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/kernel.h>
  21 #include <linux/init.h>
  22 #include <linux/sched.h>
  23 #include <linux/signal.h>
  24 #include <linux/hardirq.h>
  25
  26 #include <asm/fpsimd.h>
  27 #include <asm/cputype.h>
  28
  29 #define FPEXC_IOF       (1 << 0)
  30 #define FPEXC_DZF       (1 << 1)
  31 #define FPEXC_OFF       (1 << 2)
  32 #define FPEXC_UFF       (1 << 3)
  33 #define FPEXC_IXF       (1 << 4)
  34 #define FPEXC_IDF       (1 << 7)
  35
  36 /*
  37  * Trapped FP/ASIMD access.
  38  */
  39 void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
  40 {
  41         /* TODO: implement lazy context saving/restoring */
  42         WARN_ON(1);
  43 }
  44
  45 /*
  46  * Raise a SIGFPE for the current process.
  47  */
  48 void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
  49 {
  50         siginfo_t info;
  51         unsigned int si_code = 0;
  52
  53         if (esr & FPEXC_IOF)
  54                 si_code = FPE_FLTINV;
  55         else if (esr & FPEXC_DZF)
  56                 si_code = FPE_FLTDIV;
  57         else if (esr & FPEXC_OFF)
  58                 si_code = FPE_FLTOVF;
  59         else if (esr & FPEXC_UFF)
  60                 si_code = FPE_FLTUND;
  61         else if (esr & FPEXC_IXF)
  62                 si_code = FPE_FLTRES;
  63
  64         memset(&info, 0, sizeof(info));
  65         info.si_signo = SIGFPE;
  66         info.si_code = si_code;
  67         info.si_addr = (void __user *)instruction_pointer(regs);
  68
  69         send_sig_info(SIGFPE, &info, current);
  70 }
  71
  72 void fpsimd_thread_switch(struct task_struct *next)
  73 {
  74         /* check if not kernel threads */
  75         if (current->mm)
  76                 fpsimd_save_state(&current->thread.fpsimd_state);
  77         if (next->mm)
  78                 fpsimd_load_state(&next->thread.fpsimd_state);
  79 }
  80
  81 void fpsimd_flush_thread(void)
  82 {
  83         preempt_disable();
  84         memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
  85         fpsimd_load_state(&current->thread.fpsimd_state);
  86         preempt_enable();
  87 }
  88
  89 #ifdef CONFIG_KERNEL_MODE_NEON
  90
  91 /*
  92  * Kernel-side NEON support functions
  93  */
  94 void kernel_neon_begin(void)
  95 {
  96         /* Avoid using the NEON in interrupt context */
  97         BUG_ON(in_interrupt());
  98         preempt_disable();
  99
 100         if (current->mm)
 101                 fpsimd_save_state(&current->thread.fpsimd_state);
 102 }
 103 EXPORT_SYMBOL(kernel_neon_begin);
 104
 105 void kernel_neon_end(void)
 106 {
 107         if (current->mm)
 108                 fpsimd_load_state(&current->thread.fpsimd_state);
 109
 110         preempt_enable();
 111 }
 112 EXPORT_SYMBOL(kernel_neon_end);
 113
 114 #endif /* CONFIG_KERNEL_MODE_NEON */
 115
 116 /*
 117  * FP/SIMD support code initialisation.
 118  */
 119 static int __init fpsimd_init(void)
 120 {
 121         u64 pfr = read_cpuid(ID_AA64PFR0_EL1);
 122
 123         if (pfr & (0xf << 16)) {
 124                 pr_notice("Floating-point is not implemented\n");
 125                 return 0;
 126         }
 127         elf_hwcap |= HWCAP_FP;
 128
 129         if (pfr & (0xf << 20))
 130                 pr_notice("Advanced SIMD is not implemented\n");
 131         else
 132                 elf_hwcap |= HWCAP_ASIMD;
 133
 134         return 0;
 135 }
 136 late_initcall(fpsimd_init);