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
  28 register unsigned long gp_in_global __asm__("gp");
  29
  30 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  31 #include <linux/stackprotector.h>
  32 unsigned long __stack_chk_guard __read_mostly;
  33 EXPORT_SYMBOL(__stack_chk_guard);
  34 #endif
  35
  36 extern asmlinkage void ret_from_fork(void);
  37 extern asmlinkage void ret_from_kernel_thread(void);
  38
  39 void arch_cpu_idle(void)
  40 {
  41         cpu_do_idle();
  42         raw_local_irq_enable();
  43 }
  44
  45 void __show_regs(struct pt_regs *regs)
  46 {
  47         show_regs_print_info(KERN_DEFAULT);
  48
  49         if (!user_mode(regs)) {
  50                 pr_cont("epc : %pS\n", (void *)regs->epc);
  51                 pr_cont(" ra : %pS\n", (void *)regs->ra);
  52         }
  53
  54         pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
  55                 regs->epc, regs->ra, regs->sp);
  56         pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
  57                 regs->gp, regs->tp, regs->t0);
  58         pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
  59                 regs->t1, regs->t2, regs->s0);
  60         pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
  61                 regs->s1, regs->a0, regs->a1);
  62         pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
  63                 regs->a2, regs->a3, regs->a4);
  64         pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
  65                 regs->a5, regs->a6, regs->a7);
  66         pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
  67                 regs->s2, regs->s3, regs->s4);
  68         pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
  69                 regs->s5, regs->s6, regs->s7);
  70         pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
  71                 regs->s8, regs->s9, regs->s10);
  72         pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
  73                 regs->s11, regs->t3, regs->t4);
  74         pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
  75                 regs->t5, regs->t6);
  76
  77         pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
  78                 regs->status, regs->badaddr, regs->cause);
  79 }
  80 void show_regs(struct pt_regs *regs)
  81 {
  82         __show_regs(regs);
  83         if (!user_mode(regs))
  84                 dump_backtrace(regs, NULL, KERN_DEFAULT);
  85 }
  86
  87 #ifdef CONFIG_COMPAT
  88 static bool compat_mode_supported __read_mostly;
  89
  90 bool compat_elf_check_arch(Elf32_Ehdr *hdr)
  91 {
  92         return compat_mode_supported &&
  93                hdr->e_machine == EM_RISCV &&
  94                hdr->e_ident[EI_CLASS] == ELFCLASS32;
  95 }
  96
  97 static int __init compat_mode_detect(void)
  98 {
  99         unsigned long tmp = csr_read(CSR_STATUS);
 100
 101         csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
 102         compat_mode_supported =
 103                         (csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
 104
 105         csr_write(CSR_STATUS, tmp);
 106
 107         pr_info("riscv: ELF compat mode %s",
 108                         compat_mode_supported ? "supported" : "failed");
 109
 110         return 0;
 111 }
 112 early_initcall(compat_mode_detect);
 113 #endif
 114
 115 void start_thread(struct pt_regs *regs, unsigned long pc,
 116         unsigned long sp)
 117 {
 118         regs->status = SR_PIE;
 119         if (has_fpu()) {
 120                 regs->status |= SR_FS_INITIAL;
 121                 /*
 122                  * Restore the initial value to the FP register
 123                  * before starting the user program.
 124                  */
 125                 fstate_restore(current, regs);
 126         }
 127         regs->epc = pc;
 128         regs->sp = sp;
 129
 130 #ifdef CONFIG_64BIT
 131         regs->status &= ~SR_UXL;
 132
 133         if (is_compat_task())
 134                 regs->status |= SR_UXL_32;
 135         else
 136                 regs->status |= SR_UXL_64;
 137 #endif
 138 }
 139
 140 void flush_thread(void)
 141 {
 142 #ifdef CONFIG_FPU
 143         /*
 144          * Reset FPU state and context
 145          *      frm: round to nearest, ties to even (IEEE default)
 146          *      fflags: accrued exceptions cleared
 147          */
 148         fstate_off(current, task_pt_regs(current));
 149         memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
 150 #endif
 151 }
 152
 153 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 154 {
 155         fstate_save(src, task_pt_regs(src));
 156         *dst = *src;
 157         return 0;
 158 }
 159
 160 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 161 {
 162         unsigned long clone_flags = args->flags;
 163         unsigned long usp = args->stack;
 164         unsigned long tls = args->tls;
 165         struct pt_regs *childregs = task_pt_regs(p);
 166
 167         /* p->thread holds context to be restored by __switch_to() */
 168         if (unlikely(args->fn)) {
 169                 /* Kernel thread */
 170                 memset(childregs, 0, sizeof(struct pt_regs));
 171                 childregs->gp = gp_in_global;
 172                 /* Supervisor/Machine, irqs on: */
 173                 childregs->status = SR_PP | SR_PIE;
 174
 175                 p->thread.ra = (unsigned long)ret_from_kernel_thread;
 176                 p->thread.s[0] = (unsigned long)args->fn;
 177                 p->thread.s[1] = (unsigned long)args->fn_arg;
 178         } else {
 179                 *childregs = *(current_pt_regs());
 180                 if (usp) /* User fork */
 181                         childregs->sp = usp;
 182                 if (clone_flags & CLONE_SETTLS)
 183                         childregs->tp = tls;
 184                 childregs->a0 = 0; /* Return value of fork() */
 185                 p->thread.ra = (unsigned long)ret_from_fork;
 186         }
 187         p->thread.sp = (unsigned long)childregs; /* kernel sp */
 188         return 0;
 189 }