common.h

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/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */
 
#ifndef MBEDTLS_LIBRARY_COMMON_H
#define MBEDTLS_LIBRARY_COMMON_H
 
#include "mbedtls/build_info.h"
#include "alignment.h"
 
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <stddef.h>
 
#if defined(__ARM_NEON)
#include <arm_neon.h>
#define MBEDTLS_HAVE_NEON_INTRINSICS
#elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
#include <arm64_neon.h>
#define MBEDTLS_HAVE_NEON_INTRINSICS
#endif
 
#if defined(MBEDTLS_TEST_HOOKS)
#define MBEDTLS_STATIC_TESTABLE
#else
#define MBEDTLS_STATIC_TESTABLE static
#endif
 
#if defined(MBEDTLS_TEST_HOOKS)
extern void (*mbedtls_test_hook_test_fail)(const char *test, int line, const char *file);
#define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) \
    do { \
        if ((!(TEST)) && ((*mbedtls_test_hook_test_fail) != NULL)) \
        { \
            (*mbedtls_test_hook_test_fail)( #TEST, __LINE__, __FILE__); \
        } \
    } while (0)
#else
#define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST)
#endif /* defined(MBEDTLS_TEST_HOOKS) */
 
/* A correct implementation of ARRAY_LENGTH, but which silently gives
 * a nonsensical result if called with a pointer rather than an array. */
#define ARRAY_LENGTH_UNSAFE(array)            \
    (sizeof(array) / sizeof(*(array)))
 
#if defined(__GNUC__)
/* Test if arg and &(arg)[0] have the same type. This is true if arg is
 * an array but not if it's a pointer. */
#define IS_ARRAY_NOT_POINTER(arg)                                     \
    (!__builtin_types_compatible_p(__typeof__(arg),                \
                                   __typeof__(&(arg)[0])))
/* A compile-time constant with the value 0. If `const_expr` is not a
 * compile-time constant with a nonzero value, cause a compile-time error. */
#define STATIC_ASSERT_EXPR(const_expr)                                \
    (0 && sizeof(struct { unsigned int STATIC_ASSERT : 1 - 2 * !(const_expr); }))
 
/* Return the scalar value `value` (possibly promoted). This is a compile-time
 * constant if `value` is. `condition` must be a compile-time constant.
 * If `condition` is false, arrange to cause a compile-time error. */
#define STATIC_ASSERT_THEN_RETURN(condition, value)   \
    (STATIC_ASSERT_EXPR(condition) ? 0 : (value))
 
#define ARRAY_LENGTH(array)                                           \
    (STATIC_ASSERT_THEN_RETURN(IS_ARRAY_NOT_POINTER(array),         \
                               ARRAY_LENGTH_UNSAFE(array)))
 
#else
/* If we aren't sure the compiler supports our non-standard tricks,
 * fall back to the unsafe implementation. */
#define ARRAY_LENGTH(array) ARRAY_LENGTH_UNSAFE(array)
#endif
#define MBEDTLS_ALLOW_PRIVATE_ACCESS
 
void mbedtls_zeroize_and_free(void *buf, size_t len);
 
static inline unsigned char *mbedtls_buffer_offset(
    unsigned char *p, size_t n)
{
    return p == NULL ? NULL : p + n;
}
 
static inline const unsigned char *mbedtls_buffer_offset_const(
    const unsigned char *p, size_t n)
{
    return p == NULL ? NULL : p + n;
}
 
/* Always inline mbedtls_xor() for similar reasons as mbedtls_xor_no_simd(). */
#if defined(__IAR_SYSTEMS_ICC__)
#pragma inline = forced
#elif defined(__GNUC__)
__attribute__((always_inline))
#endif
static inline void mbedtls_xor(unsigned char *r,
                               const unsigned char *a,
                               const unsigned char *b,
                               size_t n)
{
    size_t i = 0;
#if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
#if defined(MBEDTLS_HAVE_NEON_INTRINSICS) && \
    (!(defined(MBEDTLS_COMPILER_IS_GCC) && MBEDTLS_GCC_VERSION < 70300))
    /* Old GCC versions generate a warning here, so disable the NEON path for these compilers */
    for (; (i + 16) <= n; i += 16) {
        uint8x16_t v1 = vld1q_u8(a + i);
        uint8x16_t v2 = vld1q_u8(b + i);
        uint8x16_t x = veorq_u8(v1, v2);
        vst1q_u8(r + i, x);
    }
#if defined(__IAR_SYSTEMS_ICC__)
    /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case
     * where n is a constant multiple of 16.
     * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time
     * constant, and is a very small perf regression if n is not a compile-time constant. */
    if (n % 16 == 0) {
        return;
    }
#endif
#elif defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
    /* This codepath probably only makes sense on architectures with 64-bit registers */
    for (; (i + 8) <= n; i += 8) {
        uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
        mbedtls_put_unaligned_uint64(r + i, x);
    }
#if defined(__IAR_SYSTEMS_ICC__)
    if (n % 8 == 0) {
        return;
    }
#endif
#else
    for (; (i + 4) <= n; i += 4) {
        uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
        mbedtls_put_unaligned_uint32(r + i, x);
    }
#if defined(__IAR_SYSTEMS_ICC__)
    if (n % 4 == 0) {
        return;
    }
#endif
#endif
#endif
    for (; i < n; i++) {
        r[i] = a[i] ^ b[i];
    }
}
 
/* Always inline mbedtls_xor_no_simd() as we see significant perf regressions when it does not get
 * inlined (e.g., observed about 3x perf difference in gcm_mult_largetable with gcc 7 - 12) */
#if defined(__IAR_SYSTEMS_ICC__)
#pragma inline = forced
#elif defined(__GNUC__)
__attribute__((always_inline))
#endif
static inline void mbedtls_xor_no_simd(unsigned char *r,
                                       const unsigned char *a,
                                       const unsigned char *b,
                                       size_t n)
{
    size_t i = 0;
#if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
#if defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
    /* This codepath probably only makes sense on architectures with 64-bit registers */
    for (; (i + 8) <= n; i += 8) {
        uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
        mbedtls_put_unaligned_uint64(r + i, x);
    }
#if defined(__IAR_SYSTEMS_ICC__)
    /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case
     * where n is a constant multiple of 8.
     * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time
     * constant, and is a very small perf regression if n is not a compile-time constant. */
    if (n % 8 == 0) {
        return;
    }
#endif
#else
    for (; (i + 4) <= n; i += 4) {
        uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
        mbedtls_put_unaligned_uint32(r + i, x);
    }
#if defined(__IAR_SYSTEMS_ICC__)
    if (n % 4 == 0) {
        return;
    }
#endif
#endif
#endif
    for (; i < n; i++) {
        r[i] = a[i] ^ b[i];
    }
}
 
/* Fix MSVC C99 compatible issue
 *      MSVC support __func__ from visual studio 2015( 1900 )
 *      Use MSVC predefine macro to avoid name check fail.
 */
#if (defined(_MSC_VER) && (_MSC_VER <= 1900))
#define /*no-check-names*/ __func__ __FUNCTION__
#endif
 
/* Define `asm` for compilers which don't define it. */
/* *INDENT-OFF* */
#ifndef asm
#if defined(__IAR_SYSTEMS_ICC__)
#define asm __asm
#else
#define asm __asm__
#endif
#endif
/* *INDENT-ON* */
 
/*
 * Define the constraint used for read-only pointer operands to aarch64 asm.
 *
 * This is normally the usual "r", but for aarch64_32 (aka ILP32,
 * as found in watchos), "p" is required to avoid warnings from clang.
 *
 * Note that clang does not recognise '+p' or '=p', and armclang
 * does not recognise 'p' at all. Therefore, to update a pointer from
 * aarch64 assembly, it is necessary to use something like:
 *
 * uintptr_t uptr = (uintptr_t) ptr;
 * asm( "ldr x4, [%x0], #8" ... : "+r" (uptr) : : )
 * ptr = (void*) uptr;
 *
 * Note that the "x" in "%x0" is neccessary; writing "%0" will cause warnings.
 */
#if defined(__aarch64__) && defined(MBEDTLS_HAVE_ASM)
#if UINTPTR_MAX == 0xfffffffful
/* ILP32: Specify the pointer operand slightly differently, as per #7787. */
#define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "p"
#elif UINTPTR_MAX == 0xfffffffffffffffful
/* Normal case (64-bit pointers): use "r" as the constraint for pointer operands to asm */
#define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "r"
#else
#error "Unrecognised pointer size for aarch64"
#endif
#endif
 
/* Always provide a static assert macro, so it can be used unconditionally.
 * It does nothing on systems where we don't know how to define a static assert.
 */
/* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it
 * defines static_assert even with -std=c99, but then complains about it.
 */
#if defined(static_assert) && !defined(__FreeBSD__)
#define MBEDTLS_STATIC_ASSERT(expr, msg)    static_assert(expr, msg)
#else
/* Make sure `MBEDTLS_STATIC_ASSERT(expr, msg);` is valid both inside and
 * outside a function. We choose a struct declaration, which can be repeated
 * any number of times and does not need a matching definition. */
#define MBEDTLS_STATIC_ASSERT(expr, msg)                                \
    struct ISO_C_does_not_allow_extra_semicolon_outside_of_a_function
#endif
 
#if defined(__has_builtin)
#define MBEDTLS_HAS_BUILTIN(x) __has_builtin(x)
#else
#define MBEDTLS_HAS_BUILTIN(x) 0
#endif
 
/* Define compiler branch hints */
#if MBEDTLS_HAS_BUILTIN(__builtin_expect)
#define MBEDTLS_LIKELY(x)       __builtin_expect(!!(x), 1)
#define MBEDTLS_UNLIKELY(x)     __builtin_expect(!!(x), 0)
#else
#define MBEDTLS_LIKELY(x)       x
#define MBEDTLS_UNLIKELY(x)     x
#endif
 
/* MBEDTLS_ASSUME may be used to provide additional information to the compiler
 * which can result in smaller code-size. */
#if MBEDTLS_HAS_BUILTIN(__builtin_assume)
/* clang provides __builtin_assume */
#define MBEDTLS_ASSUME(x)       __builtin_assume(x)
#elif MBEDTLS_HAS_BUILTIN(__builtin_unreachable)
/* gcc and IAR can use __builtin_unreachable */
#define MBEDTLS_ASSUME(x)       do { if (!(x)) __builtin_unreachable(); } while (0)
#elif defined(_MSC_VER)
/* Supported by MSVC since VS 2005 */
#define MBEDTLS_ASSUME(x)       __assume(x)
#else
#define MBEDTLS_ASSUME(x)       do { } while (0)
#endif
 
/* For gcc -Os, override with -O2 for a given function.
 *
 * This will not affect behaviour for other optimisation settings, e.g. -O0.
 */
#if defined(MBEDTLS_COMPILER_IS_GCC) && defined(__OPTIMIZE_SIZE__)
#define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE __attribute__((optimize("-O2")))
#else
#define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE
#endif
 
/* Suppress compiler warnings for unused functions and variables. */
#if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__has_attribute)
#    if __has_attribute(unused)
#        define MBEDTLS_MAYBE_UNUSED __attribute__((unused))
#    endif
#endif
#if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__GNUC__)
#    define MBEDTLS_MAYBE_UNUSED __attribute__((unused))
#endif
#if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__IAR_SYSTEMS_ICC__) && defined(__VER__)
/* IAR does support __attribute__((unused)), but only if the -e flag (extended language support)
 * is given; the pragma always works.
 * Unfortunately the pragma affects the rest of the file where it is used, but this is harmless.
 * Check for version 5.2 or later - this pragma may be supported by earlier versions, but I wasn't
 * able to find documentation).
 */
#    if (__VER__ >= 5020000)
#        define MBEDTLS_MAYBE_UNUSED _Pragma("diag_suppress=Pe177")
#    endif
#endif
#if !defined(MBEDTLS_MAYBE_UNUSED) && defined(_MSC_VER)
#    define MBEDTLS_MAYBE_UNUSED __pragma(warning(suppress:4189))
#endif
#if !defined(MBEDTLS_MAYBE_UNUSED)
#    define MBEDTLS_MAYBE_UNUSED
#endif
 
/* GCC >= 15 has a warning 'unterminated-string-initialization' which complains if you initialize
 * a string into an array without space for a terminating NULL character. In some places in the
 * codebase this behaviour is intended, so we add the macro MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
 * to suppress the warning in these places.
 */
#if defined(__has_attribute)
#if __has_attribute(nonstring)
#define MBEDTLS_HAS_ATTRIBUTE_NONSTRING
#endif /* __has_attribute(nonstring) */
#endif /* __has_attribute */
#if defined(MBEDTLS_HAS_ATTRIBUTE_NONSTRING)
#define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING __attribute__((nonstring))
#else
#define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
#endif /* MBEDTLS_HAS_ATTRIBUTE_NONSTRING */
 
#endif /* MBEDTLS_LIBRARY_COMMON_H */