arch/powerpc/lib/feature-fixups.c

   1 /*
   2  *  Copyright (C) 2001 Ben. Herrenschmidt (benh@kernel.crashing.org)
   3  *
   4  *  Modifications for ppc64:
   5  *      Copyright (C) 2003 Dave Engebretsen <engebret@us.ibm.com>
   6  *
   7  *  Copyright 2008 Michael Ellerman, IBM Corporation.
   8  *
   9  *  This program is free software; you can redistribute it and/or
  10  *  modify it under the terms of the GNU General Public License
  11  *  as published by the Free Software Foundation; either version
  12  *  2 of the License, or (at your option) any later version.
  13  */
  14
  15 #include <linux/types.h>
  16 #include <linux/jump_label.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <linux/init.h>
  20 #include <linux/sched/mm.h>
  21 #include <asm/cputable.h>
  22 #include <asm/code-patching.h>
  23 #include <asm/page.h>
  24 #include <asm/sections.h>
  25 #include <asm/setup.h>
  26 #include <asm/firmware.h>
  27
  28 struct fixup_entry {
  29         unsigned long   mask;
  30         unsigned long   value;
  31         long            start_off;
  32         long            end_off;
  33         long            alt_start_off;
  34         long            alt_end_off;
  35 };
  36
  37 static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
  38 {
  39         /*
  40          * We store the offset to the code as a negative offset from
  41          * the start of the alt_entry, to support the VDSO. This
  42          * routine converts that back into an actual address.
  43          */
  44         return (unsigned int *)((unsigned long)fcur + offset);
  45 }
  46
  47 static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
  48                                  unsigned int *alt_start, unsigned int *alt_end)
  49 {
  50         unsigned int instr;
  51
  52         instr = *src;
  53
  54         if (instr_is_relative_branch(*src)) {
  55                 unsigned int *target = (unsigned int *)branch_target(src);
  56
  57                 /* Branch within the section doesn't need translating */
  58                 if (target < alt_start || target >= alt_end) {
  59                         instr = translate_branch(dest, src);
  60                         if (!instr)
  61                                 return 1;
  62                 }
  63         }
  64
  65         patch_instruction(dest, instr);
  66
  67         return 0;
  68 }
  69
  70 static int patch_feature_section(unsigned long value, struct fixup_entry *fcur)
  71 {
  72         unsigned int *start, *end, *alt_start, *alt_end, *src, *dest;
  73
  74         start = calc_addr(fcur, fcur->start_off);
  75         end = calc_addr(fcur, fcur->end_off);
  76         alt_start = calc_addr(fcur, fcur->alt_start_off);
  77         alt_end = calc_addr(fcur, fcur->alt_end_off);
  78
  79         if ((alt_end - alt_start) > (end - start))
  80                 return 1;
  81
  82         if ((value & fcur->mask) == fcur->value)
  83                 return 0;
  84
  85         src = alt_start;
  86         dest = start;
  87
  88         for (; src < alt_end; src++, dest++) {
  89                 if (patch_alt_instruction(src, dest, alt_start, alt_end))
  90                         return 1;
  91         }
  92
  93         for (; dest < end; dest++)
  94                 patch_instruction(dest, PPC_INST_NOP);
  95
  96         return 0;
  97 }
  98
  99 void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 100 {
 101         struct fixup_entry *fcur, *fend;
 102
 103         fcur = fixup_start;
 104         fend = fixup_end;
 105
 106         for (; fcur < fend; fcur++) {
 107                 if (patch_feature_section(value, fcur)) {
 108                         WARN_ON(1);
 109                         printk("Unable to patch feature section at %p - %p" \
 110                                 " with %p - %p\n",
 111                                 calc_addr(fcur, fcur->start_off),
 112                                 calc_addr(fcur, fcur->end_off),
 113                                 calc_addr(fcur, fcur->alt_start_off),
 114                                 calc_addr(fcur, fcur->alt_end_off));
 115                 }
 116         }
 117 }
 118
 119 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 120 {
 121         long *start, *end;
 122         unsigned int *dest;
 123
 124         if (!(value & CPU_FTR_LWSYNC))
 125                 return ;
 126
 127         start = fixup_start;
 128         end = fixup_end;
 129
 130         for (; start < end; start++) {
 131                 dest = (void *)start + *start;
 132                 patch_instruction(dest, PPC_INST_LWSYNC);
 133         }
 134 }
 135
 136 static void do_final_fixups(void)
 137 {
 138 #if defined(CONFIG_PPC64) && defined(CONFIG_RELOCATABLE)
 139         int *src, *dest;
 140         unsigned long length;
 141
 142         if (PHYSICAL_START == 0)
 143                 return;
 144
 145         src = (int *)(KERNELBASE + PHYSICAL_START);
 146         dest = (int *)KERNELBASE;
 147         length = (__end_interrupts - _stext) / sizeof(int);
 148
 149         while (length--) {
 150                 patch_instruction(dest, *src);
 151                 src++;
 152                 dest++;
 153         }
 154 #endif
 155 }
 156
 157 static unsigned long __initdata saved_cpu_features;
 158 static unsigned int __initdata saved_mmu_features;
 159 #ifdef CONFIG_PPC64
 160 static unsigned long __initdata saved_firmware_features;
 161 #endif
 162
 163 void __init apply_feature_fixups(void)
 164 {
 165         struct cpu_spec *spec = PTRRELOC(*PTRRELOC(&cur_cpu_spec));
 166
 167         *PTRRELOC(&saved_cpu_features) = spec->cpu_features;
 168         *PTRRELOC(&saved_mmu_features) = spec->mmu_features;
 169
 170         /*
 171          * Apply the CPU-specific and firmware specific fixups to kernel text
 172          * (nop out sections not relevant to this CPU or this firmware).
 173          */
 174         do_feature_fixups(spec->cpu_features,
 175                           PTRRELOC(&__start___ftr_fixup),
 176                           PTRRELOC(&__stop___ftr_fixup));
 177
 178         do_feature_fixups(spec->mmu_features,
 179                           PTRRELOC(&__start___mmu_ftr_fixup),
 180                           PTRRELOC(&__stop___mmu_ftr_fixup));
 181
 182         do_lwsync_fixups(spec->cpu_features,
 183                          PTRRELOC(&__start___lwsync_fixup),
 184                          PTRRELOC(&__stop___lwsync_fixup));
 185
 186 #ifdef CONFIG_PPC64
 187         saved_firmware_features = powerpc_firmware_features;
 188         do_feature_fixups(powerpc_firmware_features,
 189                           &__start___fw_ftr_fixup, &__stop___fw_ftr_fixup);
 190 #endif
 191         do_final_fixups();
 192 }
 193
 194 void __init setup_feature_keys(void)
 195 {
 196         /*
 197          * Initialise jump label. This causes all the cpu/mmu_has_feature()
 198          * checks to take on their correct polarity based on the current set of
 199          * CPU/MMU features.
 200          */
 201         jump_label_init();
 202         cpu_feature_keys_init();
 203         mmu_feature_keys_init();
 204 }
 205
 206 static int __init check_features(void)
 207 {
 208         WARN(saved_cpu_features != cur_cpu_spec->cpu_features,
 209              "CPU features changed after feature patching!\n");
 210         WARN(saved_mmu_features != cur_cpu_spec->mmu_features,
 211              "MMU features changed after feature patching!\n");
 212 #ifdef CONFIG_PPC64
 213         WARN(saved_firmware_features != powerpc_firmware_features,
 214              "Firmware features changed after feature patching!\n");
 215 #endif
 216
 217         return 0;
 218 }
 219 late_initcall(check_features);
 220
 221 #ifdef CONFIG_FTR_FIXUP_SELFTEST
 222
 223 #define check(x)        \
 224         if (!(x)) printk("feature-fixups: test failed at line %d\n", __LINE__);
 225
 226 /* This must be after the text it fixes up, vmlinux.lds.S enforces that atm */
 227 static struct fixup_entry fixup;
 228
 229 static long calc_offset(struct fixup_entry *entry, unsigned int *p)
 230 {
 231         return (unsigned long)p - (unsigned long)entry;
 232 }
 233
 234 static void test_basic_patching(void)
 235 {
 236         extern unsigned int ftr_fixup_test1;
 237         extern unsigned int end_ftr_fixup_test1;
 238         extern unsigned int ftr_fixup_test1_orig;
 239         extern unsigned int ftr_fixup_test1_expected;
 240         int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
 241
 242         fixup.value = fixup.mask = 8;
 243         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
 244         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
 245         fixup.alt_start_off = fixup.alt_end_off = 0;
 246
 247         /* Sanity check */
 248         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 249
 250         /* Check we don't patch if the value matches */
 251         patch_feature_section(8, &fixup);
 252         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 253
 254         /* Check we do patch if the value doesn't match */
 255         patch_feature_section(0, &fixup);
 256         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
 257
 258         /* Check we do patch if the mask doesn't match */
 259         memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
 260         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 261         patch_feature_section(~8, &fixup);
 262         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
 263 }
 264
 265 static void test_alternative_patching(void)
 266 {
 267         extern unsigned int ftr_fixup_test2;
 268         extern unsigned int end_ftr_fixup_test2;
 269         extern unsigned int ftr_fixup_test2_orig;
 270         extern unsigned int ftr_fixup_test2_alt;
 271         extern unsigned int ftr_fixup_test2_expected;
 272         int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
 273
 274         fixup.value = fixup.mask = 0xF;
 275         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
 276         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
 277         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
 278         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
 279
 280         /* Sanity check */
 281         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 282
 283         /* Check we don't patch if the value matches */
 284         patch_feature_section(0xF, &fixup);
 285         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 286
 287         /* Check we do patch if the value doesn't match */
 288         patch_feature_section(0, &fixup);
 289         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
 290
 291         /* Check we do patch if the mask doesn't match */
 292         memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
 293         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 294         patch_feature_section(~0xF, &fixup);
 295         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
 296 }
 297
 298 static void test_alternative_case_too_big(void)
 299 {
 300         extern unsigned int ftr_fixup_test3;
 301         extern unsigned int end_ftr_fixup_test3;
 302         extern unsigned int ftr_fixup_test3_orig;
 303         extern unsigned int ftr_fixup_test3_alt;
 304         int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
 305
 306         fixup.value = fixup.mask = 0xC;
 307         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
 308         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
 309         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
 310         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
 311
 312         /* Sanity check */
 313         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 314
 315         /* Expect nothing to be patched, and the error returned to us */
 316         check(patch_feature_section(0xF, &fixup) == 1);
 317         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 318         check(patch_feature_section(0, &fixup) == 1);
 319         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 320         check(patch_feature_section(~0xF, &fixup) == 1);
 321         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 322 }
 323
 324 static void test_alternative_case_too_small(void)
 325 {
 326         extern unsigned int ftr_fixup_test4;
 327         extern unsigned int end_ftr_fixup_test4;
 328         extern unsigned int ftr_fixup_test4_orig;
 329         extern unsigned int ftr_fixup_test4_alt;
 330         extern unsigned int ftr_fixup_test4_expected;
 331         int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
 332         unsigned long flag;
 333
 334         /* Check a high-bit flag */
 335         flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
 336         fixup.value = fixup.mask = flag;
 337         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
 338         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
 339         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
 340         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
 341
 342         /* Sanity check */
 343         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 344
 345         /* Check we don't patch if the value matches */
 346         patch_feature_section(flag, &fixup);
 347         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 348
 349         /* Check we do patch if the value doesn't match */
 350         patch_feature_section(0, &fixup);
 351         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
 352
 353         /* Check we do patch if the mask doesn't match */
 354         memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
 355         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 356         patch_feature_section(~flag, &fixup);
 357         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
 358 }
 359
 360 static void test_alternative_case_with_branch(void)
 361 {
 362         extern unsigned int ftr_fixup_test5;
 363         extern unsigned int end_ftr_fixup_test5;
 364         extern unsigned int ftr_fixup_test5_expected;
 365         int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
 366
 367         check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
 368 }
 369
 370 static void test_alternative_case_with_external_branch(void)
 371 {
 372         extern unsigned int ftr_fixup_test6;
 373         extern unsigned int end_ftr_fixup_test6;
 374         extern unsigned int ftr_fixup_test6_expected;
 375         int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
 376
 377         check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
 378 }
 379
 380 static void test_cpu_macros(void)
 381 {
 382         extern u8 ftr_fixup_test_FTR_macros;
 383         extern u8 ftr_fixup_test_FTR_macros_expected;
 384         unsigned long size = &ftr_fixup_test_FTR_macros_expected -
 385                              &ftr_fixup_test_FTR_macros;
 386
 387         /* The fixups have already been done for us during boot */
 388         check(memcmp(&ftr_fixup_test_FTR_macros,
 389                      &ftr_fixup_test_FTR_macros_expected, size) == 0);
 390 }
 391
 392 static void test_fw_macros(void)
 393 {
 394 #ifdef CONFIG_PPC64
 395         extern u8 ftr_fixup_test_FW_FTR_macros;
 396         extern u8 ftr_fixup_test_FW_FTR_macros_expected;
 397         unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
 398                              &ftr_fixup_test_FW_FTR_macros;
 399
 400         /* The fixups have already been done for us during boot */
 401         check(memcmp(&ftr_fixup_test_FW_FTR_macros,
 402                      &ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
 403 #endif
 404 }
 405
 406 static void test_lwsync_macros(void)
 407 {
 408         extern u8 lwsync_fixup_test;
 409         extern u8 end_lwsync_fixup_test;
 410         extern u8 lwsync_fixup_test_expected_LWSYNC;
 411         extern u8 lwsync_fixup_test_expected_SYNC;
 412         unsigned long size = &end_lwsync_fixup_test -
 413                              &lwsync_fixup_test;
 414
 415         /* The fixups have already been done for us during boot */
 416         if (cur_cpu_spec->cpu_features & CPU_FTR_LWSYNC) {
 417                 check(memcmp(&lwsync_fixup_test,
 418                              &lwsync_fixup_test_expected_LWSYNC, size) == 0);
 419         } else {
 420                 check(memcmp(&lwsync_fixup_test,
 421                              &lwsync_fixup_test_expected_SYNC, size) == 0);
 422         }
 423 }
 424
 425 static int __init test_feature_fixups(void)
 426 {
 427         printk(KERN_DEBUG "Running feature fixup self-tests ...\n");
 428
 429         test_basic_patching();
 430         test_alternative_patching();
 431         test_alternative_case_too_big();
 432         test_alternative_case_too_small();
 433         test_alternative_case_with_branch();
 434         test_alternative_case_with_external_branch();
 435         test_cpu_macros();
 436         test_fw_macros();
 437         test_lwsync_macros();
 438
 439         return 0;
 440 }
 441 late_initcall(test_feature_fixups);
 442
 443 #endif /* CONFIG_FTR_FIXUP_SELFTEST */