/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
 *  Copyright (c) 2013 Joyent, Inc.  All rights reserved.
 *  Copyright 2021 RackTop Systems, Inc.
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <expand.h>
#include <shared.h>

#ifdef  SUPPORT_NETBOOT
#include <grub.h>
#endif

#include <cpu.h>

#define EVF_DEFINED     0x01
#define EVF_VALUESET    0x02

typedef struct variable {
        char v_name[EV_NAMELEN];
        unsigned int v_flags;
        char v_value[220];      /* 256 - EV_NAMELEN - sizeof (fields) */
} variable_t;

static variable_t expvars[32];
static const unsigned int nexpvars = 32;

int
set_variable(const char *name, const char *value)
{
        unsigned int i;
        unsigned int avail = nexpvars;

        if (strlen(name) >= sizeof (expvars[0].v_name))
                return (ERR_WONT_FIT);

        if (value != NULL && strlen(value) >= sizeof (expvars[0].v_value))
                return (ERR_WONT_FIT);

        for (i = 0; i < nexpvars; i++) {
                if (expvars[i].v_flags & EVF_DEFINED) {
                        if (grub_strcmp(expvars[i].v_name, name) == 0)
                                break;
                } else if (i < avail) {
                        avail = i;
                }
        }

        if (i == nexpvars) {
                if (avail == nexpvars)
                        return (ERR_WONT_FIT);

                i = avail;
                (void) grub_strcpy(expvars[i].v_name, name);
                expvars[i].v_flags = EVF_DEFINED;
        }

        if (value != NULL) {
                (void) grub_strcpy(expvars[i].v_value, value);
                expvars[i].v_flags |= EVF_VALUESET;
        } else {
                expvars[i].v_flags &= ~EVF_VALUESET;
        }

        return (0);
}

const char *
get_variable(const char *name)
{
        unsigned int i;

        for (i = 0; i < nexpvars; i++) {
                if (!(expvars[i].v_flags & EVF_DEFINED))
                        continue;
                if (grub_strcmp(expvars[i].v_name, name) == 0) {
                        if (expvars[i].v_flags & EVF_VALUESET)
                                return (expvars[i].v_value);
                        return ("");
                }
        }

        return (NULL);
}

static int
detect_target_operating_mode(void)
{
        int ret, ah;

        /*
         * This function returns 16 bits.  The upper 8 are the value of %ah
         * after calling int 15/ec00.  The lower 8 bits are zero if the BIOS
         * call left CF clear, nonzero otherwise.
         */
        ret = get_target_operating_mode();
        ah = ret >> 8;
        ret &= 0xff;

        if (ah == 0x86 && ret != 0) {
                grub_printf("[BIOS 'Detect Target Operating Mode' "
                    "callback unsupported on this platform]\n");
                return (1);     /* unsupported, ignore */
        }

        if (ah == 0 && ret == 0) {
                grub_printf("[BIOS accepted mixed-mode target setting!]\n");
                return (1);     /* told the bios what we're up to */
        }

        if (ah == 0 && ret != 0) {
                grub_printf("fatal: BIOS reports this machine CANNOT run in "
                    "mixed 32/64-bit mode!\n");
                return (0);
        }

        grub_printf("warning: BIOS Detect Target Operating Mode callback "
            "confused.\n         %%ax >> 8 = 0x%x, carry = %d\n", ah, ret);

        return (1);
}

static int
amd64_config_cpu(void)
{
        struct amd64_cpuid_regs __vcr, *vcr = &__vcr;
        uint32_t maxeax;
        uint32_t max_maxeax = 0x100;
        char vendor[13];
        int isamd64 = 0;
        uint32_t stdfeatures = 0, xtdfeatures = 0;
        uint64_t efer;

        /*
         * This check may seem silly, but if the C preprocesor symbol __amd64
         * is #defined during compilation, something that may outwardly seem
         * like a good idea, uts/common/sys/isa_defs.h will #define _LP64,
         * which will cause uts/common/sys/int_types.h to typedef uint64_t as
         * an unsigned long - which is only 4 bytes in size when using a 32-bit
         * compiler.
         *
         * If that happens, all the page table translation routines will fail
         * horribly, so check the size of uint64_t just to insure some degree
         * of sanity in future operations.
         */
        /*LINTED [sizeof result is invarient]*/
        if (sizeof (uint64_t) != 8)
                prom_panic("grub compiled improperly, unable to boot "
                    "64-bit AMD64 executables");

        /*
         * If the CPU doesn't support the CPUID instruction, it's definitely
         * not an AMD64.
         */
        if (amd64_cpuid_supported() == 0)
                return (0);

        amd64_cpuid_insn(0, vcr);

        maxeax = vcr->r_eax;
        {
                /*LINTED [vendor string from cpuid data]*/
                uint32_t *iptr = (uint32_t *)vendor;

                *iptr++ = vcr->r_ebx;
                *iptr++ = vcr->r_edx;
                *iptr++ = vcr->r_ecx;

                vendor[12] = '\0';
        }

        if (maxeax > max_maxeax) {
                grub_printf("cpu: warning, maxeax was 0x%x -> 0x%x\n",
                    maxeax, max_maxeax);
                maxeax = max_maxeax;
        }

        if (maxeax < 1)
                return (0);     /* no additional functions, not an AMD64 */
        else {
                uint_t family, model, step;

                amd64_cpuid_insn(1, vcr);

                /*
                 * All AMD64/IA32e processors technically SHOULD report
                 * themselves as being in family 0xf, but for some reason
                 * Simics doesn't, and this may change in the future, so
                 * don't error out if it's not true.
                 */
                if ((family = BITX(vcr->r_eax, 11, 8)) == 0xf)
                        family += BITX(vcr->r_eax, 27, 20);

                if ((model = BITX(vcr->r_eax, 7, 4)) == 0xf)
                        model += BITX(vcr->r_eax, 19, 16) << 4;
                step = BITX(vcr->r_eax, 3, 0);

                grub_printf("cpu: '%s' family %d model %d step %d\n",
                    vendor, family, model, step);
                stdfeatures = vcr->r_edx;
        }

        amd64_cpuid_insn(0x80000000, vcr);

        if (vcr->r_eax & 0x80000000) {
                uint32_t xmaxeax = vcr->r_eax;
                const uint32_t max_xmaxeax = 0x80000100;

                if (xmaxeax > max_xmaxeax) {
                        grub_printf("amd64: warning, xmaxeax was "
                            "0x%x -> 0x%x\n", xmaxeax, max_xmaxeax);
                        xmaxeax = max_xmaxeax;
                }

                if (xmaxeax >= 0x80000001) {
                        amd64_cpuid_insn(0x80000001, vcr);
                        xtdfeatures = vcr->r_edx;
                }
        }

        if (BITX(xtdfeatures, 29, 29))          /* long mode */
                isamd64++;
        else
                grub_printf("amd64: CPU does NOT support long mode\n");

        if (!BITX(stdfeatures, 0, 0)) {
                grub_printf("amd64: CPU does NOT support FPU\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 4, 4)) {
                grub_printf("amd64: CPU does NOT support TSC\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 5, 5)) {
                grub_printf("amd64: CPU does NOT support MSRs\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 6, 6)) {
                grub_printf("amd64: CPU does NOT support PAE\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 8, 8)) {
                grub_printf("amd64: CPU does NOT support CX8\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 13, 13)) {
                grub_printf("amd64: CPU does NOT support PGE\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 19, 19)) {
                grub_printf("amd64: CPU does NOT support CLFSH\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 23, 23)) {
                grub_printf("amd64: CPU does NOT support MMX\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 24, 24)) {
                grub_printf("amd64: CPU does NOT support FXSR\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 25, 25)) {
                grub_printf("amd64: CPU does NOT support SSE\n");
                isamd64--;
        }

        if (!BITX(stdfeatures, 26, 26)) {
                grub_printf("amd64: CPU does NOT support SSE2\n");
                isamd64--;
        }

        if (isamd64 < 1) {
                grub_printf("amd64: CPU does not support amd64 executables.\n");
                return (0);
        }

        amd64_rdmsr(MSR_AMD_EFER, &efer);
        if (efer & AMD_EFER_SCE)
                grub_printf("amd64: EFER_SCE (syscall/sysret) already "
                    "enabled\n");
        if (efer & AMD_EFER_NXE)
                grub_printf("amd64: EFER_NXE (no-exec prot) already enabled\n");
        if (efer & AMD_EFER_LME)
                grub_printf("amd64: EFER_LME (long mode) already enabled\n");

        return (detect_target_operating_mode());
}

static int
isamd64()
{
        static int ret = -1;

        if (ret == -1)
                ret = amd64_config_cpu();

        return (ret);
}

static int
check_min_mem64(void)
{
        if (min_mem64 == 0)
                return (1);

        if ((mbi.mem_upper / 10240) * 11 >= min_mem64)
                return (1);

        return (0);
}

/*
 * Given the nul-terminated input string s, expand all variable references
 * within that string into the buffer pointed to by d, which must be of length
 * not less than len bytes.
 *
 * We also expand the special case tokens "$ISADIR" and "$ZFS-BOOTFS" here.
 *
 * If the string will not fit, returns ERR_WONT_FIT.
 * If a nonexistent variable is referenced, returns ERR_NOVAR.
 * Otherwise, returns 0.  The resulting string is nul-terminated.  On error,
 * the contents of the destination buffer are undefined.
 */
int
expand_string(const char *s, char *d, unsigned int len)
{
        unsigned int i;
        int vlen;
        const char *p;
        char *q;
        const char *start;
        char name[EV_NAMELEN];
        const char *val;

        for (p = s, q = d; *p != '\0' && q < d + len; ) {
                /* Special case: $ISADIR */
                if (grub_strncmp(p, "$ISADIR", 7) == 0) {
                        if (isamd64() && check_min_mem64()) {
                                if (q + 5 >= d + len)
                                        return (ERR_WONT_FIT);
                                (void) grub_memcpy(q, "amd64", 5);
                                q += 5; /* amd64 */
                        }
                        p += 7; /* $ISADIR */
                        continue;
                }
                /* Special case: $ZFS-BOOTFS */
                if (grub_strncmp(p, "$ZFS-BOOTFS", 11) == 0 &&
                    is_zfs_mount != 0) {
                        if (current_bootpath[0] == '\0' &&
                            current_devid[0] == '\0') {
                                return (ERR_NO_BOOTPATH);
                        }

                        /* zfs-bootfs=%s/%u */
                        vlen = (current_bootfs_obj > 0) ? 10 : 0;
                        vlen += 11;
                        vlen += strlen(current_rootpool);

                        /* ,bootpath=\"%s\" */
                        if (current_bootpath[0] != '\0')
                                vlen += 12 + strlen(current_bootpath);

                        /* ,diskdevid=\"%s\" */
                        if (current_devid[0] != '\0')
                                vlen += 13 + strlen(current_devid);

                        if (current_bootguid != 0) {
                                vlen += grub_sprintf(NULL,
                                    ",zfs-bootpool=\"%llu\"", current_bootguid);
                        }
                        if (current_bootvdev != 0) {
                                vlen += grub_sprintf(NULL,
                                    ",zfs-bootvdev=\"%llu\"", current_bootvdev);
                        }

                        if (q + vlen >= d + len)
                                return (ERR_WONT_FIT);

                        if (current_bootfs_obj > 0) {
                                q += grub_sprintf(q, "zfs-bootfs=%s/%u",
                                    current_rootpool, current_bootfs_obj);
                        } else {
                                q += grub_sprintf(q, "zfs-bootfs=%s",
                                    current_rootpool);
                        }
                        if (current_bootpath[0] != '\0') {
                                q += grub_sprintf(q, ",bootpath=\"%s\"",
                                    current_bootpath);
                        }
                        if (current_devid[0] != '\0') {
                                q += grub_sprintf(q, ",diskdevid=\"%s\"",
                                    current_devid);
                        }
                        if (current_bootguid != 0) {
                                q += grub_sprintf(q, ",zfs-bootpool=\"%llu\"",
                                    current_bootguid);
                        }
                        if (current_bootvdev != 0) {
                                q += grub_sprintf(q, ",zfs-bootvdev=\"%llu\"",
                                    current_bootvdev);
                        }

                        p += 11;        /* $ZFS-BOOTFS */
                        continue;
                }
                if (*p == '$' && *(p + 1) == '{') {
                        start = p + 2;
                        for (p = start; *p != '\0' && *p != '}' &&
                            p - start < sizeof (name) - 1; p++) {
                                name[p - start] = *p;
                        }
                        /*
                         * Unterminated reference.  Copy verbatim.
                         */
                        if (p - start >= sizeof (name) - 1 || *p != '}') {
                                p = start;
                                *q++ = '$';
                                *q++ = '{';
                                continue;
                        }

                        name[p - start] = '\0';
                        val = get_variable(name);
                        if (val == NULL)
                                return (ERR_NOVAR);

                        if ((vlen = grub_strlen(val)) >= q + len - d)
                                return (ERR_WONT_FIT);

                        (void) grub_memcpy(q, val, vlen);
                        q += vlen;
                        p++;
                } else {
                        *q++ = *p++;
                }
        }

        if (q >= d + len)
                return (ERR_WONT_FIT);

        *q = '\0';

        return (0);
}

void
dump_variables(void)
{
        unsigned int i;

        for (i = 0; i < nexpvars; i++) {
                if (!(expvars[i].v_flags & EVF_DEFINED))
                        continue;
                (void) grub_printf("[%u] '%s' => '%s'\n", i, expvars[i].v_name,
                    (expvars[i].v_flags & EVF_VALUESET) ?
                    expvars[i].v_value : "");
        }
}