Subversion Repositories test_project

/*

 *  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, 2006

 *

 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>

 */

#include <linux/kprobes.h>

#include <linux/ptrace.h>

#include <linux/preempt.h>

#include <linux/stop_machine.h>

#include <linux/kdebug.h>

#include <asm/cacheflush.h>

#include <asm/sections.h>

#include <asm/uaccess.h>

#include <linux/module.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)

{

        /* Make sure the probe isn't going on a difficult instruction */

        if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))

                return -EINVAL;

        if ((unsigned long)p->addr & 0x01) {

                printk("Attempt to register kprobe at an unaligned address\n");

                return -EINVAL;

                }

        /* Use the get_insn_slot() facility for correctness */

        if (!(p->ainsn.insn = get_insn_slot()))

                return -ENOMEM;

        memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));

        get_instruction_type(&p->ainsn);

        p->opcode = *p->addr;

        return 0;

}

int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)

{

        switch (*(__u8 *) instruction) {

        case 0x0c:      /* bassm */

        case 0x0b:      /* bsm   */

        case 0x83:      /* diag  */

        case 0x44:      /* ex    */

                return -EINVAL;

        }

        switch (*(__u16 *) instruction) {

        case 0x0101:    /* pr    */

        case 0xb25a:    /* bsa   */

        case 0xb240:    /* bakr  */

        case 0xb258:    /* bsg   */

        case 0xb218:    /* pc    */

        case 0xb228:    /* pt    */

                return -EINVAL;

        }

        return 0;

}

void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)

{

        /* default fixup method */

        ainsn->fixup = FIXUP_PSW_NORMAL;

        /* save r1 operand */

        ainsn->reg = (*ainsn->insn & 0xf0) >> 4;

        /* save the instruction length (pop 5-5) in bytes */

        switch (*(__u8 *) (ainsn->insn) >> 6) {

        case 0:

                ainsn->ilen = 2;

                break;

        case 1:

        case 2:

                ainsn->ilen = 4;

                break;

        case 3:

                ainsn->ilen = 6;

                break;

        }

        switch (*(__u8 *) ainsn->insn) {

        case 0x05:      /* balr */

        case 0x0d:      /* basr */

                ainsn->fixup = FIXUP_RETURN_REGISTER;

                /* if r2 = 0, no branch will be taken */

                if ((*ainsn->insn & 0x0f) == 0)

                        ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;

                break;

        case 0x06:      /* bctr */

        case 0x07:      /* bcr  */

                ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

                break;

        case 0x45:      /* bal  */

        case 0x4d:      /* bas  */

                ainsn->fixup = FIXUP_RETURN_REGISTER;

                break;

        case 0x47:      /* bc   */

        case 0x46:      /* bct  */

        case 0x86:      /* bxh  */

        case 0x87:      /* bxle */

                ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

                break;

        case 0x82:      /* lpsw */

                ainsn->fixup = FIXUP_NOT_REQUIRED;

                break;

        case 0xb2:      /* lpswe */

                if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {

                        ainsn->fixup = FIXUP_NOT_REQUIRED;

                }

                break;

        case 0xa7:      /* bras */

                if ((*ainsn->insn & 0x0f) == 0x05) {

                        ainsn->fixup |= FIXUP_RETURN_REGISTER;

                }

                break;

        case 0xc0:

                if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */

                        || (*ainsn->insn & 0x0f) == 0x05) /* brasl */

                ainsn->fixup |= FIXUP_RETURN_REGISTER;

                break;

        case 0xeb:

                if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||   /* bxhg  */

                        *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */

                        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

                }

                break;

        case 0xe3:      /* bctg */

                if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {

                        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

                }

                break;

        }

}

static int __kprobes swap_instruction(void *aref)

{

        struct ins_replace_args *args = aref;

        u32 *addr;

        u32 instr;

        int err = -EFAULT;

        /*

         * Text segment is read-only, hence we use stura to bypass dynamic

         * address translation to exchange the instruction. Since stura

         * always operates on four bytes, but we only want to exchange two

         * bytes do some calculations to get things right. In addition we

         * shall not cross any page boundaries (vmalloc area!) when writing

         * the new instruction.

         */

        addr = (u32 *)((unsigned long)args->ptr & -4UL);

        if ((unsigned long)args->ptr & 2)

                instr = ((*addr) & 0xffff0000) | args->new;

        else

                instr = ((*addr) & 0x0000ffff) | args->new << 16;

        asm volatile(

                "       lra     %1,0(%1)\n"

                "0:     stura   %2,%1\n"

                "1:     la      %0,0\n"

                "2:\n"

                EX_TABLE(0b,2b)

                : "+d" (err)

                : "a" (addr), "d" (instr)

                : "memory", "cc");

        return err;

}

void __kprobes arch_arm_kprobe(struct kprobe *p)

{

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        unsigned long status = kcb->kprobe_status;

        struct ins_replace_args args;

        args.ptr = p->addr;

        args.old = p->opcode;

        args.new = BREAKPOINT_INSTRUCTION;

        kcb->kprobe_status = KPROBE_SWAP_INST;

        stop_machine_run(swap_instruction, &args, NR_CPUS);

        kcb->kprobe_status = status;

}

void __kprobes arch_disarm_kprobe(struct kprobe *p)

{

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        unsigned long status = kcb->kprobe_status;

        struct ins_replace_args args;

        args.ptr = p->addr;

        args.old = BREAKPOINT_INSTRUCTION;

        args.new = p->opcode;

        kcb->kprobe_status = KPROBE_SWAP_INST;

        stop_machine_run(swap_instruction, &args, NR_CPUS);

        kcb->kprobe_status = status;

}

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)

{

        per_cr_bits kprobe_per_regs[1];

        memset(kprobe_per_regs, 0, sizeof(per_cr_bits));

        regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;

        /* Set up the per control reg info, will pass to lctl */

        kprobe_per_regs[0].em_instruction_fetch = 1;

        kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;

        kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;

        /* Set the PER control regs, turns on single step for this address */

        __ctl_load(kprobe_per_regs, 9, 11);

        regs->psw.mask |= PSW_MASK_PER;

        regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);

}

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.kprobe_saved_imask = kcb->kprobe_saved_imask;

        memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,

                                        sizeof(kcb->kprobe_saved_ctl));

}

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_imask = kcb->prev_kprobe.kprobe_saved_imask;

        memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,

                                        sizeof(kcb->kprobe_saved_ctl));

}

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

                                                struct kprobe_ctlblk *kcb)

{

        __get_cpu_var(current_kprobe) = p;

        /* Save the interrupt and per flags */

        kcb->kprobe_saved_imask = regs->psw.mask &

            (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);

        /* Save the control regs that govern PER */

        __ctl_store(kcb->kprobe_saved_ctl, 9, 11);

}

/* 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->gprs[14];

        /* Replace the return addr with trampoline addr */

        regs->gprs[14] = (unsigned long)&kretprobe_trampoline;

}

static int __kprobes kprobe_handler(struct pt_regs *regs)

{

        struct kprobe *p;

        int ret = 0;

        unsigned long *addr = (unsigned long *)

                ((regs->psw.addr & PSW_ADDR_INSN) - 2);

        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) {

                        if (kcb->kprobe_status == KPROBE_HIT_SS &&

                            *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {

                                regs->psw.mask &= ~PSW_MASK_PER;

                                regs->psw.mask |= kcb->kprobe_saved_imask;

                                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)

                /*

                 * No kprobe at this address. The fault has not been

                 * caused by a kprobe breakpoint. The race of breakpoint

                 * vs. kprobe remove does not exist because on s390 we

                 * use stop_machine_run to arm/disarm the breakpoints.

                 */

                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:

        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: bcr 0,0\n");

}

/*

 * Called when the probe at kretprobe trampoline is hit

 */

static 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->psw.addr = orig_ret_address | PSW_ADDR_AMODE;

        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)

{

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        regs->psw.addr &= PSW_ADDR_INSN;

        if (p->ainsn.fixup & FIXUP_PSW_NORMAL)

                regs->psw.addr = (unsigned long)p->addr +

                                ((unsigned long)regs->psw.addr -

                                 (unsigned long)p->ainsn.insn);

        if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)

                if ((unsigned long)regs->psw.addr -

                    (unsigned long)p->ainsn.insn == p->ainsn.ilen)

                        regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;

        if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)

                regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +

                                                (regs->gprs[p->ainsn.reg] -

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

                                                | PSW_ADDR_AMODE;

        regs->psw.addr |= PSW_ADDR_AMODE;

        /* turn off PER mode */

        regs->psw.mask &= ~PSW_MASK_PER;

        /* Restore the original per control regs */

        __ctl_load(kcb->kprobe_saved_ctl, 9, 11);

        regs->psw.mask |= kcb->kprobe_saved_imask;

}

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);

        /*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, psw mask

         * will have PER set, in which case, continue the remaining processing

         * of do_single_step, as if this is not a probe hit.

         */

        if (regs->psw.mask & PSW_MASK_PER) {

                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_SWAP_INST:

                /* We are here because the instruction replacement failed */

                return 0;

        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->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;

                regs->psw.mask &= ~PSW_MASK_PER;

                regs->psw.mask |= kcb->kprobe_saved_imask;

                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.

                 */

                entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);

                if (entry) {

                        regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;

                        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;

        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_TRAP:

                /* kprobe_running() needs smp_processor_id() */

                preempt_disable();

                if (kprobe_running() &&

                    kprobe_fault_handler(args->regs, args->trapnr))

                        ret = NOTIFY_STOP;

                preempt_enable();

                break;

        default:

                break;

        }

        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();

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

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

        regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;

        /* r14 is the function return address */

        kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];

        /* r15 is the stack pointer */

        kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];

        addr = (unsigned long)kcb->jprobe_saved_r15;

        memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,

               MIN_STACK_SIZE(addr));

        return 1;

}

void __kprobes jprobe_return(void)

{

        asm volatile(".word 0x0002");

}

void __kprobes jprobe_return_end(void)

{

        asm volatile("bcr 0,0");

}

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

{

        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

        unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);

        /* Put the regs back */

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

        /* put the stack back */

        memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,

               MIN_STACK_SIZE(stack_addr));

        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)

{