arch/powerpc/platforms/powermac/bootx_init.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Early boot support code for BootX bootloader
   4  *
   5  *  Copyright (C) 2005 Ben. Herrenschmidt (benh@kernel.crashing.org)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/string.h>
  10 #include <linux/init.h>
  11 #include <generated/utsrelease.h>
  12 #include <asm/sections.h>
  13 #include <asm/prom.h>
  14 #include <asm/page.h>
  15 #include <asm/bootx.h>
  16 #include <asm/btext.h>
  17 #include <asm/io.h>
  18 #include <asm/setup.h>
  19
  20 #undef DEBUG
  21 #define SET_BOOT_BAT
  22
  23 #ifdef DEBUG
  24 #define DBG(fmt...) do { bootx_printf(fmt); } while(0)
  25 #else
  26 #define DBG(fmt...) do { } while(0)
  27 #endif
  28
  29 extern void __start(unsigned long r3, unsigned long r4, unsigned long r5);
  30
  31 static unsigned long __initdata bootx_dt_strbase;
  32 static unsigned long __initdata bootx_dt_strend;
  33 static unsigned long __initdata bootx_node_chosen;
  34 static boot_infos_t * __initdata bootx_info;
  35 static char __initdata bootx_disp_path[256];
  36
  37 /* Is boot-info compatible ? */
  38 #define BOOT_INFO_IS_COMPATIBLE(bi) \
  39         ((bi)->compatible_version <= BOOT_INFO_VERSION)
  40 #define BOOT_INFO_IS_V2_COMPATIBLE(bi)  ((bi)->version >= 2)
  41 #define BOOT_INFO_IS_V4_COMPATIBLE(bi)  ((bi)->version >= 4)
  42
  43 #ifdef CONFIG_BOOTX_TEXT
  44 static void __init bootx_printf(const char *format, ...)
  45 {
  46         const char *p, *q, *s;
  47         va_list args;
  48         unsigned long v;
  49
  50         va_start(args, format);
  51         for (p = format; *p != 0; p = q) {
  52                 for (q = p; *q != 0 && *q != '\n' && *q != '%'; ++q)
  53                         ;
  54                 if (q > p)
  55                         btext_drawtext(p, q - p);
  56                 if (*q == 0)
  57                         break;
  58                 if (*q == '\n') {
  59                         ++q;
  60                         btext_flushline();
  61                         btext_drawstring("\r\n");
  62                         btext_flushline();
  63                         continue;
  64                 }
  65                 ++q;
  66                 if (*q == 0)
  67                         break;
  68                 switch (*q) {
  69                 case 's':
  70                         ++q;
  71                         s = va_arg(args, const char *);
  72                         if (s == NULL)
  73                                 s = "<NULL>";
  74                         btext_drawstring(s);
  75                         break;
  76                 case 'x':
  77                         ++q;
  78                         v = va_arg(args, unsigned long);
  79                         btext_drawhex(v);
  80                         break;
  81                 }
  82         }
  83         va_end(args);
  84 }
  85 #else /* CONFIG_BOOTX_TEXT */
  86 static void __init bootx_printf(const char *format, ...) {}
  87 #endif /* CONFIG_BOOTX_TEXT */
  88
  89 static void * __init bootx_early_getprop(unsigned long base,
  90                                          unsigned long node,
  91                                          char *prop)
  92 {
  93         struct bootx_dt_node *np = (struct bootx_dt_node *)(base + node);
  94         u32 *ppp = &np->properties;
  95
  96         while(*ppp) {
  97                 struct bootx_dt_prop *pp =
  98                         (struct bootx_dt_prop *)(base + *ppp);
  99
 100                 if (strcmp((char *)((unsigned long)pp->name + base),
 101                            prop) == 0) {
 102                         return (void *)((unsigned long)pp->value + base);
 103                 }
 104                 ppp = &pp->next;
 105         }
 106         return NULL;
 107 }
 108
 109 #define dt_push_token(token, mem) \
 110         do { \
 111                 *(mem) = ALIGN(*(mem),4); \
 112                 *((u32 *)*(mem)) = token; \
 113                 *(mem) += 4; \
 114         } while(0)
 115
 116 static unsigned long __init bootx_dt_find_string(char *str)
 117 {
 118         char *s, *os;
 119
 120         s = os = (char *)bootx_dt_strbase;
 121         s += 4;
 122         while (s <  (char *)bootx_dt_strend) {
 123                 if (strcmp(s, str) == 0)
 124                         return s - os;
 125                 s += strlen(s) + 1;
 126         }
 127         return 0;
 128 }
 129
 130 static void __init bootx_dt_add_prop(char *name, void *data, int size,
 131                                   unsigned long *mem_end)
 132 {
 133         unsigned long soff = bootx_dt_find_string(name);
 134         if (data == NULL)
 135                 size = 0;
 136         if (soff == 0) {
 137                 bootx_printf("WARNING: Can't find string index for <%s>\n",
 138                              name);
 139                 return;
 140         }
 141         if (size > 0x20000) {
 142                 bootx_printf("WARNING: ignoring large property ");
 143                 bootx_printf("%s length 0x%x\n", name, size);
 144                 return;
 145         }
 146         dt_push_token(OF_DT_PROP, mem_end);
 147         dt_push_token(size, mem_end);
 148         dt_push_token(soff, mem_end);
 149
 150         /* push property content */
 151         if (size && data) {
 152                 memcpy((void *)*mem_end, data, size);
 153                 *mem_end = ALIGN(*mem_end + size, 4);
 154         }
 155 }
 156
 157 static void __init bootx_add_chosen_props(unsigned long base,
 158                                           unsigned long *mem_end)
 159 {
 160         u32 val;
 161
 162         bootx_dt_add_prop("linux,bootx", NULL, 0, mem_end);
 163
 164         if (bootx_info->kernelParamsOffset) {
 165                 char *args = (char *)((unsigned long)bootx_info) +
 166                         bootx_info->kernelParamsOffset;
 167                 bootx_dt_add_prop("bootargs", args, strlen(args) + 1, mem_end);
 168         }
 169         if (bootx_info->ramDisk) {
 170                 val = ((unsigned long)bootx_info) + bootx_info->ramDisk;
 171                 bootx_dt_add_prop("linux,initrd-start", &val, 4, mem_end);
 172                 val += bootx_info->ramDiskSize;
 173                 bootx_dt_add_prop("linux,initrd-end", &val, 4, mem_end);
 174         }
 175         if (strlen(bootx_disp_path))
 176                 bootx_dt_add_prop("linux,stdout-path", bootx_disp_path,
 177                                   strlen(bootx_disp_path) + 1, mem_end);
 178 }
 179
 180 static void __init bootx_add_display_props(unsigned long base,
 181                                            unsigned long *mem_end,
 182                                            int has_real_node)
 183 {
 184         boot_infos_t *bi = bootx_info;
 185         u32 tmp;
 186
 187         if (has_real_node) {
 188                 bootx_dt_add_prop("linux,boot-display", NULL, 0, mem_end);
 189                 bootx_dt_add_prop("linux,opened", NULL, 0, mem_end);
 190         } else
 191                 bootx_dt_add_prop("linux,bootx-noscreen", NULL, 0, mem_end);
 192
 193         tmp = bi->dispDeviceDepth;
 194         bootx_dt_add_prop("linux,bootx-depth", &tmp, 4, mem_end);
 195         tmp = bi->dispDeviceRect[2] - bi->dispDeviceRect[0];
 196         bootx_dt_add_prop("linux,bootx-width", &tmp, 4, mem_end);
 197         tmp = bi->dispDeviceRect[3] - bi->dispDeviceRect[1];
 198         bootx_dt_add_prop("linux,bootx-height", &tmp, 4, mem_end);
 199         tmp = bi->dispDeviceRowBytes;
 200         bootx_dt_add_prop("linux,bootx-linebytes", &tmp, 4, mem_end);
 201         tmp = (u32)bi->dispDeviceBase;
 202         if (tmp == 0)
 203                 tmp = (u32)bi->logicalDisplayBase;
 204         tmp += bi->dispDeviceRect[1] * bi->dispDeviceRowBytes;
 205         tmp += bi->dispDeviceRect[0] * ((bi->dispDeviceDepth + 7) / 8);
 206         bootx_dt_add_prop("linux,bootx-addr", &tmp, 4, mem_end);
 207 }
 208
 209 static void __init bootx_dt_add_string(char *s, unsigned long *mem_end)
 210 {
 211         unsigned int l = strlen(s) + 1;
 212         memcpy((void *)*mem_end, s, l);
 213         bootx_dt_strend = *mem_end = *mem_end + l;
 214 }
 215
 216 static void __init bootx_scan_dt_build_strings(unsigned long base,
 217                                                unsigned long node,
 218                                                unsigned long *mem_end)
 219 {
 220         struct bootx_dt_node *np = (struct bootx_dt_node *)(base + node);
 221         u32 *cpp, *ppp = &np->properties;
 222         unsigned long soff;
 223         char *namep;
 224
 225         /* Keep refs to known nodes */
 226         namep = np->full_name ? (char *)(base + np->full_name) : NULL;
 227         if (namep == NULL) {
 228                 bootx_printf("Node without a full name !\n");
 229                 namep = "";
 230         }
 231         DBG("* strings: %s\n", namep);
 232
 233         if (!strcmp(namep, "/chosen")) {
 234                 DBG(" detected /chosen ! adding properties names !\n");
 235                 bootx_dt_add_string("linux,bootx", mem_end);
 236                 bootx_dt_add_string("linux,stdout-path", mem_end);
 237                 bootx_dt_add_string("linux,initrd-start", mem_end);
 238                 bootx_dt_add_string("linux,initrd-end", mem_end);
 239                 bootx_dt_add_string("bootargs", mem_end);
 240                 bootx_node_chosen = node;
 241         }
 242         if (node == bootx_info->dispDeviceRegEntryOffset) {
 243                 DBG(" detected display ! adding properties names !\n");
 244                 bootx_dt_add_string("linux,boot-display", mem_end);
 245                 bootx_dt_add_string("linux,opened", mem_end);
 246                 strlcpy(bootx_disp_path, namep, sizeof(bootx_disp_path));
 247         }
 248
 249         /* get and store all property names */
 250         while (*ppp) {
 251                 struct bootx_dt_prop *pp =
 252                         (struct bootx_dt_prop *)(base + *ppp);
 253
 254                 namep = pp->name ? (char *)(base + pp->name) : NULL;
 255                 if (namep == NULL || strcmp(namep, "name") == 0)
 256                         goto next;
 257                 /* get/create string entry */
 258                 soff = bootx_dt_find_string(namep);
 259                 if (soff == 0)
 260                         bootx_dt_add_string(namep, mem_end);
 261         next:
 262                 ppp = &pp->next;
 263         }
 264
 265         /* do all our children */
 266         cpp = &np->child;
 267         while(*cpp) {
 268                 np = (struct bootx_dt_node *)(base + *cpp);
 269                 bootx_scan_dt_build_strings(base, *cpp, mem_end);
 270                 cpp = &np->sibling;
 271         }
 272 }
 273
 274 static void __init bootx_scan_dt_build_struct(unsigned long base,
 275                                               unsigned long node,
 276                                               unsigned long *mem_end)
 277 {
 278         struct bootx_dt_node *np = (struct bootx_dt_node *)(base + node);
 279         u32 *cpp, *ppp = &np->properties;
 280         char *namep, *p, *ep, *lp;
 281         int l;
 282
 283         dt_push_token(OF_DT_BEGIN_NODE, mem_end);
 284
 285         /* get the node's full name */
 286         namep = np->full_name ? (char *)(base + np->full_name) : NULL;
 287         if (namep == NULL)
 288                 namep = "";
 289         l = strlen(namep);
 290
 291         DBG("* struct: %s\n", namep);
 292
 293         /* Fixup an Apple bug where they have bogus \0 chars in the
 294          * middle of the path in some properties, and extract
 295          * the unit name (everything after the last '/').
 296          */
 297         memcpy((void *)*mem_end, namep, l + 1);
 298         namep = (char *)*mem_end;
 299         for (lp = p = namep, ep = namep + l; p < ep; p++) {
 300                 if (*p == '/')
 301                         lp = namep;
 302                 else if (*p != 0)
 303                         *lp++ = *p;
 304         }
 305         *lp = 0;
 306         *mem_end = ALIGN((unsigned long)lp + 1, 4);
 307
 308         /* get and store all properties */
 309         while (*ppp) {
 310                 struct bootx_dt_prop *pp =
 311                         (struct bootx_dt_prop *)(base + *ppp);
 312
 313                 namep = pp->name ? (char *)(base + pp->name) : NULL;
 314                 /* Skip "name" */
 315                 if (namep == NULL || !strcmp(namep, "name"))
 316                         goto next;
 317                 /* Skip "bootargs" in /chosen too as we replace it */
 318                 if (node == bootx_node_chosen && !strcmp(namep, "bootargs"))
 319                         goto next;
 320
 321                 /* push property head */
 322                 bootx_dt_add_prop(namep,
 323                                   pp->value ? (void *)(base + pp->value): NULL,
 324                                   pp->length, mem_end);
 325         next:
 326                 ppp = &pp->next;
 327         }
 328
 329         if (node == bootx_node_chosen) {
 330                 bootx_add_chosen_props(base, mem_end);
 331                 if (bootx_info->dispDeviceRegEntryOffset == 0)
 332                         bootx_add_display_props(base, mem_end, 0);
 333         }
 334         else if (node == bootx_info->dispDeviceRegEntryOffset)
 335                 bootx_add_display_props(base, mem_end, 1);
 336
 337         /* do all our children */
 338         cpp = &np->child;
 339         while(*cpp) {
 340                 np = (struct bootx_dt_node *)(base + *cpp);
 341                 bootx_scan_dt_build_struct(base, *cpp, mem_end);
 342                 cpp = &np->sibling;
 343         }
 344
 345         dt_push_token(OF_DT_END_NODE, mem_end);
 346 }
 347
 348 static unsigned long __init bootx_flatten_dt(unsigned long start)
 349 {
 350         boot_infos_t *bi = bootx_info;
 351         unsigned long mem_start, mem_end;
 352         struct boot_param_header *hdr;
 353         unsigned long base;
 354         u64 *rsvmap;
 355
 356         /* Start using memory after the big blob passed by BootX, get
 357          * some space for the header
 358          */
 359         mem_start = mem_end = ALIGN(((unsigned long)bi) + start, 4);
 360         DBG("Boot params header at: %x\n", mem_start);
 361         hdr = (struct boot_param_header *)mem_start;
 362         mem_end += sizeof(struct boot_param_header);
 363         rsvmap = (u64 *)(ALIGN(mem_end, 8));
 364         hdr->off_mem_rsvmap = ((unsigned long)rsvmap) - mem_start;
 365         mem_end = ((unsigned long)rsvmap) + 8 * sizeof(u64);
 366
 367         /* Get base of tree */
 368         base = ((unsigned long)bi) + bi->deviceTreeOffset;
 369
 370         /* Build string array */
 371         DBG("Building string array at: %x\n", mem_end);
 372         DBG("Device Tree Base=%x\n", base);
 373         bootx_dt_strbase = mem_end;
 374         mem_end += 4;
 375         bootx_dt_strend = mem_end;
 376         bootx_scan_dt_build_strings(base, 4, &mem_end);
 377         /* Add some strings */
 378         bootx_dt_add_string("linux,bootx-noscreen", &mem_end);
 379         bootx_dt_add_string("linux,bootx-depth", &mem_end);
 380         bootx_dt_add_string("linux,bootx-width", &mem_end);
 381         bootx_dt_add_string("linux,bootx-height", &mem_end);
 382         bootx_dt_add_string("linux,bootx-linebytes", &mem_end);
 383         bootx_dt_add_string("linux,bootx-addr", &mem_end);
 384         /* Wrap up strings */
 385         hdr->off_dt_strings = bootx_dt_strbase - mem_start;
 386         hdr->dt_strings_size = bootx_dt_strend - bootx_dt_strbase;
 387
 388         /* Build structure */
 389         mem_end = ALIGN(mem_end, 16);
 390         DBG("Building device tree structure at: %x\n", mem_end);
 391         hdr->off_dt_struct = mem_end - mem_start;
 392         bootx_scan_dt_build_struct(base, 4, &mem_end);
 393         dt_push_token(OF_DT_END, &mem_end);
 394
 395         /* Finish header */
 396         hdr->boot_cpuid_phys = 0;
 397         hdr->magic = OF_DT_HEADER;
 398         hdr->totalsize = mem_end - mem_start;
 399         hdr->version = OF_DT_VERSION;
 400         /* Version 16 is not backward compatible */
 401         hdr->last_comp_version = 0x10;
 402
 403         /* Reserve the whole thing and copy the reserve map in, we
 404          * also bump mem_reserve_cnt to cause further reservations to
 405          * fail since it's too late.
 406          */
 407         mem_end = ALIGN(mem_end, PAGE_SIZE);
 408         DBG("End of boot params: %x\n", mem_end);
 409         rsvmap[0] = mem_start;
 410         rsvmap[1] = mem_end;
 411         if (bootx_info->ramDisk) {
 412                 rsvmap[2] = ((unsigned long)bootx_info) + bootx_info->ramDisk;
 413                 rsvmap[3] = rsvmap[2] + bootx_info->ramDiskSize;
 414                 rsvmap[4] = 0;
 415                 rsvmap[5] = 0;
 416         } else {
 417                 rsvmap[2] = 0;
 418                 rsvmap[3] = 0;
 419         }
 420
 421         return (unsigned long)hdr;
 422 }
 423
 424
 425 #ifdef CONFIG_BOOTX_TEXT
 426 static void __init btext_welcome(boot_infos_t *bi)
 427 {
 428         unsigned long flags;
 429         unsigned long pvr;
 430
 431         bootx_printf("Welcome to Linux, kernel " UTS_RELEASE "\n");
 432         bootx_printf("\nlinked at        : 0x%x", KERNELBASE);
 433         bootx_printf("\nframe buffer at  : 0x%x", bi->dispDeviceBase);
 434         bootx_printf(" (phys), 0x%x", bi->logicalDisplayBase);
 435         bootx_printf(" (log)");
 436         bootx_printf("\nklimit           : 0x%x",(unsigned long)klimit);
 437         bootx_printf("\nboot_info at     : 0x%x", bi);
 438         __asm__ __volatile__ ("mfmsr %0" : "=r" (flags));
 439         bootx_printf("\nMSR              : 0x%x", flags);
 440         __asm__ __volatile__ ("mfspr %0, 287" : "=r" (pvr));
 441         bootx_printf("\nPVR              : 0x%x", pvr);
 442         pvr >>= 16;
 443         if (pvr > 1) {
 444             __asm__ __volatile__ ("mfspr %0, 1008" : "=r" (flags));
 445             bootx_printf("\nHID0             : 0x%x", flags);
 446         }
 447         if (pvr == 8 || pvr == 12 || pvr == 0x800c) {
 448             __asm__ __volatile__ ("mfspr %0, 1019" : "=r" (flags));
 449             bootx_printf("\nICTC             : 0x%x", flags);
 450         }
 451 #ifdef DEBUG
 452         bootx_printf("\n\n");
 453         bootx_printf("bi->deviceTreeOffset   : 0x%x\n",
 454                      bi->deviceTreeOffset);
 455         bootx_printf("bi->deviceTreeSize     : 0x%x\n",
 456                      bi->deviceTreeSize);
 457 #endif
 458         bootx_printf("\n\n");
 459 }
 460 #endif /* CONFIG_BOOTX_TEXT */
 461
 462 void __init bootx_init(unsigned long r3, unsigned long r4)
 463 {
 464         boot_infos_t *bi = (boot_infos_t *) r4;
 465         unsigned long hdr;
 466         unsigned long space;
 467         unsigned long ptr;
 468         char *model;
 469         unsigned long offset = reloc_offset();
 470
 471         reloc_got2(offset);
 472
 473         bootx_info = bi;
 474
 475         /* We haven't cleared any bss at this point, make sure
 476          * what we need is initialized
 477          */
 478         bootx_dt_strbase = bootx_dt_strend = 0;
 479         bootx_node_chosen = 0;
 480         bootx_disp_path[0] = 0;
 481
 482         if (!BOOT_INFO_IS_V2_COMPATIBLE(bi))
 483                 bi->logicalDisplayBase = bi->dispDeviceBase;
 484
 485         /* Fixup depth 16 -> 15 as that's what MacOS calls 16bpp */
 486         if (bi->dispDeviceDepth == 16)
 487                 bi->dispDeviceDepth = 15;
 488
 489
 490 #ifdef CONFIG_BOOTX_TEXT
 491         ptr = (unsigned long)bi->logicalDisplayBase;
 492         ptr += bi->dispDeviceRect[1] * bi->dispDeviceRowBytes;
 493         ptr += bi->dispDeviceRect[0] * ((bi->dispDeviceDepth + 7) / 8);
 494         btext_setup_display(bi->dispDeviceRect[2] - bi->dispDeviceRect[0],
 495                             bi->dispDeviceRect[3] - bi->dispDeviceRect[1],
 496                             bi->dispDeviceDepth, bi->dispDeviceRowBytes,
 497                             (unsigned long)bi->logicalDisplayBase);
 498         btext_clearscreen();
 499         btext_flushscreen();
 500 #endif /* CONFIG_BOOTX_TEXT */
 501
 502         /*
 503          * Test if boot-info is compatible.  Done only in config
 504          * CONFIG_BOOTX_TEXT since there is nothing much we can do
 505          * with an incompatible version, except display a message
 506          * and eventually hang the processor...
 507          *
 508          * I'll try to keep enough of boot-info compatible in the
 509          * future to always allow display of this message;
 510          */
 511         if (!BOOT_INFO_IS_COMPATIBLE(bi)) {
 512                 bootx_printf(" !!! WARNING - Incompatible version"
 513                              " of BootX !!!\n\n\n");
 514                 for (;;)
 515                         ;
 516         }
 517         if (bi->architecture != BOOT_ARCH_PCI) {
 518                 bootx_printf(" !!! WARNING - Unsupported machine"
 519                              " architecture !\n");
 520                 for (;;)
 521                         ;
 522         }
 523
 524 #ifdef CONFIG_BOOTX_TEXT
 525         btext_welcome(bi);
 526 #endif
 527
 528         /* New BootX enters kernel with MMU off, i/os are not allowed
 529          * here. This hack will have been done by the boostrap anyway.
 530          */
 531         if (bi->version < 4) {
 532                 /*
 533                  * XXX If this is an iMac, turn off the USB controller.
 534                  */
 535                 model = (char *) bootx_early_getprop(r4 + bi->deviceTreeOffset,
 536                                                      4, "model");
 537                 if (model
 538                     && (strcmp(model, "iMac,1") == 0
 539                         || strcmp(model, "PowerMac1,1") == 0)) {
 540                         bootx_printf("iMac,1 detected, shutting down USB\n");
 541                         out_le32((unsigned __iomem *)0x80880008, 1);    /* XXX */
 542                 }
 543         }
 544
 545         /* Get a pointer that points above the device tree, args, ramdisk,
 546          * etc... to use for generating the flattened tree
 547          */
 548         if (bi->version < 5) {
 549                 space = bi->deviceTreeOffset + bi->deviceTreeSize;
 550                 if (bi->ramDisk >= space)
 551                         space = bi->ramDisk + bi->ramDiskSize;
 552         } else
 553                 space = bi->totalParamsSize;
 554
 555         bootx_printf("Total space used by parameters & ramdisk: 0x%x\n", space);
 556
 557         /* New BootX will have flushed all TLBs and enters kernel with
 558          * MMU switched OFF, so this should not be useful anymore.
 559          */
 560         if (bi->version < 4) {
 561                 unsigned long x __maybe_unused;
 562
 563                 bootx_printf("Touching pages...\n");
 564
 565                 /*
 566                  * Touch each page to make sure the PTEs for them
 567                  * are in the hash table - the aim is to try to avoid
 568                  * getting DSI exceptions while copying the kernel image.
 569                  */
 570                 for (ptr = ((unsigned long) &_stext) & PAGE_MASK;
 571                      ptr < (unsigned long)bi + space; ptr += PAGE_SIZE)
 572                         x = *(volatile unsigned long *)ptr;
 573         }
 574
 575         /* Ok, now we need to generate a flattened device-tree to pass
 576          * to the kernel
 577          */
 578         bootx_printf("Preparing boot params...\n");
 579
 580         hdr = bootx_flatten_dt(space);
 581
 582 #ifdef CONFIG_BOOTX_TEXT
 583 #ifdef SET_BOOT_BAT
 584         bootx_printf("Preparing BAT...\n");
 585         btext_prepare_BAT();
 586 #else
 587         btext_unmap();
 588 #endif
 589 #endif
 590
 591         reloc_got2(-offset);
 592
 593         __start(hdr, KERNELBASE + offset, 0);
 594 }