/* * 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 "vfpinstr.h" #include "vfp.h" /* * Our undef handlers (in entry.S) */ void vfp_testing_entry(void); void vfp_support_entry(void); void vfp_null_entry(void); 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 * - 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. */ 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; printk(KERN_ERR "VFP: Error: %s\n", reason); printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n", fmrx(FPEXC), fmrx(FPSCR), inst); for (i = 0; i < 32; i += 2) printk(KERN_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)); } #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) { printk(KERN_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(); } /* * 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. * * Both CPU_DYING and CPU_STARTING are called on the CPU which * is being offlined/onlined. */ static int vfp_hotplug(struct notifier_block *b, unsigned long action, void *hcpu) { if (action == CPU_DYING || action == CPU_DYING_FROZEN) { vfp_force_reload((long)hcpu, current_thread_info()); } else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN) vfp_enable(NULL); return NOTIFY_OK; } /* * VFP support code initialisation. */ static int __init vfp_init(void) { unsigned int vfpsid; unsigned int cpu_arch = cpu_architecture(); 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; printk(KERN_INFO "VFP support v0.3: "); if (VFP_arch) printk("not present\n"); else if (vfpsid & FPSID_NODOUBLE) { printk("no double precision support\n"); } else { hotcpu_notifier(vfp_hotplug, 0); VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */ printk("implementor %02x architecture %d part %02x variant %x rev %x\n", (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT, (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT, (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT, (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT, (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT); 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; #ifdef CONFIG_VFPv3 if (VFP_arch >= 2) { elf_hwcap |= HWCAP_VFPv3; /* * Check for VFPv3 D16 and VFPv4 D16. CPUs in * this configuration only have 16 x 64bit * registers. */ if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) elf_hwcap |= HWCAP_VFPv3D16; /* also v4-D16 */ else elf_hwcap |= HWCAP_VFPD32; } #endif /* * 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 ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { #ifdef CONFIG_NEON if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100) elf_hwcap |= HWCAP_NEON; #endif #ifdef CONFIG_VFPv3 if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000) elf_hwcap |= HWCAP_VFPv4; #endif } } return 0; } late_initcall(vfp_init);