACK_SIZE, \
		(unsigned long)current_thread_info() + THREAD_START_SP - (addr))

		#define flush_insns(addr, cnt) \
		flush_icache_range((unsigned long)(addr), \
		(unsigned long)(addr) + \
		sizeof(kprobe_opcode_t) * (cnt))

		/* 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;
		int is;

		if (addr & 0x3)
		return -EINVAL;

		insn = *p->addr;
		p->opcode = insn;
		p->ainsn.insn = tmp_insn;

		switch (arm_kprobe_decode_insn(insn, &p->ainsn)) {
		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, MAX_INSN_SIZE);
		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)
		{
		*p->addr = KPROBE_BREAKPOINT_INSTRUCTION;
		flush_insns(p->addr, 1);
		}

		void __kprobes arch_disarm_kprobe(struct kprobe *p)
		{
		*p->addr = p->opcode;
		flush_insns(p->addr, 1);
		}

		void __kprobes arch_remove_kprobe(struct kprobe *p)
		{
		if (p->ainsn.insn) {
		mutex_lock(&kprobe_mutex);
		free_insn_slot(p->ainsn.insn, 0);
		mutex_unlock(&kprobe_mutex);
		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)
		{
		__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)
		{
		__get_cpu_var(current_kprobe) = p;
		}

		static void __kprobes singlestep(struct kprobe p, struct pt_regs regs,
		struct kprobe_ctlblk *kcb)
		{
		regs->ARM_pc += 4;
		p->ainsn.insn_handler(p, 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;
		kprobe_opcode_t addr = (kprobe_opcode_t )regs->ARM_pc;

		kcb = get_kprobe_ctlblk();
		cur = kprobe_running();
		p = get_kprobe(addr);

		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 {
		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 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 kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
		{
		kprobe_handler(regs);
		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.
		*/
		static void __attribute__((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"
		"mov pc, lr \n\t"
		: : : "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 node, tmp;
		unsigned long flags, orig_ret_address = 0;
		unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;

		INIT_HLIST_HEAD(&empty_rp);
		spin_lock_irqsave(&kretprobe_lock, flags);
		head = kretprobe_inst_table_head(current);

		/*
		* 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, 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;
		get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
		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);
		spin_unlock_irqrestore(&kretprobe_lock, flags);

		hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
		hlist_del(&ri->hlist);
		kfree(ri);
		}

		return (void *)orig_ret_address;
		}

		/* 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->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;

		kcb->jprobe_saved_regs = *regs;
		memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr));
		regs->ARM_pc = (long)jp->entry;
		regs->ARM_cpsr \|= PSR_I_BIT;
		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.
		*/
		"sub sp, %0, %1 \n\t"
		"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.
		*/
		"ldr r0, [sp, %4] \n\t"
		"msr cpsr_cxsf, r0 \n\t"
		"ldmia sp, {r0 - pc} \n\t"
		:
		: "r" (kcb->jprobe_saved_regs.ARM_sp),
		"I" (sizeof(struct pt_regs)),
		"J" (offsetof(struct pt_regs, ARM_sp)),
		"J" (offsetof(struct pt_regs, ARM_pc)),
		"J" (offsetof(struct pt_regs, ARM_cpsr))
		: "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;
		}

		static struct undef_hook kprobes_break_hook = {
		.instr_mask = 0xffffffff,
		.instr_val = KPROBE_BREAKPOINT_INSTRUCTION,
		.cpsr_mask = MODE_MASK,
		.cpsr_val = SVC_MODE,
		.fn = kprobe_trap_handler,
		};

		int __init arch_init_kprobes()
		{
		arm_kprobe_decode_init();
		register_undef_hook(&kprobes_break_hook);
		return 0;
		}

include/asm-arm/kprobes.h

+29 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,16 @@

		#include <linux/types.h>
		#include <linux/ptrace.h>
		#include <linux/percpu.h>

		#define ARCH_SUPPORTS_KRETPROBES
		#define __ARCH_WANT_KPROBES_INSN_SLOT
		#define MAX_INSN_SIZE 2
		#define MAX_STACK_SIZE 64 /* 32 would probably be OK */

		#define regs_return_value(regs) ((regs)->ARM_r0)
		#define flush_insn_slot(p) do { } while (0)
		#define kretprobe_blacklist_size 0

		typedef u32 kprobe_opcode_t;

		@@ -30,6 +40,25 @@ struct arch_specific_insn {
		kprobe_insn_handler_t *insn_handler;
		};

		struct prev_kprobe {
		struct kprobe *kp;
		unsigned int status;
		};

		/* per-cpu kprobe control block */
		struct kprobe_ctlblk {
		unsigned int kprobe_status;
		struct prev_kprobe prev_kprobe;
		struct pt_regs jprobe_saved_regs;
		char jprobes_stack[MAX_STACK_SIZE];
		};

		void arch_remove_kprobe(struct kprobe *);

		int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
		int kprobe_exceptions_notify(struct notifier_block *self,
		unsigned long val, void *data);

		enum kprobe_insn {
		INSN_REJECTED,
		INSN_GOOD,

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