/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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
 *
 * Portions Copyright 2006-2008 John Birrell jb@freebsd.org
 * Portions Copyright 2013 Justin Hibbits jhibbits@freebsd.org
 *
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/param.h>
#include <sys/dtrace.h>
#include <machine/md_var.h>

#include "fbt.h"

#define FBT_PATCHVAL            0x7ffff808
#define FBT_MFLR_R0             0x7c0802a6
#define FBT_MTLR_R0             0x7c0803a6
#define FBT_BLR                 0x4e800020
#define FBT_BCTR                0x4e800030
#define FBT_BRANCH              0x48000000
#define FBT_BR_MASK             0x03fffffc
#define FBT_IS_JUMP(instr)      ((instr & ~FBT_BR_MASK) == FBT_BRANCH)

#define FBT_AFRAMES     5

int
fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
{
        solaris_cpu_t *cpu = &solaris_cpu[curcpu];
        fbt_probe_t *fbt = fbt_probetab[FBT_ADDR2NDX(addr)];
        uintptr_t tmp;

        for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
                if ((uintptr_t)fbt->fbtp_patchpoint == addr) {
                        if (fbt->fbtp_roffset == 0) {
                                cpu->cpu_dtrace_caller = addr;

                                dtrace_probe(fbt->fbtp_id, frame->fixreg[3],
                                    frame->fixreg[4], frame->fixreg[5],
                                    frame->fixreg[6], frame->fixreg[7]);

                                cpu->cpu_dtrace_caller = 0;
                        } else {

                                dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset,
                                    rval, 0, 0, 0);
                                /*
                                 * The caller doesn't have the fbt item, so
                                 * fixup tail calls here.
                                 */
                                if (fbt->fbtp_rval == DTRACE_INVOP_JUMP) {
                                        frame->srr0 = (uintptr_t)fbt->fbtp_patchpoint;
                                        tmp = fbt->fbtp_savedval & FBT_BR_MASK;
                                        /* Sign extend. */
                                        if (tmp & 0x02000000)
#ifdef __powerpc64__
                                                tmp |= 0xfffffffffc000000ULL;
#else
                                                tmp |= 0xfc000000UL;
#endif
                                        frame->srr0 += tmp;
                                }
                                cpu->cpu_dtrace_caller = 0;
                        }

                        return (fbt->fbtp_rval);
                }
        }

        return (0);
}

void
fbt_patch_tracepoint(fbt_probe_t *fbt, fbt_patchval_t val)
{

        *fbt->fbtp_patchpoint = val;
        __syncicache(fbt->fbtp_patchpoint, 4);
}

int
fbt_provide_module_function(linker_file_t lf, int symindx,
    linker_symval_t *symval, void *opaque)
{
        char *modname = opaque;
        const char *name = symval->name;
        fbt_probe_t *fbt, *retfbt;
        int j;
        uint32_t *instr, *limit;

#ifdef __powerpc64__
#if !defined(_CALL_ELF) || _CALL_ELF == 1
        /*
         * PowerPC64 uses '.' prefixes on symbol names, ignore it, but only
         * allow symbols with the '.' prefix, so that we don't get the function
         * descriptor instead.
         */
        if (name[0] == '.')
                name++;
        else
                return (0);
#endif
#endif

        if (fbt_excluded(name))
                return (0);

        instr = (uint32_t *) symval->value;
        limit = (uint32_t *) (symval->value + symval->size);

        for (; instr < limit; instr++)
                if (*instr == FBT_MFLR_R0)
                        break;

        if (*instr != FBT_MFLR_R0)
                return (0);

        fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
        fbt->fbtp_name = name;
        fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
            name, FBT_ENTRY, FBT_AFRAMES, fbt);
        fbt->fbtp_patchpoint = instr;
        fbt->fbtp_ctl = lf;
        fbt->fbtp_loadcnt = lf->loadcnt;
        fbt->fbtp_savedval = *instr;
        fbt->fbtp_patchval = FBT_PATCHVAL;
        fbt->fbtp_rval = DTRACE_INVOP_MFLR_R0;
        fbt->fbtp_symindx = symindx;

        fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
        fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;

        lf->fbt_nentries++;

        retfbt = NULL;
again:
        if (instr >= limit)
                return (0);

        /*
         * We (desperately) want to avoid erroneously instrumenting a
         * jump table. To determine if we're looking at a true instruction
         * sequence or an inline jump table that happens to contain the same
         * byte sequences, we resort to some heuristic sleeze:  we treat this
         * instruction as being contained within a pointer, and see if that
         * pointer points to within the body of the function.  If it does, we
         * refuse to instrument it.
         */
        {
                uint32_t *ptr;

                ptr = *(uint32_t **)instr;

                if (ptr >= (uint32_t *) symval->value && ptr < limit) {
                        instr++;
                        goto again;
                }
        }

        if (*instr != FBT_MTLR_R0) {
                instr++;
                goto again;
        }

        instr++;

        for (j = 0; j < 12 && instr < limit; j++, instr++) {
                if ((*instr == FBT_BCTR) || (*instr == FBT_BLR) ||
                    FBT_IS_JUMP(*instr))
                        break;
        }

        if (!(*instr == FBT_BCTR || *instr == FBT_BLR || FBT_IS_JUMP(*instr)))
                goto again;

        /*
         * We have a winner!
         */
        fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
        fbt->fbtp_name = name;

        if (retfbt == NULL) {
                fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
                    name, FBT_RETURN, FBT_AFRAMES, fbt);
        } else {
                retfbt->fbtp_probenext = fbt;
                fbt->fbtp_id = retfbt->fbtp_id;
        }

        retfbt = fbt;
        fbt->fbtp_patchpoint = instr;
        fbt->fbtp_ctl = lf;
        fbt->fbtp_loadcnt = lf->loadcnt;
        fbt->fbtp_symindx = symindx;

        if (*instr == FBT_BCTR)
                fbt->fbtp_rval = DTRACE_INVOP_BCTR;
        else if (*instr == FBT_BLR)
                fbt->fbtp_rval = DTRACE_INVOP_BLR;
        else
                fbt->fbtp_rval = DTRACE_INVOP_JUMP;

        fbt->fbtp_roffset =
            (uintptr_t)((uint8_t *)instr - (uint8_t *)symval->value);

        fbt->fbtp_savedval = *instr;
        fbt->fbtp_patchval = FBT_PATCHVAL;
        fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
        fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;

        lf->fbt_nentries++;

        instr += 4;
        goto again;
}