arch/riscv/kernel/process.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   4  *  Chen Liqin <liqin.chen@sunplusct.com>
   5  *  Lennox Wu <lennox.wu@sunplusct.com>
   6  * Copyright (C) 2012 Regents of the University of California
   7  * Copyright (C) 2017 SiFive
   8  */
   9
  10 #include <linux/cpu.h>
  11 #include <linux/kernel.h>
  12 #include <linux/sched.h>
  13 #include <linux/sched/debug.h>
  14 #include <linux/sched/task_stack.h>
  15 #include <linux/tick.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/uaccess.h>
  18
  19 #include <asm/unistd.h>
  20 #include <asm/processor.h>
  21 #include <asm/csr.h>
  22 #include <asm/stacktrace.h>
  23 #include <asm/string.h>
  24 #include <asm/switch_to.h>
  25 #include <asm/thread_info.h>
  26 #include <asm/cpuidle.h>
  27 #include <asm/vector.h>
  28 #include <asm/cpufeature.h>
  29
  30 register unsigned long gp_in_global __asm__("gp");
  31
  32 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  33 #include <linux/stackprotector.h>
  34 unsigned long __stack_chk_guard __read_mostly;
  35 EXPORT_SYMBOL(__stack_chk_guard);
  36 #endif
  37
  38 extern asmlinkage void ret_from_fork(void);
  39
  40 void arch_cpu_idle(void)
  41 {
  42         cpu_do_idle();
  43 }
  44
  45 int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
  46 {
  47         if (!unaligned_ctl_available())
  48                 return -EINVAL;
  49
  50         tsk->thread.align_ctl = val;
  51         return 0;
  52 }
  53
  54 int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
  55 {
  56         if (!unaligned_ctl_available())
  57                 return -EINVAL;
  58
  59         return put_user(tsk->thread.align_ctl, (unsigned long __user *)adr);
  60 }
  61
  62 void __show_regs(struct pt_regs *regs)
  63 {
  64         show_regs_print_info(KERN_DEFAULT);
  65
  66         if (!user_mode(regs)) {
  67                 pr_cont("epc : %pS\n", (void *)regs->epc);
  68                 pr_cont(" ra : %pS\n", (void *)regs->ra);
  69         }
  70
  71         pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
  72                 regs->epc, regs->ra, regs->sp);
  73         pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
  74                 regs->gp, regs->tp, regs->t0);
  75         pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
  76                 regs->t1, regs->t2, regs->s0);
  77         pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
  78                 regs->s1, regs->a0, regs->a1);
  79         pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
  80                 regs->a2, regs->a3, regs->a4);
  81         pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
  82                 regs->a5, regs->a6, regs->a7);
  83         pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
  84                 regs->s2, regs->s3, regs->s4);
  85         pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
  86                 regs->s5, regs->s6, regs->s7);
  87         pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
  88                 regs->s8, regs->s9, regs->s10);
  89         pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
  90                 regs->s11, regs->t3, regs->t4);
  91         pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
  92                 regs->t5, regs->t6);
  93
  94         pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
  95                 regs->status, regs->badaddr, regs->cause);
  96 }
  97 void show_regs(struct pt_regs *regs)
  98 {
  99         __show_regs(regs);
 100         if (!user_mode(regs))
 101                 dump_backtrace(regs, NULL, KERN_DEFAULT);
 102 }
 103
 104 #ifdef CONFIG_COMPAT
 105 static bool compat_mode_supported __read_mostly;
 106
 107 bool compat_elf_check_arch(Elf32_Ehdr *hdr)
 108 {
 109         return compat_mode_supported &&
 110                hdr->e_machine == EM_RISCV &&
 111                hdr->e_ident[EI_CLASS] == ELFCLASS32;
 112 }
 113
 114 static int __init compat_mode_detect(void)
 115 {
 116         unsigned long tmp = csr_read(CSR_STATUS);
 117
 118         csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
 119         compat_mode_supported =
 120                         (csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
 121
 122         csr_write(CSR_STATUS, tmp);
 123
 124         pr_info("riscv: ELF compat mode %s",
 125                         compat_mode_supported ? "supported" : "unsupported");
 126
 127         return 0;
 128 }
 129 early_initcall(compat_mode_detect);
 130 #endif
 131
 132 void start_thread(struct pt_regs *regs, unsigned long pc,
 133         unsigned long sp)
 134 {
 135         regs->status = SR_PIE;
 136         if (has_fpu()) {
 137                 regs->status |= SR_FS_INITIAL;
 138                 /*
 139                  * Restore the initial value to the FP register
 140                  * before starting the user program.
 141                  */
 142                 fstate_restore(current, regs);
 143         }
 144         regs->epc = pc;
 145         regs->sp = sp;
 146
 147 #ifdef CONFIG_64BIT
 148         regs->status &= ~SR_UXL;
 149
 150         if (is_compat_task())
 151                 regs->status |= SR_UXL_32;
 152         else
 153                 regs->status |= SR_UXL_64;
 154 #endif
 155 }
 156
 157 void flush_thread(void)
 158 {
 159 #ifdef CONFIG_FPU
 160         /*
 161          * Reset FPU state and context
 162          *      frm: round to nearest, ties to even (IEEE default)
 163          *      fflags: accrued exceptions cleared
 164          */
 165         fstate_off(current, task_pt_regs(current));
 166         memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
 167 #endif
 168 #ifdef CONFIG_RISCV_ISA_V
 169         /* Reset vector state */
 170         riscv_v_vstate_ctrl_init(current);
 171         riscv_v_vstate_off(task_pt_regs(current));
 172         kfree(current->thread.vstate.datap);
 173         memset(&current->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
 174 #endif
 175 }
 176
 177 void arch_release_task_struct(struct task_struct *tsk)
 178 {
 179         /* Free the vector context of datap. */
 180         if (has_vector())
 181                 kfree(tsk->thread.vstate.datap);
 182 }
 183
 184 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 185 {
 186         fstate_save(src, task_pt_regs(src));
 187         *dst = *src;
 188         /* clear entire V context, including datap for a new task */
 189         memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
 190
 191         return 0;
 192 }
 193
 194 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 195 {
 196         unsigned long clone_flags = args->flags;
 197         unsigned long usp = args->stack;
 198         unsigned long tls = args->tls;
 199         struct pt_regs *childregs = task_pt_regs(p);
 200
 201         memset(&p->thread.s, 0, sizeof(p->thread.s));
 202
 203         /* p->thread holds context to be restored by __switch_to() */
 204         if (unlikely(args->fn)) {
 205                 /* Kernel thread */
 206                 memset(childregs, 0, sizeof(struct pt_regs));
 207                 childregs->gp = gp_in_global;
 208                 /* Supervisor/Machine, irqs on: */
 209                 childregs->status = SR_PP | SR_PIE;
 210
 211                 p->thread.s[0] = (unsigned long)args->fn;
 212                 p->thread.s[1] = (unsigned long)args->fn_arg;
 213         } else {
 214                 *childregs = *(current_pt_regs());
 215                 /* Turn off status.VS */
 216                 riscv_v_vstate_off(childregs);
 217                 if (usp) /* User fork */
 218                         childregs->sp = usp;
 219                 if (clone_flags & CLONE_SETTLS)
 220                         childregs->tp = tls;
 221                 childregs->a0 = 0; /* Return value of fork() */
 222                 p->thread.s[0] = 0;
 223         }
 224         p->thread.ra = (unsigned long)ret_from_fork;
 225         p->thread.sp = (unsigned long)childregs; /* kernel sp */
 226         return 0;
 227 }