Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *  Kernel Probes (KProbes)

 *

 * 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/kprobes.h>

#include <linux/ptrace.h>

#include <linux/preempt.h>

#include <linux/module.h>

#include <linux/kdebug.h>

#include <asm/cacheflush.h>

#include <asm/sstep.h>

#include <asm/uaccess.h>

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};

int __kprobes 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) || IS_RFI(insn)) {

                printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");

                ret = -EINVAL;

        }

        /* insn must be on a special executable page on ppc64 */

        if (!ret) {

                p->ainsn.insn = get_insn_slot();

                if (!p->ainsn.insn)

                        ret = -ENOMEM;

        }

        if (!ret) {

                memcpy(p->ainsn.insn, p->addr,

                                MAX_INSN_SIZE * sizeof(kprobe_opcode_t));

                p->opcode = *p->addr;

                flush_icache_range((unsigned long)p->ainsn.insn,

                        (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));

        }

        p->ainsn.boostable = 0;

        return ret;

}

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));

}

void __kprobes arch_remove_kprobe(struct kprobe *p)

{

        mutex_lock(&kprobe_mutex);

        free_insn_slot(p->ainsn.insn, 0);

        mutex_unlock(&kprobe_mutex);

}

static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)

{

        regs->msr |= MSR_SE;

        /*

         * On powerpc we should single step on the original

         * instruction even if the probed insn is a trap

         * variant as values in regs could play a part in

         * if the trap is taken or not

         */

        regs->nip = (unsigned long)p->ainsn.insn;

}

static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)

{

        kcb->prev_kprobe.kp = kprobe_running();

        kcb->prev_kprobe.status = kcb->kprobe_status;

        kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;

}

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;

        kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;

}

static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,

                                struct kprobe_ctlblk *kcb)

{

        __get_cpu_var(current_kprobe) = p;

        kcb->kprobe_saved_msr = regs->msr;

}

/* 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->link;

        /* Replace the return addr with trampoline addr */

        regs->link = (unsigned long)kretprobe_trampoline;

}

static int __kprobes kprobe_handler(struct pt_regs *regs)

{

        struct kprobe *p;

        int ret = 0;

        unsigned int *addr = (unsigned int *)regs->nip;

        struct kprobe_ctlblk *kcb;

        /*

         * We don't want to be preempted for the entire

         * duration of kprobe processing

         */

        preempt_disable();

        kcb = get_kprobe_ctlblk();

        /* Check we're not actually recursing */

        if (kprobe_running()) {

                p = get_kprobe(addr);

                if (p) {

                        kprobe_opcode_t insn = *p->ainsn.insn;

                        if (kcb->kprobe_status == KPROBE_HIT_SS &&

                                        is_trap(insn)) {

                                regs->msr &= ~MSR_SE;

                                regs->msr |= kcb->kprobe_saved_msr;

                                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);

                        kcb->kprobe_saved_msr = regs->msr;

                        kprobes_inc_nmissed_count(p);

                        prepare_singlestep(p, regs);

                        kcb->kprobe_status = KPROBE_REENTER;

                        return 1;

                } else {

                        if (*addr != BREAKPOINT_INSTRUCTION) {

                                /* If trap variant, then it belongs not to us */

                                kprobe_opcode_t cur_insn = *addr;

                                if (is_trap(cur_insn))

                                        goto no_kprobe;

                                /* The breakpoint instruction was removed by

                                 * another cpu right after we hit, no further

                                 * handling of this interrupt is appropriate

                                 */

                                ret = 1;

                                goto no_kprobe;

                        }

                        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) {

                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_trap(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;

        }

        kcb->kprobe_status = KPROBE_HIT_ACTIVE;

        set_current_kprobe(p, regs, kcb);

        if (p->pre_handler && p->pre_handler(p, regs))

                /* handler has already set things up, so skip ss setup */

                return 1;

ss_probe:

        if (p->ainsn.boostable >= 0) {

                unsigned int insn = *p->ainsn.insn;

                /* regs->nip is also adjusted if emulate_step returns 1 */

                ret = emulate_step(regs, insn);

                if (ret > 0) {

                        /*

                         * Once this instruction has been boosted

                         * successfully, set the boostable flag

                         */

                        if (unlikely(p->ainsn.boostable == 0))

                                p->ainsn.boostable = 1;

                        if (p->post_handler)

                                p->post_handler(p, regs, 0);

                        kcb->kprobe_status = KPROBE_HIT_SSDONE;

                        reset_current_kprobe();

                        preempt_enable_no_resched();

                        return 1;

                } else if (ret < 0) {

                        /*

                         * We don't allow kprobes on mtmsr(d)/rfi(d), etc.

                         * So, we should never get here... but, its still

                         * good to catch them, just in case...

                         */

                        printk("Can't step on instruction %x\n", insn);

                        BUG();

                } else if (ret == 0)

                        /* This instruction can't be boosted */

                        p->ainsn.boostable = -1;

        }

        prepare_singlestep(p, regs);

        kcb->kprobe_status = KPROBE_HIT_SS;

        return 1;

no_kprobe:

        preempt_enable_no_resched();

        return ret;

}

/*

 * Function return probe trampoline:

 *      - init_kprobes() establishes a probepoint here

 *      - When the probed function returns, this probe

 *              causes the handlers to fire

 */

void kretprobe_trampoline_holder(void)

{

        asm volatile(".global kretprobe_trampoline\n"

                        "kretprobe_trampoline:\n"

                        "nop\n");

}

/*

 * Called when the probe at kretprobe trampoline is hit

 */

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);

        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 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)

                        ri->rp->handler(ri, regs);

                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->nip = orig_ret_address;

        reset_current_kprobe();

        spin_unlock_irqrestore(&kretprobe_lock, flags);

        preempt_enable_no_resched();

        hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {

                hlist_del(&ri->hlist);

                kfree(ri);

        }

        /*

         * By returning a non-zero value, we are telling

         * kprobe_handler() that we don't want the post_handler

         * to run (and have re-enabled preemption)

         */

        return 1;

}

/*

 * 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 __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)

{

        int ret;

        unsigned int insn = *p->ainsn.insn;

        regs->nip = (unsigned long)p->addr;

        ret = emulate_step(regs, insn);

        if (ret == 0)

                regs->nip = (unsigned long)p->addr + 4;

}

static int __kprobes post_kprobe_handler(struct pt_regs *regs)

{

        struct kprobe *cur = kprobe_running();

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        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);

        }

        resume_execution(cur, regs);

        regs->msr |= kcb->kprobe_saved_msr;

        /*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();

        /*

         * 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;

}

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 and the nip points back to the probe address

                 * and allow the page fault handler to continue as a

                 * normal page fault.

                 */

                regs->nip = (unsigned long)cur->addr;

                regs->msr &= ~MSR_SE;

                regs->msr |= kcb->kprobe_saved_msr;

                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 accouting

                 * 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->nip)) != NULL) {

                        regs->nip = 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 die_args *args = (struct die_args *)data;

        int ret = NOTIFY_DONE;

        if (args->regs && user_mode(args->regs))

                return ret;

        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;

        default:

                break;

        }

        return ret;

}

#ifdef CONFIG_PPC64

unsigned long arch_deref_entry_point(void *entry)

{

        return (unsigned long)(((func_descr_t *)entry)->entry);

}

#endif

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();

        memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));

        /* setup return addr to the jprobe handler routine */

        regs->nip = arch_deref_entry_point(jp->entry);

#ifdef CONFIG_PPC64

        regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);

#endif

        return 1;

}

void __kprobes jprobe_return(void)

{

        asm volatile("trap" ::: "memory");

}

void __kprobes jprobe_return_end(void)

{

};

int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)

{

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        /*

         * 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, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));

        preempt_enable_no_resched();

        return 1;

}

static struct kprobe trampoline_p = {

        .addr = (kprobe_opcode_t *) &kretprobe_trampoline,

        .pre_handler = trampoline_probe_handler

};

int __init arch_init_kprobes(void)

{

        return register_kprobe(&trampoline_p);

}

int __kprobes arch_trampoline_kprobe(struct kprobe *p)

{

        if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)

                return 1;

        return 0;

}