text: /*
   *  linux/arch/arm/vfp/vfpmodule.c
   *
   *  Copyright (C) 2004 ARM Limited.
   *  Written by Deep Blue Solutions Limited.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/types.h>
  #include <linux/cpu.h>
  #include <linux/cpu_pm.h>
  #include <linux/hardirq.h>
  #include <linux/kernel.h>
  #include <linux/notifier.h>
  #include <linux/signal.h>
  #include <linux/sched/signal.h>
  #include <linux/smp.h>
  #include <linux/init.h>
  #include <linux/uaccess.h>
  #include <linux/user.h>
  #include <linux/export.h>
  
  #include <asm/cp15.h>
  #include <asm/cputype.h>
  #include <asm/system_info.h>
  #include <asm/thread_notify.h>
  #include <asm/vfp.h>
  
  #include "vfpinstr.h"
  #include "vfp.h"
  
  /*
   * Our undef handlers (in entry.S)
   */
  asmlinkage void vfp_testing_entry(void);
  asmlinkage void vfp_support_entry(void);
  asmlinkage void vfp_null_entry(void);
  
  asmlinkage void (*vfp_vector)(void) = vfp_null_entry;
  
  /*
   * Dual-use variable.
   * Used in startup: set to non-zero if VFP checks fail
   * After startup, holds VFP architecture
   */
  unsigned int VFP_arch;
  
  /*
   * The pointer to the vfpstate structure of the thread which currently
   * owns the context held in the VFP hardware, or NULL if the hardware
   * context is invalid.
   *
   * For UP, this is sufficient to tell which thread owns the VFP context.
   * However, for SMP, we also need to check the CPU number stored in the
   * saved state too to catch migrations.
   */
  union vfp_state *vfp_current_hw_state[NR_CPUS];
  
  /*
   * Is 'thread's most up to date state stored in this CPUs hardware?
   * Must be called from non-preemptible context.
   */
  static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread)
  {
  #ifdef CONFIG_SMP
  	if (thread->vfpstate.hard.cpu != cpu)
  		return false;
  #endif
  	return vfp_current_hw_state[cpu] == &thread->vfpstate;
  }
  
  /*
   * Force a reload of the VFP context from the thread structure.  We do
   * this by ensuring that access to the VFP hardware is disabled, and
   * clear vfp_current_hw_state.  Must be called from non-preemptible context.
   */
  static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
  {
  	if (vfp_state_in_hw(cpu, thread)) {
  		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  		vfp_current_hw_state[cpu] = NULL;
  	}
  #ifdef CONFIG_SMP
  	thread->vfpstate.hard.cpu = NR_CPUS;
  #endif
  }
  
  /*
   * Per-thread VFP initialization.
   */
  static void vfp_thread_flush(struct thread_info *thread)
  {
  	union vfp_state *vfp = &thread->vfpstate;
  	unsigned int cpu;
  
  	/*
  	 * Disable VFP to ensure we initialize it first.  We must ensure
  	 * that the modification of vfp_current_hw_state[] and hardware
  	 * disable are done for the same CPU and without preemption.
  	 *
  	 * Do this first to ensure that preemption won't overwrite our
  	 * state saving should access to the VFP be enabled at this point.
  	 */
  	cpu = get_cpu();
  	if (vfp_current_hw_state[cpu] == vfp)
  		vfp_current_hw_state[cpu] = NULL;
  	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  	put_cpu();
  
  	memset(vfp, 0, sizeof(union vfp_state));
  
  	vfp->hard.fpexc = FPEXC_EN;
  	vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
  #ifdef CONFIG_SMP
  	vfp->hard.cpu = NR_CPUS;
  #endif
  }
  
  static void vfp_thread_exit(struct thread_info *thread)
  {
  	/* release case: Per-thread VFP cleanup. */
  	union vfp_state *vfp = &thread->vfpstate;
  	unsigned int cpu = get_cpu();
  
  	if (vfp_current_hw_state[cpu] == vfp)
  		vfp_current_hw_state[cpu] = NULL;
  	put_cpu();
  }
  
  static void vfp_thread_copy(struct thread_info *thread)
  {
  	struct thread_info *parent = current_thread_info();
  
  	vfp_sync_hwstate(parent);
  	thread->vfpstate = parent->vfpstate;
  #ifdef CONFIG_SMP
  	thread->vfpstate.hard.cpu = NR_CPUS;
  #endif
  }
  
  /*
   * When this function is called with the following 'cmd's, the following
   * is true while this function is being run:
   *  THREAD_NOFTIFY_SWTICH:
   *   - the previously running thread will not be scheduled onto another CPU.
   *   - the next thread to be run (v) will not be running on another CPU.
   *   - thread->cpu is the local CPU number
   *   - not preemptible as we're called in the middle of a thread switch
   *  THREAD_NOTIFY_FLUSH:
   *   - the thread (v) will be running on the local CPU, so
   *	v === current_thread_info()
   *   - thread->cpu is the local CPU number at the time it is accessed,
   *	but may change at any time.
   *   - we could be preempted if tree preempt rcu is enabled, so
   *	it is unsafe to use thread->cpu.
   *  THREAD_NOTIFY_EXIT
   *   - we could be preempted if tree preempt rcu is enabled, so
   *	it is unsafe to use thread->cpu.
   */
  static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
  {
  	struct thread_info *thread = v;
  	u32 fpexc;
  #ifdef CONFIG_SMP
  	unsigned int cpu;
  #endif
  
  	switch (cmd) {
  	case THREAD_NOTIFY_SWITCH:
  		fpexc = fmrx(FPEXC);
  
  #ifdef CONFIG_SMP
  		cpu = thread->cpu;
  
  		/*
  		 * On SMP, if VFP is enabled, save the old state in
  		 * case the thread migrates to a different CPU. The
  		 * restoring is done lazily.
  		 */
  		if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu])
  			vfp_save_state(vfp_current_hw_state[cpu], fpexc);
  #endif
  
  		/*
  		 * Always disable VFP so we can lazily save/restore the
  		 * old state.
  		 */
  		fmxr(FPEXC, fpexc & ~FPEXC_EN);
  		break;
  
  	case THREAD_NOTIFY_FLUSH:
  		vfp_thread_flush(thread);
  		break;
  
  	case THREAD_NOTIFY_EXIT:
  		vfp_thread_exit(thread);
  		break;
  
  	case THREAD_NOTIFY_COPY:
  		vfp_thread_copy(thread);
  		break;
  	}
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block vfp_notifier_block = {
  	.notifier_call	= vfp_notifier,
  };
  
  /*
   * Raise a SIGFPE for the current process.
   * sicode describes the signal being raised.
   */
  static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
  {
  	siginfo_t info;
  
  	clear_siginfo(&info);
  	info.si_signo = SIGFPE;
  	info.si_code = sicode;
  	info.si_addr = (void __user *)(instruction_pointer(regs) - 4);
  
  	/*
  	 * This is the same as NWFPE, because it's not clear what
  	 * this is used for
  	 */
  	current->thread.error_code = 0;
  	current->thread.trap_no = 6;
  
  	send_sig_info(SIGFPE, &info, current);
  }
  
  static void vfp_panic(char *reason, u32 inst)
  {
  	int i;
  
  	pr_err("VFP: Error: %s\n", reason);
  	pr_err("VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
  		fmrx(FPEXC), fmrx(FPSCR), inst);
  	for (i = 0; i < 32; i += 2)
  		pr_err("VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
  		       i, vfp_get_float(i), i+1, vfp_get_float(i+1));
  }
  
  /*
   * Process bitmask of exception conditions.
   */
  static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
  {
  	int si_code = 0;
  
  	pr_debug("VFP: raising exceptions %08x\n", exceptions);
  
  	if (exceptions == VFP_EXCEPTION_ERROR) {
  		vfp_panic("unhandled bounce", inst);
  		vfp_raise_sigfpe(FPE_FLTINV, regs);
  		return;
  	}
  
  	/*
  	 * If any of the status flags are set, update the FPSCR.
  	 * Comparison instructions always return at least one of
  	 * these flags set.
  	 */
  	if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
  		fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);
  
  	fpscr |= exceptions;
  
  	fmxr(FPSCR, fpscr);
  
  #define RAISE(stat,en,sig)				\
  	if (exceptions & stat && fpscr & en)		\
  		si_code = sig;
  
  	/*
  	 * These are arranged in priority order, least to highest.
  	 */
  	RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV);
  	RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
  	RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
  	RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
  	RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);
  
  	if (si_code)
  		vfp_raise_sigfpe(si_code, regs);
  }
  
  /*
   * Emulate a VFP instruction.
   */
  static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
  {
  	u32 exceptions = VFP_EXCEPTION_ERROR;
  
  	pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);
  
  	if (INST_CPRTDO(inst)) {
  		if (!INST_CPRT(inst)) {
  			/*
  			 * CPDO
  			 */
  			if (vfp_single(inst)) {
  				exceptions = vfp_single_cpdo(inst, fpscr);
  			} else {
  				exceptions = vfp_double_cpdo(inst, fpscr);
  			}
  		} else {
  			/*
  			 * A CPRT instruction can not appear in FPINST2, nor
  			 * can it cause an exception.  Therefore, we do not
  			 * have to emulate it.
  			 */
  		}
  	} else {
  		/*
  		 * A CPDT instruction can not appear in FPINST2, nor can
  		 * it cause an exception.  Therefore, we do not have to
  		 * emulate it.
  		 */
  	}
  	return exceptions & ~VFP_NAN_FLAG;
  }
  
  /*
   * Package up a bounce condition.
   */
  void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
  {
  	u32 fpscr, orig_fpscr, fpsid, exceptions;
  
  	pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);
  
  	/*
  	 * At this point, FPEXC can have the following configuration:
  	 *
  	 *  EX DEX IXE
  	 *  0   1   x   - synchronous exception
  	 *  1   x   0   - asynchronous exception
  	 *  1   x   1   - sychronous on VFP subarch 1 and asynchronous on later
  	 *  0   0   1   - synchronous on VFP9 (non-standard subarch 1
  	 *                implementation), undefined otherwise
  	 *
  	 * Clear various bits and enable access to the VFP so we can
  	 * handle the bounce.
  	 */
  	fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK));
  
  	fpsid = fmrx(FPSID);
  	orig_fpscr = fpscr = fmrx(FPSCR);
  
  	/*
  	 * Check for the special VFP subarch 1 and FPSCR.IXE bit case
  	 */
  	if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT)
  	    && (fpscr & FPSCR_IXE)) {
  		/*
  		 * Synchronous exception, emulate the trigger instruction
  		 */
  		goto emulate;
  	}
  
  	if (fpexc & FPEXC_EX) {
  #ifndef CONFIG_CPU_FEROCEON
  		/*
  		 * Asynchronous exception. The instruction is read from FPINST
  		 * and the interrupted instruction has to be restarted.
  		 */
  		trigger = fmrx(FPINST);
  		regs->ARM_pc -= 4;
  #endif
  	} else if (!(fpexc & FPEXC_DEX)) {
  		/*
  		 * Illegal combination of bits. It can be caused by an
  		 * unallocated VFP instruction but with FPSCR.IXE set and not
  		 * on VFP subarch 1.
  		 */
  		 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs);
  		goto exit;
  	}
  
  	/*
  	 * Modify fpscr to indicate the number of iterations remaining.
  	 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates
  	 * whether FPEXC.VECITR or FPSCR.LEN is used.
  	 */
  	if (fpexc & (FPEXC_EX | FPEXC_VV)) {
  		u32 len;
  
  		len = fpexc + (1 << FPEXC_LENGTH_BIT);
  
  		fpscr &= ~FPSCR_LENGTH_MASK;
  		fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
  	}
  
  	/*
  	 * Handle the first FP instruction.  We used to take note of the
  	 * FPEXC bounce reason, but this appears to be unreliable.
  	 * Emulate the bounced instruction instead.
  	 */
  	exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
  	if (exceptions)
  		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
  
  	/*
  	 * If there isn't a second FP instruction, exit now. Note that
  	 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
  	 */
  	if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V))
  		goto exit;
  
  	/*
  	 * The barrier() here prevents fpinst2 being read
  	 * before the condition above.
  	 */
  	barrier();
  	trigger = fmrx(FPINST2);
  
   emulate:
  	exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs);
  	if (exceptions)
  		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
   exit:
  	preempt_enable();
  }
  
  static void vfp_enable(void *unused)
  {
  	u32 access;
  
  	BUG_ON(preemptible());
  	access = get_copro_access();
  
  	/*
  	 * Enable full access to VFP (cp10 and cp11)
  	 */
  	set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11));
  }
  
  /* Called by platforms on which we want to disable VFP because it may not be
   * present on all CPUs within a SMP complex. Needs to be called prior to
   * vfp_init().
   */
  void vfp_disable(void)
  {
  	if (VFP_arch) {
  		pr_debug("%s: should be called prior to vfp_init\n", __func__);
  		return;
  	}
  	VFP_arch = 1;
  }
  
  #ifdef CONFIG_CPU_PM
  static int vfp_pm_suspend(void)
  {
  	struct thread_info *ti = current_thread_info();
  	u32 fpexc = fmrx(FPEXC);
  
  	/* if vfp is on, then save state for resumption */
  	if (fpexc & FPEXC_EN) {
  		pr_debug("%s: saving vfp state\n", __func__);
  		vfp_save_state(&ti->vfpstate, fpexc);
  
  		/* disable, just in case */
  		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  	} else if (vfp_current_hw_state[ti->cpu]) {
  #ifndef CONFIG_SMP
  		fmxr(FPEXC, fpexc | FPEXC_EN);
  		vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc);
  		fmxr(FPEXC, fpexc);
  #endif
  	}
  
  	/* clear any information we had about last context state */
  	vfp_current_hw_state[ti->cpu] = NULL;
  
  	return 0;
  }
  
  static void vfp_pm_resume(void)
  {
  	/* ensure we have access to the vfp */
  	vfp_enable(NULL);
  
  	/* and disable it to ensure the next usage restores the state */
  	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  }
  
  static int vfp_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd,
  	void *v)
  {
  	switch (cmd) {
  	case CPU_PM_ENTER:
  		vfp_pm_suspend();
  		break;
  	case CPU_PM_ENTER_FAILED:
  	case CPU_PM_EXIT:
  		vfp_pm_resume();
  		break;
  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block vfp_cpu_pm_notifier_block = {
  	.notifier_call = vfp_cpu_pm_notifier,
  };
  
  static void vfp_pm_init(void)
  {
  	cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block);
  }
  
  #else
  static inline void vfp_pm_init(void) { }
  #endif /* CONFIG_CPU_PM */
  
  /*
   * Ensure that the VFP state stored in 'thread->vfpstate' is up to date
   * with the hardware state.
   */
  void vfp_sync_hwstate(struct thread_info *thread)
  {
  	unsigned int cpu = get_cpu();
  
  	if (vfp_state_in_hw(cpu, thread)) {
  		u32 fpexc = fmrx(FPEXC);
  
  		/*
  		 * Save the last VFP state on this CPU.
  		 */
  		fmxr(FPEXC, fpexc | FPEXC_EN);
  		vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN);
  		fmxr(FPEXC, fpexc);
  	}
  
  	put_cpu();
  }
  
  /* Ensure that the thread reloads the hardware VFP state on the next use. */
  void vfp_flush_hwstate(struct thread_info *thread)
  {
  	unsigned int cpu = get_cpu();
  
  	vfp_force_reload(cpu, thread);
  
  	put_cpu();
  }
  
  /*
   * Save the current VFP state into the provided structures and prepare
   * for entry into a new function (signal handler).
   */
  int vfp_preserve_user_clear_hwstate(struct user_vfp __user *ufp,
  				    struct user_vfp_exc __user *ufp_exc)
  {
  	struct thread_info *thread = current_thread_info();
  	struct vfp_hard_struct *hwstate = &thread->vfpstate.hard;
  	int err = 0;
  
  	/* Ensure that the saved hwstate is up-to-date. */
  	vfp_sync_hwstate(thread);
  
  	/*
  	 * Copy the floating point registers. There can be unused
  	 * registers see asm/hwcap.h for details.
  	 */
  	err |= __copy_to_user(&ufp->fpregs, &hwstate->fpregs,
  			      sizeof(hwstate->fpregs));
  	/*
  	 * Copy the status and control register.
  	 */
  	__put_user_error(hwstate->fpscr, &ufp->fpscr, err);
  
  	/*
  	 * Copy the exception registers.
  	 */
  	__put_user_error(hwstate->fpexc, &ufp_exc->fpexc, err);
  	__put_user_error(hwstate->fpinst, &ufp_exc->fpinst, err);
  	__put_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err);
  
  	if (err)
  		return -EFAULT;
  
  	/* Ensure that VFP is disabled. */
  	vfp_flush_hwstate(thread);
  
  	/*
  	 * As per the PCS, clear the length and stride bits for function
  	 * entry.
  	 */
  	hwstate->fpscr &= ~(FPSCR_LENGTH_MASK | FPSCR_STRIDE_MASK);
  	return 0;
  }
  
  /* Sanitise and restore the current VFP state from the provided structures. */
  int vfp_restore_user_hwstate(struct user_vfp __user *ufp,
  			     struct user_vfp_exc __user *ufp_exc)
  {
  	struct thread_info *thread = current_thread_info();
  	struct vfp_hard_struct *hwstate = &thread->vfpstate.hard;
  	unsigned long fpexc;
  	int err = 0;
  
  	/* Disable VFP to avoid corrupting the new thread state. */
  	vfp_flush_hwstate(thread);
  
  	/*
  	 * Copy the floating point registers. There can be unused
  	 * registers see asm/hwcap.h for details.
  	 */
  	err |= __copy_from_user(&hwstate->fpregs, &ufp->fpregs,
  				sizeof(hwstate->fpregs));
  	/*
  	 * Copy the status and control register.
  	 */
  	__get_user_error(hwstate->fpscr, &ufp->fpscr, err);
  
  	/*
  	 * Sanitise and restore the exception registers.
  	 */
  	__get_user_error(fpexc, &ufp_exc->fpexc, err);
  
  	/* Ensure the VFP is enabled. */
  	fpexc |= FPEXC_EN;
  
  	/* Ensure FPINST2 is invalid and the exception flag is cleared. */
  	fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
  	hwstate->fpexc = fpexc;
  
  	__get_user_error(hwstate->fpinst, &ufp_exc->fpinst, err);
  	__get_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err);
  
  	return err ? -EFAULT : 0;
  }
  
  /*
   * VFP hardware can lose all context when a CPU goes offline.
   * As we will be running in SMP mode with CPU hotplug, we will save the
   * hardware state at every thread switch.  We clear our held state when
   * a CPU has been killed, indicating that the VFP hardware doesn't contain
   * a threads VFP state.  When a CPU starts up, we re-enable access to the
   * VFP hardware. The callbacks below are called on the CPU which
   * is being offlined/onlined.
   */
  static int vfp_dying_cpu(unsigned int cpu)
  {
  	vfp_current_hw_state[cpu] = NULL;
  	return 0;
  }
  
  static int vfp_starting_cpu(unsigned int unused)
  {
  	vfp_enable(NULL);
  	return 0;
  }
  
  void vfp_kmode_exception(void)
  {
  	/*
  	 * If we reach this point, a floating point exception has been raised
  	 * while running in kernel mode. If the NEON/VFP unit was enabled at the
  	 * time, it means a VFP instruction has been issued that requires
  	 * software assistance to complete, something which is not currently
  	 * supported in kernel mode.
  	 * If the NEON/VFP unit was disabled, and the location pointed to below
  	 * is properly preceded by a call to kernel_neon_begin(), something has
  	 * caused the task to be scheduled out and back in again. In this case,
  	 * rebuilding and running with CONFIG_DEBUG_ATOMIC_SLEEP enabled should
  	 * be helpful in localizing the problem.
  	 */
  	if (fmrx(FPEXC) & FPEXC_EN)
  		pr_crit("BUG: unsupported FP instruction in kernel mode\n");
  	else
  		pr_crit("BUG: FP instruction issued in kernel mode with FP unit disabled\n");
  }
  
  #ifdef CONFIG_KERNEL_MODE_NEON
  
  /*
   * Kernel-side NEON support functions
   */
  void kernel_neon_begin(void)
  {
  	struct thread_info *thread = current_thread_info();
  	unsigned int cpu;
  	u32 fpexc;
  
  	/*
  	 * Kernel mode NEON is only allowed outside of interrupt context
  	 * with preemption disabled. This will make sure that the kernel
  	 * mode NEON register contents never need to be preserved.
  	 */
  	BUG_ON(in_interrupt());
  	cpu = get_cpu();
  
  	fpexc = fmrx(FPEXC) | FPEXC_EN;
  	fmxr(FPEXC, fpexc);
  
  	/*
  	 * Save the userland NEON/VFP state. Under UP,
  	 * the owner could be a task other than 'current'
  	 */
  	if (vfp_state_in_hw(cpu, thread))
  		vfp_save_state(&thread->vfpstate, fpexc);
  #ifndef CONFIG_SMP
  	else if (vfp_current_hw_state[cpu] != NULL)
  		vfp_save_state(vfp_current_hw_state[cpu], fpexc);
  #endif
  	vfp_current_hw_state[cpu] = NULL;
  }
  EXPORT_SYMBOL(kernel_neon_begin);
  
  void kernel_neon_end(void)
  {
  	/* Disable the NEON/VFP unit. */
  	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  	put_cpu();
  }
  EXPORT_SYMBOL(kernel_neon_end);
  
  #endif /* CONFIG_KERNEL_MODE_NEON */
  
  /*
   * VFP support code initialisation.
   */
  static int __init vfp_init(void)
  {
  	unsigned int vfpsid;
  	unsigned int cpu_arch = cpu_architecture();
  
  	/*
  	 * Enable the access to the VFP on all online CPUs so the
  	 * following test on FPSID will succeed.
  	 */
  	if (cpu_arch >= CPU_ARCH_ARMv6)
  		on_each_cpu(vfp_enable, NULL, 1);
  
  	/*
  	 * First check that there is a VFP that we can use.
  	 * The handler is already setup to just log calls, so
  	 * we just need to read the VFPSID register.
  	 */
  	vfp_vector = vfp_testing_entry;
  	barrier();
  	vfpsid = fmrx(FPSID);
  	barrier();
  	vfp_vector = vfp_null_entry;
  
  	pr_info("VFP support v0.3: ");
  	if (VFP_arch) {
  		pr_cont("not present\n");
  		return 0;
  	/* Extract the architecture on CPUID scheme */
  	} else if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {
  		VFP_arch = vfpsid & FPSID_CPUID_ARCH_MASK;
  		VFP_arch >>= FPSID_ARCH_BIT;
  		/*
  		 * Check for the presence of the Advanced SIMD
  		 * load/store instructions, integer and single
  		 * precision floating point operations. Only check
  		 * for NEON if the hardware has the MVFR registers.
  		 */
  		if (IS_ENABLED(CONFIG_NEON) &&
  		   (fmrx(MVFR1) & 0x000fff00) == 0x00011100)
  			elf_hwcap |= HWCAP_NEON;
  
  		if (IS_ENABLED(CONFIG_VFPv3)) {
  			u32 mvfr0 = fmrx(MVFR0);
  			if (((mvfr0 & MVFR0_DP_MASK) >> MVFR0_DP_BIT) == 0x2 ||
  			    ((mvfr0 & MVFR0_SP_MASK) >> MVFR0_SP_BIT) == 0x2) {
  				elf_hwcap |= HWCAP_VFPv3;
  				/*
  				 * Check for VFPv3 D16 and VFPv4 D16.  CPUs in
  				 * this configuration only have 16 x 64bit
  				 * registers.
  				 */
  				if ((mvfr0 & MVFR0_A_SIMD_MASK) == 1)
  					/* also v4-D16 */
  					elf_hwcap |= HWCAP_VFPv3D16;
  				else
  					elf_hwcap |= HWCAP_VFPD32;
  			}
  
  			if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000)
  				elf_hwcap |= HWCAP_VFPv4;
  		}
  	/* Extract the architecture version on pre-cpuid scheme */
  	} else {
  		if (vfpsid & FPSID_NODOUBLE) {
  			pr_cont("no double precision support\n");
  			return 0;
  		}
  
  		VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;
  	}
  
  	cpuhp_setup_state_nocalls(CPUHP_AP_ARM_VFP_STARTING,
  				  "arm/vfp:starting", vfp_starting_cpu,
  				  vfp_dying_cpu);
  
  	vfp_vector = vfp_support_entry;
  
  	thread_register_notifier(&vfp_notifier_block);
  	vfp_pm_init();
  
  	/*
  	 * We detected VFP, and the support code is
  	 * in place; report VFP support to userspace.
  	 */
  	elf_hwcap |= HWCAP_VFP;
  
  	pr_cont("implementor %02x architecture %d part %02x variant %x rev %x\n",
  		(vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
  		VFP_arch,
  		(vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
  		(vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
  		(vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);
  
  	return 0;
  }
  
  core_initcall(vfp_init);
  