x86/fpu: Move context switch and exit to user inlines into sched.h

internal.h is a kitchen sink which needs to get out of the way to prepare
for the upcoming changes.

Move the context switch and exit to user inlines into a separate header,
which is all that code needs.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.349132461@linutronix.de

arch/x86/include/asm/fpu/internal.h

@@ -27,16 +27,11 @@
  * High level FPU state handling functions:
  */
 extern bool fpu__restore_sig(void __user *buf, int ia32_frame);
-extern void fpu__drop(struct fpu *fpu);
 extern void fpu__clear_user_states(struct fpu *fpu);
 extern int  fpu__exception_code(struct fpu *fpu, int trap_nr);
 
 extern void fpu_sync_fpstate(struct fpu *fpu);
 
-/* Clone and exit operations */
-extern int  fpu_clone(struct task_struct *dst);
-extern void fpu_flush_thread(void);
-
 /*
  * Boot time FPU initialization functions:
  */
@@ -82,7 +77,6 @@ extern void fpstate_init_soft(struct swregs_state *soft);
 #else
 static inline void fpstate_init_soft(struct swregs_state *soft) {}
 #endif
-extern void save_fpregs_to_fpstate(struct fpu *fpu);
 
 /*
  * Returns 0 on success or the trap number when the operation raises an
@@ -464,58 +458,4 @@ static inline void fpregs_restore_userregs(void)
 	clear_thread_flag(TIF_NEED_FPU_LOAD);
 }
 
-/*
- * FPU state switching for scheduling.
- *
- * This is a two-stage process:
- *
- *  - switch_fpu_prepare() saves the old state.
- *    This is done within the context of the old process.
- *
- *  - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
- *    will get loaded on return to userspace, or when the kernel needs it.
- *
- * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
- * are saved in the current thread's FPU register state.
- *
- * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
- * hold current()'s FPU registers. It is required to load the
- * registers before returning to userland or using the content
- * otherwise.
- *
- * The FPU context is only stored/restored for a user task and
- * PF_KTHREAD is used to distinguish between kernel and user threads.
- */
-static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
-{
-	if (static_cpu_has(X86_FEATURE_FPU) && !(current->flags & PF_KTHREAD)) {
-		save_fpregs_to_fpstate(old_fpu);
-		/*
-		 * The save operation preserved register state, so the
-		 * fpu_fpregs_owner_ctx is still @old_fpu. Store the
-		 * current CPU number in @old_fpu, so the next return
-		 * to user space can avoid the FPU register restore
-		 * when is returns on the same CPU and still owns the
-		 * context.
-		 */
-		old_fpu->last_cpu = cpu;
-
-		trace_x86_fpu_regs_deactivated(old_fpu);
-	}
-}
-
-/*
- * Misc helper functions:
- */
-
-/*
- * Delay loading of the complete FPU state until the return to userland.
- * PKRU is handled separately.
- */
-static inline void switch_fpu_finish(void)
-{
-	if (cpu_feature_enabled(X86_FEATURE_FPU))
-		set_thread_flag(TIF_NEED_FPU_LOAD);
-}
-
 #endif /* _ASM_X86_FPU_INTERNAL_H */

arch/x86/include/asm/fpu/sched.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_FPU_SCHED_H
+#define _ASM_X86_FPU_SCHED_H
+
+#include <linux/sched.h>
+
+#include <asm/cpufeature.h>
+#include <asm/fpu/types.h>
+
+#include <asm/trace/fpu.h>
+
+extern void save_fpregs_to_fpstate(struct fpu *fpu);
+extern void fpu__drop(struct fpu *fpu);
+extern int  fpu_clone(struct task_struct *dst);
+extern void fpu_flush_thread(void);
+
+/*
+ * FPU state switching for scheduling.
+ *
+ * This is a two-stage process:
+ *
+ *  - switch_fpu_prepare() saves the old state.
+ *    This is done within the context of the old process.
+ *
+ *  - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
+ *    will get loaded on return to userspace, or when the kernel needs it.
+ *
+ * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
+ * are saved in the current thread's FPU register state.
+ *
+ * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
+ * hold current()'s FPU registers. It is required to load the
+ * registers before returning to userland or using the content
+ * otherwise.
+ *
+ * The FPU context is only stored/restored for a user task and
+ * PF_KTHREAD is used to distinguish between kernel and user threads.
+ */
+static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
+{
+	if (cpu_feature_enabled(X86_FEATURE_FPU) &&
+	    !(current->flags & PF_KTHREAD)) {
+		save_fpregs_to_fpstate(old_fpu);
+		/*
+		 * The save operation preserved register state, so the
+		 * fpu_fpregs_owner_ctx is still @old_fpu. Store the
+		 * current CPU number in @old_fpu, so the next return
+		 * to user space can avoid the FPU register restore
+		 * when is returns on the same CPU and still owns the
+		 * context.
+		 */
+		old_fpu->last_cpu = cpu;
+
+		trace_x86_fpu_regs_deactivated(old_fpu);
+	}
+}
+
+/*
+ * Delay loading of the complete FPU state until the return to userland.
+ * PKRU is handled separately.
+ */
+static inline void switch_fpu_finish(void)
+{
+	if (cpu_feature_enabled(X86_FEATURE_FPU))
+		set_thread_flag(TIF_NEED_FPU_LOAD);
+}
+
+#endif /* _ASM_X86_FPU_SCHED_H */

arch/x86/kernel/fpu/core.c

@@ -8,6 +8,7 @@
  */
 #include <asm/fpu/internal.h>
 #include <asm/fpu/regset.h>
+#include <asm/fpu/sched.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/types.h>
 #include <asm/traps.h>

arch/x86/kernel/process.c

@@ -30,7 +30,7 @@
 #include <asm/apic.h>
 #include <linux/uaccess.h>
 #include <asm/mwait.h>
-#include <asm/fpu/internal.h>
+#include <asm/fpu/sched.h>
 #include <asm/debugreg.h>
 #include <asm/nmi.h>
 #include <asm/tlbflush.h>

arch/x86/kernel/process_32.c

@@ -41,7 +41,7 @@
 
 #include <asm/ldt.h>
 #include <asm/processor.h>
-#include <asm/fpu/internal.h>
+#include <asm/fpu/sched.h>
 #include <asm/desc.h>
 
 #include <linux/err.h>

arch/x86/kernel/process_64.c

@@ -42,7 +42,7 @@
 
 #include <asm/processor.h>
 #include <asm/pkru.h>
-#include <asm/fpu/internal.h>
+#include <asm/fpu/sched.h>
 #include <asm/mmu_context.h>
 #include <asm/prctl.h>
 #include <asm/desc.h>