Commit 2478e4b7 authored by Huacai Chen's avatar Huacai Chen
Browse files

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: default avatarWANG Xuerui <git@xen0n.name>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 8f58c571

arch/loongarch/kernel/kfpu.c

+51 −4
Original line number Diff line number Diff line
@@ -8,19 +8,40 @@ 
#include <asm/fpu.h>

#include <asm/smp.h>



static unsigned int euen_mask = CSR_EUEN_FPEN;



/*

 * The critical section between kernel_fpu_begin() and kernel_fpu_end()

 * is non-reentrant. It is the caller's responsibility to avoid reentrance.

 * See drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c as an example.

 */

static DEFINE_PER_CPU(bool, in_kernel_fpu);

static DEFINE_PER_CPU(unsigned int, euen_current);



void kernel_fpu_begin(void)

{

	unsigned int *euen_curr;



	preempt_disable();



	WARN_ON(this_cpu_read(in_kernel_fpu));



	this_cpu_write(in_kernel_fpu, true);

	euen_curr = this_cpu_ptr(&euen_current);



	if (!is_fpu_owner())

		enable_fpu();

	*euen_curr = csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN);



#ifdef CONFIG_CPU_HAS_LASX

	if (*euen_curr & CSR_EUEN_LASXEN)

		_save_lasx(&current->thread.fpu);

	else

#endif

#ifdef CONFIG_CPU_HAS_LSX

	if (*euen_curr & CSR_EUEN_LSXEN)

		_save_lsx(&current->thread.fpu);

	else

#endif

	if (*euen_curr & CSR_EUEN_FPEN)

		_save_fp(&current->thread.fpu);



	write_fcsr(LOONGARCH_FCSR0, 0);
@@ -29,15 +50,41 @@ EXPORT_SYMBOL_GPL(kernel_fpu_begin); 


void kernel_fpu_end(void)

{

	unsigned int *euen_curr;



	WARN_ON(!this_cpu_read(in_kernel_fpu));



	if (!is_fpu_owner())

		disable_fpu();

	euen_curr = this_cpu_ptr(&euen_current);



#ifdef CONFIG_CPU_HAS_LASX

	if (*euen_curr & CSR_EUEN_LASXEN)

		_restore_lasx(&current->thread.fpu);

	else

#endif

#ifdef CONFIG_CPU_HAS_LSX

	if (*euen_curr & CSR_EUEN_LSXEN)

		_restore_lsx(&current->thread.fpu);

	else

#endif

	if (*euen_curr & CSR_EUEN_FPEN)

		_restore_fp(&current->thread.fpu);



	*euen_curr = csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN);



	this_cpu_write(in_kernel_fpu, false);



	preempt_enable();

}

EXPORT_SYMBOL_GPL(kernel_fpu_end);



static int __init init_euen_mask(void)

{

	if (cpu_has_lsx)

		euen_mask |= CSR_EUEN_LSXEN;



	if (cpu_has_lasx)

		euen_mask |= CSR_EUEN_LASXEN;



	return 0;

}

arch_initcall(init_euen_mask);