/* * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published * by the Free Software Foundation. */ #ifndef __ASM_SIMD_H #define __ASM_SIMD_H #include <linux/compiler.h> #include <linux/irqflags.h> #include <linux/percpu.h> #include <linux/preempt.h> #include <linux/types.h> #ifdef CONFIG_KERNEL_MODE_NEON DECLARE_PER_CPU(bool, kernel_neon_busy); /* * may_use_simd - whether it is allowable at this time to issue SIMD * instructions or access the SIMD register file * * Callers must not assume that the result remains true beyond the next * preempt_enable() or return from softirq context. */
static __must_check inline bool may_use_simd(void) { /* * The raw_cpu_read() is racy if called with preemption enabled. * This is not a bug: kernel_neon_busy is only set when * preemption is disabled, so we cannot migrate to another CPU * while it is set, nor can we migrate to a CPU where it is set. * So, if we find it clear on some CPU then we're guaranteed to * find it clear on any CPU we could migrate to. * * If we are in between kernel_neon_begin()...kernel_neon_end(), * the flag will be set, but preemption is also disabled, so we * can't migrate to another CPU and spuriously see it become * false. */ return !in_irq() && !irqs_disabled() && !in_nmi() && !raw_cpu_read(kernel_neon_busy); }Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Dave P Martin | 30 | 100.00% | 2 | 100.00% |
| Total | 30 | 100.00% | 2 | 100.00% |
| Person | Tokens | Prop | Commits | CommitProp |
| Ard Biesheuvel | 12 | 92.31% | 1 | 50.00% |
| Dave P Martin | 1 | 7.69% | 1 | 50.00% |
| Total | 13 | 100.00% | 2 | 100.00% |
| Person | Tokens | Prop | Commits | CommitProp |
| Dave P Martin | 60 | 71.43% | 2 | 66.67% |
| Ard Biesheuvel | 24 | 28.57% | 1 | 33.33% |
| Total | 84 | 100.00% | 3 | 100.00% |