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Code Issues Releases Wiki Activity

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>
This commit is contained in:
Huacai Chen 2023-09-06 22:53:55 +08:00
parent 8f58c571bf
commit 2478e4b759
1 changed files with 51 additions and 4 deletions
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55
arch/loongarch/kernel/kfpu.c
View File

@ -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);