arch/arm64/kernel/fpsimd.c

   1 /*
   2  * FP/SIMD context switching and fault handling
   3  *
   4  * Copyright (C) 2012 ARM Ltd.
   5  * Author: Catalin Marinas <catalin.marinas@arm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/cpu_pm.h>
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/sched.h>
  24 #include <linux/signal.h>
  25 #include <linux/hardirq.h>
  26
  27 #include <asm/fpsimd.h>
  28 #include <asm/cputype.h>
  29
  30 #define FPEXC_IOF       (1 << 0)
  31 #define FPEXC_DZF       (1 << 1)
  32 #define FPEXC_OFF       (1 << 2)
  33 #define FPEXC_UFF       (1 << 3)
  34 #define FPEXC_IXF       (1 << 4)
  35 #define FPEXC_IDF       (1 << 7)
  36
  37 /*
  38  * Trapped FP/ASIMD access.
  39  */
  40 void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
  41 {
  42         /* TODO: implement lazy context saving/restoring */
  43         WARN_ON(1);
  44 }
  45
  46 /*
  47  * Raise a SIGFPE for the current process.
  48  */
  49 void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
  50 {
  51         siginfo_t info;
  52         unsigned int si_code = 0;
  53
  54         if (esr & FPEXC_IOF)
  55                 si_code = FPE_FLTINV;
  56         else if (esr & FPEXC_DZF)
  57                 si_code = FPE_FLTDIV;
  58         else if (esr & FPEXC_OFF)
  59                 si_code = FPE_FLTOVF;
  60         else if (esr & FPEXC_UFF)
  61                 si_code = FPE_FLTUND;
  62         else if (esr & FPEXC_IXF)
  63                 si_code = FPE_FLTRES;
  64
  65         memset(&info, 0, sizeof(info));
  66         info.si_signo = SIGFPE;
  67         info.si_code = si_code;
  68         info.si_addr = (void __user *)instruction_pointer(regs);
  69
  70         send_sig_info(SIGFPE, &info, current);
  71 }
  72
  73 void fpsimd_thread_switch(struct task_struct *next)
  74 {
  75         /* check if not kernel threads */
  76         if (current->mm)
  77                 fpsimd_save_state(&current->thread.fpsimd_state);
  78         if (next->mm)
  79                 fpsimd_load_state(&next->thread.fpsimd_state);
  80 }
  81
  82 void fpsimd_flush_thread(void)
  83 {
  84         preempt_disable();
  85         memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
  86         fpsimd_load_state(&current->thread.fpsimd_state);
  87         preempt_enable();
  88 }
  89
  90 #ifdef CONFIG_KERNEL_MODE_NEON
  91
  92 /*
  93  * Kernel-side NEON support functions
  94  */
  95 void kernel_neon_begin(void)
  96 {
  97         /* Avoid using the NEON in interrupt context */
  98         BUG_ON(in_interrupt());
  99         preempt_disable();
 100
 101         if (current->mm)
 102                 fpsimd_save_state(&current->thread.fpsimd_state);
 103 }
 104 EXPORT_SYMBOL(kernel_neon_begin);
 105
 106 void kernel_neon_end(void)
 107 {
 108         if (current->mm)
 109                 fpsimd_load_state(&current->thread.fpsimd_state);
 110
 111         preempt_enable();
 112 }
 113 EXPORT_SYMBOL(kernel_neon_end);
 114
 115 #endif /* CONFIG_KERNEL_MODE_NEON */
 116
 117 #ifdef CONFIG_CPU_PM
 118 static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
 119                                   unsigned long cmd, void *v)
 120 {
 121         switch (cmd) {
 122         case CPU_PM_ENTER:
 123                 if (current->mm)
 124                         fpsimd_save_state(&current->thread.fpsimd_state);
 125                 break;
 126         case CPU_PM_EXIT:
 127                 if (current->mm)
 128                         fpsimd_load_state(&current->thread.fpsimd_state);
 129                 break;
 130         case CPU_PM_ENTER_FAILED:
 131         default:
 132                 return NOTIFY_DONE;
 133         }
 134         return NOTIFY_OK;
 135 }
 136
 137 static struct notifier_block fpsimd_cpu_pm_notifier_block = {
 138         .notifier_call = fpsimd_cpu_pm_notifier,
 139 };
 140
 141 static void fpsimd_pm_init(void)
 142 {
 143         cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
 144 }
 145
 146 #else
 147 static inline void fpsimd_pm_init(void) { }
 148 #endif /* CONFIG_CPU_PM */
 149
 150 /*
 151  * FP/SIMD support code initialisation.
 152  */
 153 static int __init fpsimd_init(void)
 154 {
 155         u64 pfr = read_cpuid(ID_AA64PFR0_EL1);
 156
 157         if (pfr & (0xf << 16)) {
 158                 pr_notice("Floating-point is not implemented\n");
 159                 return 0;
 160         }
 161         elf_hwcap |= HWCAP_FP;
 162
 163         if (pfr & (0xf << 20))
 164                 pr_notice("Advanced SIMD is not implemented\n");
 165         else
 166                 elf_hwcap |= HWCAP_ASIMD;
 167
 168         fpsimd_pm_init();
 169
 170         return 0;
 171 }
 172 late_initcall(fpsimd_init);