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