| 1 | // SPDX-License-Identifier: GPL-2.0-only |
|---|---|
| 2 | /* |
| 3 | * Copyright (C) 2023 Loongson Technology Corporation Limited |
| 4 | */ |
| 5 | |
| 6 | #include <linux/cpu.h> |
| 7 | #include <linux/init.h> |
| 8 | #include <asm/fpu.h> |
| 9 | #include <asm/smp.h> |
| 10 | |
| 11 | static unsigned int euen_mask = CSR_EUEN_FPEN; |
| 12 | |
| 13 | /* |
| 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. |
| 17 | */ |
| 18 | static DEFINE_PER_CPU(bool, in_kernel_fpu); |
| 19 | static DEFINE_PER_CPU(unsigned int, euen_current); |
| 20 | |
| 21 | void kernel_fpu_begin(void) |
| 22 | { |
| 23 | unsigned int *euen_curr; |
| 24 | |
| 25 | preempt_disable(); |
| 26 | |
| 27 | WARN_ON(this_cpu_read(in_kernel_fpu)); |
| 28 | |
| 29 | this_cpu_write(in_kernel_fpu, true); |
| 30 | euen_curr = this_cpu_ptr(&euen_current); |
| 31 | |
| 32 | *euen_curr = csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN); |
| 33 | |
| 34 | #ifdef CONFIG_CPU_HAS_LASX |
| 35 | if (*euen_curr & CSR_EUEN_LASXEN) |
| 36 | _save_lasx(¤t->thread.fpu); |
| 37 | else |
| 38 | #endif |
| 39 | #ifdef CONFIG_CPU_HAS_LSX |
| 40 | if (*euen_curr & CSR_EUEN_LSXEN) |
| 41 | _save_lsx(¤t->thread.fpu); |
| 42 | else |
| 43 | #endif |
| 44 | if (*euen_curr & CSR_EUEN_FPEN) |
| 45 | _save_fp(¤t->thread.fpu); |
| 46 | |
| 47 | write_fcsr(LOONGARCH_FCSR0, 0); |
| 48 | } |
| 49 | EXPORT_SYMBOL_GPL(kernel_fpu_begin); |
| 50 | |
| 51 | void kernel_fpu_end(void) |
| 52 | { |
| 53 | unsigned int *euen_curr; |
| 54 | |
| 55 | WARN_ON(!this_cpu_read(in_kernel_fpu)); |
| 56 | |
| 57 | euen_curr = this_cpu_ptr(&euen_current); |
| 58 | |
| 59 | #ifdef CONFIG_CPU_HAS_LASX |
| 60 | if (*euen_curr & CSR_EUEN_LASXEN) |
| 61 | _restore_lasx(¤t->thread.fpu); |
| 62 | else |
| 63 | #endif |
| 64 | #ifdef CONFIG_CPU_HAS_LSX |
| 65 | if (*euen_curr & CSR_EUEN_LSXEN) |
| 66 | _restore_lsx(¤t->thread.fpu); |
| 67 | else |
| 68 | #endif |
| 69 | if (*euen_curr & CSR_EUEN_FPEN) |
| 70 | _restore_fp(¤t->thread.fpu); |
| 71 | |
| 72 | *euen_curr = csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN); |
| 73 | |
| 74 | this_cpu_write(in_kernel_fpu, false); |
| 75 | |
| 76 | preempt_enable(); |
| 77 | } |
| 78 | EXPORT_SYMBOL_GPL(kernel_fpu_end); |
| 79 | |
| 80 | static int __init init_euen_mask(void) |
| 81 | { |
| 82 | if (cpu_has_lsx) |
| 83 | euen_mask |= CSR_EUEN_LSXEN; |
| 84 | |
| 85 | if (cpu_has_lasx) |
| 86 | euen_mask |= CSR_EUEN_LASXEN; |
| 87 | |
| 88 | return 0; |
| 89 | } |
| 90 | arch_initcall(init_euen_mask); |
| 91 |