5bfb5d690f
Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
444 lines
10 KiB
C
444 lines
10 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
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* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
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* Copyright (C) 2004 Thiemo Seufer
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*/
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#include <linux/config.h>
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/ptrace.h>
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#include <linux/slab.h>
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#include <linux/mman.h>
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#include <linux/personality.h>
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#include <linux/sys.h>
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#include <linux/user.h>
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#include <linux/a.out.h>
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#include <linux/init.h>
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#include <linux/completion.h>
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#include <asm/abi.h>
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#include <asm/bootinfo.h>
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#include <asm/cpu.h>
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#include <asm/dsp.h>
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#include <asm/fpu.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/mipsregs.h>
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#include <asm/processor.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <asm/elf.h>
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#include <asm/isadep.h>
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#include <asm/inst.h>
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/*
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* The idle thread. There's no useful work to be done, so just try to conserve
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* power and have a low exit latency (ie sit in a loop waiting for somebody to
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* say that they'd like to reschedule)
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*/
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ATTRIB_NORET 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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while (!need_resched())
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if (cpu_wait)
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(*cpu_wait)();
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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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extern int do_signal(sigset_t *oldset, struct pt_regs *regs);
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extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
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/*
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* Native o32 and N64 ABI without DSP ASE
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*/
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extern int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set);
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extern int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set, siginfo_t *info);
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struct mips_abi mips_abi = {
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.do_signal = do_signal,
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#ifdef CONFIG_TRAD_SIGNALS
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.setup_frame = setup_frame,
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#endif
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.setup_rt_frame = setup_rt_frame
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};
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#ifdef CONFIG_MIPS32_O32
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/*
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* o32 compatibility on 64-bit kernels, without DSP ASE
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*/
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extern int setup_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set);
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extern int setup_rt_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set, siginfo_t *info);
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struct mips_abi mips_abi_32 = {
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.do_signal = do_signal32,
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.setup_frame = setup_frame_32,
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.setup_rt_frame = setup_rt_frame_32
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};
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#endif /* CONFIG_MIPS32_O32 */
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#ifdef CONFIG_MIPS32_N32
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/*
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* N32 on 64-bit kernels, without DSP ASE
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*/
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extern int setup_rt_frame_n32(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set, siginfo_t *info);
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struct mips_abi mips_abi_n32 = {
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.do_signal = do_signal,
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.setup_rt_frame = setup_rt_frame_n32
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};
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#endif /* CONFIG_MIPS32_N32 */
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asmlinkage void ret_from_fork(void);
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void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
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{
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unsigned long status;
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/* New thread loses kernel privileges. */
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status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
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#ifdef CONFIG_64BIT
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status &= ~ST0_FR;
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status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
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#endif
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status |= KU_USER;
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regs->cp0_status = status;
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clear_used_math();
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lose_fpu();
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if (cpu_has_dsp)
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__init_dsp();
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regs->cp0_epc = pc;
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regs->regs[29] = sp;
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current_thread_info()->addr_limit = USER_DS;
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}
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void exit_thread(void)
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{
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}
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void flush_thread(void)
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{
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}
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int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
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unsigned long unused, struct task_struct *p, struct pt_regs *regs)
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{
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struct thread_info *ti = p->thread_info;
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struct pt_regs *childregs;
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long childksp;
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p->set_child_tid = p->clear_child_tid = NULL;
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childksp = (unsigned long)ti + THREAD_SIZE - 32;
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preempt_disable();
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if (is_fpu_owner())
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save_fp(p);
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if (cpu_has_dsp)
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save_dsp(p);
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preempt_enable();
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/* set up new TSS. */
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childregs = (struct pt_regs *) childksp - 1;
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*childregs = *regs;
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childregs->regs[7] = 0; /* Clear error flag */
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#if defined(CONFIG_BINFMT_IRIX)
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if (current->personality != PER_LINUX) {
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/* Under IRIX things are a little different. */
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childregs->regs[3] = 1;
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regs->regs[3] = 0;
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}
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#endif
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childregs->regs[2] = 0; /* Child gets zero as return value */
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regs->regs[2] = p->pid;
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if (childregs->cp0_status & ST0_CU0) {
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childregs->regs[28] = (unsigned long) ti;
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childregs->regs[29] = childksp;
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ti->addr_limit = KERNEL_DS;
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} else {
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childregs->regs[29] = usp;
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ti->addr_limit = USER_DS;
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}
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p->thread.reg29 = (unsigned long) childregs;
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p->thread.reg31 = (unsigned long) ret_from_fork;
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/*
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* New tasks lose permission to use the fpu. This accelerates context
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* switching for most programs since they don't use the fpu.
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*/
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p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
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childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
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clear_tsk_thread_flag(p, TIF_USEDFPU);
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if (clone_flags & CLONE_SETTLS)
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ti->tp_value = regs->regs[7];
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return 0;
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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 *r)
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{
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memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu));
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return 1;
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}
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void dump_regs(elf_greg_t *gp, struct pt_regs *regs)
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{
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int i;
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for (i = 0; i < EF_R0; i++)
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gp[i] = 0;
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gp[EF_R0] = 0;
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for (i = 1; i <= 31; i++)
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gp[EF_R0 + i] = regs->regs[i];
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gp[EF_R26] = 0;
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gp[EF_R27] = 0;
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gp[EF_LO] = regs->lo;
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gp[EF_HI] = regs->hi;
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gp[EF_CP0_EPC] = regs->cp0_epc;
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gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
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gp[EF_CP0_STATUS] = regs->cp0_status;
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gp[EF_CP0_CAUSE] = regs->cp0_cause;
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#ifdef EF_UNUSED0
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gp[EF_UNUSED0] = 0;
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#endif
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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 thread_info *ti = tsk->thread_info;
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long ksp = (unsigned long)ti + THREAD_SIZE - 32;
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dump_regs(&(*regs)[0], (struct pt_regs *) ksp - 1);
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return 1;
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}
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int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
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{
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memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
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return 1;
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}
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/*
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* Create a kernel thread
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*/
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ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
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{
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do_exit(fn(arg));
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}
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long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
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{
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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.cp0_epc = (unsigned long) kernel_thread_helper;
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regs.cp0_status = read_c0_status();
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#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
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regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
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regs.cp0_status |= ST0_IEP;
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#else
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regs.cp0_status |= ST0_EXL;
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#endif
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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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static struct mips_frame_info {
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void *func;
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int omit_fp; /* compiled without fno-omit-frame-pointer */
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int frame_offset;
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int pc_offset;
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} schedule_frame, mfinfo[] = {
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{ schedule, 0 }, /* must be first */
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/* arch/mips/kernel/semaphore.c */
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{ __down, 1 },
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{ __down_interruptible, 1 },
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/* kernel/sched.c */
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#ifdef CONFIG_PREEMPT
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{ preempt_schedule, 0 },
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#endif
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{ wait_for_completion, 0 },
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{ interruptible_sleep_on, 0 },
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{ interruptible_sleep_on_timeout, 0 },
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{ sleep_on, 0 },
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{ sleep_on_timeout, 0 },
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{ yield, 0 },
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{ io_schedule, 0 },
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{ io_schedule_timeout, 0 },
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#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
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{ __preempt_spin_lock, 0 },
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{ __preempt_write_lock, 0 },
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#endif
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/* kernel/timer.c */
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{ schedule_timeout, 1 },
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/* { nanosleep_restart, 1 }, */
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/* lib/rwsem-spinlock.c */
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{ __down_read, 1 },
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{ __down_write, 1 },
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};
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static int mips_frame_info_initialized;
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static int __init get_frame_info(struct mips_frame_info *info)
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{
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int i;
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void *func = info->func;
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union mips_instruction *ip = (union mips_instruction *)func;
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info->pc_offset = -1;
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info->frame_offset = info->omit_fp ? 0 : -1;
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for (i = 0; i < 128; i++, ip++) {
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/* if jal, jalr, jr, stop. */
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if (ip->j_format.opcode == jal_op ||
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(ip->r_format.opcode == spec_op &&
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(ip->r_format.func == jalr_op ||
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ip->r_format.func == jr_op)))
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break;
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if (
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#ifdef CONFIG_32BIT
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ip->i_format.opcode == sw_op &&
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#endif
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#ifdef CONFIG_64BIT
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ip->i_format.opcode == sd_op &&
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#endif
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ip->i_format.rs == 29)
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{
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/* sw / sd $ra, offset($sp) */
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if (ip->i_format.rt == 31) {
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if (info->pc_offset != -1)
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continue;
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info->pc_offset =
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ip->i_format.simmediate / sizeof(long);
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}
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/* sw / sd $s8, offset($sp) */
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if (ip->i_format.rt == 30) {
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//#if 0 /* gcc 3.4 does aggressive optimization... */
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if (info->frame_offset != -1)
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continue;
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//#endif
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info->frame_offset =
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ip->i_format.simmediate / sizeof(long);
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}
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}
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}
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if (info->pc_offset == -1 || info->frame_offset == -1) {
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printk("Can't analyze prologue code at %p\n", func);
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info->pc_offset = -1;
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info->frame_offset = -1;
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return -1;
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}
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return 0;
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}
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static int __init frame_info_init(void)
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{
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int i, found;
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for (i = 0; i < ARRAY_SIZE(mfinfo); i++)
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if (get_frame_info(&mfinfo[i]))
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return -1;
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schedule_frame = mfinfo[0];
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/* bubble sort */
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do {
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struct mips_frame_info tmp;
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found = 0;
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for (i = 1; i < ARRAY_SIZE(mfinfo); i++) {
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if (mfinfo[i-1].func > mfinfo[i].func) {
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tmp = mfinfo[i];
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mfinfo[i] = mfinfo[i-1];
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mfinfo[i-1] = tmp;
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found = 1;
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}
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}
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} while (found);
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mips_frame_info_initialized = 1;
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return 0;
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}
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arch_initcall(frame_info_init);
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/*
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* Return saved PC of a blocked thread.
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*/
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unsigned long thread_saved_pc(struct task_struct *tsk)
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{
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struct thread_struct *t = &tsk->thread;
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/* New born processes are a special case */
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if (t->reg31 == (unsigned long) ret_from_fork)
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return t->reg31;
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if (schedule_frame.pc_offset < 0)
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return 0;
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return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
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}
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/* get_wchan - a maintenance nightmare^W^Wpain in the ass ... */
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unsigned long get_wchan(struct task_struct *p)
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{
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unsigned long stack_page;
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unsigned long frame, pc;
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if (!p || p == current || p->state == TASK_RUNNING)
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return 0;
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stack_page = (unsigned long)p->thread_info;
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if (!stack_page || !mips_frame_info_initialized)
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return 0;
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pc = thread_saved_pc(p);
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if (!in_sched_functions(pc))
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return pc;
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frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
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do {
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int i;
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if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
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return 0;
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for (i = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
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if (pc >= (unsigned long) mfinfo[i].func)
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break;
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}
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if (i < 0)
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break;
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if (mfinfo[i].omit_fp)
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break;
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pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
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frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
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} while (in_sched_functions(pc));
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return pc;
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}
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EXPORT_SYMBOL(get_wchan);
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