1 /** 2 * \file common.h 3 * 4 * \brief Utility macros for internal use in the library 5 */ 6 /* 7 * Copyright The Mbed TLS Contributors 8 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 9 */ 10 11 #ifndef MBEDTLS_LIBRARY_COMMON_H 12 #define MBEDTLS_LIBRARY_COMMON_H 13 14 #include "mbedtls/build_info.h" 15 #include "alignment.h" 16 17 #include <assert.h> 18 #include <stddef.h> 19 #include <stdint.h> 20 #include <stddef.h> 21 22 #if defined(__ARM_NEON) 23 /* 24 * Undefine and restore __section and __data from compiler.h to prevent 25 * collision with arm_neon.h 26 */ 27 #pragma push_macro("__section") 28 #pragma push_macro("__data") 29 #undef __section 30 #undef __data 31 #include <arm_neon.h> 32 #pragma pop_macro("__data") 33 #pragma pop_macro("__section") 34 #define MBEDTLS_HAVE_NEON_INTRINSICS 35 #elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64) 36 #include <arm64_neon.h> 37 #define MBEDTLS_HAVE_NEON_INTRINSICS 38 #endif 39 40 /** Helper to define a function as static except when building invasive tests. 41 * 42 * If a function is only used inside its own source file and should be 43 * declared `static` to allow the compiler to optimize for code size, 44 * but that function has unit tests, define it with 45 * ``` 46 * MBEDTLS_STATIC_TESTABLE int mbedtls_foo(...) { ... } 47 * ``` 48 * and declare it in a header in the `library/` directory with 49 * ``` 50 * #if defined(MBEDTLS_TEST_HOOKS) 51 * int mbedtls_foo(...); 52 * #endif 53 * ``` 54 */ 55 #if defined(MBEDTLS_TEST_HOOKS) 56 #define MBEDTLS_STATIC_TESTABLE 57 #else 58 #define MBEDTLS_STATIC_TESTABLE static 59 #endif 60 61 #if defined(MBEDTLS_TEST_HOOKS) 62 extern void (*mbedtls_test_hook_test_fail)(const char *test, int line, const char *file); 63 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) \ 64 do { \ 65 if ((!(TEST)) && ((*mbedtls_test_hook_test_fail) != NULL)) \ 66 { \ 67 (*mbedtls_test_hook_test_fail)( #TEST, __LINE__, __FILE__); \ 68 } \ 69 } while (0) 70 #else 71 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) 72 #endif /* defined(MBEDTLS_TEST_HOOKS) */ 73 74 /** \def ARRAY_LENGTH 75 * Return the number of elements of a static or stack array. 76 * 77 * \param array A value of array (not pointer) type. 78 * 79 * \return The number of elements of the array. 80 */ 81 /* A correct implementation of ARRAY_LENGTH, but which silently gives 82 * a nonsensical result if called with a pointer rather than an array. */ 83 #define ARRAY_LENGTH_UNSAFE(array) \ 84 (sizeof(array) / sizeof(*(array))) 85 86 #if defined(__GNUC__) 87 /* Test if arg and &(arg)[0] have the same type. This is true if arg is 88 * an array but not if it's a pointer. */ 89 #define IS_ARRAY_NOT_POINTER(arg) \ 90 (!__builtin_types_compatible_p(__typeof__(arg), \ 91 __typeof__(&(arg)[0]))) 92 /* A compile-time constant with the value 0. If `const_expr` is not a 93 * compile-time constant with a nonzero value, cause a compile-time error. */ 94 #define STATIC_ASSERT_EXPR(const_expr) \ 95 (0 && sizeof(struct { unsigned int STATIC_ASSERT : 1 - 2 * !(const_expr); })) 96 97 /* Return the scalar value `value` (possibly promoted). This is a compile-time 98 * constant if `value` is. `condition` must be a compile-time constant. 99 * If `condition` is false, arrange to cause a compile-time error. */ 100 #define STATIC_ASSERT_THEN_RETURN(condition, value) \ 101 (STATIC_ASSERT_EXPR(condition) ? 0 : (value)) 102 103 #define ARRAY_LENGTH(array) \ 104 (STATIC_ASSERT_THEN_RETURN(IS_ARRAY_NOT_POINTER(array), \ 105 ARRAY_LENGTH_UNSAFE(array))) 106 107 #else 108 /* If we aren't sure the compiler supports our non-standard tricks, 109 * fall back to the unsafe implementation. */ 110 #define ARRAY_LENGTH(array) ARRAY_LENGTH_UNSAFE(array) 111 #endif 112 /** Allow library to access its structs' private members. 113 * 114 * Although structs defined in header files are publicly available, 115 * their members are private and should not be accessed by the user. 116 */ 117 #define MBEDTLS_ALLOW_PRIVATE_ACCESS 118 119 /** 120 * \brief Securely zeroize a buffer then free it. 121 * 122 * Similar to making consecutive calls to 123 * \c mbedtls_platform_zeroize() and \c mbedtls_free(), but has 124 * code size savings, and potential for optimisation in the future. 125 * 126 * Guaranteed to be a no-op if \p buf is \c NULL and \p len is 0. 127 * 128 * \param buf Buffer to be zeroized then freed. 129 * \param len Length of the buffer in bytes 130 */ 131 void mbedtls_zeroize_and_free(void *buf, size_t len); 132 133 /** Return an offset into a buffer. 134 * 135 * This is just the addition of an offset to a pointer, except that this 136 * function also accepts an offset of 0 into a buffer whose pointer is null. 137 * (`p + n` has undefined behavior when `p` is null, even when `n == 0`. 138 * A null pointer is a valid buffer pointer when the size is 0, for example 139 * as the result of `malloc(0)` on some platforms.) 140 * 141 * \param p Pointer to a buffer of at least n bytes. 142 * This may be \p NULL if \p n is zero. 143 * \param n An offset in bytes. 144 * \return Pointer to offset \p n in the buffer \p p. 145 * Note that this is only a valid pointer if the size of the 146 * buffer is at least \p n + 1. 147 */ 148 static inline unsigned char *mbedtls_buffer_offset( 149 unsigned char *p, size_t n) 150 { 151 return p == NULL ? NULL : p + n; 152 } 153 154 /** Return an offset into a read-only buffer. 155 * 156 * Similar to mbedtls_buffer_offset(), but for const pointers. 157 * 158 * \param p Pointer to a buffer of at least n bytes. 159 * This may be \p NULL if \p n is zero. 160 * \param n An offset in bytes. 161 * \return Pointer to offset \p n in the buffer \p p. 162 * Note that this is only a valid pointer if the size of the 163 * buffer is at least \p n + 1. 164 */ 165 static inline const unsigned char *mbedtls_buffer_offset_const( 166 const unsigned char *p, size_t n) 167 { 168 return p == NULL ? NULL : p + n; 169 } 170 171 /* Always inline mbedtls_xor() for similar reasons as mbedtls_xor_no_simd(). */ 172 #if defined(__IAR_SYSTEMS_ICC__) 173 #pragma inline = forced 174 #elif defined(__GNUC__) 175 __attribute__((always_inline)) 176 #endif 177 /** 178 * Perform a fast block XOR operation, such that 179 * r[i] = a[i] ^ b[i] where 0 <= i < n 180 * 181 * \param r Pointer to result (buffer of at least \p n bytes). \p r 182 * may be equal to either \p a or \p b, but behaviour when 183 * it overlaps in other ways is undefined. 184 * \param a Pointer to input (buffer of at least \p n bytes) 185 * \param b Pointer to input (buffer of at least \p n bytes) 186 * \param n Number of bytes to process. 187 * 188 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or 189 * mbedtls_xor_no_simd() (these are functionally equivalent). 190 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in 191 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar 192 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where 193 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster. 194 * For targets without SIMD support, they will behave the same. 195 */ 196 static inline void mbedtls_xor(unsigned char *r, 197 const unsigned char *a, 198 const unsigned char *b, 199 size_t n) 200 { 201 size_t i = 0; 202 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS) 203 #if defined(MBEDTLS_HAVE_NEON_INTRINSICS) && \ 204 (!(defined(MBEDTLS_COMPILER_IS_GCC) && MBEDTLS_GCC_VERSION < 70300)) 205 /* Old GCC versions generate a warning here, so disable the NEON path for these compilers */ 206 for (; (i + 16) <= n; i += 16) { 207 uint8x16_t v1 = vld1q_u8(a + i); 208 uint8x16_t v2 = vld1q_u8(b + i); 209 uint8x16_t x = veorq_u8(v1, v2); 210 vst1q_u8(r + i, x); 211 } 212 #if defined(__IAR_SYSTEMS_ICC__) || defined(MBEDTLS_COMPILER_IS_GCC) 213 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case 214 * where n is a constant multiple of 16. 215 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time 216 * constant, and is a very small perf regression if n is not a compile-time constant. 217 * GCC 14.2 outputs a warning "array subscript 48 is outside array bounds" if we don't return 218 * early. */ 219 if (n % 16 == 0) { 220 return; 221 } 222 #endif 223 #elif defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64) 224 /* This codepath probably only makes sense on architectures with 64-bit registers */ 225 for (; (i + 8) <= n; i += 8) { 226 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i); 227 mbedtls_put_unaligned_uint64(r + i, x); 228 } 229 #if defined(__IAR_SYSTEMS_ICC__) 230 if (n % 8 == 0) { 231 return; 232 } 233 #endif 234 #else 235 for (; (i + 4) <= n; i += 4) { 236 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i); 237 mbedtls_put_unaligned_uint32(r + i, x); 238 } 239 #if defined(__IAR_SYSTEMS_ICC__) 240 if (n % 4 == 0) { 241 return; 242 } 243 #endif 244 #endif 245 #endif 246 for (; i < n; i++) { 247 r[i] = a[i] ^ b[i]; 248 } 249 } 250 251 /* Always inline mbedtls_xor_no_simd() as we see significant perf regressions when it does not get 252 * inlined (e.g., observed about 3x perf difference in gcm_mult_largetable with gcc 7 - 12) */ 253 #if defined(__IAR_SYSTEMS_ICC__) 254 #pragma inline = forced 255 #elif defined(__GNUC__) 256 __attribute__((always_inline)) 257 #endif 258 /** 259 * Perform a fast block XOR operation, such that 260 * r[i] = a[i] ^ b[i] where 0 <= i < n 261 * 262 * In some situations, this can perform better than mbedtls_xor() (e.g., it's about 5% 263 * better in AES-CBC). 264 * 265 * \param r Pointer to result (buffer of at least \p n bytes). \p r 266 * may be equal to either \p a or \p b, but behaviour when 267 * it overlaps in other ways is undefined. 268 * \param a Pointer to input (buffer of at least \p n bytes) 269 * \param b Pointer to input (buffer of at least \p n bytes) 270 * \param n Number of bytes to process. 271 * 272 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or 273 * mbedtls_xor_no_simd() (these are functionally equivalent). 274 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in 275 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar 276 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where 277 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster. 278 * For targets without SIMD support, they will behave the same. 279 */ 280 static inline void mbedtls_xor_no_simd(unsigned char *r, 281 const unsigned char *a, 282 const unsigned char *b, 283 size_t n) 284 { 285 size_t i = 0; 286 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS) 287 #if defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64) 288 /* This codepath probably only makes sense on architectures with 64-bit registers */ 289 for (; (i + 8) <= n; i += 8) { 290 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i); 291 mbedtls_put_unaligned_uint64(r + i, x); 292 } 293 #if defined(__IAR_SYSTEMS_ICC__) 294 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case 295 * where n is a constant multiple of 8. 296 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time 297 * constant, and is a very small perf regression if n is not a compile-time constant. */ 298 if (n % 8 == 0) { 299 return; 300 } 301 #endif 302 #else 303 for (; (i + 4) <= n; i += 4) { 304 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i); 305 mbedtls_put_unaligned_uint32(r + i, x); 306 } 307 #if defined(__IAR_SYSTEMS_ICC__) 308 if (n % 4 == 0) { 309 return; 310 } 311 #endif 312 #endif 313 #endif 314 for (; i < n; i++) { 315 r[i] = a[i] ^ b[i]; 316 } 317 } 318 319 /* Fix MSVC C99 compatible issue 320 * MSVC support __func__ from visual studio 2015( 1900 ) 321 * Use MSVC predefine macro to avoid name check fail. 322 */ 323 #if (defined(_MSC_VER) && (_MSC_VER <= 1900)) 324 #define /*no-check-names*/ __func__ __FUNCTION__ 325 #endif 326 327 /* Define `asm` for compilers which don't define it. */ 328 /* *INDENT-OFF* */ 329 #ifndef asm 330 #if defined(__IAR_SYSTEMS_ICC__) 331 #define asm __asm 332 #else 333 #define asm __asm__ 334 #endif 335 #endif 336 /* *INDENT-ON* */ 337 338 /* 339 * Define the constraint used for read-only pointer operands to aarch64 asm. 340 * 341 * This is normally the usual "r", but for aarch64_32 (aka ILP32, 342 * as found in watchos), "p" is required to avoid warnings from clang. 343 * 344 * Note that clang does not recognise '+p' or '=p', and armclang 345 * does not recognise 'p' at all. Therefore, to update a pointer from 346 * aarch64 assembly, it is necessary to use something like: 347 * 348 * uintptr_t uptr = (uintptr_t) ptr; 349 * asm( "ldr x4, [%x0], #8" ... : "+r" (uptr) : : ) 350 * ptr = (void*) uptr; 351 * 352 * Note that the "x" in "%x0" is neccessary; writing "%0" will cause warnings. 353 */ 354 #if defined(__aarch64__) && defined(MBEDTLS_HAVE_ASM) 355 #if UINTPTR_MAX == 0xfffffffful 356 /* ILP32: Specify the pointer operand slightly differently, as per #7787. */ 357 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "p" 358 #elif UINTPTR_MAX == 0xfffffffffffffffful 359 /* Normal case (64-bit pointers): use "r" as the constraint for pointer operands to asm */ 360 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "r" 361 #else 362 #error "Unrecognised pointer size for aarch64" 363 #endif 364 #endif 365 366 /* Always provide a static assert macro, so it can be used unconditionally. 367 * It does nothing on systems where we don't know how to define a static assert. 368 */ 369 /* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it 370 * defines static_assert even with -std=c99, but then complains about it. 371 */ 372 #if defined(static_assert) && !defined(__FreeBSD__) 373 #define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg) 374 #else 375 /* Make sure `MBEDTLS_STATIC_ASSERT(expr, msg);` is valid both inside and 376 * outside a function. We choose a struct declaration, which can be repeated 377 * any number of times and does not need a matching definition. */ 378 #define MBEDTLS_STATIC_ASSERT(expr, msg) \ 379 struct ISO_C_does_not_allow_extra_semicolon_outside_of_a_function 380 #endif 381 382 #if defined(__has_builtin) 383 #define MBEDTLS_HAS_BUILTIN(x) __has_builtin(x) 384 #else 385 #define MBEDTLS_HAS_BUILTIN(x) 0 386 #endif 387 388 /* Define compiler branch hints */ 389 #if MBEDTLS_HAS_BUILTIN(__builtin_expect) 390 #define MBEDTLS_LIKELY(x) __builtin_expect(!!(x), 1) 391 #define MBEDTLS_UNLIKELY(x) __builtin_expect(!!(x), 0) 392 #else 393 #define MBEDTLS_LIKELY(x) x 394 #define MBEDTLS_UNLIKELY(x) x 395 #endif 396 397 /* MBEDTLS_ASSUME may be used to provide additional information to the compiler 398 * which can result in smaller code-size. */ 399 #if MBEDTLS_HAS_BUILTIN(__builtin_assume) 400 /* clang provides __builtin_assume */ 401 #define MBEDTLS_ASSUME(x) __builtin_assume(x) 402 #elif MBEDTLS_HAS_BUILTIN(__builtin_unreachable) 403 /* gcc and IAR can use __builtin_unreachable */ 404 #define MBEDTLS_ASSUME(x) do { if (!(x)) __builtin_unreachable(); } while (0) 405 #elif defined(_MSC_VER) 406 /* Supported by MSVC since VS 2005 */ 407 #define MBEDTLS_ASSUME(x) __assume(x) 408 #else 409 #define MBEDTLS_ASSUME(x) do { } while (0) 410 #endif 411 412 /* For gcc -Os, override with -O2 for a given function. 413 * 414 * This will not affect behaviour for other optimisation settings, e.g. -O0. 415 */ 416 #if defined(MBEDTLS_COMPILER_IS_GCC) && defined(__OPTIMIZE_SIZE__) 417 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE __attribute__((optimize("-O2"))) 418 #else 419 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE 420 #endif 421 422 /* Suppress compiler warnings for unused functions and variables. */ 423 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__has_attribute) 424 # if __has_attribute(unused) 425 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused)) 426 # endif 427 #endif 428 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__GNUC__) 429 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused)) 430 #endif 431 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__IAR_SYSTEMS_ICC__) && defined(__VER__) 432 /* IAR does support __attribute__((unused)), but only if the -e flag (extended language support) 433 * is given; the pragma always works. 434 * Unfortunately the pragma affects the rest of the file where it is used, but this is harmless. 435 * Check for version 5.2 or later - this pragma may be supported by earlier versions, but I wasn't 436 * able to find documentation). 437 */ 438 # if (__VER__ >= 5020000) 439 # define MBEDTLS_MAYBE_UNUSED _Pragma("diag_suppress=Pe177") 440 # endif 441 #endif 442 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(_MSC_VER) 443 # define MBEDTLS_MAYBE_UNUSED __pragma(warning(suppress:4189)) 444 #endif 445 #if !defined(MBEDTLS_MAYBE_UNUSED) 446 # define MBEDTLS_MAYBE_UNUSED 447 #endif 448 449 #endif /* MBEDTLS_LIBRARY_COMMON_H */ 450