LXR linux/arch/arm/include/asm/neon.h

   1/*
   2 * linux/arch/arm/include/asm/neon.h
   3 *
   4 * Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 */
  10
  11#include <asm/hwcap.h>
  12
  13#define cpu_has_neon()          (!!(elf_hwcap & HWCAP_NEON))
  14
  15#ifdef __ARM_NEON__
  16
  17/*
  18 * If you are affected by the BUILD_BUG below, it probably means that you are
  19 * using NEON code /and/ calling the kernel_neon_begin() function from the same
  20 * compilation unit. To prevent issues that may arise from GCC reordering or
  21 * generating(1) NEON instructions outside of these begin/end functions, the
  22 * only supported way of using NEON code in the kernel is by isolating it in a
  23 * separate compilation unit, and calling it from another unit from inside a
  24 * kernel_neon_begin/kernel_neon_end pair.
  25 *
  26 * (1) Current GCC (4.7) might generate NEON instructions at O3 level if
  27 *     -mpfu=neon is set.
  28 */
  29
  30#define kernel_neon_begin() \
  31        BUILD_BUG_ON_MSG(1, "kernel_neon_begin() called from NEON code")
  32
  33#else
  34void kernel_neon_begin(void);
  35#endif
  36void kernel_neon_end(void);
  37