LXR linux/arch/sh/kernel/process

   1/*
   2 * arch/sh/kernel/process.c
   3 *
   4 * This file handles the architecture-dependent parts of process handling..
   5 *
   6 *  Copyright (C) 1995  Linus Torvalds
   7 *
   8 *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
   9 *                   Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
  10 *                   Copyright (C) 2002 - 2008  Paul Mundt
  11 *
  12 * This file is subject to the terms and conditions of the GNU General Public
  13 * License.  See the file "COPYING" in the main directory of this archive
  14 * for more details.
  15 */
  16#include <linux/module.h>
  17#include <linux/mm.h>
  18#include <linux/slab.h>
  19#include <linux/elfcore.h>
  20#include <linux/kallsyms.h>
  21#include <linux/fs.h>
  22#include <linux/ftrace.h>
  23#include <linux/hw_breakpoint.h>
  24#include <linux/prefetch.h>
  25#include <linux/stackprotector.h>
  26#include <asm/uaccess.h>
  27#include <asm/mmu_context.h>
  28#include <asm/fpu.h>
  29#include <asm/syscalls.h>
  30#include <asm/switch_to.h>
  31
  32void show_regs(struct pt_regs * regs)
  33{
  34        printk("\n");
  35        show_regs_print_info(KERN_DEFAULT);
  36
  37        print_symbol("PC is at %s\n", instruction_pointer(regs));
  38        print_symbol("PR is at %s\n", regs->pr);
  39
  40        printk("PC  : %08lx SP  : %08lx SR  : %08lx ",
  41               regs->pc, regs->regs[15], regs->sr);
  42#ifdef CONFIG_MMU
  43        printk("TEA : %08x\n", __raw_readl(MMU_TEA));
  44#else
  45        printk("\n");
  46#endif
  47
  48        printk("R0  : %08lx R1  : %08lx R2  : %08lx R3  : %08lx\n",
  49               regs->regs[0],regs->regs[1],
  50               regs->regs[2],regs->regs[3]);
  51        printk("R4  : %08lx R5  : %08lx R6  : %08lx R7  : %08lx\n",
  52               regs->regs[4],regs->regs[5],
  53               regs->regs[6],regs->regs[7]);
  54        printk("R8  : %08lx R9  : %08lx R10 : %08lx R11 : %08lx\n",
  55               regs->regs[8],regs->regs[9],
  56               regs->regs[10],regs->regs[11]);
  57        printk("R12 : %08lx R13 : %08lx R14 : %08lx\n",
  58               regs->regs[12],regs->regs[13],
  59               regs->regs[14]);
  60        printk("MACH: %08lx MACL: %08lx GBR : %08lx PR  : %08lx\n",
  61               regs->mach, regs->macl, regs->gbr, regs->pr);
  62
  63        show_trace(NULL, (unsigned long *)regs->regs[15], regs);
  64        show_code(regs);
  65}
  66
  67void start_thread(struct pt_regs *regs, unsigned long new_pc,
  68                  unsigned long new_sp)
  69{
  70        regs->pr = 0;
  71        regs->sr = SR_FD;
  72        regs->pc = new_pc;
  73        regs->regs[15] = new_sp;
  74
  75        free_thread_xstate(current);
  76}
  77EXPORT_SYMBOL(start_thread);
  78
  79/*
  80 * Free current thread data structures etc..
  81 */
  82void exit_thread(void)
  83{
  84}
  85
  86void flush_thread(void)
  87{
  88        struct task_struct *tsk = current;
  89
  90        flush_ptrace_hw_breakpoint(tsk);
  91
  92#if defined(CONFIG_SH_FPU)
  93        /* Forget lazy FPU state */
  94        clear_fpu(tsk, task_pt_regs(tsk));
  95        clear_used_math();
  96#endif
  97}
  98
  99void release_thread(struct task_struct *dead_task)
 100{
 101        /* do nothing */
 102}
 103
 104/* Fill in the fpu structure for a core dump.. */
 105int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 106{
 107        int fpvalid = 0;
 108
 109#if defined(CONFIG_SH_FPU)
 110        struct task_struct *tsk = current;
 111
 112        fpvalid = !!tsk_used_math(tsk);
 113        if (fpvalid)
 114                fpvalid = !fpregs_get(tsk, NULL, 0,
 115                                      sizeof(struct user_fpu_struct),
 116                                      fpu, NULL);
 117#endif
 118
 119        return fpvalid;
 120}
 121EXPORT_SYMBOL(dump_fpu);
 122
 123asmlinkage void ret_from_fork(void);
 124asmlinkage void ret_from_kernel_thread(void);
 125
 126int copy_thread(unsigned long clone_flags, unsigned long usp,
 127                unsigned long arg, struct task_struct *p)
 128{
 129        struct thread_info *ti = task_thread_info(p);
 130        struct pt_regs *childregs;
 131
 132#if defined(CONFIG_SH_DSP)
 133        struct task_struct *tsk = current;
 134
 135        if (is_dsp_enabled(tsk)) {
 136                /* We can use the __save_dsp or just copy the struct:
 137                 * __save_dsp(p);
 138                 * p->thread.dsp_status.status |= SR_DSP
 139                 */
 140                p->thread.dsp_status = tsk->thread.dsp_status;
 141        }
 142#endif
 143
 144        memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 145
 146        childregs = task_pt_regs(p);
 147        p->thread.sp = (unsigned long) childregs;
 148        if (unlikely(p->flags & PF_KTHREAD)) {
 149                memset(childregs, 0, sizeof(struct pt_regs));
 150                p->thread.pc = (unsigned long) ret_from_kernel_thread;
 151                childregs->regs[4] = arg;
 152                childregs->regs[5] = usp;
 153                childregs->sr = SR_MD;
 154#if defined(CONFIG_SH_FPU)
 155                childregs->sr |= SR_FD;
 156#endif
 157                ti->addr_limit = KERNEL_DS;
 158                ti->status &= ~TS_USEDFPU;
 159                p->fpu_counter = 0;
 160                return 0;
 161        }
 162        *childregs = *current_pt_regs();
 163
 164        if (usp)
 165                childregs->regs[15] = usp;
 166        ti->addr_limit = USER_DS;
 167
 168        if (clone_flags & CLONE_SETTLS)
 169                childregs->gbr = childregs->regs[0];
 170
 171        childregs->regs[0] = 0; /* Set return value for child */
 172        p->thread.pc = (unsigned long) ret_from_fork;
 173        return 0;
 174}
 175
 176/*
 177 *      switch_to(x,y) should switch tasks from x to y.
 178 *
 179 */
 180__notrace_funcgraph struct task_struct *
 181__switch_to(struct task_struct *prev, struct task_struct *next)
 182{
 183        struct thread_struct *next_t = &next->thread;
 184
 185#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
 186        __stack_chk_guard = next->stack_canary;
 187#endif
 188
 189        unlazy_fpu(prev, task_pt_regs(prev));
 190
 191        /* we're going to use this soon, after a few expensive things */
 192        if (next->fpu_counter > 5)
 193                prefetch(next_t->xstate);
 194
 195#ifdef CONFIG_MMU
 196        /*
 197         * Restore the kernel mode register
 198         *      k7 (r7_bank1)
 199         */
 200        asm volatile("ldc       %0, r7_bank"
 201                     : /* no output */
 202                     : "r" (task_thread_info(next)));
 203#endif
 204
 205        /*
 206         * If the task has used fpu the last 5 timeslices, just do a full
 207         * restore of the math state immediately to avoid the trap; the
 208         * chances of needing FPU soon are obviously high now
 209         */
 210        if (next->fpu_counter > 5)
 211                __fpu_state_restore();
 212
 213        return prev;
 214}
 215
 216unsigned long get_wchan(struct task_struct *p)
 217{
 218        unsigned long pc;
 219
 220        if (!p || p == current || p->state == TASK_RUNNING)
 221                return 0;
 222
 223        /*
 224         * The same comment as on the Alpha applies here, too ...
 225         */
 226        pc = thread_saved_pc(p);
 227
 228#ifdef CONFIG_FRAME_POINTER
 229        if (in_sched_functions(pc)) {
 230                unsigned long schedule_frame = (unsigned long)p->thread.sp;
 231                return ((unsigned long *)schedule_frame)[21];
 232        }
 233#endif
 234
 235        return pc;
 236}
 237