64c7c8f885
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce confusion, and make their semantics rigid. Improves efficiency of resched_task and some cpu_idle routines. * In resched_task: - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held, and as we hold it during resched_task, then there is no need for an atomic test and set there. The only other time this should be set is when the task's quantum expires, in the timer interrupt - this is protected against because the rq lock is irq-safe. - If TIF_NEED_RESCHED is set, then we don't need to do anything. It won't get unset until the task get's schedule()d off. - If we are running on the same CPU as the task we resched, then set TIF_NEED_RESCHED and no further action is required. - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set after TIF_NEED_RESCHED has been set, then we need to send an IPI. Using these rules, we are able to remove the test and set operation in resched_task, and make clear the previously vague semantics of POLLING_NRFLAG. * In idle routines: - Enter cpu_idle with preempt disabled. When the need_resched() condition becomes true, explicitly call schedule(). This makes things a bit clearer (IMO), but haven't updated all architectures yet. - Many do a test and clear of TIF_NEED_RESCHED for some reason. According to the resched_task rules, this isn't needed (and actually breaks the assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock held). So remove that. Generally one less locked memory op when switching to the idle thread. - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner most polling idle loops. The above resched_task semantics allow it to be set until before the last time need_resched() is checked before going into a halt requiring interrupt wakeup. Many idle routines simply never enter such a halt, and so POLLING_NRFLAG can be always left set, completely eliminating resched IPIs when rescheduling the idle task. POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
522 lines
12 KiB
C
522 lines
12 KiB
C
/* $Id: process.c,v 1.28 2004/05/05 16:54:23 lethal Exp $
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*
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* linux/arch/sh/kernel/process.c
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*
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* Copyright (C) 1995 Linus Torvalds
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*
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* SuperH version: Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
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*/
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/*
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* This file handles the architecture-dependent parts of process handling..
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*/
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#include <linux/module.h>
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#include <linux/unistd.h>
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#include <linux/mm.h>
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#include <linux/elfcore.h>
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#include <linux/slab.h>
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#include <linux/a.out.h>
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#include <linux/ptrace.h>
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#include <linux/platform.h>
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#include <linux/kallsyms.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/elf.h>
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#if defined(CONFIG_SH_HS7751RVOIP)
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#include <asm/hs7751rvoip/hs7751rvoip.h>
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#elif defined(CONFIG_SH_RTS7751R2D)
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#include <asm/rts7751r2d/rts7751r2d.h>
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#endif
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static int hlt_counter=0;
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int ubc_usercnt = 0;
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#define HARD_IDLE_TIMEOUT (HZ / 3)
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void disable_hlt(void)
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{
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hlt_counter++;
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}
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EXPORT_SYMBOL(disable_hlt);
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void enable_hlt(void)
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{
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hlt_counter--;
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}
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EXPORT_SYMBOL(enable_hlt);
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void cpu_idle(void)
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{
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/* endless idle loop with no priority at all */
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while (1) {
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if (hlt_counter) {
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while (!need_resched())
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cpu_relax();
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} else {
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while (!need_resched())
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cpu_sleep();
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}
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preempt_enable_no_resched();
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schedule();
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preempt_disable();
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}
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}
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void machine_restart(char * __unused)
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{
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/* SR.BL=1 and invoke address error to let CPU reset (manual reset) */
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asm volatile("ldc %0, sr\n\t"
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"mov.l @%1, %0" : : "r" (0x10000000), "r" (0x80000001));
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}
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void machine_halt(void)
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{
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#if defined(CONFIG_SH_HS7751RVOIP)
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unsigned short value;
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value = ctrl_inw(PA_OUTPORTR);
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ctrl_outw((value & 0xffdf), PA_OUTPORTR);
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#elif defined(CONFIG_SH_RTS7751R2D)
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ctrl_outw(0x0001, PA_POWOFF);
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#endif
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while (1)
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cpu_sleep();
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}
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void machine_power_off(void)
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{
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#if defined(CONFIG_SH_HS7751RVOIP)
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unsigned short value;
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value = ctrl_inw(PA_OUTPORTR);
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ctrl_outw((value & 0xffdf), PA_OUTPORTR);
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#elif defined(CONFIG_SH_RTS7751R2D)
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ctrl_outw(0x0001, PA_POWOFF);
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#endif
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}
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void show_regs(struct pt_regs * regs)
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{
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printk("\n");
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printk("Pid : %d, Comm: %20s\n", current->pid, current->comm);
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print_symbol("PC is at %s\n", regs->pc);
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printk("PC : %08lx SP : %08lx SR : %08lx ",
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regs->pc, regs->regs[15], regs->sr);
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#ifdef CONFIG_MMU
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printk("TEA : %08x ", ctrl_inl(MMU_TEA));
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#else
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printk(" ");
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#endif
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printk("%s\n", print_tainted());
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printk("R0 : %08lx R1 : %08lx R2 : %08lx R3 : %08lx\n",
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regs->regs[0],regs->regs[1],
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regs->regs[2],regs->regs[3]);
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printk("R4 : %08lx R5 : %08lx R6 : %08lx R7 : %08lx\n",
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regs->regs[4],regs->regs[5],
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regs->regs[6],regs->regs[7]);
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printk("R8 : %08lx R9 : %08lx R10 : %08lx R11 : %08lx\n",
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regs->regs[8],regs->regs[9],
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regs->regs[10],regs->regs[11]);
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printk("R12 : %08lx R13 : %08lx R14 : %08lx\n",
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regs->regs[12],regs->regs[13],
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regs->regs[14]);
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printk("MACH: %08lx MACL: %08lx GBR : %08lx PR : %08lx\n",
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regs->mach, regs->macl, regs->gbr, regs->pr);
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/*
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* If we're in kernel mode, dump the stack too..
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*/
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if (!user_mode(regs)) {
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extern void show_task(unsigned long *sp);
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unsigned long sp = regs->regs[15];
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show_task((unsigned long *)sp);
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}
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}
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/*
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* Create a kernel thread
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*/
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/*
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* This is the mechanism for creating a new kernel thread.
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*
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*/
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extern void kernel_thread_helper(void);
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__asm__(".align 5\n"
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"kernel_thread_helper:\n\t"
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"jsr @r5\n\t"
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" nop\n\t"
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"mov.l 1f, r1\n\t"
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"jsr @r1\n\t"
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" mov r0, r4\n\t"
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".align 2\n\t"
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"1:.long do_exit");
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int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
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{ /* Don't use this in BL=1(cli). Or else, CPU resets! */
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struct pt_regs regs;
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memset(®s, 0, sizeof(regs));
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regs.regs[4] = (unsigned long) arg;
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regs.regs[5] = (unsigned long) fn;
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regs.pc = (unsigned long) kernel_thread_helper;
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regs.sr = (1 << 30);
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/* Ok, create the new process.. */
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return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
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}
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/*
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* Free current thread data structures etc..
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*/
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void exit_thread(void)
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{
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if (current->thread.ubc_pc) {
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current->thread.ubc_pc = 0;
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ubc_usercnt -= 1;
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}
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}
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void flush_thread(void)
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{
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#if defined(CONFIG_SH_FPU)
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struct task_struct *tsk = current;
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struct pt_regs *regs = (struct pt_regs *)
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((unsigned long)tsk->thread_info
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+ THREAD_SIZE - sizeof(struct pt_regs)
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- sizeof(unsigned long));
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/* Forget lazy FPU state */
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clear_fpu(tsk, regs);
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clear_used_math();
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#endif
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}
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void release_thread(struct task_struct *dead_task)
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{
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/* do nothing */
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}
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/* Fill in the fpu structure for a core dump.. */
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int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
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{
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int fpvalid = 0;
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#if defined(CONFIG_SH_FPU)
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struct task_struct *tsk = current;
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fpvalid = !!tsk_used_math(tsk);
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if (fpvalid) {
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unlazy_fpu(tsk, regs);
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memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
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}
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#endif
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return fpvalid;
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}
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/*
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* Capture the user space registers if the task is not running (in user space)
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*/
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int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
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{
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struct pt_regs ptregs;
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ptregs = *(struct pt_regs *)
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((unsigned long)tsk->thread_info + THREAD_SIZE
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- sizeof(struct pt_regs)
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#ifdef CONFIG_SH_DSP
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- sizeof(struct pt_dspregs)
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#endif
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- sizeof(unsigned long));
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elf_core_copy_regs(regs, &ptregs);
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return 1;
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}
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int
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dump_task_fpu (struct task_struct *tsk, elf_fpregset_t *fpu)
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{
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int fpvalid = 0;
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#if defined(CONFIG_SH_FPU)
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fpvalid = !!tsk_used_math(tsk);
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if (fpvalid) {
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struct pt_regs *regs = (struct pt_regs *)
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((unsigned long)tsk->thread_info
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+ THREAD_SIZE - sizeof(struct pt_regs)
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- sizeof(unsigned long));
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unlazy_fpu(tsk, regs);
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memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
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}
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#endif
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return fpvalid;
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}
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asmlinkage void ret_from_fork(void);
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int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
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unsigned long unused,
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struct task_struct *p, struct pt_regs *regs)
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{
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struct pt_regs *childregs;
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#if defined(CONFIG_SH_FPU)
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struct task_struct *tsk = current;
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unlazy_fpu(tsk, regs);
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p->thread.fpu = tsk->thread.fpu;
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copy_to_stopped_child_used_math(p);
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#endif
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childregs = ((struct pt_regs *)
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(THREAD_SIZE + (unsigned long) p->thread_info)
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#ifdef CONFIG_SH_DSP
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- sizeof(struct pt_dspregs)
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#endif
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- sizeof(unsigned long)) - 1;
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*childregs = *regs;
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if (user_mode(regs)) {
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childregs->regs[15] = usp;
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} else {
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childregs->regs[15] = (unsigned long)p->thread_info + THREAD_SIZE;
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}
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if (clone_flags & CLONE_SETTLS) {
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childregs->gbr = childregs->regs[0];
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}
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childregs->regs[0] = 0; /* Set return value for child */
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p->thread.sp = (unsigned long) childregs;
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p->thread.pc = (unsigned long) ret_from_fork;
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p->thread.ubc_pc = 0;
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return 0;
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}
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/*
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* fill in the user structure for a core dump..
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*/
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void dump_thread(struct pt_regs * regs, struct user * dump)
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{
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dump->magic = CMAGIC;
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dump->start_code = current->mm->start_code;
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dump->start_data = current->mm->start_data;
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dump->start_stack = regs->regs[15] & ~(PAGE_SIZE - 1);
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dump->u_tsize = (current->mm->end_code - dump->start_code) >> PAGE_SHIFT;
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dump->u_dsize = (current->mm->brk + (PAGE_SIZE-1) - dump->start_data) >> PAGE_SHIFT;
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dump->u_ssize = (current->mm->start_stack - dump->start_stack +
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PAGE_SIZE - 1) >> PAGE_SHIFT;
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/* Debug registers will come here. */
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dump->regs = *regs;
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dump->u_fpvalid = dump_fpu(regs, &dump->fpu);
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}
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/* Tracing by user break controller. */
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static void
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ubc_set_tracing(int asid, unsigned long pc)
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{
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ctrl_outl(pc, UBC_BARA);
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/* We don't have any ASID settings for the SH-2! */
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if (cpu_data->type != CPU_SH7604)
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ctrl_outb(asid, UBC_BASRA);
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ctrl_outl(0, UBC_BAMRA);
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if (cpu_data->type == CPU_SH7729) {
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ctrl_outw(BBR_INST | BBR_READ | BBR_CPU, UBC_BBRA);
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ctrl_outl(BRCR_PCBA | BRCR_PCTE, UBC_BRCR);
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} else {
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ctrl_outw(BBR_INST | BBR_READ, UBC_BBRA);
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ctrl_outw(BRCR_PCBA, UBC_BRCR);
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}
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}
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/*
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* switch_to(x,y) should switch tasks from x to y.
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*
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*/
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struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
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{
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#if defined(CONFIG_SH_FPU)
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struct pt_regs *regs = (struct pt_regs *)
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((unsigned long)prev->thread_info
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+ THREAD_SIZE - sizeof(struct pt_regs)
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- sizeof(unsigned long));
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unlazy_fpu(prev, regs);
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#endif
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#ifdef CONFIG_PREEMPT
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{
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unsigned long flags;
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struct pt_regs *regs;
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local_irq_save(flags);
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regs = (struct pt_regs *)
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((unsigned long)prev->thread_info
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+ THREAD_SIZE - sizeof(struct pt_regs)
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#ifdef CONFIG_SH_DSP
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- sizeof(struct pt_dspregs)
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#endif
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- sizeof(unsigned long));
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if (user_mode(regs) && regs->regs[15] >= 0xc0000000) {
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int offset = (int)regs->regs[15];
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/* Reset stack pointer: clear critical region mark */
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regs->regs[15] = regs->regs[1];
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if (regs->pc < regs->regs[0])
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/* Go to rewind point */
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regs->pc = regs->regs[0] + offset;
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}
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local_irq_restore(flags);
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}
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#endif
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/*
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* Restore the kernel mode register
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* k7 (r7_bank1)
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*/
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asm volatile("ldc %0, r7_bank"
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: /* no output */
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: "r" (next->thread_info));
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#ifdef CONFIG_MMU
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/* If no tasks are using the UBC, we're done */
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if (ubc_usercnt == 0)
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/* If no tasks are using the UBC, we're done */;
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else if (next->thread.ubc_pc && next->mm) {
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ubc_set_tracing(next->mm->context & MMU_CONTEXT_ASID_MASK,
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next->thread.ubc_pc);
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} else {
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ctrl_outw(0, UBC_BBRA);
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ctrl_outw(0, UBC_BBRB);
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}
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#endif
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return prev;
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}
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asmlinkage int sys_fork(unsigned long r4, unsigned long r5,
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unsigned long r6, unsigned long r7,
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struct pt_regs regs)
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{
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#ifdef CONFIG_MMU
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return do_fork(SIGCHLD, regs.regs[15], ®s, 0, NULL, NULL);
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#else
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/* fork almost works, enough to trick you into looking elsewhere :-( */
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return -EINVAL;
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#endif
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}
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asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
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unsigned long parent_tidptr,
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unsigned long child_tidptr,
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struct pt_regs regs)
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{
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if (!newsp)
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newsp = regs.regs[15];
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return do_fork(clone_flags, newsp, ®s, 0,
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(int __user *)parent_tidptr, (int __user *)child_tidptr);
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}
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/*
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* This is trivial, and on the face of it looks like it
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* could equally well be done in user mode.
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*
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* Not so, for quite unobvious reasons - register pressure.
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* In user mode vfork() cannot have a stack frame, and if
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* done by calling the "clone()" system call directly, you
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* do not have enough call-clobbered registers to hold all
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* the information you need.
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*/
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asmlinkage int sys_vfork(unsigned long r4, unsigned long r5,
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unsigned long r6, unsigned long r7,
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struct pt_regs regs)
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{
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return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.regs[15], ®s,
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0, NULL, NULL);
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}
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/*
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* sys_execve() executes a new program.
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*/
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asmlinkage int sys_execve(char *ufilename, char **uargv,
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char **uenvp, unsigned long r7,
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struct pt_regs regs)
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{
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int error;
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char *filename;
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filename = getname((char __user *)ufilename);
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error = PTR_ERR(filename);
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if (IS_ERR(filename))
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goto out;
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error = do_execve(filename,
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(char __user * __user *)uargv,
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(char __user * __user *)uenvp,
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®s);
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if (error == 0) {
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task_lock(current);
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current->ptrace &= ~PT_DTRACE;
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task_unlock(current);
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}
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putname(filename);
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out:
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return error;
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}
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unsigned long get_wchan(struct task_struct *p)
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{
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unsigned long schedule_frame;
|
|
unsigned long pc;
|
|
|
|
if (!p || p == current || p->state == TASK_RUNNING)
|
|
return 0;
|
|
|
|
/*
|
|
* The same comment as on the Alpha applies here, too ...
|
|
*/
|
|
pc = thread_saved_pc(p);
|
|
if (in_sched_functions(pc)) {
|
|
schedule_frame = ((unsigned long *)(long)p->thread.sp)[1];
|
|
return (unsigned long)((unsigned long *)schedule_frame)[1];
|
|
}
|
|
return pc;
|
|
}
|
|
|
|
asmlinkage void break_point_trap(unsigned long r4, unsigned long r5,
|
|
unsigned long r6, unsigned long r7,
|
|
struct pt_regs regs)
|
|
{
|
|
/* Clear tracing. */
|
|
ctrl_outw(0, UBC_BBRA);
|
|
ctrl_outw(0, UBC_BBRB);
|
|
current->thread.ubc_pc = 0;
|
|
ubc_usercnt -= 1;
|
|
|
|
force_sig(SIGTRAP, current);
|
|
}
|
|
|
|
asmlinkage void break_point_trap_software(unsigned long r4, unsigned long r5,
|
|
unsigned long r6, unsigned long r7,
|
|
struct pt_regs regs)
|
|
{
|
|
regs.pc -= 2;
|
|
force_sig(SIGTRAP, current);
|
|
}
|