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
  25 #include <asm/fpsimd.h>
  26 #include <asm/cputype.h>
  27
  28 #define FPEXC_IOF       (1 << 0)
  29 #define FPEXC_DZF       (1 << 1)
  30 #define FPEXC_OFF       (1 << 2)
  31 #define FPEXC_UFF       (1 << 3)
  32 #define FPEXC_IXF       (1 << 4)
  33 #define FPEXC_IDF       (1 << 7)
  34
  35 /*
  36  * Trapped FP/ASIMD access.
  37  */
  38 void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
  39 {
  40         /* TODO: implement lazy context saving/restoring */
  41         WARN_ON(1);
  42 }
  43
  44 /*
  45  * Raise a SIGFPE for the current process.
  46  */
  47 void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
  48 {
  49         siginfo_t info;
  50         unsigned int si_code = 0;
  51
  52         if (esr & FPEXC_IOF)
  53                 si_code = FPE_FLTINV;
  54         else if (esr & FPEXC_DZF)
  55                 si_code = FPE_FLTDIV;
  56         else if (esr & FPEXC_OFF)
  57                 si_code = FPE_FLTOVF;
  58         else if (esr & FPEXC_UFF)
  59                 si_code = FPE_FLTUND;
  60         else if (esr & FPEXC_IXF)
  61                 si_code = FPE_FLTRES;
  62
  63         memset(&info, 0, sizeof(info));
  64         info.si_signo = SIGFPE;
  65         info.si_code = si_code;
  66         info.si_addr = (void __user *)instruction_pointer(regs);
  67
  68         send_sig_info(SIGFPE, &info, current);
  69 }
  70
  71 void fpsimd_thread_switch(struct task_struct *next)
  72 {
  73         /* check if not kernel threads */
  74         if (current->mm)
  75                 fpsimd_save_state(&current->thread.fpsimd_state);
  76         if (next->mm)
  77                 fpsimd_load_state(&next->thread.fpsimd_state);
  78 }
  79
  80 void fpsimd_flush_thread(void)
  81 {
  82         memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
  83         fpsimd_load_state(&current->thread.fpsimd_state);
  84 }
  85
  86 /*
  87  * FP/SIMD support code initialisation.
  88  */
  89 static int __init fpsimd_init(void)
  90 {
  91         u64 pfr = read_cpuid(ID_AA64PFR0_EL1);
  92
  93         if (pfr & (0xf << 16)) {
  94                 pr_notice("Floating-point is not implemented\n");
  95                 return 0;
  96         }
  97         elf_hwcap |= HWCAP_FP;
  98
  99         if (pfr & (0xf << 20))
 100                 pr_notice("Advanced SIMD is not implemented\n");
 101         else
 102                 elf_hwcap |= HWCAP_ASIMD;
 103
 104         return 0;
 105 }
 106 late_initcall(fpsimd_init);