[linux-2.6-block.git] / arch / sparc64 / kernel / kprobes.c

/* arch/sparc64/kernel/kprobes.c
 *
 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <asm/kdebug.h>
#include <asm/signal.h>
#include <asm/cacheflush.h>

/* We do not have hardware single-stepping on sparc64.
 * So we implement software single-stepping with breakpoint
 * traps.  The top-level scheme is similar to that used
 * in the x86 kprobes implementation.
 *
 * In the kprobe->ainsn.insn[] array we store the original
 * instruction at index zero and a break instruction at
 * index one.
 *
 * When we hit a kprobe we:
 * - Run the pre-handler
 * - Remember "regs->tnpc" and interrupt level stored in
 *   "regs->tstate" so we can restore them later
 * - Disable PIL interrupts
 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
 * - Mark that we are actively in a kprobe
 *
 * At this point we wait for the second breakpoint at
 * kprobe->ainsn.insn[1] to hit.  When it does we:
 * - Run the post-handler
 * - Set regs->tpc to "remembered" regs->tnpc stored above,
 *   restore the PIL interrupt level in "regs->tstate" as well
 * - Make any adjustments necessary to regs->tnpc in order
 *   to handle relative branches correctly.  See below.
 * - Mark that we are no longer actively in a kprobe.
 */

int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
	return 0;
}

void __kprobes arch_copy_kprobe(struct kprobe *p)
{
	p->ainsn.insn[0] = *p->addr;
	p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
	p->opcode = *p->addr;
}

void __kprobes arch_arm_kprobe(struct kprobe *p)
{
	*p->addr = BREAKPOINT_INSTRUCTION;
	flushi(p->addr);
}

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

void __kprobes arch_remove_kprobe(struct kprobe *p)
{
}

static struct kprobe *current_kprobe;
static unsigned long current_kprobe_orig_tnpc;
static unsigned long current_kprobe_orig_tstate_pil;
static unsigned int kprobe_status;
static struct kprobe *kprobe_prev;
static unsigned long kprobe_orig_tnpc_prev;
static unsigned long kprobe_orig_tstate_pil_prev;
static unsigned int kprobe_status_prev;

static inline void save_previous_kprobe(void)
{
	kprobe_status_prev = kprobe_status;
	kprobe_orig_tnpc_prev = current_kprobe_orig_tnpc;
	kprobe_orig_tstate_pil_prev = current_kprobe_orig_tstate_pil;
	kprobe_prev = current_kprobe;
}

static inline void restore_previous_kprobe(void)
{
	kprobe_status = kprobe_status_prev;
	current_kprobe_orig_tnpc = kprobe_orig_tnpc_prev;
	current_kprobe_orig_tstate_pil = kprobe_orig_tstate_pil_prev;
	current_kprobe = kprobe_prev;
}

static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
{
	current_kprobe_orig_tnpc = regs->tnpc;
	current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
	current_kprobe = p;
}

static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
	regs->tstate |= TSTATE_PIL;

	/*single step inline, if it a breakpoint instruction*/
	if (p->opcode == BREAKPOINT_INSTRUCTION) {
		regs->tpc = (unsigned long) p->addr;
		regs->tnpc = current_kprobe_orig_tnpc;
	} else {
		regs->tpc = (unsigned long) &p->ainsn.insn[0];
		regs->tnpc = (unsigned long) &p->ainsn.insn[1];
	}
}

static int __kprobes kprobe_handler(struct pt_regs *regs)
{
	struct kprobe *p;
	void *addr = (void *) regs->tpc;
	int ret = 0;

	preempt_disable();

	if (kprobe_running()) {
		/* We *are* holding lock here, so this is safe.
		 * Disarm the probe we just hit, and ignore it.
		 */
		p = get_kprobe(addr);
		if (p) {
			if (kprobe_status == KPROBE_HIT_SS) {
				regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
					current_kprobe_orig_tstate_pil);
				unlock_kprobes();
				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();
			set_current_kprobe(p, regs);
			p->nmissed++;
			kprobe_status = KPROBE_REENTER;
			prepare_singlestep(p, regs);
			return 1;
		} else {
			p = current_kprobe;
			if (p->break_handler && p->break_handler(p, regs))
				goto ss_probe;
		}
		/* If it's not ours, can't be delete race, (we hold lock). */
		goto no_kprobe;
	}

	lock_kprobes();
	p = get_kprobe(addr);
	if (!p) {
		unlock_kprobes();
		if (*(u32 *)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;
		}
		/* Not one of ours: let kernel handle it */
		goto no_kprobe;
	}

	set_current_kprobe(p, regs);
	kprobe_status = KPROBE_HIT_ACTIVE;
	if (p->pre_handler && p->pre_handler(p, regs))
		return 1;

ss_probe:
	prepare_singlestep(p, regs);
	kprobe_status = KPROBE_HIT_SS;
	return 1;

no_kprobe:
	preempt_enable_no_resched();
	return ret;
}

/* If INSN is a relative control transfer instruction,
 * return the corrected branch destination value.
 *
 * The original INSN location was REAL_PC, it actually
 * executed at PC and produced destination address NPC.
 */
static unsigned long __kprobes relbranch_fixup(u32 insn, unsigned long real_pc,
					       unsigned long pc,
					       unsigned long npc)
{
	/* Branch not taken, no mods necessary.  */
	if (npc == pc + 0x4UL)
		return real_pc + 0x4UL;

	/* The three cases are call, branch w/prediction,
	 * and traditional branch.
	 */
	if ((insn & 0xc0000000) == 0x40000000 ||
	    (insn & 0xc1c00000) == 0x00400000 ||
	    (insn & 0xc1c00000) == 0x00800000) {
		/* The instruction did all the work for us
		 * already, just apply the offset to the correct
		 * instruction location.
		 */
		return (real_pc + (npc - pc));
	}

	return real_pc + 0x4UL;
}

/* If INSN is an instruction which writes it's PC location
 * into a destination register, fix that up.
 */
static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
				  unsigned long real_pc)
{
	unsigned long *slot = NULL;

	/* Simplest cast is call, which always uses %o7 */
	if ((insn & 0xc0000000) == 0x40000000) {
		slot = &regs->u_regs[UREG_I7];
	}

	/* Jmpl encodes the register inside of the opcode */
	if ((insn & 0xc1f80000) == 0x81c00000) {
		unsigned long rd = ((insn >> 25) & 0x1f);

		if (rd <= 15) {
			slot = &regs->u_regs[rd];
		} else {
			/* Hard case, it goes onto the stack. */
			flushw_all();

			rd -= 16;
			slot = (unsigned long *)
				(regs->u_regs[UREG_FP] + STACK_BIAS);
			slot += rd;
		}
	}
	if (slot != NULL)
		*slot = real_pc;
}

/*
 * Called after single-stepping.  p->addr is the address of the
 * instruction whose first byte has been replaced by the breakpoint
 * instruction.  To avoid the SMP problems that can occur when we
 * temporarily put back the original opcode to single-step, we
 * single-stepped a copy of the instruction.  The address of this
 * copy is p->ainsn.insn.
 *
 * This function prepares to return from the post-single-step
 * breakpoint trap.
 */
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
{
	u32 insn = p->ainsn.insn[0];

	regs->tpc = current_kprobe_orig_tnpc;
	regs->tnpc = relbranch_fixup(insn,
				     (unsigned long) p->addr,
				     (unsigned long) &p->ainsn.insn[0],
				     regs->tnpc);
	retpc_fixup(regs, insn, (unsigned long) p->addr);

	regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
			current_kprobe_orig_tstate_pil);
}

static inline int post_kprobe_handler(struct pt_regs *regs)
{
	if (!kprobe_running())
		return 0;

	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
		kprobe_status = KPROBE_HIT_SSDONE;
		current_kprobe->post_handler(current_kprobe, regs, 0);
	}

	resume_execution(current_kprobe, regs);

	/*Restore back the original saved kprobes variables and continue. */
	if (kprobe_status == KPROBE_REENTER) {
		restore_previous_kprobe();
		goto out;
	}
	unlock_kprobes();
out:
	preempt_enable_no_resched();

	return 1;
}

/* Interrupts disabled, kprobe_lock held. */
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
	if (current_kprobe->fault_handler
	    && current_kprobe->fault_handler(current_kprobe, regs, trapnr))
		return 1;

	if (kprobe_status & KPROBE_HIT_SS) {
		resume_execution(current_kprobe, regs);

		unlock_kprobes();
		preempt_enable_no_resched();
	}
	return 0;
}

/*
 * Wrapper routine to for handling exceptions.
 */
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
				       unsigned long val, void *data)
{
	struct die_args *args = (struct die_args *)data;
	switch (val) {
	case DIE_DEBUG:
		if (kprobe_handler(args->regs))
			return NOTIFY_STOP;
		break;
	case DIE_DEBUG_2:
		if (post_kprobe_handler(args->regs))
			return NOTIFY_STOP;
		break;
	case DIE_GPF:
		if (kprobe_running() &&
		    kprobe_fault_handler(args->regs, args->trapnr))
			return NOTIFY_STOP;
		break;
	case DIE_PAGE_FAULT:
		if (kprobe_running() &&
		    kprobe_fault_handler(args->regs, args->trapnr))
			return NOTIFY_STOP;
		break;
	default:
		break;
	}
	return NOTIFY_DONE;
}

asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
				      struct pt_regs *regs)
{
	BUG_ON(trap_level != 0x170 && trap_level != 0x171);

	if (user_mode(regs)) {
		local_irq_enable();
		bad_trap(regs, trap_level);
		return;
	}

	/* trap_level == 0x170 --> ta 0x70
	 * trap_level == 0x171 --> ta 0x71
	 */
	if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
		       (trap_level == 0x170) ? "debug" : "debug_2",
		       regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
		bad_trap(regs, trap_level);
}

/* Jprobes support.  */
static struct pt_regs jprobe_saved_regs;
static struct pt_regs *jprobe_saved_regs_location;
static struct sparc_stackf jprobe_saved_stack;

int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct jprobe *jp = container_of(p, struct jprobe, kp);

	jprobe_saved_regs_location = regs;
	memcpy(&jprobe_saved_regs, regs, sizeof(*regs));

	/* Save a whole stack frame, this gets arguments
	 * pushed onto the stack after using up all the
	 * arg registers.
	 */
	memcpy(&jprobe_saved_stack,
	       (char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
	       sizeof(jprobe_saved_stack));

	regs->tpc  = (unsigned long) jp->entry;
	regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
	regs->tstate |= TSTATE_PIL;

	return 1;
}

void __kprobes jprobe_return(void)
{
	preempt_enable_no_resched();
	__asm__ __volatile__(
		".globl	jprobe_return_trap_instruction\n"
"jprobe_return_trap_instruction:\n\t"
		"ta 0x70");
}

extern void jprobe_return_trap_instruction(void);

extern void __show_regs(struct pt_regs * regs);

int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
	u32 *addr = (u32 *) regs->tpc;

	if (addr == (u32 *) jprobe_return_trap_instruction) {
		if (jprobe_saved_regs_location != regs) {
			printk("JPROBE: Current regs (%p) does not match "
			       "saved regs (%p).\n",
			       regs, jprobe_saved_regs_location);
			printk("JPROBE: Saved registers\n");
			__show_regs(jprobe_saved_regs_location);
			printk("JPROBE: Current registers\n");
			__show_regs(regs);
			BUG();
		}
		/* Restore old register state.  Do pt_regs
		 * first so that UREG_FP is the original one for
		 * the stack frame restore.
		 */
		memcpy(regs, &jprobe_saved_regs, sizeof(*regs));

		memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
		       &jprobe_saved_stack,
		       sizeof(jprobe_saved_stack));

		return 1;
	}
	return 0;
}

/* architecture specific initialization */
int arch_init_kprobes(void)
{
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/* arch/sparc64/kernel/kprobes.c
	2	*
	3	* Copyright (C) 2004 David S. Miller <davem@davemloft.net>
	4	*/
	5
	6	#include <linux/config.h>
	7	#include <linux/kernel.h>
	8	#include <linux/kprobes.h>
1da177e4 LT	9	#include <asm/kdebug.h>
1da177e4 LT	10	#include <asm/signal.h>
05e14cb3	11	#include <asm/cacheflush.h>
1da177e4 LT	12
	13	/* We do not have hardware single-stepping on sparc64.
	14	* So we implement software single-stepping with breakpoint
	15	* traps. The top-level scheme is similar to that used
	16	* in the x86 kprobes implementation.
	17	*
	18	* In the kprobe->ainsn.insn[] array we store the original
	19	* instruction at index zero and a break instruction at
	20	* index one.
	21	*
	22	* When we hit a kprobe we:
	23	* - Run the pre-handler
	24	* - Remember "regs->tnpc" and interrupt level stored in
	25	* "regs->tstate" so we can restore them later
	26	* - Disable PIL interrupts
	27	* - Set regs->tpc to point to kprobe->ainsn.insn[0]
	28	* - Set regs->tnpc to point to kprobe->ainsn.insn[1]
	29	* - Mark that we are actively in a kprobe
	30	*
	31	* At this point we wait for the second breakpoint at
	32	* kprobe->ainsn.insn[1] to hit. When it does we:
	33	* - Run the post-handler
	34	* - Set regs->tpc to "remembered" regs->tnpc stored above,
	35	* restore the PIL interrupt level in "regs->tstate" as well
	36	* - Make any adjustments necessary to regs->tnpc in order
	37	* to handle relative branches correctly. See below.
	38	* - Mark that we are no longer actively in a kprobe.
	39	*/
	40
05e14cb3	41	int __kprobes arch_prepare_kprobe(struct kprobe *p)
1da177e4 LT	42	{
	43	return 0;
	44	}
	45
05e14cb3	46	void __kprobes arch_copy_kprobe(struct kprobe *p)
1da177e4 LT	47	{
	48	p->ainsn.insn[0] = *p->addr;
	49	p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
7e1048b1 RL	50	p->opcode = *p->addr;
	51	}
	52
05e14cb3	53	void __kprobes arch_arm_kprobe(struct kprobe *p)
7e1048b1 RL	54	{
	55	*p->addr = BREAKPOINT_INSTRUCTION;
	56	flushi(p->addr);
	57	}
	58
05e14cb3	59	void __kprobes arch_disarm_kprobe(struct kprobe *p)
7e1048b1 RL	60	{
	61	*p->addr = p->opcode;
	62	flushi(p->addr);
1da177e4 LT	63	}
1da177e4 LT	64
05e14cb3	65	void __kprobes arch_remove_kprobe(struct kprobe *p)
1da177e4 LT	66	{
	67	}
	68
1da177e4 LT	69	static struct kprobe *current_kprobe;
	70	static unsigned long current_kprobe_orig_tnpc;
	71	static unsigned long current_kprobe_orig_tstate_pil;
	72	static unsigned int kprobe_status;
e539c233 PP	73	static struct kprobe *kprobe_prev;
	74	static unsigned long kprobe_orig_tnpc_prev;
	75	static unsigned long kprobe_orig_tstate_pil_prev;
	76	static unsigned int kprobe_status_prev;
1da177e4	77
e539c233 PP	78	static inline void save_previous_kprobe(void)
	79	{
	80	kprobe_status_prev = kprobe_status;
	81	kprobe_orig_tnpc_prev = current_kprobe_orig_tnpc;
	82	kprobe_orig_tstate_pil_prev = current_kprobe_orig_tstate_pil;
	83	kprobe_prev = current_kprobe;
	84	}
	85
	86	static inline void restore_previous_kprobe(void)
	87	{
	88	kprobe_status = kprobe_status_prev;
	89	current_kprobe_orig_tnpc = kprobe_orig_tnpc_prev;
	90	current_kprobe_orig_tstate_pil = kprobe_orig_tstate_pil_prev;
	91	current_kprobe = kprobe_prev;
	92	}
	93
	94	static inline void set_current_kprobe(struct kprobe p, struct pt_regs regs)
1da177e4 LT	95	{
	96	current_kprobe_orig_tnpc = regs->tnpc;
	97	current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
e539c233 PP	98	current_kprobe = p;
	99	}
	100
	101	static inline void prepare_singlestep(struct kprobe p, struct pt_regs regs)
	102	{
1da177e4 LT	103	regs->tstate \|= TSTATE_PIL;
	104
	105	/single step inline, if it a breakpoint instruction/
	106	if (p->opcode == BREAKPOINT_INSTRUCTION) {
	107	regs->tpc = (unsigned long) p->addr;
	108	regs->tnpc = current_kprobe_orig_tnpc;
	109	} else {
	110	regs->tpc = (unsigned long) &p->ainsn.insn[0];
	111	regs->tnpc = (unsigned long) &p->ainsn.insn[1];
	112	}
	113	}
	114
05e14cb3	115	static int __kprobes kprobe_handler(struct pt_regs *regs)
1da177e4 LT	116	{
	117	struct kprobe *p;
	118	void addr = (void ) regs->tpc;
	119	int ret = 0;
	120
	121	preempt_disable();
	122
	123	if (kprobe_running()) {
	124	/* We are holding lock here, so this is safe.
	125	* Disarm the probe we just hit, and ignore it.
	126	*/
	127	p = get_kprobe(addr);
	128	if (p) {
	129	if (kprobe_status == KPROBE_HIT_SS) {
	130	regs->tstate = ((regs->tstate & ~TSTATE_PIL) \|
	131	current_kprobe_orig_tstate_pil);
	132	unlock_kprobes();
	133	goto no_kprobe;
	134	}
e539c233 PP	135	/* We have reentered the kprobe_handler(), since
	136	* another probe was hit while within the handler.
	137	* We here save the original kprobes variables and
	138	* just single step on the instruction of the new probe
	139	* without calling any user handlers.
	140	*/
	141	save_previous_kprobe();
	142	set_current_kprobe(p, regs);
	143	p->nmissed++;
	144	kprobe_status = KPROBE_REENTER;
	145	prepare_singlestep(p, regs);
	146	return 1;
1da177e4 LT	147	} else {
	148	p = current_kprobe;
	149	if (p->break_handler && p->break_handler(p, regs))
	150	goto ss_probe;
	151	}
	152	/* If it's not ours, can't be delete race, (we hold lock). */
	153	goto no_kprobe;
	154	}
	155
	156	lock_kprobes();
	157	p = get_kprobe(addr);
	158	if (!p) {
	159	unlock_kprobes();
	160	if ((u32 )addr != BREAKPOINT_INSTRUCTION) {
	161	/*
	162	* The breakpoint instruction was removed right
	163	* after we hit it. Another cpu has removed
	164	* either a probepoint or a debugger breakpoint
	165	* at this address. In either case, no further
	166	* handling of this interrupt is appropriate.
	167	*/
	168	ret = 1;
	169	}
	170	/* Not one of ours: let kernel handle it */
	171	goto no_kprobe;
	172	}
	173
e539c233	174	set_current_kprobe(p, regs);
1da177e4	175	kprobe_status = KPROBE_HIT_ACTIVE;
1da177e4 LT	176	if (p->pre_handler && p->pre_handler(p, regs))
	177	return 1;
	178
	179	ss_probe:
	180	prepare_singlestep(p, regs);
	181	kprobe_status = KPROBE_HIT_SS;
	182	return 1;
	183
	184	no_kprobe:
	185	preempt_enable_no_resched();
	186	return ret;
	187	}
	188
	189	/* If INSN is a relative control transfer instruction,
	190	* return the corrected branch destination value.
	191	*
	192	* The original INSN location was REAL_PC, it actually
	193	* executed at PC and produced destination address NPC.
	194	*/
05e14cb3 PP	195	static unsigned long __kprobes relbranch_fixup(u32 insn, unsigned long real_pc,
	196	unsigned long pc,
	197	unsigned long npc)
1da177e4 LT	198	{
	199	/* Branch not taken, no mods necessary. */
	200	if (npc == pc + 0x4UL)
	201	return real_pc + 0x4UL;
	202
	203	/* The three cases are call, branch w/prediction,
	204	* and traditional branch.
	205	*/
	206	if ((insn & 0xc0000000) == 0x40000000 \|\|
	207	(insn & 0xc1c00000) == 0x00400000 \|\|
	208	(insn & 0xc1c00000) == 0x00800000) {
	209	/* The instruction did all the work for us
	210	* already, just apply the offset to the correct
	211	* instruction location.
	212	*/
	213	return (real_pc + (npc - pc));
	214	}
	215
	216	return real_pc + 0x4UL;
	217	}
	218
	219	/* If INSN is an instruction which writes it's PC location
	220	* into a destination register, fix that up.
	221	*/
05e14cb3 PP	222	static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
05e14cb3 PP	223	unsigned long real_pc)
1da177e4 LT	224	{
	225	unsigned long *slot = NULL;
	226
	227	/* Simplest cast is call, which always uses %o7 */
	228	if ((insn & 0xc0000000) == 0x40000000) {
	229	slot = &regs->u_regs[UREG_I7];
	230	}
	231
	232	/* Jmpl encodes the register inside of the opcode */
	233	if ((insn & 0xc1f80000) == 0x81c00000) {
	234	unsigned long rd = ((insn >> 25) & 0x1f);
	235
	236	if (rd <= 15) {
	237	slot = &regs->u_regs[rd];
	238	} else {
	239	/* Hard case, it goes onto the stack. */
	240	flushw_all();
	241
	242	rd -= 16;
	243	slot = (unsigned long *)
	244	(regs->u_regs[UREG_FP] + STACK_BIAS);
	245	slot += rd;
	246	}
	247	}
	248	if (slot != NULL)
	249	*slot = real_pc;
	250	}
	251
	252	/*
	253	* Called after single-stepping. p->addr is the address of the
	254	* instruction whose first byte has been replaced by the breakpoint
	255	* instruction. To avoid the SMP problems that can occur when we
	256	* temporarily put back the original opcode to single-step, we
	257	* single-stepped a copy of the instruction. The address of this
	258	* copy is p->ainsn.insn.
	259	*
	260	* This function prepares to return from the post-single-step
	261	* breakpoint trap.
	262	*/
05e14cb3	263	static void __kprobes resume_execution(struct kprobe p, struct pt_regs regs)
1da177e4 LT	264	{
	265	u32 insn = p->ainsn.insn[0];
	266
	267	regs->tpc = current_kprobe_orig_tnpc;
	268	regs->tnpc = relbranch_fixup(insn,
	269	(unsigned long) p->addr,
	270	(unsigned long) &p->ainsn.insn[0],
	271	regs->tnpc);
	272	retpc_fixup(regs, insn, (unsigned long) p->addr);
	273
	274	regs->tstate = ((regs->tstate & ~TSTATE_PIL) \|
	275	current_kprobe_orig_tstate_pil);
	276	}
	277
	278	static inline int post_kprobe_handler(struct pt_regs *regs)
	279	{
	280	if (!kprobe_running())
	281	return 0;
	282
e539c233 PP	283	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
e539c233 PP	284	kprobe_status = KPROBE_HIT_SSDONE;
1da177e4	285	current_kprobe->post_handler(current_kprobe, regs, 0);
e539c233	286	}
1da177e4 LT	287
	288	resume_execution(current_kprobe, regs);
	289
e539c233 PP	290	/Restore back the original saved kprobes variables and continue. /
	291	if (kprobe_status == KPROBE_REENTER) {
	292	restore_previous_kprobe();
	293	goto out;
	294	}
1da177e4	295	unlock_kprobes();
e539c233	296	out:
1da177e4 LT	297	preempt_enable_no_resched();
	298
	299	return 1;
	300	}
	301
	302	/* Interrupts disabled, kprobe_lock held. */
	303	static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
	304	{
	305	if (current_kprobe->fault_handler
	306	&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
	307	return 1;
	308
	309	if (kprobe_status & KPROBE_HIT_SS) {
	310	resume_execution(current_kprobe, regs);
	311
	312	unlock_kprobes();
	313	preempt_enable_no_resched();
	314	}
	315	return 0;
	316	}
	317
	318	/*
	319	* Wrapper routine to for handling exceptions.
	320	*/
05e14cb3 PP	321	int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
05e14cb3 PP	322	unsigned long val, void *data)
1da177e4 LT	323	{
	324	struct die_args args = (struct die_args )data;
	325	switch (val) {
	326	case DIE_DEBUG:
	327	if (kprobe_handler(args->regs))
	328	return NOTIFY_STOP;
	329	break;
	330	case DIE_DEBUG_2:
	331	if (post_kprobe_handler(args->regs))
	332	return NOTIFY_STOP;
	333	break;
	334	case DIE_GPF:
	335	if (kprobe_running() &&
	336	kprobe_fault_handler(args->regs, args->trapnr))
	337	return NOTIFY_STOP;
	338	break;
	339	case DIE_PAGE_FAULT:
	340	if (kprobe_running() &&
	341	kprobe_fault_handler(args->regs, args->trapnr))
	342	return NOTIFY_STOP;
	343	break;
	344	default:
	345	break;
	346	}
	347	return NOTIFY_DONE;
	348	}
	349
05e14cb3 PP	350	asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
05e14cb3 PP	351	struct pt_regs *regs)
1da177e4 LT	352	{
	353	BUG_ON(trap_level != 0x170 && trap_level != 0x171);
	354
	355	if (user_mode(regs)) {
	356	local_irq_enable();
	357	bad_trap(regs, trap_level);
	358	return;
	359	}
	360
	361	/* trap_level == 0x170 --> ta 0x70
	362	* trap_level == 0x171 --> ta 0x71
	363	*/
	364	if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
	365	(trap_level == 0x170) ? "debug" : "debug_2",
	366	regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
	367	bad_trap(regs, trap_level);
	368	}
	369
	370	/* Jprobes support. */
	371	static struct pt_regs jprobe_saved_regs;
	372	static struct pt_regs *jprobe_saved_regs_location;
	373	static struct sparc_stackf jprobe_saved_stack;
	374
05e14cb3	375	int __kprobes setjmp_pre_handler(struct kprobe p, struct pt_regs regs)
1da177e4 LT	376	{
	377	struct jprobe *jp = container_of(p, struct jprobe, kp);
	378
	379	jprobe_saved_regs_location = regs;
	380	memcpy(&jprobe_saved_regs, regs, sizeof(*regs));
	381
	382	/* Save a whole stack frame, this gets arguments
	383	* pushed onto the stack after using up all the
	384	* arg registers.
	385	*/
	386	memcpy(&jprobe_saved_stack,
	387	(char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
	388	sizeof(jprobe_saved_stack));
	389
	390	regs->tpc = (unsigned long) jp->entry;
	391	regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
	392	regs->tstate \|= TSTATE_PIL;
	393
	394	return 1;
	395	}
	396
05e14cb3	397	void __kprobes jprobe_return(void)
1da177e4 LT	398	{
	399	preempt_enable_no_resched();
	400	__asm__ __volatile__(
	401	".globl jprobe_return_trap_instruction\n"
	402	"jprobe_return_trap_instruction:\n\t"
	403	"ta 0x70");
	404	}
	405
	406	extern void jprobe_return_trap_instruction(void);
	407
	408	extern void __show_regs(struct pt_regs * regs);
	409
05e14cb3	410	int __kprobes longjmp_break_handler(struct kprobe p, struct pt_regs regs)
1da177e4 LT	411	{
	412	u32 addr = (u32 ) regs->tpc;
	413
	414	if (addr == (u32 *) jprobe_return_trap_instruction) {
	415	if (jprobe_saved_regs_location != regs) {
	416	printk("JPROBE: Current regs (%p) does not match "
	417	"saved regs (%p).\n",
	418	regs, jprobe_saved_regs_location);
	419	printk("JPROBE: Saved registers\n");
	420	__show_regs(jprobe_saved_regs_location);
	421	printk("JPROBE: Current registers\n");
	422	__show_regs(regs);
	423	BUG();
	424	}
	425	/* Restore old register state. Do pt_regs
	426	* first so that UREG_FP is the original one for
	427	* the stack frame restore.
	428	*/
	429	memcpy(regs, &jprobe_saved_regs, sizeof(*regs));
	430
	431	memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
	432	&jprobe_saved_stack,
	433	sizeof(jprobe_saved_stack));
	434
	435	return 1;
	436	}
	437	return 0;
	438	}
e539c233	439
6772926b RL	440	/* architecture specific initialization */
	441	int arch_init_kprobes(void)
	442	{
	443	return 0;
	444	}