platform_bionic/libc/arch-riscv64/dynamic_function_dispatch.cpp

/*
 * Copyright (C) 2023 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <fcntl.h>
#include <stddef.h>
#include <sys/syscall.h>
#include <unistd.h>

#include <private/bionic_ifuncs.h>

extern "C" {

static __always_inline int ifunc_faccessat(int dir_fd, const char* path, int mode) {
  register long a0 __asm__("a0") = dir_fd;
  register long a1 __asm__("a1") = reinterpret_cast<long>(path);
  register long a2 __asm__("a2") = mode;
  register long a7 __asm__("a7") = __NR_faccessat;
  __asm__("ecall" : "=r"(a0) : "r"(a0), "r"(a1), "r"(a2), "r"(a7) : "memory");
  return a0;
}

static bool have_fast_v() {
  static bool result = []() {
    // We don't want to do a full "bogomips" test, so just check for the
    // presence of a file that would indicate that we're running in qemu.
    return ifunc_faccessat(AT_FDCWD, "/dev/hvc0", F_OK) != 0;
  }();
  return result;
}

typedef void* memchr_func(const void*, int, size_t);
DEFINE_IFUNC_FOR(memchr) {
  if (have_fast_v()) RETURN_FUNC(memchr_func, memchr_v);
  RETURN_FUNC(memchr_func, memchr_gc);
}

typedef int memcmp_func(const void*, const void*, size_t);
DEFINE_IFUNC_FOR(memcmp) {
  if (have_fast_v()) RETURN_FUNC(memcmp_func, memcmp_v);
  RETURN_FUNC(memcmp_func, memcmp_gc);
}

typedef void* memcpy_func(void*, const void*, size_t);
DEFINE_IFUNC_FOR(memcpy) {
  if (have_fast_v()) RETURN_FUNC(memcpy_func, memcpy_v);
  RETURN_FUNC(memcpy_func, memcpy_gc);
}

typedef void* memmove_func(void*, const void*, size_t);
DEFINE_IFUNC_FOR(memmove) {
  if (have_fast_v()) RETURN_FUNC(memmove_func, memmove_v);
  RETURN_FUNC(memmove_func, memmove_gc);
}

typedef void* memset_func(void*, int, size_t);
DEFINE_IFUNC_FOR(memset) {
  if (have_fast_v()) RETURN_FUNC(memset_func, memset_v);
  RETURN_FUNC(memset_func, memset_gc);
}

typedef char* stpcpy_func(char*, const char*);
DEFINE_IFUNC_FOR(stpcpy) {
  if (have_fast_v()) RETURN_FUNC(stpcpy_func, stpcpy_v);
  RETURN_FUNC(stpcpy_func, stpcpy_gc);
}

typedef char* strcat_func(char*, const char*);
DEFINE_IFUNC_FOR(strcat) {
  if (have_fast_v()) RETURN_FUNC(strcat_func, strcat_v);
  RETURN_FUNC(strcat_func, strcat_gc);
}

typedef char* strchr_func(const char*, int);
DEFINE_IFUNC_FOR(strchr) {
  if (have_fast_v()) RETURN_FUNC(strchr_func, strchr_v);
  RETURN_FUNC(strchr_func, strchr_gc);
}

typedef int strcmp_func(const char*, const char*);
DEFINE_IFUNC_FOR(strcmp) {
  if (have_fast_v()) RETURN_FUNC(strcmp_func, strcmp_v);
  RETURN_FUNC(strcmp_func, strcmp_gc);
}

typedef char* strcpy_func(char*, const char*);
DEFINE_IFUNC_FOR(strcpy) {
  if (have_fast_v()) RETURN_FUNC(strcpy_func, strcpy_v);
  RETURN_FUNC(strcpy_func, strcpy_gc);
}

typedef size_t strlen_func(const char*);
DEFINE_IFUNC_FOR(strlen) {
  if (have_fast_v()) RETURN_FUNC(strlen_func, strlen_v);
  RETURN_FUNC(strlen_func, strlen_gc);
}

typedef char* strncat_func(char*, const char*, size_t);
DEFINE_IFUNC_FOR(strncat) {
  if (have_fast_v()) RETURN_FUNC(strncat_func, strncat_v);
  RETURN_FUNC(strncat_func, strncat_gc);
}

typedef int strncmp_func(const char*, const char*, size_t);
DEFINE_IFUNC_FOR(strncmp) {
  if (have_fast_v()) RETURN_FUNC(strncmp_func, strncmp_v);
  RETURN_FUNC(strncmp_func, strncmp_gc);
}

typedef char* strncpy_func(char*, const char*, size_t);
DEFINE_IFUNC_FOR(strncpy) {
  if (have_fast_v()) RETURN_FUNC(strncpy_func, strncpy_v);
  RETURN_FUNC(strncpy_func, strncpy_gc);
}

typedef size_t strnlen_func(const char*, size_t);
DEFINE_IFUNC_FOR(strnlen) {
  if (have_fast_v()) RETURN_FUNC(strnlen_func, strnlen_v);
  RETURN_FUNC(strnlen_func, strnlen_gc);
}

}  // extern "C"