1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2023 Loongson Technology Corporation Limited
7 #include <linux/init.h>
11 static unsigned int euen_mask = CSR_EUEN_FPEN;
14 * The critical section between kernel_fpu_begin() and kernel_fpu_end()
15 * is non-reentrant. It is the caller's responsibility to avoid reentrance.
16 * See drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c as an example.
18 static DEFINE_PER_CPU(bool, in_kernel_fpu);
19 static DEFINE_PER_CPU(unsigned int, euen_current);
21 void kernel_fpu_begin(void)
23 unsigned int *euen_curr;
27 WARN_ON(this_cpu_read(in_kernel_fpu));
29 this_cpu_write(in_kernel_fpu, true);
30 euen_curr = this_cpu_ptr(&euen_current);
32 *euen_curr = csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN);
34 #ifdef CONFIG_CPU_HAS_LASX
35 if (*euen_curr & CSR_EUEN_LASXEN)
36 _save_lasx(¤t->thread.fpu);
39 #ifdef CONFIG_CPU_HAS_LSX
40 if (*euen_curr & CSR_EUEN_LSXEN)
41 _save_lsx(¤t->thread.fpu);
44 if (*euen_curr & CSR_EUEN_FPEN)
45 _save_fp(¤t->thread.fpu);
47 write_fcsr(LOONGARCH_FCSR0, 0);
49 EXPORT_SYMBOL_GPL(kernel_fpu_begin);
51 void kernel_fpu_end(void)
53 unsigned int *euen_curr;
55 WARN_ON(!this_cpu_read(in_kernel_fpu));
57 euen_curr = this_cpu_ptr(&euen_current);
59 #ifdef CONFIG_CPU_HAS_LASX
60 if (*euen_curr & CSR_EUEN_LASXEN)
61 _restore_lasx(¤t->thread.fpu);
64 #ifdef CONFIG_CPU_HAS_LSX
65 if (*euen_curr & CSR_EUEN_LSXEN)
66 _restore_lsx(¤t->thread.fpu);
69 if (*euen_curr & CSR_EUEN_FPEN)
70 _restore_fp(¤t->thread.fpu);
72 *euen_curr = csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN);
74 this_cpu_write(in_kernel_fpu, false);
78 EXPORT_SYMBOL_GPL(kernel_fpu_end);
80 static int __init init_euen_mask(void)
83 euen_mask |= CSR_EUEN_LSXEN;
86 euen_mask |= CSR_EUEN_LASXEN;
90 arch_initcall(init_euen_mask);