/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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; memset(&info, 0, sizeof(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(0, 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_force_reload(cpu, current_thread_info()); 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, "AP_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);