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_NOP_INSTR);
  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();
 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 #ifdef CONFIG_FTR_FIXUP_SELFTEST
 114
 115 #define check(x)        \
 116         if (!(x)) printk("feature-fixups: test failed at line %d\n", __LINE__);
 117
 118 /* This must be after the text it fixes up, vmlinux.lds.S enforces that atm */
 119 static struct fixup_entry fixup;
 120
 121 static long calc_offset(struct fixup_entry *entry, unsigned int *p)
 122 {
 123         return (unsigned long)p - (unsigned long)entry;
 124 }
 125
 126 void test_basic_patching(void)
 127 {
 128         extern unsigned int ftr_fixup_test1;
 129         extern unsigned int end_ftr_fixup_test1;
 130         extern unsigned int ftr_fixup_test1_orig;
 131         extern unsigned int ftr_fixup_test1_expected;
 132         int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
 133
 134         fixup.value = fixup.mask = 8;
 135         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
 136         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
 137         fixup.alt_start_off = fixup.alt_end_off = 0;
 138
 139         /* Sanity check */
 140         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 141
 142         /* Check we don't patch if the value matches */
 143         patch_feature_section(8, &fixup);
 144         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 145
 146         /* Check we do patch if the value doesn't match */
 147         patch_feature_section(0, &fixup);
 148         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
 149
 150         /* Check we do patch if the mask doesn't match */
 151         memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
 152         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
 153         patch_feature_section(~8, &fixup);
 154         check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
 155 }
 156
 157 static void test_alternative_patching(void)
 158 {
 159         extern unsigned int ftr_fixup_test2;
 160         extern unsigned int end_ftr_fixup_test2;
 161         extern unsigned int ftr_fixup_test2_orig;
 162         extern unsigned int ftr_fixup_test2_alt;
 163         extern unsigned int ftr_fixup_test2_expected;
 164         int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
 165
 166         fixup.value = fixup.mask = 0xF;
 167         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
 168         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
 169         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
 170         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
 171
 172         /* Sanity check */
 173         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 174
 175         /* Check we don't patch if the value matches */
 176         patch_feature_section(0xF, &fixup);
 177         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 178
 179         /* Check we do patch if the value doesn't match */
 180         patch_feature_section(0, &fixup);
 181         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
 182
 183         /* Check we do patch if the mask doesn't match */
 184         memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
 185         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
 186         patch_feature_section(~0xF, &fixup);
 187         check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
 188 }
 189
 190 static void test_alternative_case_too_big(void)
 191 {
 192         extern unsigned int ftr_fixup_test3;
 193         extern unsigned int end_ftr_fixup_test3;
 194         extern unsigned int ftr_fixup_test3_orig;
 195         extern unsigned int ftr_fixup_test3_alt;
 196         int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
 197
 198         fixup.value = fixup.mask = 0xC;
 199         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
 200         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
 201         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
 202         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
 203
 204         /* Sanity check */
 205         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 206
 207         /* Expect nothing to be patched, and the error returned to us */
 208         check(patch_feature_section(0xF, &fixup) == 1);
 209         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 210         check(patch_feature_section(0, &fixup) == 1);
 211         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 212         check(patch_feature_section(~0xF, &fixup) == 1);
 213         check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
 214 }
 215
 216 static void test_alternative_case_too_small(void)
 217 {
 218         extern unsigned int ftr_fixup_test4;
 219         extern unsigned int end_ftr_fixup_test4;
 220         extern unsigned int ftr_fixup_test4_orig;
 221         extern unsigned int ftr_fixup_test4_alt;
 222         extern unsigned int ftr_fixup_test4_expected;
 223         int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
 224         unsigned long flag;
 225
 226         /* Check a high-bit flag */
 227         flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
 228         fixup.value = fixup.mask = flag;
 229         fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
 230         fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
 231         fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
 232         fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
 233
 234         /* Sanity check */
 235         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 236
 237         /* Check we don't patch if the value matches */
 238         patch_feature_section(flag, &fixup);
 239         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 240
 241         /* Check we do patch if the value doesn't match */
 242         patch_feature_section(0, &fixup);
 243         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
 244
 245         /* Check we do patch if the mask doesn't match */
 246         memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
 247         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
 248         patch_feature_section(~flag, &fixup);
 249         check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
 250 }
 251
 252 static void test_alternative_case_with_branch(void)
 253 {
 254         extern unsigned int ftr_fixup_test5;
 255         extern unsigned int end_ftr_fixup_test5;
 256         extern unsigned int ftr_fixup_test5_expected;
 257         int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
 258
 259         check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
 260 }
 261
 262 static void test_alternative_case_with_external_branch(void)
 263 {
 264         extern unsigned int ftr_fixup_test6;
 265         extern unsigned int end_ftr_fixup_test6;
 266         extern unsigned int ftr_fixup_test6_expected;
 267         int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
 268
 269         check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
 270 }
 271
 272 static void test_cpu_macros(void)
 273 {
 274         extern void ftr_fixup_test_FTR_macros;
 275         extern void ftr_fixup_test_FTR_macros_expected;
 276         unsigned long size = &ftr_fixup_test_FTR_macros_expected -
 277                              &ftr_fixup_test_FTR_macros;
 278
 279         /* The fixups have already been done for us during boot */
 280         check(memcmp(&ftr_fixup_test_FTR_macros,
 281                      &ftr_fixup_test_FTR_macros_expected, size) == 0);
 282 }
 283
 284 static void test_fw_macros(void)
 285 {
 286 #ifdef CONFIG_PPC64
 287         extern void ftr_fixup_test_FW_FTR_macros;
 288         extern void ftr_fixup_test_FW_FTR_macros_expected;
 289         unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
 290                              &ftr_fixup_test_FW_FTR_macros;
 291
 292         /* The fixups have already been done for us during boot */
 293         check(memcmp(&ftr_fixup_test_FW_FTR_macros,
 294                      &ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
 295 #endif
 296 }
 297
 298 static int __init test_feature_fixups(void)
 299 {
 300         printk(KERN_DEBUG "Running feature fixup self-tests ...\n");
 301
 302         test_basic_patching();
 303         test_alternative_patching();
 304         test_alternative_case_too_big();
 305         test_alternative_case_too_small();
 306         test_alternative_case_with_branch();
 307         test_alternative_case_with_external_branch();
 308         test_cpu_macros();
 309         test_fw_macros();
 310
 311         return 0;
 312 }
 313 late_initcall(test_feature_fixups);
 314
 315 #endif /* CONFIG_FTR_FIXUP_SELFTEST */