/*
 * 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 2015 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 "fbt.h"

#define FBT_PATCHVAL    DTRACE_PATCHVAL
#define FBT_AFRAMES     4

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)
                        continue;

                cpu->cpu_dtrace_caller = addr;

                if (fbt->fbtp_roffset == 0) {
                        dtrace_probe(fbt->fbtp_id, frame->tf_x[0],
                            frame->tf_x[1], frame->tf_x[2],
                            frame->tf_x[3], frame->tf_x[4]);
                } else {
                        dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset, rval,
                            0, 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)
{
        void *addr;

        if (!arm64_get_writable_addr(fbt->fbtp_patchpoint, &addr))
                panic("%s: Unable to write new instruction", __func__);

        *(fbt_patchval_t *)addr = val;
        cpu_icache_sync_range(fbt->fbtp_patchpoint, 4);
}

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

        modname = opaque;
        name = symval->name;

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

        /*
         * Instrumenting certain exception handling functions can lead to FBT
         * recursion, so exclude from instrumentation.
         */
         if (strcmp(name, "handle_el1h_sync") == 0 ||
            strcmp(name, "do_el1h_sync") == 0)
                return (0);

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

        /*
         * Ignore any bti instruction at the start of the function
         * we need to keep it there for any indirect branches calling
         * the function on Armv8.5+
         */
        if ((*instr & BTI_MASK) == BTI_INSTR)
                instr++;

        /*
         * If the first instruction is a nop it's a specially marked
         * asm function. We only support a nop first as it's not a normal
         * part of the function prologue.
         */
        if (*instr == NOP_INSTR)
                goto found;

        /* Look for stp (pre-indexed) or sub operation */
        for (; instr < limit; instr++) {
                /*
                 * Functions start with "stp xt1, xt2, [xn, <const>]!" or
                 * "sub sp, sp, <const>".
                 *
                 * Sometimes the compiler will have a sub instruction that is
                 * not of the above type so don't stop if we see one.
                 */
                if ((*instr & LDP_STP_MASK) == STP_64) {
                        /*
                         * Assume any other store of this type means we are
                         * past the function prologue.
                         */
                        if (((*instr >> ADDR_SHIFT) & ADDR_MASK) == 31)
                                break;
                } else if ((*instr & SUB_MASK) == SUB_INSTR &&
                    ((*instr >> SUB_RD_SHIFT) & SUB_R_MASK) == 31 &&
                    ((*instr >> SUB_RN_SHIFT) & SUB_R_MASK) == 31)
                        break;
        }
found:
        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 = FBT_PATCHVAL;
        if ((*instr & SUB_MASK) == SUB_INSTR)
                fbt->fbtp_rval = DTRACE_INVOP_SUB;
        else
                fbt->fbtp_rval = DTRACE_INVOP_STP;
        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++) {
                if (*instr == RET_INSTR)
                        break;
                else if ((*instr & B_MASK) == B_INSTR) {
                        offs = (*instr & B_DATA_MASK);
                        target = instr + offs;
                        start = (uint32_t *)symval->value;
                        if (target >= limit || target < start)
                                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;
        if ((*instr & B_MASK) == B_INSTR)
                fbt->fbtp_rval = DTRACE_INVOP_B;
        else
                fbt->fbtp_rval = DTRACE_INVOP_RET;
        fbt->fbtp_roffset = (uintptr_t)instr - (uintptr_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++;
        goto again;
}