arch/sh/kernel/process_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * arch/sh/kernel/process.c
   4  *
   5  * This file handles the architecture-dependent parts of process handling..
   6  *
   7  *  Copyright (C) 1995  Linus Torvalds
   8  *
   9  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  10  *                   Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
  11  *                   Copyright (C) 2002 - 2008  Paul Mundt
  12  */
  13 #include <linux/module.h>
  14 #include <linux/mm.h>
  15 #include <linux/sched/debug.h>
  16 #include <linux/sched/task.h>
  17 #include <linux/sched/task_stack.h>
  18 #include <linux/slab.h>
  19 #include <linux/elfcore.h>
  20 #include <linux/fs.h>
  21 #include <linux/ftrace.h>
  22 #include <linux/hw_breakpoint.h>
  23 #include <linux/prefetch.h>
  24 #include <linux/stackprotector.h>
  25 #include <linux/uaccess.h>
  26 #include <asm/mmu_context.h>
  27 #include <asm/fpu.h>
  28 #include <asm/syscalls.h>
  29 #include <asm/switch_to.h>
  30
  31 void show_regs(struct pt_regs * regs)
  32 {
  33         pr_info("\n");
  34         show_regs_print_info(KERN_DEFAULT);
  35
  36         pr_info("PC is at %pS\n", (void *)instruction_pointer(regs));
  37         pr_info("PR is at %pS\n", (void *)regs->pr);
  38
  39         pr_info("PC  : %08lx SP  : %08lx SR  : %08lx ", regs->pc,
  40                 regs->regs[15], regs->sr);
  41 #ifdef CONFIG_MMU
  42         pr_cont("TEA : %08x\n", __raw_readl(MMU_TEA));
  43 #else
  44         pr_cont("\n");
  45 #endif
  46
  47         pr_info("R0  : %08lx R1  : %08lx R2  : %08lx R3  : %08lx\n",
  48                 regs->regs[0], regs->regs[1], regs->regs[2], regs->regs[3]);
  49         pr_info("R4  : %08lx R5  : %08lx R6  : %08lx R7  : %08lx\n",
  50                 regs->regs[4], regs->regs[5], regs->regs[6], regs->regs[7]);
  51         pr_info("R8  : %08lx R9  : %08lx R10 : %08lx R11 : %08lx\n",
  52                 regs->regs[8], regs->regs[9], regs->regs[10], regs->regs[11]);
  53         pr_info("R12 : %08lx R13 : %08lx R14 : %08lx\n",
  54                 regs->regs[12], regs->regs[13], regs->regs[14]);
  55         pr_info("MACH: %08lx MACL: %08lx GBR : %08lx PR  : %08lx\n",
  56                 regs->mach, regs->macl, regs->gbr, regs->pr);
  57
  58         show_trace(NULL, (unsigned long *)regs->regs[15], regs, KERN_DEFAULT);
  59         show_code(regs);
  60 }
  61
  62 void start_thread(struct pt_regs *regs, unsigned long new_pc,
  63                   unsigned long new_sp)
  64 {
  65         regs->pr = 0;
  66         regs->sr = SR_FD;
  67         regs->pc = new_pc;
  68         regs->regs[15] = new_sp;
  69
  70         free_thread_xstate(current);
  71 }
  72 EXPORT_SYMBOL(start_thread);
  73
  74 void flush_thread(void)
  75 {
  76         struct task_struct *tsk = current;
  77
  78         flush_ptrace_hw_breakpoint(tsk);
  79
  80 #if defined(CONFIG_SH_FPU)
  81         /* Forget lazy FPU state */
  82         clear_fpu(tsk, task_pt_regs(tsk));
  83         clear_used_math();
  84 #endif
  85 }
  86
  87 asmlinkage void ret_from_fork(void);
  88 asmlinkage void ret_from_kernel_thread(void);
  89
  90 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
  91 {
  92         unsigned long clone_flags = args->flags;
  93         unsigned long usp = args->stack;
  94         unsigned long tls = args->tls;
  95         struct thread_info *ti = task_thread_info(p);
  96         struct pt_regs *childregs;
  97
  98 #if defined(CONFIG_SH_DSP)
  99         struct task_struct *tsk = current;
 100
 101         if (is_dsp_enabled(tsk)) {
 102                 /* We can use the __save_dsp or just copy the struct:
 103                  * __save_dsp(p);
 104                  * p->thread.dsp_status.status |= SR_DSP
 105                  */
 106                 p->thread.dsp_status = tsk->thread.dsp_status;
 107         }
 108 #endif
 109
 110         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 111
 112         childregs = task_pt_regs(p);
 113         p->thread.sp = (unsigned long) childregs;
 114         if (unlikely(args->fn)) {
 115                 memset(childregs, 0, sizeof(struct pt_regs));
 116                 p->thread.pc = (unsigned long) ret_from_kernel_thread;
 117                 childregs->regs[4] = (unsigned long) args->fn_arg;
 118                 childregs->regs[5] = (unsigned long) args->fn;
 119                 childregs->sr = SR_MD;
 120 #if defined(CONFIG_SH_FPU)
 121                 childregs->sr |= SR_FD;
 122 #endif
 123                 ti->status &= ~TS_USEDFPU;
 124                 p->thread.fpu_counter = 0;
 125                 return 0;
 126         }
 127         *childregs = *current_pt_regs();
 128
 129         if (usp)
 130                 childregs->regs[15] = usp;
 131
 132         if (clone_flags & CLONE_SETTLS)
 133                 childregs->gbr = tls;
 134
 135         childregs->regs[0] = 0; /* Set return value for child */
 136         p->thread.pc = (unsigned long) ret_from_fork;
 137         return 0;
 138 }
 139
 140 /*
 141  *      switch_to(x,y) should switch tasks from x to y.
 142  *
 143  */
 144 __notrace_funcgraph struct task_struct *
 145 __switch_to(struct task_struct *prev, struct task_struct *next)
 146 {
 147         struct thread_struct *next_t = &next->thread;
 148
 149 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
 150         __stack_chk_guard = next->stack_canary;
 151 #endif
 152
 153         unlazy_fpu(prev, task_pt_regs(prev));
 154
 155         /* we're going to use this soon, after a few expensive things */
 156         if (next->thread.fpu_counter > 5)
 157                 prefetch(next_t->xstate);
 158
 159 #ifdef CONFIG_MMU
 160         /*
 161          * Restore the kernel mode register
 162          *      k7 (r7_bank1)
 163          */
 164         asm volatile("ldc       %0, r7_bank"
 165                      : /* no output */
 166                      : "r" (task_thread_info(next)));
 167 #endif
 168
 169         /*
 170          * If the task has used fpu the last 5 timeslices, just do a full
 171          * restore of the math state immediately to avoid the trap; the
 172          * chances of needing FPU soon are obviously high now
 173          */
 174         if (next->thread.fpu_counter > 5)
 175                 __fpu_state_restore();
 176
 177         return prev;
 178 }
 179
 180 unsigned long __get_wchan(struct task_struct *p)
 181 {
 182         unsigned long pc;
 183
 184         /*
 185          * The same comment as on the Alpha applies here, too ...
 186          */
 187         pc = thread_saved_pc(p);
 188
 189 #ifdef CONFIG_FRAME_POINTER
 190         if (in_sched_functions(pc)) {
 191                 unsigned long schedule_frame = (unsigned long)p->thread.sp;
 192                 return ((unsigned long *)schedule_frame)[21];
 193         }
 194 #endif
 195
 196         return pc;
 197 }