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