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