arch/powerpc/lib/test-code-patching.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright 2008 Michael Ellerman, IBM Corporation.
   4  */
   5
   6 #include <linux/vmalloc.h>
   7 #include <linux/init.h>
   8
   9 #include <asm/code-patching.h>
  10
  11 static int __init instr_is_branch_to_addr(const u32 *instr, unsigned long addr)
  12 {
  13         if (instr_is_branch_iform(ppc_inst_read(instr)) ||
  14             instr_is_branch_bform(ppc_inst_read(instr)))
  15                 return branch_target(instr) == addr;
  16
  17         return 0;
  18 }
  19
  20 static void __init test_trampoline(void)
  21 {
  22         asm ("nop;nop;\n");
  23 }
  24
  25 #define check(x)        do {    \
  26         if (!(x))               \
  27                 pr_err("code-patching: test failed at line %d\n", __LINE__); \
  28 } while (0)
  29
  30 static void __init test_branch_iform(void)
  31 {
  32         int err;
  33         ppc_inst_t instr;
  34         u32 tmp[2];
  35         u32 *iptr = tmp;
  36         unsigned long addr = (unsigned long)tmp;
  37
  38         /* The simplest case, branch to self, no flags */
  39         check(instr_is_branch_iform(ppc_inst(0x48000000)));
  40         /* All bits of target set, and flags */
  41         check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
  42         /* High bit of opcode set, which is wrong */
  43         check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
  44         /* Middle bits of opcode set, which is wrong */
  45         check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
  46
  47         /* Simplest case, branch to self with link */
  48         check(instr_is_branch_iform(ppc_inst(0x48000001)));
  49         /* All bits of targets set */
  50         check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
  51         /* Some bits of targets set */
  52         check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
  53         /* Must be a valid branch to start with */
  54         check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
  55
  56         /* Absolute branch to 0x100 */
  57         ppc_inst_write(iptr, ppc_inst(0x48000103));
  58         check(instr_is_branch_to_addr(iptr, 0x100));
  59         /* Absolute branch to 0x420fc */
  60         ppc_inst_write(iptr, ppc_inst(0x480420ff));
  61         check(instr_is_branch_to_addr(iptr, 0x420fc));
  62         /* Maximum positive relative branch, + 20MB - 4B */
  63         ppc_inst_write(iptr, ppc_inst(0x49fffffc));
  64         check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
  65         /* Smallest negative relative branch, - 4B */
  66         ppc_inst_write(iptr, ppc_inst(0x4bfffffc));
  67         check(instr_is_branch_to_addr(iptr, addr - 4));
  68         /* Largest negative relative branch, - 32 MB */
  69         ppc_inst_write(iptr, ppc_inst(0x4a000000));
  70         check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
  71
  72         /* Branch to self, with link */
  73         err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
  74         ppc_inst_write(iptr, instr);
  75         check(instr_is_branch_to_addr(iptr, addr));
  76
  77         /* Branch to self - 0x100, with link */
  78         err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
  79         ppc_inst_write(iptr, instr);
  80         check(instr_is_branch_to_addr(iptr, addr - 0x100));
  81
  82         /* Branch to self + 0x100, no link */
  83         err = create_branch(&instr, iptr, addr + 0x100, 0);
  84         ppc_inst_write(iptr, instr);
  85         check(instr_is_branch_to_addr(iptr, addr + 0x100));
  86
  87         /* Maximum relative negative offset, - 32 MB */
  88         err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
  89         ppc_inst_write(iptr, instr);
  90         check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
  91
  92         /* Out of range relative negative offset, - 32 MB + 4*/
  93         err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
  94         check(err);
  95
  96         /* Out of range relative positive offset, + 32 MB */
  97         err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
  98         check(err);
  99
 100         /* Unaligned target */
 101         err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
 102         check(err);
 103
 104         /* Check flags are masked correctly */
 105         err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
 106         ppc_inst_write(iptr, instr);
 107         check(instr_is_branch_to_addr(iptr, addr));
 108         check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 109 }
 110
 111 static void __init test_create_function_call(void)
 112 {
 113         u32 *iptr;
 114         unsigned long dest;
 115         ppc_inst_t instr;
 116
 117         /* Check we can create a function call */
 118         iptr = (u32 *)ppc_function_entry(test_trampoline);
 119         dest = ppc_function_entry(test_create_function_call);
 120         create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
 121         patch_instruction(iptr, instr);
 122         check(instr_is_branch_to_addr(iptr, dest));
 123 }
 124
 125 static void __init test_branch_bform(void)
 126 {
 127         int err;
 128         unsigned long addr;
 129         ppc_inst_t instr;
 130         u32 tmp[2];
 131         u32 *iptr = tmp;
 132         unsigned int flags;
 133
 134         addr = (unsigned long)iptr;
 135
 136         /* The simplest case, branch to self, no flags */
 137         check(instr_is_branch_bform(ppc_inst(0x40000000)));
 138         /* All bits of target set, and flags */
 139         check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
 140         /* High bit of opcode set, which is wrong */
 141         check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
 142         /* Middle bits of opcode set, which is wrong */
 143         check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 144
 145         /* Absolute conditional branch to 0x100 */
 146         ppc_inst_write(iptr, ppc_inst(0x43ff0103));
 147         check(instr_is_branch_to_addr(iptr, 0x100));
 148         /* Absolute conditional branch to 0x20fc */
 149         ppc_inst_write(iptr, ppc_inst(0x43ff20ff));
 150         check(instr_is_branch_to_addr(iptr, 0x20fc));
 151         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 152         ppc_inst_write(iptr, ppc_inst(0x43ff7ffc));
 153         check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
 154         /* Smallest negative relative conditional branch, - 4B */
 155         ppc_inst_write(iptr, ppc_inst(0x43fffffc));
 156         check(instr_is_branch_to_addr(iptr, addr - 4));
 157         /* Largest negative relative conditional branch, - 32 KB */
 158         ppc_inst_write(iptr, ppc_inst(0x43ff8000));
 159         check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 160
 161         /* All condition code bits set & link */
 162         flags = 0x3ff000 | BRANCH_SET_LINK;
 163
 164         /* Branch to self */
 165         err = create_cond_branch(&instr, iptr, addr, flags);
 166         ppc_inst_write(iptr, instr);
 167         check(instr_is_branch_to_addr(iptr, addr));
 168
 169         /* Branch to self - 0x100 */
 170         err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
 171         ppc_inst_write(iptr, instr);
 172         check(instr_is_branch_to_addr(iptr, addr - 0x100));
 173
 174         /* Branch to self + 0x100 */
 175         err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
 176         ppc_inst_write(iptr, instr);
 177         check(instr_is_branch_to_addr(iptr, addr + 0x100));
 178
 179         /* Maximum relative negative offset, - 32 KB */
 180         err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
 181         ppc_inst_write(iptr, instr);
 182         check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 183
 184         /* Out of range relative negative offset, - 32 KB + 4*/
 185         err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
 186         check(err);
 187
 188         /* Out of range relative positive offset, + 32 KB */
 189         err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
 190         check(err);
 191
 192         /* Unaligned target */
 193         err = create_cond_branch(&instr, iptr, addr + 3, flags);
 194         check(err);
 195
 196         /* Check flags are masked correctly */
 197         err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
 198         ppc_inst_write(iptr, instr);
 199         check(instr_is_branch_to_addr(iptr, addr));
 200         check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 201 }
 202
 203 static void __init test_translate_branch(void)
 204 {
 205         unsigned long addr;
 206         void *p, *q;
 207         ppc_inst_t instr;
 208         void *buf;
 209
 210         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 211         check(buf);
 212         if (!buf)
 213                 return;
 214
 215         /* Simple case, branch to self moved a little */
 216         p = buf;
 217         addr = (unsigned long)p;
 218         create_branch(&instr, p, addr, 0);
 219         ppc_inst_write(p, instr);
 220         check(instr_is_branch_to_addr(p, addr));
 221         q = p + 4;
 222         translate_branch(&instr, q, p);
 223         ppc_inst_write(q, instr);
 224         check(instr_is_branch_to_addr(q, addr));
 225
 226         /* Maximum negative case, move b . to addr + 32 MB */
 227         p = buf;
 228         addr = (unsigned long)p;
 229         create_branch(&instr, p, addr, 0);
 230         ppc_inst_write(p, instr);
 231         q = buf + 0x2000000;
 232         translate_branch(&instr, q, p);
 233         ppc_inst_write(q, instr);
 234         check(instr_is_branch_to_addr(p, addr));
 235         check(instr_is_branch_to_addr(q, addr));
 236         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 237
 238         /* Maximum positive case, move x to x - 32 MB + 4 */
 239         p = buf + 0x2000000;
 240         addr = (unsigned long)p;
 241         create_branch(&instr, p, addr, 0);
 242         ppc_inst_write(p, instr);
 243         q = buf + 4;
 244         translate_branch(&instr, q, p);
 245         ppc_inst_write(q, instr);
 246         check(instr_is_branch_to_addr(p, addr));
 247         check(instr_is_branch_to_addr(q, addr));
 248         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 249
 250         /* Jump to x + 16 MB moved to x + 20 MB */
 251         p = buf;
 252         addr = 0x1000000 + (unsigned long)buf;
 253         create_branch(&instr, p, addr, BRANCH_SET_LINK);
 254         ppc_inst_write(p, instr);
 255         q = buf + 0x1400000;
 256         translate_branch(&instr, q, p);
 257         ppc_inst_write(q, instr);
 258         check(instr_is_branch_to_addr(p, addr));
 259         check(instr_is_branch_to_addr(q, addr));
 260
 261         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 262         p = buf + 0x1000000;
 263         addr = 0x2000000 + (unsigned long)buf;
 264         create_branch(&instr, p, addr, 0);
 265         ppc_inst_write(p, instr);
 266         q = buf + 4;
 267         translate_branch(&instr, q, p);
 268         ppc_inst_write(q, instr);
 269         check(instr_is_branch_to_addr(p, addr));
 270         check(instr_is_branch_to_addr(q, addr));
 271
 272
 273         /* Conditional branch tests */
 274
 275         /* Simple case, branch to self moved a little */
 276         p = buf;
 277         addr = (unsigned long)p;
 278         create_cond_branch(&instr, p, addr, 0);
 279         ppc_inst_write(p, instr);
 280         check(instr_is_branch_to_addr(p, addr));
 281         q = buf + 4;
 282         translate_branch(&instr, q, p);
 283         ppc_inst_write(q, instr);
 284         check(instr_is_branch_to_addr(q, addr));
 285
 286         /* Maximum negative case, move b . to addr + 32 KB */
 287         p = buf;
 288         addr = (unsigned long)p;
 289         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 290         ppc_inst_write(p, instr);
 291         q = buf + 0x8000;
 292         translate_branch(&instr, q, p);
 293         ppc_inst_write(q, instr);
 294         check(instr_is_branch_to_addr(p, addr));
 295         check(instr_is_branch_to_addr(q, addr));
 296         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 297
 298         /* Maximum positive case, move x to x - 32 KB + 4 */
 299         p = buf + 0x8000;
 300         addr = (unsigned long)p;
 301         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 302         ppc_inst_write(p, instr);
 303         q = buf + 4;
 304         translate_branch(&instr, q, p);
 305         ppc_inst_write(q, instr);
 306         check(instr_is_branch_to_addr(p, addr));
 307         check(instr_is_branch_to_addr(q, addr));
 308         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 309
 310         /* Jump to x + 12 KB moved to x + 20 KB */
 311         p = buf;
 312         addr = 0x3000 + (unsigned long)buf;
 313         create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
 314         ppc_inst_write(p, instr);
 315         q = buf + 0x5000;
 316         translate_branch(&instr, q, p);
 317         ppc_inst_write(q, instr);
 318         check(instr_is_branch_to_addr(p, addr));
 319         check(instr_is_branch_to_addr(q, addr));
 320
 321         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 322         p = buf + 0x2000;
 323         addr = 0x4000 + (unsigned long)buf;
 324         create_cond_branch(&instr, p, addr, 0);
 325         ppc_inst_write(p, instr);
 326         q = buf + 4;
 327         translate_branch(&instr, q, p);
 328         ppc_inst_write(q, instr);
 329         check(instr_is_branch_to_addr(p, addr));
 330         check(instr_is_branch_to_addr(q, addr));
 331
 332         /* Free the buffer we were using */
 333         vfree(buf);
 334 }
 335
 336 static void __init test_prefixed_patching(void)
 337 {
 338         u32 *iptr = (u32 *)ppc_function_entry(test_trampoline);
 339         u32 expected[2] = {OP_PREFIX << 26, 0};
 340         ppc_inst_t inst = ppc_inst_prefix(OP_PREFIX << 26, 0);
 341
 342         if (!IS_ENABLED(CONFIG_PPC64))
 343                 return;
 344
 345         patch_instruction(iptr, inst);
 346
 347         check(!memcmp(iptr, expected, sizeof(expected)));
 348 }
 349
 350 static int __init test_code_patching(void)
 351 {
 352         pr_info("Running code patching self-tests ...\n");
 353
 354         test_branch_iform();
 355         test_branch_bform();
 356         test_create_function_call();
 357         test_translate_branch();
 358         test_prefixed_patching();
 359
 360         return 0;
 361 }
 362 late_initcall(test_code_patching);