[PATCH 09/22] x86/fpu: Add (__)make_fpregs_active helpers

Sebastian Andrzej Siewior
2019-02-21T11:53:16Z

From: Rik van Riel <riel@surriel.com>

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 <riel@surriel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/include/asm/fpu/api.h | 11 +++++++++++
arch/x86/include/asm/fpu/internal.h | 19 +++++++++++--------
2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index b56d504af6545..73e684160f354 100644
--- 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 <linux/preempt.h>

/*
* 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.
*
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 96835d04e9343..67e4805bccb6f 100644
--- 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(struct fpu *fpu)
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, int cpu)
*/
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);
}

/*
--
2.20.1