[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / ppc64 / kernel / kprobes.c

/*
 *  Kernel Probes (KProbes)
 *  arch/ppc64/kernel/kprobes.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2002, 2004
 *
 * 2002-Oct	Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
 *		Probes initial implementation ( includes contributions from
 *		Rusty Russell).
 * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
 *		interface to access function arguments.
 * 2004-Nov	Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
 *		for PPC64
 */

#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/spinlock.h>
#include <linux/preempt.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/sstep.h>

/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE	0x00000001
#define KPROBE_HIT_SS		0x00000002

static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_saved_msr;
static struct pt_regs jprobe_saved_regs;

int arch_prepare_kprobe(struct kprobe *p)
{
	int ret = 0;
	kprobe_opcode_t insn = *p->addr;

	if ((unsigned long)p->addr & 0x03) {
		printk("Attempt to register kprobe at an unaligned address\n");
		ret = -EINVAL;
	} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
		printk("Cannot register a kprobe on rfid or mtmsrd\n");
		ret = -EINVAL;
	}
	return ret;
}

void arch_copy_kprobe(struct kprobe *p)
{
	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
	p->opcode = *p->addr;
}

void 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 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));
}

void arch_remove_kprobe(struct kprobe *p)
{
}

static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
	regs->msr |= MSR_SE;
	/*single step inline if it a breakpoint instruction*/
	if (p->opcode == BREAKPOINT_INSTRUCTION)
		regs->nip = (unsigned long)p->addr;
	else
		regs->nip = (unsigned long)&p->ainsn.insn;
}

static inline int kprobe_handler(struct pt_regs *regs)
{
	struct kprobe *p;
	int ret = 0;
	unsigned int *addr = (unsigned int *)regs->nip;

	/* Check we're not actually recursing */
	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->msr &= ~MSR_SE;
				regs->msr |= kprobe_saved_msr;
				unlock_kprobes();
				goto no_kprobe;
			}
			arch_disarm_kprobe(p);
			regs->nip = (unsigned long)p->addr;
			ret = 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 (*addr != BREAKPOINT_INSTRUCTION) {
			/*
			 * PowerPC has multiple variants of the "trap"
			 * instruction. If the current instruction is a
			 * trap variant, it could belong to someone else
			 */
			kprobe_opcode_t cur_insn = *addr;
			if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
					IS_TWI(cur_insn) || IS_TDI(cur_insn))
		       		goto no_kprobe;
			/*
			 * 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;
	}

	kprobe_status = KPROBE_HIT_ACTIVE;
	current_kprobe = p;
	kprobe_saved_msr = regs->msr;
	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);
	kprobe_status = KPROBE_HIT_SS;
	/*
	 * This preempt_disable() matches the preempt_enable_no_resched()
	 * in post_kprobe_handler().
	 */
	preempt_disable();
	return 1;

no_kprobe:
	return ret;
}

/*
 * 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.
 */
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
{
	int ret;

	regs->nip = (unsigned long)p->addr;
	ret = emulate_step(regs, p->ainsn.insn[0]);
	if (ret == 0)
		regs->nip = (unsigned long)p->addr + 4;
}

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

	if (current_kprobe->post_handler)
		current_kprobe->post_handler(current_kprobe, regs, 0);

	resume_execution(current_kprobe, regs);
	regs->msr |= kprobe_saved_msr;

	unlock_kprobes();
	preempt_enable_no_resched();

	/*
	 * if somebody else is singlestepping across a probe point, msr
	 * will have SE set, in which case, continue the remaining processing
	 * of do_debug, as if this is not a probe hit.
	 */
	if (regs->msr & MSR_SE)
		return 0;

	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);
		regs->msr &= ~MSR_SE;
		regs->msr |= kprobe_saved_msr;

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

/*
 * Wrapper routine to for handling exceptions.
 */
int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
			     void *data)
{
	struct die_args *args = (struct die_args *)data;
	int ret = NOTIFY_DONE;

	/*
	 * Interrupts are not disabled here.  We need to disable
	 * preemption, because kprobe_running() uses smp_processor_id().
	 */
	preempt_disable();
	switch (val) {
	case DIE_BPT:
		if (kprobe_handler(args->regs))
			ret = NOTIFY_STOP;
		break;
	case DIE_SSTEP:
		if (post_kprobe_handler(args->regs))
			ret = NOTIFY_STOP;
		break;
	case DIE_GPF:
	case DIE_PAGE_FAULT:
		if (kprobe_running() &&
		    kprobe_fault_handler(args->regs, args->trapnr))
			ret = NOTIFY_STOP;
		break;
	default:
		break;
	}
	preempt_enable();
	return ret;
}

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

	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));

	/* setup return addr to the jprobe handler routine */
	regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
	regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);

	return 1;
}

void jprobe_return(void)
{
	asm volatile("trap" ::: "memory");
}

void jprobe_return_end(void)
{
};

int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
	/*
	 * FIXME - we should ideally be validating that we got here 'cos
	 * of the "trap" in jprobe_return() above, before restoring the
	 * saved regs...
	 */
	memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
	return 1;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Kernel Probes (KProbes)
	3	* arch/ppc64/kernel/kprobes.c
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	18	*
	19	* Copyright (C) IBM Corporation, 2002, 2004
	20	*
	21	* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
	22	* Probes initial implementation ( includes contributions from
	23	* Rusty Russell).
	24	* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
	25	* interface to access function arguments.
	26	* 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
	27	* for PPC64
	28	*/
	29
	30	#include <linux/config.h>
	31	#include <linux/kprobes.h>
	32	#include <linux/ptrace.h>
	33	#include <linux/spinlock.h>
	34	#include <linux/preempt.h>
7e1048b1	35	#include <asm/cacheflush.h>
1da177e4 LT	36	#include <asm/kdebug.h>
	37	#include <asm/sstep.h>
	38
	39	/* kprobe_status settings */
	40	#define KPROBE_HIT_ACTIVE 0x00000001
	41	#define KPROBE_HIT_SS 0x00000002
	42
	43	static struct kprobe *current_kprobe;
	44	static unsigned long kprobe_status, kprobe_saved_msr;
	45	static struct pt_regs jprobe_saved_regs;
	46
	47	int arch_prepare_kprobe(struct kprobe *p)
	48	{
63224d1e	49	int ret = 0;
1da177e4 LT	50	kprobe_opcode_t insn = *p->addr;
1da177e4 LT	51
63224d1e AM	52	if ((unsigned long)p->addr & 0x03) {
	53	printk("Attempt to register kprobe at an unaligned address\n");
	54	ret = -EINVAL;
	55	} else if (IS_MTMSRD(insn) \|\| IS_RFID(insn)) {
	56	printk("Cannot register a kprobe on rfid or mtmsrd\n");
	57	ret = -EINVAL;
	58	}
	59	return ret;
1da177e4 LT	60	}
	61
	62	void arch_copy_kprobe(struct kprobe *p)
	63	{
	64	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
7e1048b1	65	p->opcode = *p->addr;
1da177e4 LT	66	}
1da177e4 LT	67
7e1048b1	68	void arch_arm_kprobe(struct kprobe *p)
1da177e4	69	{
7e1048b1 RL	70	*p->addr = BREAKPOINT_INSTRUCTION;
	71	flush_icache_range((unsigned long) p->addr,
	72	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
1da177e4 LT	73	}
1da177e4 LT	74
7e1048b1	75	void arch_disarm_kprobe(struct kprobe *p)
1da177e4 LT	76	{
1da177e4 LT	77	*p->addr = p->opcode;
7e1048b1 RL	78	flush_icache_range((unsigned long) p->addr,
	79	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
	80	}
	81
	82	void arch_remove_kprobe(struct kprobe *p)
	83	{
1da177e4 LT	84	}
	85
	86	static inline void prepare_singlestep(struct kprobe p, struct pt_regs regs)
	87	{
	88	regs->msr \|= MSR_SE;
	89	/single step inline if it a breakpoint instruction/
	90	if (p->opcode == BREAKPOINT_INSTRUCTION)
	91	regs->nip = (unsigned long)p->addr;
	92	else
	93	regs->nip = (unsigned long)&p->ainsn.insn;
	94	}
	95
	96	static inline int kprobe_handler(struct pt_regs *regs)
	97	{
	98	struct kprobe *p;
	99	int ret = 0;
	100	unsigned int addr = (unsigned int )regs->nip;
	101
	102	/* Check we're not actually recursing */
	103	if (kprobe_running()) {
	104	/* We are holding lock here, so this is safe.
	105	Disarm the probe we just hit, and ignore it. */
	106	p = get_kprobe(addr);
	107	if (p) {
	108	if (kprobe_status == KPROBE_HIT_SS) {
	109	regs->msr &= ~MSR_SE;
	110	regs->msr \|= kprobe_saved_msr;
	111	unlock_kprobes();
	112	goto no_kprobe;
	113	}
7e1048b1 RL	114	arch_disarm_kprobe(p);
7e1048b1 RL	115	regs->nip = (unsigned long)p->addr;
1da177e4 LT	116	ret = 1;
	117	} else {
	118	p = current_kprobe;
	119	if (p->break_handler && p->break_handler(p, regs)) {
	120	goto ss_probe;
	121	}
	122	}
	123	/* If it's not ours, can't be delete race, (we hold lock). */
	124	goto no_kprobe;
	125	}
	126
	127	lock_kprobes();
	128	p = get_kprobe(addr);
	129	if (!p) {
	130	unlock_kprobes();
	131	if (*addr != BREAKPOINT_INSTRUCTION) {
	132	/*
	133	* PowerPC has multiple variants of the "trap"
	134	* instruction. If the current instruction is a
	135	* trap variant, it could belong to someone else
	136	*/
	137	kprobe_opcode_t cur_insn = *addr;
	138	if (IS_TW(cur_insn) \|\| IS_TD(cur_insn) \|\|
	139	IS_TWI(cur_insn) \|\| IS_TDI(cur_insn))
	140	goto no_kprobe;
	141	/*
	142	* The breakpoint instruction was removed right
	143	* after we hit it. Another cpu has removed
	144	* either a probepoint or a debugger breakpoint
	145	* at this address. In either case, no further
	146	* handling of this interrupt is appropriate.
	147	*/
	148	ret = 1;
	149	}
	150	/* Not one of ours: let kernel handle it */
	151	goto no_kprobe;
	152	}
	153
	154	kprobe_status = KPROBE_HIT_ACTIVE;
	155	current_kprobe = p;
	156	kprobe_saved_msr = regs->msr;
	157	if (p->pre_handler && p->pre_handler(p, regs))
	158	/* handler has already set things up, so skip ss setup */
	159	return 1;
	160
	161	ss_probe:
	162	prepare_singlestep(p, regs);
	163	kprobe_status = KPROBE_HIT_SS;
	164	/*
	165	* This preempt_disable() matches the preempt_enable_no_resched()
	166	* in post_kprobe_handler().
	167	*/
	168	preempt_disable();
	169	return 1;
	170
	171	no_kprobe:
	172	return ret;
	173	}
	174
	175	/*
	176	* Called after single-stepping. p->addr is the address of the
	177	* instruction whose first byte has been replaced by the "breakpoint"
	178	* instruction. To avoid the SMP problems that can occur when we
	179	* temporarily put back the original opcode to single-step, we
180	* single-stepped a copy of the instruction. The address of this
181	* copy is p->ainsn.insn.
182	*/
183	static void resume_execution(struct kprobe p, struct pt_regs regs)
184	{
185	int ret;
186
187	regs->nip = (unsigned long)p->addr;
188	ret = emulate_step(regs, p->ainsn.insn[0]);
189	if (ret == 0)
190	regs->nip = (unsigned long)p->addr + 4;
1da177e4 LT	191	}
	192
	193	static inline int post_kprobe_handler(struct pt_regs *regs)
	194	{
	195	if (!kprobe_running())
	196	return 0;
	197
	198	if (current_kprobe->post_handler)
	199	current_kprobe->post_handler(current_kprobe, regs, 0);
	200
	201	resume_execution(current_kprobe, regs);
	202	regs->msr \|= kprobe_saved_msr;
	203
	204	unlock_kprobes();
	205	preempt_enable_no_resched();
	206
	207	/*
	208	* if somebody else is singlestepping across a probe point, msr
	209	* will have SE set, in which case, continue the remaining processing
	210	* of do_debug, as if this is not a probe hit.
	211	*/
	212	if (regs->msr & MSR_SE)
	213	return 0;
	214
	215	return 1;
	216	}
	217
	218	/* Interrupts disabled, kprobe_lock held. */
	219	static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
	220	{
	221	if (current_kprobe->fault_handler
	222	&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
	223	return 1;
	224
	225	if (kprobe_status & KPROBE_HIT_SS) {
	226	resume_execution(current_kprobe, regs);
f829fd23	227	regs->msr &= ~MSR_SE;
1da177e4 LT	228	regs->msr \|= kprobe_saved_msr;
	229
	230	unlock_kprobes();
	231	preempt_enable_no_resched();
	232	}
	233	return 0;
	234	}
	235
	236	/*
	237	* Wrapper routine to for handling exceptions.
	238	*/
	239	int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
	240	void *data)
	241	{
	242	struct die_args args = (struct die_args )data;
	243	int ret = NOTIFY_DONE;
	244
	245	/*
	246	* Interrupts are not disabled here. We need to disable
	247	* preemption, because kprobe_running() uses smp_processor_id().
	248	*/
	249	preempt_disable();
	250	switch (val) {
1da177e4 LT	251	case DIE_BPT:
	252	if (kprobe_handler(args->regs))
	253	ret = NOTIFY_STOP;
	254	break;
	255	case DIE_SSTEP:
	256	if (post_kprobe_handler(args->regs))
	257	ret = NOTIFY_STOP;
	258	break;
	259	case DIE_GPF:
	260	case DIE_PAGE_FAULT:
	261	if (kprobe_running() &&
	262	kprobe_fault_handler(args->regs, args->trapnr))
	263	ret = NOTIFY_STOP;
	264	break;
	265	default:
	266	break;
	267	}
	268	preempt_enable();
	269	return ret;
	270	}
	271
	272	int setjmp_pre_handler(struct kprobe p, struct pt_regs regs)
	273	{
	274	struct jprobe *jp = container_of(p, struct jprobe, kp);
	275
	276	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
	277
	278	/* setup return addr to the jprobe handler routine */
	279	regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
	280	regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
	281
	282	return 1;
	283	}
	284
	285	void jprobe_return(void)
	286	{
	287	asm volatile("trap" ::: "memory");
	288	}
	289
	290	void jprobe_return_end(void)
	291	{
	292	};
	293
	294	int longjmp_break_handler(struct kprobe p, struct pt_regs regs)
	295	{
	296	/*
	297	* FIXME - we should ideally be validating that we got here 'cos
	298	* of the "trap" in jprobe_return() above, before restoring the
	299	* saved regs...
	300	*/
	301	memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
	302	return 1;
	303	}