linux/arch/sh/kernel/process_32.c
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   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
  31void 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
  62void 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}
  72EXPORT_SYMBOL(start_thread);
  73
  74void 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
  87void release_thread(struct task_struct *dead_task)
  88{
  89        /* do nothing */
  90}
  91
  92asmlinkage void ret_from_fork(void);
  93asmlinkage void ret_from_kernel_thread(void);
  94
  95int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
  96                struct task_struct *p, unsigned long tls)
  97{
  98        struct thread_info *ti = task_thread_info(p);
  99        struct pt_regs *childregs;
 100
 101#if defined(CONFIG_SH_DSP)
 102        struct task_struct *tsk = current;
 103
 104        if (is_dsp_enabled(tsk)) {
 105                /* We can use the __save_dsp or just copy the struct:
 106                 * __save_dsp(p);
 107                 * p->thread.dsp_status.status |= SR_DSP
 108                 */
 109                p->thread.dsp_status = tsk->thread.dsp_status;
 110        }
 111#endif
 112
 113        memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 114
 115        childregs = task_pt_regs(p);
 116        p->thread.sp = (unsigned long) childregs;
 117        if (unlikely(p->flags & PF_KTHREAD)) {
 118                memset(childregs, 0, sizeof(struct pt_regs));
 119                p->thread.pc = (unsigned long) ret_from_kernel_thread;
 120                childregs->regs[4] = arg;
 121                childregs->regs[5] = usp;
 122                childregs->sr = SR_MD;
 123#if defined(CONFIG_SH_FPU)
 124                childregs->sr |= SR_FD;
 125#endif
 126                ti->addr_limit = KERNEL_DS;
 127                ti->status &= ~TS_USEDFPU;
 128                p->thread.fpu_counter = 0;
 129                return 0;
 130        }
 131        *childregs = *current_pt_regs();
 132
 133        if (usp)
 134                childregs->regs[15] = usp;
 135        ti->addr_limit = USER_DS;
 136
 137        if (clone_flags & CLONE_SETTLS)
 138                childregs->gbr = tls;
 139
 140        childregs->regs[0] = 0; /* Set return value for child */
 141        p->thread.pc = (unsigned long) ret_from_fork;
 142        return 0;
 143}
 144
 145/*
 146 *      switch_to(x,y) should switch tasks from x to y.
 147 *
 148 */
 149__notrace_funcgraph struct task_struct *
 150__switch_to(struct task_struct *prev, struct task_struct *next)
 151{
 152        struct thread_struct *next_t = &next->thread;
 153
 154#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
 155        __stack_chk_guard = next->stack_canary;
 156#endif
 157
 158        unlazy_fpu(prev, task_pt_regs(prev));
 159
 160        /* we're going to use this soon, after a few expensive things */
 161        if (next->thread.fpu_counter > 5)
 162                prefetch(next_t->xstate);
 163
 164#ifdef CONFIG_MMU
 165        /*
 166         * Restore the kernel mode register
 167         *      k7 (r7_bank1)
 168         */
 169        asm volatile("ldc       %0, r7_bank"
 170                     : /* no output */
 171                     : "r" (task_thread_info(next)));
 172#endif
 173
 174        /*
 175         * If the task has used fpu the last 5 timeslices, just do a full
 176         * restore of the math state immediately to avoid the trap; the
 177         * chances of needing FPU soon are obviously high now
 178         */
 179        if (next->thread.fpu_counter > 5)
 180                __fpu_state_restore();
 181
 182        return prev;
 183}
 184
 185unsigned long get_wchan(struct task_struct *p)
 186{
 187        unsigned long pc;
 188
 189        if (!p || p == current || p->state == TASK_RUNNING)
 190                return 0;
 191
 192        /*
 193         * The same comment as on the Alpha applies here, too ...
 194         */
 195        pc = thread_saved_pc(p);
 196
 197#ifdef CONFIG_FRAME_POINTER
 198        if (in_sched_functions(pc)) {
 199                unsigned long schedule_frame = (unsigned long)p->thread.sp;
 200                return ((unsigned long *)schedule_frame)[21];
 201        }
 202#endif
 203
 204        return pc;
 205}
 206