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