/*
 * 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
 * Portions Copyright 2013 Howard Su howardsu@freebsd.org
 * Portions Copyright 2016-2018 Ruslan Bukin <br@bsdpad.com>
 */

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

#include <sys/param.h>

#include <sys/dtrace.h>

#include <machine/riscvreg.h>
#include <machine/encoding.h>

#include "fbt.h"

#define FBT_C_PATCHVAL          MATCH_C_EBREAK
#define FBT_PATCHVAL            MATCH_EBREAK
#define FBT_AFRAMES             5

int
fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
{
        solaris_cpu_t *cpu;
        fbt_probe_t *fbt;

        cpu = &solaris_cpu[curcpu];
        fbt = fbt_probetab[FBT_ADDR2NDX(addr)];

        for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
                if ((uintptr_t)fbt->fbtp_patchpoint == addr) {
                        cpu->cpu_dtrace_caller = frame->tf_ra - INSN_SIZE;

                        if (fbt->fbtp_roffset == 0) {
                                dtrace_probe(fbt->fbtp_id, frame->tf_a[0],
                                    frame->tf_a[1], frame->tf_a[2],
                                    frame->tf_a[3], frame->tf_a[4]);
                        } else {
                                dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset,
                                    frame->tf_a[0], frame->tf_a[1], 0, 0);
                        }

                        cpu->cpu_dtrace_caller = 0;
                        return (fbt->fbtp_savedval);
                }
        }

        return (0);
}

void
fbt_patch_tracepoint(fbt_probe_t *fbt, fbt_patchval_t val)
{

        switch(fbt->fbtp_patchval) {
        case FBT_C_PATCHVAL:
                *(uint16_t *)fbt->fbtp_patchpoint = (uint16_t)val;
                fence_i();
                break;
        case FBT_PATCHVAL:
                *fbt->fbtp_patchpoint = val;
                fence_i();
                break;
        };
}

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

        modname = opaque;
        name = symval->name;

        /* Check if function is excluded from instrumentation */
        if (fbt_excluded(name))
                return (0);

        /*
         * Some assembly-language exception handlers are not suitable for
         * instrumentation.
         */
        if (strcmp(name, "cpu_exception_handler") == 0)
                return (0);
        if (strcmp(name, "cpu_exception_handler_user") == 0)
                return (0);
        if (strcmp(name, "cpu_exception_handler_supervisor") == 0)
                return (0);
        if (strcmp(name, "do_trap_supervisor") == 0)
                return (0);

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

        /* Look for sd operation */
        for (; instr < limit; instr++) {
                /* Look for a non-compressed store of ra to sp */
                if (dtrace_instr_sdsp(&instr)) {
                        rval = DTRACE_INVOP_SD;
                        patchval = FBT_PATCHVAL;
                        break;
                }

                /* Look for a 'C'-compressed store of ra to sp. */
                if (dtrace_instr_c_sdsp(&instr)) {
                        rval = DTRACE_INVOP_C_SDSP;
                        patchval = FBT_C_PATCHVAL;
                        break;
                }
        }

        if (instr >= limit)
                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 = patchval;
        fbt->fbtp_rval = rval;
        fbt->fbtp_symindx = symindx;

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

        lf->fbt_nentries++;

        retfbt = NULL;
again:
        for (; instr < limit; instr++) {
                /* Look for non-compressed return */
                if (dtrace_instr_ret(&instr)) {
                        rval = DTRACE_INVOP_RET;
                        patchval = FBT_PATCHVAL;
                        break;
                }

                /* Look for 'C'-compressed return */
                if (dtrace_instr_c_ret(&instr)) {
                        rval = DTRACE_INVOP_C_RET;
                        patchval = FBT_C_PATCHVAL;
                        break;
                }
        }

        if (instr >= limit)
                return (0);

        /*
         * 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;
        fbt->fbtp_rval = rval;
        fbt->fbtp_roffset = (uintptr_t)instr - (uintptr_t)symval->value;
        fbt->fbtp_savedval = *instr;
        fbt->fbtp_patchval = patchval;
        fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
        fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;

        lf->fbt_nentries++;

        instr++;
        goto again;
}