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         printk("\n");
  34         show_regs_print_info(KERN_DEFAULT);
  35
  36         printk("PC is at %pS\n", (void *)instruction_pointer(regs));
  37         printk("PR is at %pS\n", (void *)regs->pr);
  38
  39         printk("PC  : %08lx SP  : %08lx SR  : %08lx ",
  40                regs->pc, regs->regs[15], regs->sr);
  41 #ifdef CONFIG_MMU
  42         printk("TEA : %08x\n", __raw_readl(MMU_TEA));
  43 #else
  44         printk("\n");
  45 #endif
  46
  47         printk("R0  : %08lx R1  : %08lx R2  : %08lx R3  : %08lx\n",
  48                regs->regs[0],regs->regs[1],
  49                regs->regs[2],regs->regs[3]);
  50         printk("R4  : %08lx R5  : %08lx R6  : %08lx R7  : %08lx\n",
  51                regs->regs[4],regs->regs[5],
  52                regs->regs[6],regs->regs[7]);
  53         printk("R8  : %08lx R9  : %08lx R10 : %08lx R11 : %08lx\n",
  54                regs->regs[8],regs->regs[9],
  55                regs->regs[10],regs->regs[11]);
  56         printk("R12 : %08lx R13 : %08lx R14 : %08lx\n",
  57                regs->regs[12],regs->regs[13],
  58                regs->regs[14]);
  59         printk("MACH: %08lx MACL: %08lx GBR : %08lx PR  : %08lx\n",
  60                regs->mach, regs->macl, regs->gbr, regs->pr);
  61
  62         show_trace(NULL, (unsigned long *)regs->regs[15], regs, KERN_DEFAULT);
  63         show_code(regs);
  64 }
  65
  66 void start_thread(struct pt_regs *regs, unsigned long new_pc,
  67                   unsigned long new_sp)
  68 {
  69         regs->pr = 0;
  70         regs->sr = SR_FD;
  71         regs->pc = new_pc;
  72         regs->regs[15] = new_sp;
  73
  74         free_thread_xstate(current);
  75 }
  76 EXPORT_SYMBOL(start_thread);
  77
  78 void flush_thread(void)
  79 {
  80         struct task_struct *tsk = current;
  81
  82         flush_ptrace_hw_breakpoint(tsk);
  83
  84 #if defined(CONFIG_SH_FPU)
  85         /* Forget lazy FPU state */
  86         clear_fpu(tsk, task_pt_regs(tsk));
  87         clear_used_math();
  88 #endif
  89 }
  90
  91 void release_thread(struct task_struct *dead_task)
  92 {
  93         /* do nothing */
  94 }
  95
  96 /* Fill in the fpu structure for a core dump.. */
  97 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
  98 {
  99         int fpvalid = 0;
 100
 101 #if defined(CONFIG_SH_FPU)
 102         struct task_struct *tsk = current;
 103
 104         fpvalid = !!tsk_used_math(tsk);
 105         if (fpvalid)
 106                 fpvalid = !fpregs_get(tsk, NULL,
 107                                       (struct membuf){fpu, sizeof(*fpu)});
 108 #endif
 109
 110         return fpvalid;
 111 }
 112 EXPORT_SYMBOL(dump_fpu);
 113
 114 asmlinkage void ret_from_fork(void);
 115 asmlinkage void ret_from_kernel_thread(void);
 116
 117 int copy_thread(unsigned long clone_flags, unsigned long usp,
 118                 unsigned long arg, struct task_struct *p)
 119 {
 120         struct thread_info *ti = task_thread_info(p);
 121         struct pt_regs *childregs;
 122
 123 #if defined(CONFIG_SH_DSP)
 124         struct task_struct *tsk = current;
 125
 126         if (is_dsp_enabled(tsk)) {
 127                 /* We can use the __save_dsp or just copy the struct:
 128                  * __save_dsp(p);
 129                  * p->thread.dsp_status.status |= SR_DSP
 130                  */
 131                 p->thread.dsp_status = tsk->thread.dsp_status;
 132         }
 133 #endif
 134
 135         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 136
 137         childregs = task_pt_regs(p);
 138         p->thread.sp = (unsigned long) childregs;
 139         if (unlikely(p->flags & PF_KTHREAD)) {
 140                 memset(childregs, 0, sizeof(struct pt_regs));
 141                 p->thread.pc = (unsigned long) ret_from_kernel_thread;
 142                 childregs->regs[4] = arg;
 143                 childregs->regs[5] = usp;
 144                 childregs->sr = SR_MD;
 145 #if defined(CONFIG_SH_FPU)
 146                 childregs->sr |= SR_FD;
 147 #endif
 148                 ti->addr_limit = KERNEL_DS;
 149                 ti->status &= ~TS_USEDFPU;
 150                 p->thread.fpu_counter = 0;
 151                 return 0;
 152         }
 153         *childregs = *current_pt_regs();
 154
 155         if (usp)
 156                 childregs->regs[15] = usp;
 157         ti->addr_limit = USER_DS;
 158
 159         if (clone_flags & CLONE_SETTLS)
 160                 childregs->gbr = childregs->regs[0];
 161
 162         childregs->regs[0] = 0; /* Set return value for child */
 163         p->thread.pc = (unsigned long) ret_from_fork;
 164         return 0;
 165 }
 166
 167 /*
 168  *      switch_to(x,y) should switch tasks from x to y.
 169  *
 170  */
 171 __notrace_funcgraph struct task_struct *
 172 __switch_to(struct task_struct *prev, struct task_struct *next)
 173 {
 174         struct thread_struct *next_t = &next->thread;
 175
 176 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
 177         __stack_chk_guard = next->stack_canary;
 178 #endif
 179
 180         unlazy_fpu(prev, task_pt_regs(prev));
 181
 182         /* we're going to use this soon, after a few expensive things */
 183         if (next->thread.fpu_counter > 5)
 184                 prefetch(next_t->xstate);
 185
 186 #ifdef CONFIG_MMU
 187         /*
 188          * Restore the kernel mode register
 189          *      k7 (r7_bank1)
 190          */
 191         asm volatile("ldc       %0, r7_bank"
 192                      : /* no output */
 193                      : "r" (task_thread_info(next)));
 194 #endif
 195
 196         /*
 197          * If the task has used fpu the last 5 timeslices, just do a full
 198          * restore of the math state immediately to avoid the trap; the
 199          * chances of needing FPU soon are obviously high now
 200          */
 201         if (next->thread.fpu_counter > 5)
 202                 __fpu_state_restore();
 203
 204         return prev;
 205 }
 206
 207 unsigned long get_wchan(struct task_struct *p)
 208 {
 209         unsigned long pc;
 210
 211         if (!p || p == current || p->state == TASK_RUNNING)
 212                 return 0;
 213
 214         /*
 215          * The same comment as on the Alpha applies here, too ...
 216          */
 217         pc = thread_saved_pc(p);
 218
 219 #ifdef CONFIG_FRAME_POINTER
 220         if (in_sched_functions(pc)) {
 221                 unsigned long schedule_frame = (unsigned long)p->thread.sp;
 222                 return ((unsigned long *)schedule_frame)[21];
 223         }
 224 #endif
 225
 226         return pc;
 227 }