libdtrace/i386/dt_isadep.c

	dt_isadep.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <libgen.h>

#include <dt_impl.h>
#include <dt_pid.h>

#include <dis_tables.h>

#define DT_POPL_EBP 0x5d
#define DT_RET      0xc3
#define DT_RET16    0xc2
#define DT_LEAVE    0xc9
#define DT_JMP32    0xe9
#define DT_JMP8     0xeb
#define DT_REP      0xf3

#define DT_MOVL_EBP_ESP 0xe58b

#define DT_ISJ32(op16)  (((op16) & 0xfff0) == 0x0f80)
#define DT_ISJ8(op8)    (((op8) & 0xf0) == 0x70)

#define DT_MODRM_REG(modrm) (((modrm) >> 3) & 0x7)

static int dt_instr_size(uchar_t *, dtrace_hdl_t *, pid_t, uintptr_t, char);

/*ARGSUSED*/
int
dt_pid_create_entry_probe(struct ps_prochandle *P, dtrace_hdl_t *dtp,
    fasttrap_probe_spec_t *ftp, const GElf_Sym *symp)
{
    ftp->ftps_type = DTFTP_ENTRY;
    ftp->ftps_pc = (uintptr_t)symp->st_value;
    ftp->ftps_size = (size_t)symp->st_size;
    ftp->ftps_noffs = 1;
    ftp->ftps_offs[0] = 0;

    if (ioctl(dtp->dt_ftfd, FASTTRAPIOC_MAKEPROBE, ftp) != 0) {
        dt_dprintf("fasttrap probe creation ioctl failed: %s\n",
            strerror(errno));
        return (dt_set_errno(dtp, errno));
    }

    return (1);
}

static int
dt_pid_has_jump_table(struct ps_prochandle *P, dtrace_hdl_t *dtp,
    uint8_t *text, fasttrap_probe_spec_t *ftp, const GElf_Sym *symp)
{
    ulong_t i;
    int size;
    pid_t pid = Pstatus(P)->pr_pid;
    char dmodel = Pstatus(P)->pr_dmodel;

    /*
     * Take a pass through the function looking for a register-dependant
     * jmp instruction. This could be a jump table so we have to be
     * ultra conservative.
     */
    for (i = 0; i < ftp->ftps_size; i += size) {
        size = dt_instr_size(&text[i], dtp, pid, symp->st_value + i,
            dmodel);

        /*
         * Assume the worst if we hit an illegal instruction.
         */
        if (size <= 0) {
            dt_dprintf("error at %#lx (assuming jump table)\n", i);
            return (1);
        }

        if (text[i] == 0xff && DT_MODRM_REG(text[i + 1]) == 4) {
            dt_dprintf("found a suspected jump table at %s:%lx\n",
                ftp->ftps_func, i);
            return (1);
        }
    }

    return (0);
}

/*ARGSUSED*/
int
dt_pid_create_return_probe(struct ps_prochandle *P, dtrace_hdl_t *dtp,
    fasttrap_probe_spec_t *ftp, const GElf_Sym *symp, uint64_t *stret)
{
    uint8_t *text;
    ulong_t i, end;
    int size;
    pid_t pid = Pstatus(P)->pr_pid;
    char dmodel = Pstatus(P)->pr_dmodel;

    /*
     * We allocate a few extra bytes at the end so we don't have to check
     * for overrunning the buffer.
     */
    if ((text = calloc(1, symp->st_size + 4)) == NULL) {
        dt_dprintf("mr sparkle: malloc() failed\n");
        return (DT_PROC_ERR);
    }

    if (Pread(P, text, symp->st_size, symp->st_value) != symp->st_size) {
        dt_dprintf("mr sparkle: Pread() failed\n");
        free(text);
        return (DT_PROC_ERR);
    }

    ftp->ftps_type = DTFTP_RETURN;
    ftp->ftps_pc = (uintptr_t)symp->st_value;
    ftp->ftps_size = (size_t)symp->st_size;
    ftp->ftps_noffs = 0;

    /*
     * If there's a jump table in the function we're only willing to
     * instrument these specific (and equivalent) instruction sequences:
     *  leave
     *  [rep] ret
     * and
     *  movl    %ebp,%esp
     *  popl    %ebp
     *  [rep] ret
     *
     * We do this to avoid accidentally interpreting jump table
     * offsets as actual instructions.
     */
    if (dt_pid_has_jump_table(P, dtp, text, ftp, symp)) {
        for (i = 0, end = ftp->ftps_size; i < end; i += size) {
            size = dt_instr_size(&text[i], dtp, pid,
                symp->st_value + i, dmodel);

            /* bail if we hit an invalid opcode */
            if (size <= 0)
                break;

            if (text[i] == DT_LEAVE && text[i + 1] == DT_RET) {
                dt_dprintf("leave/ret at %lx\n", i + 1);
                ftp->ftps_offs[ftp->ftps_noffs++] = i + 1;
                size = 2;
            } else if (text[i] == DT_LEAVE &&
                text[i + 1] == DT_REP && text[i + 2] == DT_RET) {
                dt_dprintf("leave/rep ret at %lx\n", i + 1);
                ftp->ftps_offs[ftp->ftps_noffs++] = i + 1;
                size = 3;
            } else if (*(uint16_t *)&text[i] == DT_MOVL_EBP_ESP &&
                text[i + 2] == DT_POPL_EBP &&
                text[i + 3] == DT_RET) {
                dt_dprintf("movl/popl/ret at %lx\n", i + 3);
                ftp->ftps_offs[ftp->ftps_noffs++] = i + 3;
                size = 4;
            } else if (*(uint16_t *)&text[i] == DT_MOVL_EBP_ESP &&
                text[i + 2] == DT_POPL_EBP &&
                text[i + 3] == DT_REP &&
                text[i + 4] == DT_RET) {
                dt_dprintf("movl/popl/rep ret at %lx\n", i + 3);
                ftp->ftps_offs[ftp->ftps_noffs++] = i + 3;
                size = 5;
            }
        }
    } else {
        for (i = 0, end = ftp->ftps_size; i < end; i += size) {
            size = dt_instr_size(&text[i], dtp, pid,
                symp->st_value + i, dmodel);

            /* bail if we hit an invalid opcode */
            if (size <= 0)
                break;

            /* ordinary ret */
            if (size == 1 && text[i] == DT_RET)
                goto is_ret;

            /* two-byte ret */
            if (size == 2 && text[i] == DT_REP &&
                text[i + 1] == DT_RET)
                goto is_ret;

            /* ret <imm16> */
            if (size == 3 && text[i] == DT_RET16)
                goto is_ret;

            /* two-byte ret <imm16> */
            if (size == 4 && text[i] == DT_REP &&
                text[i + 1] == DT_RET16)
                goto is_ret;

            /* 32-bit displacement jmp outside of the function */
            if (size == 5 && text[i] == DT_JMP32 && symp->st_size <=
                (uintptr_t)(i + size + *(int32_t *)&text[i + 1]))
                goto is_ret;

            /* 8-bit displacement jmp outside of the function */
            if (size == 2 && text[i] == DT_JMP8 && symp->st_size <=
                (uintptr_t)(i + size + *(int8_t *)&text[i + 1]))
                goto is_ret;

            /* 32-bit disp. conditional jmp outside of the func. */
            if (size == 6 && DT_ISJ32(*(uint16_t *)&text[i]) &&
                symp->st_size <=
                (uintptr_t)(i + size + *(int32_t *)&text[i + 2]))
                goto is_ret;

            /* 8-bit disp. conditional jmp outside of the func. */
            if (size == 2 && DT_ISJ8(text[i]) && symp->st_size <=
                (uintptr_t)(i + size + *(int8_t *)&text[i + 1]))
                goto is_ret;

            continue;
is_ret:
            dt_dprintf("return at offset %lx\n", i);
            ftp->ftps_offs[ftp->ftps_noffs++] = i;
        }
    }

    free(text);
    if (ftp->ftps_noffs > 0) {
        if (ioctl(dtp->dt_ftfd, FASTTRAPIOC_MAKEPROBE, ftp) != 0) {
            dt_dprintf("fasttrap probe creation ioctl failed: %s\n",
                strerror(errno));
            return (dt_set_errno(dtp, errno));
        }
    }

    return (ftp->ftps_noffs);
}

/*ARGSUSED*/
int
dt_pid_create_offset_probe(struct ps_prochandle *P, dtrace_hdl_t *dtp,
    fasttrap_probe_spec_t *ftp, const GElf_Sym *symp, ulong_t off)
{
    ftp->ftps_type = DTFTP_OFFSETS;
    ftp->ftps_pc = (uintptr_t)symp->st_value;
    ftp->ftps_size = (size_t)symp->st_size;
    ftp->ftps_noffs = 1;

    if (strcmp("-", ftp->ftps_func) == 0) {
        ftp->ftps_offs[0] = off;
    } else {
        uint8_t *text;
        ulong_t i;
        int size;
        pid_t pid = Pstatus(P)->pr_pid;
        char dmodel = Pstatus(P)->pr_dmodel;

        if ((text = malloc(symp->st_size)) == NULL) {
            dt_dprintf("mr sparkle: malloc() failed\n");
            return (DT_PROC_ERR);
        }

        if (Pread(P, text, symp->st_size, symp->st_value) !=
            symp->st_size) {
            dt_dprintf("mr sparkle: Pread() failed\n");
            free(text);
            return (DT_PROC_ERR);
        }

        /*
         * We can't instrument offsets in functions with jump tables
         * as we might interpret a jump table offset as an
         * instruction.
         */
        if (dt_pid_has_jump_table(P, dtp, text, ftp, symp)) {
            free(text);
            return (0);
        }

        for (i = 0; i < symp->st_size; i += size) {
            if (i == off) {
                ftp->ftps_offs[0] = i;
                break;
            }

            /*
             * If we've passed the desired offset without a
             * match, then the given offset must not lie on a
             * instruction boundary.
             */
            if (i > off) {
                free(text);
                return (DT_PROC_ALIGN);
            }

            size = dt_instr_size(&text[i], dtp, pid,
                symp->st_value + i, dmodel);

            /*
             * If we hit an invalid instruction, bail as if we
             * couldn't find the offset.
             */
            if (size <= 0) {
                free(text);
                return (DT_PROC_ALIGN);
            }
        }

        free(text);
    }

    if (ioctl(dtp->dt_ftfd, FASTTRAPIOC_MAKEPROBE, ftp) != 0) {
        dt_dprintf("fasttrap probe creation ioctl failed: %s\n",
            strerror(errno));
        return (dt_set_errno(dtp, errno));
    }

    return (ftp->ftps_noffs);
}

/*ARGSUSED*/
int
dt_pid_create_glob_offset_probes(struct ps_prochandle *P, dtrace_hdl_t *dtp,
    fasttrap_probe_spec_t *ftp, const GElf_Sym *symp, const char *pattern)
{
    uint8_t *text;
    ulong_t i, end;
    int size;
    pid_t pid = Pstatus(P)->pr_pid;
    char dmodel = Pstatus(P)->pr_dmodel;

    if ((text = malloc(symp->st_size)) == NULL) {
        dt_dprintf("mr sparkle: malloc() failed\n");
        return (DT_PROC_ERR);
    }

    if (Pread(P, text, symp->st_size, symp->st_value) != symp->st_size) {
        dt_dprintf("mr sparkle: Pread() failed\n");
        free(text);
        return (DT_PROC_ERR);
    }

    /*
     * We can't instrument offsets in functions with jump tables as
     * we might interpret a jump table offset as an instruction.
     */
    if (dt_pid_has_jump_table(P, dtp, text, ftp, symp)) {
        free(text);
        return (0);
    }

    ftp->ftps_type = DTFTP_OFFSETS;
    ftp->ftps_pc = (uintptr_t)symp->st_value;
    ftp->ftps_size = (size_t)symp->st_size;
    ftp->ftps_noffs = 0;

    end = ftp->ftps_size;

    if (strcmp("*", pattern) == 0) {
        for (i = 0; i < end; i += size) {
            ftp->ftps_offs[ftp->ftps_noffs++] = i;

            size = dt_instr_size(&text[i], dtp, pid,
                symp->st_value + i, dmodel);

            /* bail if we hit an invalid opcode */
            if (size <= 0)
                break;
        }
    } else {
        char name[sizeof (i) * 2 + 1];

        for (i = 0; i < end; i += size) {
            (void) snprintf(name, sizeof (name), "%x", i);
            if (gmatch(name, pattern))
                ftp->ftps_offs[ftp->ftps_noffs++] = i;

            size = dt_instr_size(&text[i], dtp, pid,
                symp->st_value + i, dmodel);

            /* bail if we hit an invalid opcode */
            if (size <= 0)
                break;
        }
    }

    free(text);
    if (ftp->ftps_noffs > 0) {
        if (ioctl(dtp->dt_ftfd, FASTTRAPIOC_MAKEPROBE, ftp) != 0) {
            dt_dprintf("fasttrap probe creation ioctl failed: %s\n",
                strerror(errno));
            return (dt_set_errno(dtp, errno));
        }
    }

    return (ftp->ftps_noffs);
}

typedef struct dtrace_dis {
    uchar_t *instr;
    dtrace_hdl_t *dtp;
    pid_t pid;
    uintptr_t addr;
} dtrace_dis_t;

static int
dt_getbyte(void *data)
{
    dtrace_dis_t    *dis = data;
    int ret = *dis->instr;

    if (ret == FASTTRAP_INSTR) {
        fasttrap_instr_query_t instr;

        instr.ftiq_pid = dis->pid;
        instr.ftiq_pc = dis->addr;

        /*
         * If we hit a byte that looks like the fasttrap provider's
         * trap instruction (which doubles as the breakpoint
         * instruction for debuggers) we need to query the kernel
         * for the real value. This may just be part of an immediate
         * value so there's no need to return an error if the
         * kernel doesn't know about this address.
         */
        if (ioctl(dis->dtp->dt_ftfd, FASTTRAPIOC_GETINSTR, &instr) == 0)
            ret = instr.ftiq_instr;
    }

    dis->addr++;
    dis->instr++;

    return (ret);
}

static int
dt_instr_size(uchar_t *instr, dtrace_hdl_t *dtp, pid_t pid, uintptr_t addr,
    char dmodel)
{
    dtrace_dis_t data;
    dis86_t x86dis;
    uint_t cpu_mode;

    data.instr = instr;
    data.dtp = dtp;
    data.pid = pid;
    data.addr = addr;

    x86dis.d86_data = &data;
    x86dis.d86_get_byte = dt_getbyte;
    x86dis.d86_check_func = NULL;

    cpu_mode = (dmodel == PR_MODEL_ILP32) ? SIZE32 : SIZE64;

    if (dtrace_disx86(&x86dis, cpu_mode) != 0)
        return (-1);

    /*
     * If the instruction was a single-byte breakpoint, there may be
     * another debugger attached to this process. The original instruction
     * can't be recovered so this must fail.
     */
    if (x86dis.d86_len == 1 && instr[0] == FASTTRAP_INSTR)
        return (-1);

    return (x86dis.d86_len);
}