tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
LoongArch: Allow usage of LSX/LASX in the kernel
Allow usage of LSX/LASX in the kernel by extending kernel_fpu_begin()
and kernel_fpu_end().
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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arch/loongarch/kernel/kfpu.c
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arch/loongarch/kernel/kfpu.c
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#include <asm/fpu.h>
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#include <asm/smp.h>
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static unsigned int euen_mask = CSR_EUEN_FPEN;
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/*
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* The critical section between kernel_fpu_begin() and kernel_fpu_end()
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* is non-reentrant. It is the caller's responsibility to avoid reentrance.
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* See drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c as an example.
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*/
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static DEFINE_PER_CPU(bool, in_kernel_fpu);
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static DEFINE_PER_CPU(unsigned int, euen_current);
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void kernel_fpu_begin(void)
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{
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unsigned int *euen_curr;
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preempt_disable();
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WARN_ON(this_cpu_read(in_kernel_fpu));
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this_cpu_write(in_kernel_fpu, true);
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euen_curr = this_cpu_ptr(&euen_current);
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if (!is_fpu_owner())
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enable_fpu();
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*euen_curr = csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN);
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#ifdef CONFIG_CPU_HAS_LASX
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if (*euen_curr & CSR_EUEN_LASXEN)
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_save_lasx(¤t->thread.fpu);
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else
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#endif
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#ifdef CONFIG_CPU_HAS_LSX
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if (*euen_curr & CSR_EUEN_LSXEN)
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_save_lsx(¤t->thread.fpu);
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else
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#endif
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if (*euen_curr & CSR_EUEN_FPEN)
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_save_fp(¤t->thread.fpu);
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write_fcsr(LOONGARCH_FCSR0, 0);
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void kernel_fpu_end(void)
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{
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unsigned int *euen_curr;
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WARN_ON(!this_cpu_read(in_kernel_fpu));
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if (!is_fpu_owner())
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disable_fpu();
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euen_curr = this_cpu_ptr(&euen_current);
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#ifdef CONFIG_CPU_HAS_LASX
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if (*euen_curr & CSR_EUEN_LASXEN)
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_restore_lasx(¤t->thread.fpu);
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else
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#endif
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#ifdef CONFIG_CPU_HAS_LSX
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if (*euen_curr & CSR_EUEN_LSXEN)
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_restore_lsx(¤t->thread.fpu);
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else
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#endif
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if (*euen_curr & CSR_EUEN_FPEN)
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_restore_fp(¤t->thread.fpu);
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*euen_curr = csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN);
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this_cpu_write(in_kernel_fpu, false);
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preempt_enable();
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}
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EXPORT_SYMBOL_GPL(kernel_fpu_end);
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static int __init init_euen_mask(void)
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{
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if (cpu_has_lsx)
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euen_mask |= CSR_EUEN_LSXEN;
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if (cpu_has_lasx)
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euen_mask |= CSR_EUEN_LASXEN;
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return 0;
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}
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arch_initcall(init_euen_mask);