[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / sh / kernel / kprobes.c

/*
 * Kernel probes (kprobes) for SuperH
 *
 * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
 * 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 <linux/kprobes.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
#include <linux/kdebug.h>
#include <asm/cacheflush.h>
#include <asm/uaccess.h>

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);
}
Commit	Line	Data
d39f5450 CS	1	/*
	2	* Kernel probes (kprobes) for SuperH
	3	*
	4	* Copyright (C) 2007 Chris Smith <chris.smith@st.com>
	5	* Copyright (C) 2006 Lineo Solutions, Inc.
	6	*
	7	* This file is subject to the terms and conditions of the GNU General Public
	8	* License. See the file "COPYING" in the main directory of this archive
	9	* for more details.
	10	*/
	11	#include <linux/kprobes.h>
	12	#include <linux/module.h>
	13	#include <linux/ptrace.h>
	14	#include <linux/preempt.h>
	15	#include <linux/kdebug.h>
	16	#include <asm/cacheflush.h>
	17	#include <asm/uaccess.h>
	18
	19	DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
	20	DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
	21
	22	static struct kprobe saved_current_opcode;
	23	static struct kprobe saved_next_opcode;
	24	static struct kprobe saved_next_opcode2;
	25
	26	#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
	27	#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
	28	#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
	29	#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
	30	#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
	31	#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
	32
	33	#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
	34	#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
	35
	36	#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
	37	#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
	38
	39	#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
	40	#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
	41
	42	int __kprobes arch_prepare_kprobe(struct kprobe *p)
	43	{
	44	kprobe_opcode_t opcode = (kprobe_opcode_t ) (p->addr);
	45
	46	if (OPCODE_RTE(opcode))
	47	return -EFAULT; /* Bad breakpoint */
	48
	49	p->opcode = opcode;
	50
	51	return 0;
	52	}
	53
	54	void __kprobes arch_copy_kprobe(struct kprobe *p)
	55	{
	56	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
	57	p->opcode = *p->addr;
	58	}
	59
	60	void __kprobes arch_arm_kprobe(struct kprobe *p)
	61	{
	62	*p->addr = BREAKPOINT_INSTRUCTION;
	63	flush_icache_range((unsigned long)p->addr,
	64	(unsigned long)p->addr + sizeof(kprobe_opcode_t));
65	}
66
67	void __kprobes arch_disarm_kprobe(struct kprobe *p)
68	{
69	*p->addr = p->opcode;
70	flush_icache_range((unsigned long)p->addr,
71	(unsigned long)p->addr + sizeof(kprobe_opcode_t));
72	}
73
74	int __kprobes arch_trampoline_kprobe(struct kprobe *p)
75	{
76	if (*p->addr == BREAKPOINT_INSTRUCTION)
77	return 1;
78
79	return 0;
80	}
81
82	/**
83	* If an illegal slot instruction exception occurs for an address
84	* containing a kprobe, remove the probe.
85	*
86	* Returns 0 if the exception was handled successfully, 1 otherwise.
87	*/
88	int __kprobes kprobe_handle_illslot(unsigned long pc)
89	{
90	struct kprobe p = get_kprobe((kprobe_opcode_t ) pc + 1);
91
92	if (p != NULL) {
93	printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
94	(unsigned int)pc + 2);
95	unregister_kprobe(p);
96	return 0;
97	}
98
99	return 1;
100	}
101
102	void __kprobes arch_remove_kprobe(struct kprobe *p)
103	{
104	if (saved_next_opcode.addr != 0x0) {
105	arch_disarm_kprobe(p);
106	arch_disarm_kprobe(&saved_next_opcode);
107	saved_next_opcode.addr = 0x0;
108	saved_next_opcode.opcode = 0x0;
109
110	if (saved_next_opcode2.addr != 0x0) {
111	arch_disarm_kprobe(&saved_next_opcode2);
112	saved_next_opcode2.addr = 0x0;
113	saved_next_opcode2.opcode = 0x0;
114	}
115	}
116	}
117
4eb5845d	118	static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
d39f5450 CS	119	{
	120	kcb->prev_kprobe.kp = kprobe_running();
	121	kcb->prev_kprobe.status = kcb->kprobe_status;
	122	}
	123
4eb5845d	124	static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
d39f5450 CS	125	{
	126	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
	127	kcb->kprobe_status = kcb->prev_kprobe.status;
	128	}
	129
4eb5845d PM	130	static void __kprobes set_current_kprobe(struct kprobe p, struct pt_regs regs,
4eb5845d PM	131	struct kprobe_ctlblk *kcb)
d39f5450 CS	132	{
	133	__get_cpu_var(current_kprobe) = p;
	134	}
	135
	136	/*
	137	* Singlestep is implemented by disabling the current kprobe and setting one
	138	* on the next instruction, following branches. Two probes are set if the
	139	* branch is conditional.
	140	*/
4eb5845d	141	static void __kprobes prepare_singlestep(struct kprobe p, struct pt_regs regs)
d39f5450 CS	142	{
	143	kprobe_opcode_t *addr = NULL;
	144	saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
	145	addr = saved_current_opcode.addr;
	146
	147	if (p != NULL) {
	148	arch_disarm_kprobe(p);
	149
	150	if (OPCODE_JSR(p->opcode) \|\| OPCODE_JMP(p->opcode)) {
	151	unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
	152	saved_next_opcode.addr =
	153	(kprobe_opcode_t *) regs->regs[reg_nr];
	154	} else if (OPCODE_BRA(p->opcode) \|\| OPCODE_BSR(p->opcode)) {
	155	unsigned long disp = (p->opcode & 0x0FFF);
	156	saved_next_opcode.addr =
	157	(kprobe_opcode_t ) (regs->pc + 4 + disp 2);
	158
	159	} else if (OPCODE_BRAF(p->opcode) \|\| OPCODE_BSRF(p->opcode)) {
	160	unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
	161	saved_next_opcode.addr =
	162	(kprobe_opcode_t *) (regs->pc + 4 +
	163	regs->regs[reg_nr]);
	164
	165	} else if (OPCODE_RTS(p->opcode)) {
	166	saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr;
	167
	168	} else if (OPCODE_BF(p->opcode) \|\| OPCODE_BT(p->opcode)) {
	169	unsigned long disp = (p->opcode & 0x00FF);
	170	/* case 1 */
	171	saved_next_opcode.addr = p->addr + 1;
	172	/* case 2 */
	173	saved_next_opcode2.addr =
	174	(kprobe_opcode_t ) (regs->pc + 4 + disp 2);
	175	saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
	176	arch_arm_kprobe(&saved_next_opcode2);
	177
	178	} else if (OPCODE_BF_S(p->opcode) \|\| OPCODE_BT_S(p->opcode)) {
	179	unsigned long disp = (p->opcode & 0x00FF);
	180	/* case 1 */
	181	saved_next_opcode.addr = p->addr + 2;
	182	/* case 2 */
	183	saved_next_opcode2.addr =
	184	(kprobe_opcode_t ) (regs->pc + 4 + disp 2);
	185	saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
	186	arch_arm_kprobe(&saved_next_opcode2);
	187
	188	} else {
	189	saved_next_opcode.addr = p->addr + 1;
	190	}
	191
	192	saved_next_opcode.opcode = *(saved_next_opcode.addr);
	193	arch_arm_kprobe(&saved_next_opcode);
	194	}
	195	}
	196
	197	/* Called with kretprobe_lock held */
	198	void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
	199	struct pt_regs *regs)
	200	{
	201	ri->ret_addr = (kprobe_opcode_t *) regs->pr;
	202
	203	/* Replace the return addr with trampoline addr */
	204	regs->pr = (unsigned long)kretprobe_trampoline;
	205	}
206
207	static int __kprobes kprobe_handler(struct pt_regs *regs)
208	{
209	struct kprobe *p;
210	int ret = 0;
211	kprobe_opcode_t *addr = NULL;
212	struct kprobe_ctlblk *kcb;
213
214	/*
215	* We don't want to be preempted for the entire
216	* duration of kprobe processing
217	*/
218	preempt_disable();
219	kcb = get_kprobe_ctlblk();
220
221	addr = (kprobe_opcode_t *) (regs->pc);
222
223	/* Check we're not actually recursing */
224	if (kprobe_running()) {
225	p = get_kprobe(addr);
226	if (p) {
227	if (kcb->kprobe_status == KPROBE_HIT_SS &&
228	*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
229	goto no_kprobe;
230	}
231	/* We have reentered the kprobe_handler(), since
232	* another probe was hit while within the handler.
233	* We here save the original kprobes variables and
234	* just single step on the instruction of the new probe
235	* without calling any user handlers.
236	*/
237	save_previous_kprobe(kcb);
238	set_current_kprobe(p, regs, kcb);
239	kprobes_inc_nmissed_count(p);
240	prepare_singlestep(p, regs);
241	kcb->kprobe_status = KPROBE_REENTER;
242	return 1;
243	} else {
244	p = __get_cpu_var(current_kprobe);
245	if (p->break_handler && p->break_handler(p, regs)) {
246	goto ss_probe;
247	}
248	}
249	goto no_kprobe;
250	}
251
252	p = get_kprobe(addr);
253	if (!p) {
254	/* Not one of ours: let kernel handle it */
734db377 PM	255	if ((kprobe_opcode_t )addr != BREAKPOINT_INSTRUCTION) {
	256	/*
	257	* The breakpoint instruction was removed right
	258	* after we hit it. Another cpu has removed
	259	* either a probepoint or a debugger breakpoint
	260	* at this address. In either case, no further
	261	* handling of this interrupt is appropriate.
	262	*/
	263	ret = 1;
	264	}
	265
d39f5450 CS	266	goto no_kprobe;
	267	}
	268
	269	set_current_kprobe(p, regs, kcb);
	270	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
	271
	272	if (p->pre_handler && p->pre_handler(p, regs))
	273	/* handler has already set things up, so skip ss setup */
	274	return 1;
	275
4eb5845d	276	ss_probe:
d39f5450 CS	277	prepare_singlestep(p, regs);
	278	kcb->kprobe_status = KPROBE_HIT_SS;
	279	return 1;
	280
4eb5845d	281	no_kprobe:
d39f5450 CS	282	preempt_enable_no_resched();
	283	return ret;
	284	}
	285
	286	/*
	287	* For function-return probes, init_kprobes() establishes a probepoint
	288	* here. When a retprobed function returns, this probe is hit and
	289	* trampoline_probe_handler() runs, calling the kretprobe's handler.
	290	*/
e7cb016e	291	static void __used kretprobe_trampoline_holder(void)
d39f5450	292	{
6eb2139b PM	293	asm volatile (".globl kretprobe_trampoline\n"
	294	"kretprobe_trampoline:\n\t"
	295	"nop\n");
d39f5450 CS	296	}
	297
	298	/*
	299	* Called when we hit the probe point at kretprobe_trampoline
	300	*/
	301	int __kprobes trampoline_probe_handler(struct kprobe p, struct pt_regs regs)
	302	{
	303	struct kretprobe_instance *ri = NULL;
	304	struct hlist_head *head, empty_rp;
	305	struct hlist_node node, tmp;
	306	unsigned long flags, orig_ret_address = 0;
	307	unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
	308
	309	INIT_HLIST_HEAD(&empty_rp);
	310	kretprobe_hash_lock(current, &head, &flags);
	311
	312	/*
	313	* It is possible to have multiple instances associated with a given
	314	* task either because an multiple functions in the call path
	315	* have a return probe installed on them, and/or more then one return
	316	* return probe was registered for a target function.
	317	*
	318	* We can handle this because:
	319	* - instances are always inserted at the head of the list
	320	* - when multiple return probes are registered for the same
	321	* function, the first instance's ret_addr will point to the
	322	* real return address, and all the rest will point to
	323	* kretprobe_trampoline
	324	*/
	325	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
	326	if (ri->task != current)
	327	/* another task is sharing our hash bucket */
	328	continue;
	329
	330	if (ri->rp && ri->rp->handler) {
	331	__get_cpu_var(current_kprobe) = &ri->rp->kp;
	332	ri->rp->handler(ri, regs);
	333	__get_cpu_var(current_kprobe) = NULL;
	334	}
	335
	336	orig_ret_address = (unsigned long)ri->ret_addr;
	337	recycle_rp_inst(ri, &empty_rp);
	338
	339	if (orig_ret_address != trampoline_address)
	340	/*
	341	* This is the real return address. Any other
	342	* instances associated with this task are for
	343	* other calls deeper on the call stack
	344	*/
	345	break;
	346	}
	347
	348	kretprobe_assert(ri, orig_ret_address, trampoline_address);
	349
	350	regs->pc = orig_ret_address;
	351	kretprobe_hash_unlock(current, &flags);
	352
	353	preempt_enable_no_resched();
	354
	355	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
	356	hlist_del(&ri->hlist);
	357	kfree(ri);
	358	}
	359
360	return orig_ret_address;
361	}
362
4eb5845d	363	static int __kprobes post_kprobe_handler(struct pt_regs *regs)
d39f5450 CS	364	{
	365	struct kprobe *cur = kprobe_running();
	366	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	367	kprobe_opcode_t *addr = NULL;
	368	struct kprobe *p = NULL;
	369
	370	if (!cur)
	371	return 0;
	372
	373	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
	374	kcb->kprobe_status = KPROBE_HIT_SSDONE;
	375	cur->post_handler(cur, regs, 0);
	376	}
	377
	378	if (saved_next_opcode.addr != 0x0) {
	379	arch_disarm_kprobe(&saved_next_opcode);
	380	saved_next_opcode.addr = 0x0;
	381	saved_next_opcode.opcode = 0x0;
	382
	383	addr = saved_current_opcode.addr;
	384	saved_current_opcode.addr = 0x0;
	385
	386	p = get_kprobe(addr);
	387	arch_arm_kprobe(p);
	388
	389	if (saved_next_opcode2.addr != 0x0) {
	390	arch_disarm_kprobe(&saved_next_opcode2);
	391	saved_next_opcode2.addr = 0x0;
	392	saved_next_opcode2.opcode = 0x0;
	393	}
	394	}
	395
4eb5845d	396	/* Restore back the original saved kprobes variables and continue. */
d39f5450 CS	397	if (kcb->kprobe_status == KPROBE_REENTER) {
	398	restore_previous_kprobe(kcb);
	399	goto out;
	400	}
4eb5845d	401
d39f5450 CS	402	reset_current_kprobe();
d39f5450 CS	403
4eb5845d	404	out:
d39f5450 CS	405	preempt_enable_no_resched();
	406
	407	return 1;
	408	}
	409
037c10a6	410	int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
d39f5450 CS	411	{
	412	struct kprobe *cur = kprobe_running();
	413	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	414	const struct exception_table_entry *entry;
	415
	416	switch (kcb->kprobe_status) {
	417	case KPROBE_HIT_SS:
	418	case KPROBE_REENTER:
	419	/*
	420	* We are here because the instruction being single
	421	* stepped caused a page fault. We reset the current
	422	* kprobe, point the pc back to the probe address
	423	* and allow the page fault handler to continue as a
	424	* normal page fault.
	425	*/
	426	regs->pc = (unsigned long)cur->addr;
	427	if (kcb->kprobe_status == KPROBE_REENTER)
	428	restore_previous_kprobe(kcb);
	429	else
	430	reset_current_kprobe();
	431	preempt_enable_no_resched();
	432	break;
	433	case KPROBE_HIT_ACTIVE:
	434	case KPROBE_HIT_SSDONE:
	435	/*
	436	* We increment the nmissed count for accounting,
	437	* we can also use npre/npostfault count for accounting
	438	* these specific fault cases.
	439	*/
	440	kprobes_inc_nmissed_count(cur);
	441
	442	/*
	443	* We come here because instructions in the pre/post
	444	* handler caused the page_fault, this could happen
	445	* if handler tries to access user space by
	446	* copy_from_user(), get_user() etc. Let the
	447	* user-specified handler try to fix it first.
	448	*/
	449	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
	450	return 1;
	451
	452	/*
	453	* In case the user-specified fault handler returned
	454	* zero, try to fix up.
	455	*/
	456	if ((entry = search_exception_tables(regs->pc)) != NULL) {
	457	regs->pc = entry->fixup;
	458	return 1;
	459	}
	460
	461	/*
	462	* fixup_exception() could not handle it,
	463	* Let do_page_fault() fix it.
	464	*/
	465	break;
	466	default:
	467	break;
	468	}
4eb5845d	469
d39f5450 CS	470	return 0;
	471	}
	472
	473	/*
	474	* Wrapper routine to for handling exceptions.
	475	*/
	476	int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
	477	unsigned long val, void *data)
	478	{
	479	struct kprobe *p = NULL;
	480	struct die_args args = (struct die_args )data;
	481	int ret = NOTIFY_DONE;
	482	kprobe_opcode_t *addr = NULL;
	483	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	484
	485	addr = (kprobe_opcode_t *) (args->regs->pc);
	486	if (val == DIE_TRAP) {
	487	if (!kprobe_running()) {
	488	if (kprobe_handler(args->regs)) {
	489	ret = NOTIFY_STOP;
	490	} else {
	491	/* Not a kprobe trap */
ee386de7	492	ret = NOTIFY_DONE;
d39f5450 CS	493	}
	494	} else {
	495	p = get_kprobe(addr);
	496	if ((kcb->kprobe_status == KPROBE_HIT_SS) \|\|
	497	(kcb->kprobe_status == KPROBE_REENTER)) {
	498	if (post_kprobe_handler(args->regs))
	499	ret = NOTIFY_STOP;
	500	} else {
	501	if (kprobe_handler(args->regs)) {
	502	ret = NOTIFY_STOP;
	503	} else {
	504	p = __get_cpu_var(current_kprobe);
4eb5845d PM	505	if (p->break_handler &&
4eb5845d PM	506	p->break_handler(p, args->regs))
d39f5450 CS	507	ret = NOTIFY_STOP;
	508	}
	509	}
	510	}
	511	}
	512
	513	return ret;
	514	}
	515
	516	int __kprobes setjmp_pre_handler(struct kprobe p, struct pt_regs regs)
	517	{
	518	struct jprobe *jp = container_of(p, struct jprobe, kp);
	519	unsigned long addr;
	520	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	521
	522	kcb->jprobe_saved_regs = *regs;
	523	kcb->jprobe_saved_r15 = regs->regs[15];
	524	addr = kcb->jprobe_saved_r15;
	525
	526	/*
	527	* TBD: As Linus pointed out, gcc assumes that the callee
	528	* owns the argument space and could overwrite it, e.g.
	529	* tailcall optimization. So, to be absolutely safe
	530	* we also save and restore enough stack bytes to cover
	531	* the argument area.
	532	*/
	533	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
	534	MIN_STACK_SIZE(addr));
	535
	536	regs->pc = (unsigned long)(jp->entry);
	537
	538	return 1;
	539	}
	540
	541	void __kprobes jprobe_return(void)
	542	{
174b5c99	543	asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
d39f5450 CS	544	}
	545
	546	int __kprobes longjmp_break_handler(struct kprobe p, struct pt_regs regs)
	547	{
	548	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
d39f5450	549	unsigned long stack_addr = kcb->jprobe_saved_r15;
4eb5845d	550	u8 addr = (u8 )regs->pc;
d39f5450	551
4eb5845d PM	552	if ((addr >= (u8 *)jprobe_return) &&
4eb5845d PM	553	(addr <= (u8 *)jprobe_return_end)) {
d39f5450 CS	554	*regs = kcb->jprobe_saved_regs;
d39f5450 CS	555
4eb5845d	556	memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack,
d39f5450 CS	557	MIN_STACK_SIZE(stack_addr));
	558
	559	kcb->kprobe_status = KPROBE_HIT_SS;
247bc6d2	560	preempt_enable_no_resched();
d39f5450 CS	561	return 1;
d39f5450 CS	562	}
4eb5845d	563
d39f5450 CS	564	return 0;
	565	}
	566
	567	static struct kprobe trampoline_p = {
4eb5845d	568	.addr = (kprobe_opcode_t *)&kretprobe_trampoline,
d39f5450 CS	569	.pre_handler = trampoline_probe_handler
	570	};
	571
	572	int __init arch_init_kprobes(void)
	573	{
	574	saved_next_opcode.addr = 0x0;
	575	saved_next_opcode.opcode = 0x0;
	576
	577	saved_current_opcode.addr = 0x0;
	578	saved_current_opcode.opcode = 0x0;
	579
	580	saved_next_opcode2.addr = 0x0;
	581	saved_next_opcode2.opcode = 0x0;
	582
	583	return register_kprobe(&trampoline_p);
	584	}