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Diffstat (limited to 'arch/arm/vfp/vfpmodule.c')
| -rw-r--r-- | arch/arm/vfp/vfpmodule.c | 870 |
1 files changed, 870 insertions, 0 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c new file mode 100644 index 000000000..2cb355c1b --- /dev/null +++ b/arch/arm/vfp/vfpmodule.c @@ -0,0 +1,870 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/vfp/vfpmodule.c + * + * Copyright (C) 2004 ARM Limited. + * Written by Deep Blue Solutions Limited. + */ +#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/traps.h> +#include <asm/vfp.h> + +#include "vfpinstr.h" +#include "vfp.h" + +/* + * Our undef handlers (in entry.S) + */ +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 + */ +static unsigned int __initdata 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) +{ + /* + * 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_fault(SIGFPE, sicode, + (void __user *)(instruction_pointer(regs) - 4), + 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 __init 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 *ufp, + struct user_vfp_exc *ufp_exc) +{ + struct thread_info *thread = current_thread_info(); + struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; + + /* 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. + */ + memcpy(&ufp->fpregs, &hwstate->fpregs, sizeof(hwstate->fpregs)); + + /* + * Copy the status and control register. + */ + ufp->fpscr = hwstate->fpscr; + + /* + * Copy the exception registers. + */ + ufp_exc->fpexc = hwstate->fpexc; + ufp_exc->fpinst = hwstate->fpinst; + ufp_exc->fpinst2 = hwstate->fpinst2; + + /* 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 *ufp, struct user_vfp_exc *ufp_exc) +{ + struct thread_info *thread = current_thread_info(); + struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; + unsigned long fpexc; + + /* 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. + */ + memcpy(&hwstate->fpregs, &ufp->fpregs, sizeof(hwstate->fpregs)); + /* + * Copy the status and control register. + */ + hwstate->fpscr = ufp->fpscr; + + /* + * Sanitise and restore the exception registers. + */ + fpexc = ufp_exc->fpexc; + + /* 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; + + hwstate->fpinst = ufp_exc->fpinst; + hwstate->fpinst2 = ufp_exc->fpinst2; + + return 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; +} + +#ifdef CONFIG_KERNEL_MODE_NEON + +static int vfp_kmode_exception(struct pt_regs *regs, unsigned int instr) +{ + /* + * 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"); + pr_crit("FPEXC == 0x%08x\n", fmrx(FPEXC)); + return 1; +} + +static struct undef_hook vfp_kmode_exception_hook[] = {{ + .instr_mask = 0xfe000000, + .instr_val = 0xf2000000, + .cpsr_mask = MODE_MASK | PSR_T_BIT, + .cpsr_val = SVC_MODE, + .fn = vfp_kmode_exception, +}, { + .instr_mask = 0xff100000, + .instr_val = 0xf4000000, + .cpsr_mask = MODE_MASK | PSR_T_BIT, + .cpsr_val = SVC_MODE, + .fn = vfp_kmode_exception, +}, { + .instr_mask = 0xef000000, + .instr_val = 0xef000000, + .cpsr_mask = MODE_MASK | PSR_T_BIT, + .cpsr_val = SVC_MODE | PSR_T_BIT, + .fn = vfp_kmode_exception, +}, { + .instr_mask = 0xff100000, + .instr_val = 0xf9000000, + .cpsr_mask = MODE_MASK | PSR_T_BIT, + .cpsr_val = SVC_MODE | PSR_T_BIT, + .fn = vfp_kmode_exception, +}, { + .instr_mask = 0x0c000e00, + .instr_val = 0x0c000a00, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, + .fn = vfp_kmode_exception, +}}; + +static int __init vfp_kmode_exception_hook_init(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(vfp_kmode_exception_hook); i++) + register_undef_hook(&vfp_kmode_exception_hook[i]); + return 0; +} +subsys_initcall(vfp_kmode_exception_hook_init); + +/* + * 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 */ + +static int __init vfp_detect(struct pt_regs *regs, unsigned int instr) +{ + VFP_arch = UINT_MAX; /* mark as not present */ + regs->ARM_pc += 4; + return 0; +} + +static struct undef_hook vfp_detect_hook __initdata = { + .instr_mask = 0x0c000e00, + .instr_val = 0x0c000a00, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, + .fn = vfp_detect, +}; + +/* + * 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. + */ + register_undef_hook(&vfp_detect_hook); + barrier(); + vfpsid = fmrx(FPSID); + barrier(); + unregister_undef_hook(&vfp_detect_hook); + 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); |