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+/*
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+ * linux/arch/arm/vfp/vfpmodule.c
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+ *
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+ * Copyright (C) 2004 ARM Limited.
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+ * Written by Deep Blue Solutions Limited.
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+#include <linux/types.h>
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+#include <linux/cpu.h>
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+#include <linux/cpu_pm.h>
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+#include <linux/hardirq.h>
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+#include <linux/kernel.h>
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+#include <linux/notifier.h>
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+#include <linux/signal.h>
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+#include <linux/sched.h>
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+#include <linux/smp.h>
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+#include <linux/init.h>
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+#include <linux/uaccess.h>
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+#include <linux/user.h>
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+
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+#include <asm/cp15.h>
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+#include <asm/cputype.h>
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+#include <asm/system_info.h>
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+#include <asm/thread_notify.h>
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+#include <asm/vfp.h>
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+
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+#include "vfpinstr.h"
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+#include "vfp.h"
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+
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+/*
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+ * Our undef handlers (in entry.S)
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+ */
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+void vfp_testing_entry(void);
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+void vfp_support_entry(void);
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+void vfp_null_entry(void);
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+
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+void (*vfp_vector)(void) = vfp_null_entry;
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+
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+/*
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+ * Dual-use variable.
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+ * Used in startup: set to non-zero if VFP checks fail
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+ * After startup, holds VFP architecture
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+ */
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+unsigned int VFP_arch;
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+
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+/*
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+ * The pointer to the vfpstate structure of the thread which currently
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+ * owns the context held in the VFP hardware, or NULL if the hardware
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+ * context is invalid.
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+ *
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+ * For UP, this is sufficient to tell which thread owns the VFP context.
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+ * However, for SMP, we also need to check the CPU number stored in the
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+ * saved state too to catch migrations.
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+ */
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+union vfp_state *vfp_current_hw_state[NR_CPUS];
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+
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+/*
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+ * Is 'thread's most up to date state stored in this CPUs hardware?
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+ * Must be called from non-preemptible context.
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+ */
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+static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread)
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+{
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+#ifdef CONFIG_SMP
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+ if (thread->vfpstate.hard.cpu != cpu)
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+ return false;
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+#endif
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+ return vfp_current_hw_state[cpu] == &thread->vfpstate;
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+}
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+
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+/*
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+ * Force a reload of the VFP context from the thread structure. We do
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+ * this by ensuring that access to the VFP hardware is disabled, and
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+ * clear vfp_current_hw_state. Must be called from non-preemptible context.
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+ */
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+static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
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+{
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+ if (vfp_state_in_hw(cpu, thread)) {
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+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
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+ vfp_current_hw_state[cpu] = NULL;
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+ }
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+#ifdef CONFIG_SMP
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+ thread->vfpstate.hard.cpu = NR_CPUS;
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+#endif
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+}
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+
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+/*
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+ * Per-thread VFP initialization.
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+ */
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+static void vfp_thread_flush(struct thread_info *thread)
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+{
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+ union vfp_state *vfp = &thread->vfpstate;
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+ unsigned int cpu;
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+
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+ /*
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+ * Disable VFP to ensure we initialize it first. We must ensure
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+ * that the modification of vfp_current_hw_state[] and hardware
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+ * disable are done for the same CPU and without preemption.
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+ *
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+ * Do this first to ensure that preemption won't overwrite our
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+ * state saving should access to the VFP be enabled at this point.
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+ */
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+ cpu = get_cpu();
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+ if (vfp_current_hw_state[cpu] == vfp)
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+ vfp_current_hw_state[cpu] = NULL;
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+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
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+ put_cpu();
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+
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+ memset(vfp, 0, sizeof(union vfp_state));
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+
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+ vfp->hard.fpexc = FPEXC_EN;
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+ vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
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+#ifdef CONFIG_SMP
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+ vfp->hard.cpu = NR_CPUS;
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+#endif
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+}
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+
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+static void vfp_thread_exit(struct thread_info *thread)
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+{
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+ /* release case: Per-thread VFP cleanup. */
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+ union vfp_state *vfp = &thread->vfpstate;
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+ unsigned int cpu = get_cpu();
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+
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+ if (vfp_current_hw_state[cpu] == vfp)
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+ vfp_current_hw_state[cpu] = NULL;
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+ put_cpu();
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+}
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+
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+static void vfp_thread_copy(struct thread_info *thread)
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+{
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+ struct thread_info *parent = current_thread_info();
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+
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+ vfp_sync_hwstate(parent);
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+ thread->vfpstate = parent->vfpstate;
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+#ifdef CONFIG_SMP
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+ thread->vfpstate.hard.cpu = NR_CPUS;
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+#endif
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+}
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+
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+/*
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+ * When this function is called with the following 'cmd's, the following
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+ * is true while this function is being run:
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+ * THREAD_NOFTIFY_SWTICH:
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+ * - the previously running thread will not be scheduled onto another CPU.
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+ * - the next thread to be run (v) will not be running on another CPU.
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+ * - thread->cpu is the local CPU number
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+ * - not preemptible as we're called in the middle of a thread switch
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+ * THREAD_NOTIFY_FLUSH:
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+ * - the thread (v) will be running on the local CPU, so
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+ * v === current_thread_info()
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+ * - thread->cpu is the local CPU number at the time it is accessed,
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+ * but may change at any time.
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+ * - we could be preempted if tree preempt rcu is enabled, so
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+ * it is unsafe to use thread->cpu.
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+ * THREAD_NOTIFY_EXIT
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+ * - the thread (v) will be running on the local CPU, so
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+ * v === current_thread_info()
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+ * - thread->cpu is the local CPU number at the time it is accessed,
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+ * but may change at any time.
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+ * - we could be preempted if tree preempt rcu is enabled, so
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+ * it is unsafe to use thread->cpu.
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+ */
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+static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
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+{
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+ struct thread_info *thread = v;
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+ u32 fpexc;
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+#ifdef CONFIG_SMP
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+ unsigned int cpu;
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