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