1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * linux/arch/arm/include/asm/neon.h
4  *
5  * Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
6  */
7 
8 #include <asm/hwcap.h>
9 
10 #define cpu_has_neon()		(!!(elf_hwcap & HWCAP_NEON))
11 
12 #ifdef __ARM_NEON__
13 
14 /*
15  * If you are affected by the BUILD_BUG below, it probably means that you are
16  * using NEON code /and/ calling the kernel_neon_begin() function from the same
17  * compilation unit. To prevent issues that may arise from GCC reordering or
18  * generating(1) NEON instructions outside of these begin/end functions, the
19  * only supported way of using NEON code in the kernel is by isolating it in a
20  * separate compilation unit, and calling it from another unit from inside a
21  * kernel_neon_begin/kernel_neon_end pair.
22  *
23  * (1) Current GCC (4.7) might generate NEON instructions at O3 level if
24  *     -mpfu=neon is set.
25  */
26 
27 #define kernel_neon_begin() \
28 	BUILD_BUG_ON_MSG(1, "kernel_neon_begin() called from NEON code")
29 
30 #else
31 void kernel_neon_begin(void);
32 #endif
33 void kernel_neon_end(void);
34