x86/fpu: Rename fpu::fpstate_active to fpu::initialized

The x86 FPU code used to have a complex state machine where both the FPU
registers and the FPU state context could be 'active' (or inactive)
independently of each other - which enabled features like lazy FPU restore.

Much of this complexity is gone in the current code: now we basically can
have FPU-less tasks (kernel threads) that don't use (and save/restore) FPU
state at all, plus full FPU users that save/restore directly with no laziness
whatsoever.

But the fpu::fpstate_active still carries bits of the old complexity - meanwhile
this flag has become a simple flag that shows whether the FPU context saving
area in the thread struct is initialized and used, or not.

Rename it to fpu::initialized to express this simplicity in the name as well.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-30-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/ia32/ia32_signal.c

@@ -231,7 +231,7 @@ static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 		 ksig->ka.sa.sa_restorer)
 		sp = (unsigned long) ksig->ka.sa.sa_restorer;
 
-	if (fpu->fpstate_active) {
+	if (fpu->initialized) {
 		unsigned long fx_aligned, math_size;
 
 		sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);

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

@@ -527,7 +527,7 @@ static inline void fpregs_activate(struct fpu *fpu)
 static inline void
 switch_fpu_prepare(struct fpu *old_fpu, int cpu)
 {
-	if (old_fpu->fpstate_active) {
+	if (old_fpu->initialized) {
 		if (!copy_fpregs_to_fpstate(old_fpu))
 			old_fpu->last_cpu = -1;
 		else
@@ -550,7 +550,7 @@ switch_fpu_prepare(struct fpu *old_fpu, int cpu)
 static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu)
 {
 	bool preload = static_cpu_has(X86_FEATURE_FPU) &&
-		       new_fpu->fpstate_active;
+		       new_fpu->initialized;
 
 	if (preload) {
 		if (!fpregs_state_valid(new_fpu, cpu))

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

@@ -293,13 +293,13 @@ struct fpu {
 	unsigned int			last_cpu;
 
 	/*
-	 * @fpstate_active:
+	 * @initialized:
 	 *
-	 * This flag indicates whether this context is active: if the task
+	 * This flag indicates whether this context is initialized: if the task
 	 * is not running then we can restore from this context, if the task
 	 * is running then we should save into this context.
 	 */
-	unsigned char			fpstate_active;
+	unsigned char			initialized;
 
 	/*
 	 * @state:

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

@@ -12,22 +12,22 @@ DECLARE_EVENT_CLASS(x86_fpu,
 
 	TP_STRUCT__entry(
 		__field(struct fpu *, fpu)
-		__field(bool, fpstate_active)
+		__field(bool, initialized)
 		__field(u64, xfeatures)
 		__field(u64, xcomp_bv)
 		),
 
 	TP_fast_assign(
 		__entry->fpu		= fpu;
-		__entry->fpstate_active	= fpu->fpstate_active;
+		__entry->initialized	= fpu->initialized;
 		if (boot_cpu_has(X86_FEATURE_OSXSAVE)) {
 			__entry->xfeatures = fpu->state.xsave.header.xfeatures;
 			__entry->xcomp_bv  = fpu->state.xsave.header.xcomp_bv;
 		}
 	),
-	TP_printk("x86/fpu: %p fpstate_active: %d xfeatures: %llx xcomp_bv: %llx",
+	TP_printk("x86/fpu: %p initialized: %d xfeatures: %llx xcomp_bv: %llx",
 			__entry->fpu,
-			__entry->fpstate_active,
+			__entry->initialized,
 			__entry->xfeatures,
 			__entry->xcomp_bv
 	)

arch/x86/kernel/fpu/core.c

@@ -100,7 +100,7 @@ void __kernel_fpu_begin(void)
 
 	kernel_fpu_disable();
 
-	if (fpu->fpstate_active) {
+	if (fpu->initialized) {
 		/*
 		 * Ignore return value -- we don't care if reg state
 		 * is clobbered.
@@ -116,7 +116,7 @@ void __kernel_fpu_end(void)
 {
 	struct fpu *fpu = &current->thread.fpu;
 
-	if (fpu->fpstate_active)
+	if (fpu->initialized)
 		copy_kernel_to_fpregs(&fpu->state);
 
 	kernel_fpu_enable();
@@ -148,7 +148,7 @@ void fpu__save(struct fpu *fpu)
 
 	preempt_disable();
 	trace_x86_fpu_before_save(fpu);
-	if (fpu->fpstate_active) {
+	if (fpu->initialized) {
 		if (!copy_fpregs_to_fpstate(fpu)) {
 			copy_kernel_to_fpregs(&fpu->state);
 		}
@@ -191,7 +191,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 {
 	dst_fpu->last_cpu = -1;
 
-	if (!src_fpu->fpstate_active || !static_cpu_has(X86_FEATURE_FPU))
+	if (!src_fpu->initialized || !static_cpu_has(X86_FEATURE_FPU))
 		return 0;
 
 	WARN_ON_FPU(src_fpu != &current->thread.fpu);
@@ -240,13 +240,13 @@ void fpu__activate_curr(struct fpu *fpu)
 {
 	WARN_ON_FPU(fpu != &current->thread.fpu);
 
-	if (!fpu->fpstate_active) {
+	if (!fpu->initialized) {
 		fpstate_init(&fpu->state);
 		trace_x86_fpu_init_state(fpu);
 
 		trace_x86_fpu_activate_state(fpu);
 		/* Safe to do for the current task: */
-		fpu->fpstate_active = 1;
+		fpu->initialized = 1;
 	}
 }
 EXPORT_SYMBOL_GPL(fpu__activate_curr);
@@ -271,13 +271,13 @@ void fpu__activate_fpstate_read(struct fpu *fpu)
 	if (fpu == &current->thread.fpu) {
 		fpu__save(fpu);
 	} else {
-		if (!fpu->fpstate_active) {
+		if (!fpu->initialized) {
 			fpstate_init(&fpu->state);
 			trace_x86_fpu_init_state(fpu);
 
 			trace_x86_fpu_activate_state(fpu);
 			/* Safe to do for current and for stopped child tasks: */
-			fpu->fpstate_active = 1;
+			fpu->initialized = 1;
 		}
 	}
 }
@@ -303,7 +303,7 @@ void fpu__activate_fpstate_write(struct fpu *fpu)
 	 */
 	WARN_ON_FPU(fpu == &current->thread.fpu);
 
-	if (fpu->fpstate_active) {
+	if (fpu->initialized) {
 		/* Invalidate any lazy state: */
 		__fpu_invalidate_fpregs_state(fpu);
 	} else {
@@ -312,7 +312,7 @@ void fpu__activate_fpstate_write(struct fpu *fpu)
 
 		trace_x86_fpu_activate_state(fpu);
 		/* Safe to do for stopped child tasks: */
-		fpu->fpstate_active = 1;
+		fpu->initialized = 1;
 	}
 }
 
@@ -354,7 +354,7 @@ void fpu__drop(struct fpu *fpu)
 	preempt_disable();
 
 	if (fpu == &current->thread.fpu) {
-		if (fpu->fpstate_active) {
+		if (fpu->initialized) {
 			/* Ignore delayed exceptions from user space */
 			asm volatile("1: fwait\n"
 				     "2:\n"
@@ -363,7 +363,7 @@ void fpu__drop(struct fpu *fpu)
 		}
 	}
 
-	fpu->fpstate_active = 0;
+	fpu->initialized = 0;
 
 	trace_x86_fpu_dropped(fpu);
 

arch/x86/kernel/fpu/init.c

@@ -240,7 +240,7 @@ static void __init fpu__init_system_ctx_switch(void)
 	WARN_ON_FPU(!on_boot_cpu);
 	on_boot_cpu = 0;
 
-	WARN_ON_FPU(current->thread.fpu.fpstate_active);
+	WARN_ON_FPU(current->thread.fpu.initialized);
 }
 
 /*

arch/x86/kernel/fpu/regset.c

@@ -16,14 +16,14 @@ int regset_fpregs_active(struct task_struct *target, const struct user_regset *r
 {
 	struct fpu *target_fpu = &target->thread.fpu;
 
-	return target_fpu->fpstate_active ? regset->n : 0;
+	return target_fpu->initialized ? regset->n : 0;
 }
 
 int regset_xregset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
 {
 	struct fpu *target_fpu = &target->thread.fpu;
 
-	if (boot_cpu_has(X86_FEATURE_FXSR) && target_fpu->fpstate_active)
+	if (boot_cpu_has(X86_FEATURE_FXSR) && target_fpu->initialized)
 		return regset->n;
 	else
 		return 0;
@@ -380,7 +380,7 @@ int dump_fpu(struct pt_regs *regs, struct user_i387_struct *ufpu)
 	struct fpu *fpu = &tsk->thread.fpu;
 	int fpvalid;
 
-	fpvalid = fpu->fpstate_active;
+	fpvalid = fpu->initialized;
 	if (fpvalid)
 		fpvalid = !fpregs_get(tsk, NULL,
 				      0, sizeof(struct user_i387_ia32_struct),

arch/x86/kernel/fpu/signal.c

@@ -171,7 +171,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 			sizeof(struct user_i387_ia32_struct), NULL,
 			(struct _fpstate_32 __user *) buf) ? -1 : 1;
 
-	if (fpu->fpstate_active || using_compacted_format()) {
+	if (fpu->initialized || using_compacted_format()) {
 		/* Save the live register state to the user directly. */
 		if (copy_fpregs_to_sigframe(buf_fx))
 			return -1;
@@ -315,12 +315,12 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		int err = 0;
 
 		/*
-		 * Drop the current fpu which clears fpu->fpstate_active. This ensures
+		 * Drop the current fpu which clears fpu->initialized. This ensures
 		 * that any context-switch during the copy of the new state,
 		 * avoids the intermediate state from getting restored/saved.
 		 * Thus avoiding the new restored state from getting corrupted.
 		 * We will be ready to restore/save the state only after
-		 * fpu->fpstate_active is again set.
+		 * fpu->initialized is again set.
 		 */
 		fpu__drop(fpu);
 
@@ -342,7 +342,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 			sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
 		}
 
-		fpu->fpstate_active = 1;
+		fpu->initialized = 1;
 		preempt_disable();
 		fpu__restore(fpu);
 		preempt_enable();

arch/x86/kernel/fpu/xstate.c

@@ -867,7 +867,7 @@ const void *get_xsave_field_ptr(int xsave_state)
 {
 	struct fpu *fpu = &current->thread.fpu;
 
-	if (!fpu->fpstate_active)
+	if (!fpu->initialized)
 		return NULL;
 	/*
 	 * fpu__save() takes the CPU's xstate registers

arch/x86/kernel/signal.c

@@ -263,7 +263,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 		sp = (unsigned long) ka->sa.sa_restorer;
 	}
 
-	if (fpu->fpstate_active) {
+	if (fpu->initialized) {
 		sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
 					  &buf_fx, &math_size);
 		*fpstate = (void __user *)sp;
@@ -279,7 +279,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 		return (void __user *)-1L;
 
 	/* save i387 and extended state */
-	if (fpu->fpstate_active &&
+	if (fpu->initialized &&
 	    copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
 		return (void __user *)-1L;
 
@@ -755,7 +755,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 		/*
 		 * Ensure the signal handler starts with the new fpu state.
 		 */
-		if (fpu->fpstate_active)
+		if (fpu->initialized)
 			fpu__clear(fpu);
 	}
 	signal_setup_done(failed, ksig, stepping);

arch/x86/mm/pkeys.c

@@ -44,7 +44,7 @@ int __execute_only_pkey(struct mm_struct *mm)
 	 */
 	preempt_disable();
 	if (!need_to_set_mm_pkey &&
-	    current->thread.fpu.fpstate_active &&
+	    current->thread.fpu.initialized &&
 	    !__pkru_allows_read(read_pkru(), execute_only_pkey)) {
 		preempt_enable();
 		return execute_only_pkey;