From: Rik van Riel Date: Sun, 9 Sep 2018 18:30:45 +0200 Subject: [PATCH 09/27] x86/fpu: Add (__)make_fpregs_active helpers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.0/older/patches-5.0.10-rt7.tar.xz Add helper function that ensures the floating point registers for the current task are active. Use with preemption disabled. Signed-off-by: Rik van Riel Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/include/asm/fpu/api.h | 11 +++++++++++ arch/x86/include/asm/fpu/internal.h | 19 +++++++++++-------- 2 files changed, 22 insertions(+), 8 deletions(-) --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -10,6 +10,7 @@ #ifndef _ASM_X86_FPU_API_H #define _ASM_X86_FPU_API_H +#include /* * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It @@ -22,6 +23,16 @@ extern void kernel_fpu_begin(void); extern void kernel_fpu_end(void); extern bool irq_fpu_usable(void); +static inline void fpregs_lock(void) +{ + preempt_disable(); +} + +static inline void fpregs_unlock(void) +{ + preempt_enable(); +} + /* * Query the presence of one or more xfeatures. Works on any legacy CPU as well. * --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -515,6 +515,15 @@ static inline void fpregs_activate(struc trace_x86_fpu_regs_activated(fpu); } +static inline void __fpregs_load_activate(struct fpu *fpu, int cpu) +{ + if (!fpregs_state_valid(fpu, cpu)) { + if (current->mm) + copy_kernel_to_fpregs(&fpu->state); + fpregs_activate(fpu); + } +} + /* * FPU state switching for scheduling. * @@ -553,14 +562,8 @@ switch_fpu_prepare(struct fpu *old_fpu, */ static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu) { - if (static_cpu_has(X86_FEATURE_FPU)) { - if (!fpregs_state_valid(new_fpu, cpu)) { - if (current->mm) - copy_kernel_to_fpregs(&new_fpu->state); - } - - fpregs_activate(new_fpu); - } + if (static_cpu_has(X86_FEATURE_FPU)) + __fpregs_load_activate(new_fpu, cpu); } /*