crypto/fipsmodule/ml_kem/mlkem/sys.h

/*
 * Copyright (c) 2024-2025 The mlkem-native project authors
 * SPDX-License-Identifier: Apache-2.0
 */
#ifndef MLK_SYS_H
#define MLK_SYS_H

/* Check if we're running on an AArch64 little endian system. _M_ARM64 is set by
 * MSVC. */
#if defined(__AARCH64EL__) || defined(_M_ARM64)
#define MLK_SYS_AARCH64
#endif

/* Check if we're running on an AArch64 big endian system. */
#if defined(__AARCH64EB__)
#define MLK_SYS_AARCH64_EB
#endif

#if defined(__x86_64__)
#define MLK_SYS_X86_64
#if defined(__AVX2__)
#define MLK_SYS_X86_64_AVX2
#endif
#endif /* __x86_64__ */

#if defined(_WIN32)
#define MLK_SYS_WINDOWS
#endif

#if !defined(MLK_CONFIG_NO_ASM) && (defined(__GNUC__) || defined(__clang__))
#define MLK_HAVE_INLINE_ASM
#endif

/* Try to find endianness, if not forced through CFLAGS already */
#if !defined(MLK_SYS_LITTLE_ENDIAN) && !defined(MLK_SYS_BIG_ENDIAN)
#if defined(__BYTE_ORDER__)
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define MLK_SYS_LITTLE_ENDIAN
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define MLK_SYS_BIG_ENDIAN
#else
#error "__BYTE_ORDER__ defined, but don't recognize value."
#endif
#endif /* __BYTE_ORDER__ */
#endif /* !MLK_SYS_LITTLE_ENDIAN && !MLK_SYS_BIG_ENDIAN */

/* If MLK_FORCE_AARCH64 is set, assert that we're indeed on an AArch64 system.
 */
#if defined(MLK_FORCE_AARCH64) && !defined(MLK_SYS_AARCH64)
#error "MLK_FORCE_AARCH64 is set, but we don't seem to be on an AArch64 system."
#endif

/* If MLK_FORCE_AARCH64_EB is set, assert that we're indeed on a big endian
 * AArch64 system. */
#if defined(MLK_FORCE_AARCH64_EB) && !defined(MLK_SYS_AARCH64_EB)
#error \
    "MLK_FORCE_AARCH64_EB is set, but we don't seem to be on an AArch64 system."
#endif

/* If MLK_FORCE_X86_64 is set, assert that we're indeed on an X86_64 system. */
#if defined(MLK_FORCE_X86_64) && !defined(MLK_SYS_X86_64)
#error "MLK_FORCE_X86_64 is set, but we don't seem to be on an X86_64 system."
#endif

/*
 * C90 does not have the inline compiler directive yet.
 * We don't use it in C90 builds.
 * However, in that case the compiler warns about some inline functions in
 * header files not being used in every compilation unit that includes that
 * header. To work around it we silence that warning in that case using
 * __attribute__((unused)).
 */

/* Do not use inline for C90 builds*/
#if !defined(MLK_INLINE)
#if !defined(inline)
#if defined(_MSC_VER)
#define MLK_INLINE __inline
/* Don't combine __inline and __forceinline */
#define MLK_ALWAYS_INLINE __forceinline
#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
#define MLK_INLINE inline
#define MLK_ALWAYS_INLINE MLK_INLINE __attribute__((always_inline))
#else
#define MLK_INLINE __attribute__((unused))
#define MLK_ALWAYS_INLINE MLK_INLINE
#endif

#else /* !inline */
#define MLK_INLINE inline
#define MLK_ALWAYS_INLINE MLK_INLINE __attribute__((always_inline))
#endif /* inline */
#endif /* !MLK_INLINE */

/*
 * C90 does not have the restrict compiler directive yet.
 * We don't use it in C90 builds.
 */
#if !defined(restrict)
#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
#define MLK_RESTRICT restrict
#else
#define MLK_RESTRICT
#endif

#else /* !restrict */

#define MLK_RESTRICT restrict
#endif /* restrict */

#define MLK_DEFAULT_ALIGN 32
#define MLK_ALIGN_UP(N) \
  ((((N) + (MLK_DEFAULT_ALIGN - 1)) / MLK_DEFAULT_ALIGN) * MLK_DEFAULT_ALIGN)
#if defined(__GNUC__)
#define MLK_ALIGN __attribute__((aligned(MLK_DEFAULT_ALIGN)))
#elif defined(_MSC_VER)
#define MLK_ALIGN __declspec(align(MLK_DEFAULT_ALIGN))
#else
#define MLK_ALIGN /* No known support for alignment constraints */
#endif


/* New X86_64 CPUs support Conflow-flow protection using the CET instructions.
 * When enabled (through -fcf-protection=), all compilation units (including
 * empty ones) need to support CET for this to work.
 * For assembly, this means that source files need to signal support for
 * CET by setting the appropriate note.gnu.property section.
 * This can be achieved by including the <cet.h> header in all assembly file.
 * This file also provides the _CET_ENDBR macro which needs to be placed at
 * every potential target of an indirect branch.
 * If CET is enabled _CET_ENDBR maps to the endbr64 instruction, otherwise
 * it is empty.
 * In case the compiler does not support CET (e.g., <gcc8, <clang11),
 * the __CET__ macro is not set and we default to nothing.
 * Note that we only issue _CET_ENDBR instructions through the MLK_ASM_FN_SYMBOL
 * macro as the global symbols are the only possible targets of indirect
 * branches in our code.
 */
#if defined(MLK_SYS_X86_64)
#if defined(__CET__)
#include <cet.h>
#define MLK_CET_ENDBR _CET_ENDBR
#else
#define MLK_CET_ENDBR
#endif
#endif /* MLK_SYS_X86_64 */

#if defined(MLK_CONFIG_CT_TESTING_ENABLED) && !defined(__ASSEMBLER__)
#include <valgrind/memcheck.h>
#define MLK_CT_TESTING_SECRET(ptr, len) \
  VALGRIND_MAKE_MEM_UNDEFINED((ptr), (len))
#define MLK_CT_TESTING_DECLASSIFY(ptr, len) \
  VALGRIND_MAKE_MEM_DEFINED((ptr), (len))
#else /* MLK_CONFIG_CT_TESTING_ENABLED && !__ASSEMBLER__ */
#define MLK_CT_TESTING_SECRET(ptr, len) \
  do                                    \
  {                                     \
  } while (0)
#define MLK_CT_TESTING_DECLASSIFY(ptr, len) \
  do                                        \
  {                                         \
  } while (0)
#endif /* !(MLK_CONFIG_CT_TESTING_ENABLED && !__ASSEMBLER__) */

#if defined(__GNUC__) || defined(clang)
#define MLK_MUST_CHECK_RETURN_VALUE __attribute__((warn_unused_result))
#else
#define MLK_MUST_CHECK_RETURN_VALUE
#endif

#endif /* !MLK_SYS_H */