/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others. * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org) * Copyright (C) 1999, 2000 Silicon Graphics, Inc. * Copyright (C) 2004 Thiemo Seufer */ #include <linux/errno.h> #include <linux/module.h> #include <linux/sched.h> #include <linux/tick.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/stddef.h> #include <linux/unistd.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/personality.h> #include <linux/sys.h> #include <linux/user.h> #include <linux/init.h> #include <linux/completion.h> #include <linux/kallsyms.h> #include <linux/random.h> #include <asm/asm.h> #include <asm/bootinfo.h> #include <asm/cpu.h> #include <asm/dsp.h> #include <asm/fpu.h> #include <asm/pgtable.h> #include <asm/system.h> #include <asm/mipsregs.h> #include <asm/processor.h> #include <asm/uaccess.h> #include <asm/io.h> #include <asm/elf.h> #include <asm/isadep.h> #include <asm/inst.h> #include <asm/stacktrace.h> /* * The idle thread. There's no useful work to be done, so just try to conserve * power and have a low exit latency (ie sit in a loop waiting for somebody to * say that they'd like to reschedule) */ void __noreturn cpu_idle(void) { int cpu; /* CPU is going idle. */ cpu = smp_processor_id(); /* endless idle loop with no priority at all */ while (1) { tick_nohz_stop_sched_tick(1); while (!need_resched() && cpu_online(cpu)) { #ifdef CONFIG_MIPS_MT_SMTC extern void smtc_idle_loop_hook(void); smtc_idle_loop_hook(); #endif if (cpu_wait) { /* Don't trace irqs off for idle */ stop_critical_timings(); (*cpu_wait)(); start_critical_timings(); } } #ifdef CONFIG_HOTPLUG_CPU if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) && (system_state == SYSTEM_RUNNING || system_state == SYSTEM_BOOTING)) play_dead(); #endif tick_nohz_restart_sched_tick(); preempt_enable_no_resched(); schedule(); preempt_disable(); } } asmlinkage void ret_from_fork(void); void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) { unsigned long status; /* New thread loses kernel privileges. */ status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); #ifdef CONFIG_64BIT status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; #endif status |= KU_USER; regs->cp0_status = status; clear_used_math(); clear_fpu_owner(); if (cpu_has_dsp) __init_dsp(); regs->cp0_epc = pc; regs->regs[29] = sp; current_thread_info()->addr_limit = USER_DS; } void exit_thread(void) { } void flush_thread(void) { } int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long unused, struct task_struct *p, struct pt_regs *regs) { struct thread_info *ti = task_thread_info(p); struct pt_regs *childregs; unsigned long childksp; p->set_child_tid = p->clear_child_tid = NULL; childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; preempt_disable(); if (is_fpu_owner()) save_fp(p); if (cpu_has_dsp) save_dsp(p); preempt_enable(); /* set up new TSS. */ childregs = (struct pt_regs *) childksp - 1; /* Put the stack after the struct pt_regs. */ childksp = (unsigned long) childregs; *childregs = *regs; childregs->regs[7] = 0; /* Clear error flag */ childregs->regs[2] = 0; /* Child gets zero as return value */ regs->regs[2] = p->pid; if (childregs->cp0_status & ST0_CU0) { childregs->regs[28] = (unsigned long) ti; childregs->regs[29] = childksp; ti->addr_limit = KERNEL_DS; } else { childregs->regs[29] = usp; ti->addr_limit = USER_DS; } p->thread.reg29 = (unsigned long) childregs; p->thread.reg31 = (unsigned long) ret_from_fork; /* * New tasks lose permission to use the fpu. This accelerates context * switching for most programs since they don't use the fpu. */ p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); #ifdef CONFIG_MIPS_MT_SMTC /* * SMTC restores TCStatus after Status, and the CU bits * are aliased there. */ childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); #endif clear_tsk_thread_flag(p, TIF_USEDFPU); #ifdef CONFIG_MIPS_MT_FPAFF clear_tsk_thread_flag(p, TIF_FPUBOUND); #endif /* CONFIG_MIPS_MT_FPAFF */ if (clone_flags & CLONE_SETTLS) ti->tp_value = regs->regs[7]; return 0; } /* Fill in the fpu structure for a core dump.. */ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) { memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); return 1; } void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) { int i; for (i = 0; i < EF_R0; i++) gp[i] = 0; gp[EF_R0] = 0; for (i = 1; i <= 31; i++) gp[EF_R0 + i] = regs->regs[i]; gp[EF_R26] = 0; gp[EF_R27] = 0; gp[EF_LO] = regs->lo; gp[EF_HI] = regs->hi; gp[EF_CP0_EPC] = regs->cp0_epc; gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; gp[EF_CP0_STATUS] = regs->cp0_status; gp[EF_CP0_CAUSE] = regs->cp0_cause; #ifdef EF_UNUSED0 gp[EF_UNUSED0] = 0; #endif } int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) { elf_dump_regs(*regs, task_pt_regs(tsk)); return 1; } int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) { memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); return 1; } /* * Create a kernel thread */ static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) { do_exit(fn(arg)); } long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) { struct pt_regs regs; memset(®s, 0, sizeof(regs)); regs.regs[4] = (unsigned long) arg; regs.regs[5] = (unsigned long) fn; regs.cp0_epc = (unsigned long) kernel_thread_helper; regs.cp0_status = read_c0_status(); #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); #else regs.cp0_status |= ST0_EXL; #endif /* Ok, create the new process.. */ return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); } /* * */ struct mips_frame_info { void *func; unsigned long func_size; int frame_size; int pc_offset; }; static inline int is_ra_save_ins(union mips_instruction *ip) { /* sw / sd $ra, offset($sp) */ return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && ip->i_format.rs == 29 && ip->i_format.rt == 31; } static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) { if (ip->j_format.opcode == jal_op) return 1; if (ip->r_format.opcode != spec_op) return 0; return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; } static inline int is_sp_move_ins(union mips_instruction *ip) { /* addiu/daddiu sp,sp,-imm */ if (ip->i_format.rs != 29 || ip->i_format.rt != 29) return 0; if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) return 1; return 0; } static int get_frame_info(struct mips_frame_info *info) { union mips_instruction *ip = info->func; unsigned max_insns = info->func_size / sizeof(union mips_instruction); unsigned i; info->pc_offset = -1; info->frame_size = 0; if (!ip) goto err; if (max_insns == 0) max_insns = 128U; /* unknown function size */ max_insns = min(128U, max_insns); for (i = 0; i < max_insns; i++, ip++) { if (is_jal_jalr_jr_ins(ip)) break; if (!info->frame_size) { if (is_sp_move_ins(ip)) info->frame_size = - ip->i_format.simmediate; continue; } if (info->pc_offset == -1 && is_ra_save_ins(ip)) { info->pc_offset = ip->i_format.simmediate / sizeof(long); break; } } if (info->frame_size && info->pc_offset >= 0) /* nested */ return 0; if (info->pc_offset < 0) /* leaf */ return 1; /* prologue seems boggus... */ err: return -1; } static struct mips_frame_info schedule_mfi __read_mostly; static int __init frame_info_init(void) { unsigned long size = 0; #ifdef CONFIG_KALLSYMS unsigned long ofs; kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); #endif schedule_mfi.func = schedule; schedule_mfi.func_size = size; get_frame_info(&schedule_mfi); /* * Without schedule() frame info, result given by * thread_saved_pc() and get_wchan() are not reliable. */ if (schedule_mfi.pc_offset < 0) printk("Can't analyze schedule() prologue at %p\n", schedule); return 0; } arch_initcall(frame_info_init); /* * Return saved PC of a blocked thread. */ unsigned long thread_saved_pc(struct task_struct *tsk) { struct thread_struct *t = &tsk->thread; /* New born processes are a special case */ if (t->reg31 == (unsigned long) ret_from_fork) return t->reg31; if (schedule_mfi.pc_offset < 0) return 0; return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; } #ifdef CONFIG_KALLSYMS /* used by show_backtrace() */ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, unsigned long pc, unsigned long *ra) { unsigned long stack_page; struct mips_frame_info info; unsigned long size, ofs; int leaf; extern void ret_from_irq(void); extern void ret_from_exception(void); stack_page = (unsigned long)task_stack_page(task); if (!stack_page) return 0; /* * If we reached the bottom of interrupt context, * return saved pc in pt_regs. */ if (pc == (unsigned long)ret_from_irq || pc == (unsigned long)ret_from_exception) { struct pt_regs *regs; if (*sp >= stack_page && *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { regs = (struct pt_regs *)*sp; pc = regs->cp0_epc; if (__kernel_text_address(pc)) { *sp = regs->regs[29]; *ra = regs->regs[31]; return pc; } } return 0; } if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) return 0; /* * Return ra if an exception occured at the first instruction */ if (unlikely(ofs == 0)) { pc = *ra; *ra = 0; return pc; } info.func = (void *)(pc - ofs); info.func_size = ofs; /* analyze from start to ofs */ leaf = get_frame_info(&info); if (leaf < 0) return 0; if (*sp < stack_page || *sp + info.frame_size > stack_page + THREAD_SIZE - 32) return 0; if (leaf) /* * For some extreme cases, get_frame_info() can * consider wrongly a nested function as a leaf * one. In that cases avoid to return always the * same value. */ pc = pc != *ra ? *ra : 0; else pc = ((unsigned long *)(*sp))[info.pc_offset]; *sp += info.frame_size; *ra = 0; return __kernel_text_address(pc) ? pc : 0; } #endif /* * get_wchan - a maintenance nightmare^W^Wpain in the ass ... */ unsigned long get_wchan(struct task_struct *task) { unsigned long pc = 0; #ifdef CONFIG_KALLSYMS unsigned long sp; unsigned long ra = 0; #endif if (!task || task == current || task->state == TASK_RUNNING) goto out; if (!task_stack_page(task)) goto out; pc = thread_saved_pc(task); #ifdef CONFIG_KALLSYMS sp = task->thread.reg29 + schedule_mfi.frame_size; while (in_sched_functions(pc)) pc = unwind_stack(task, &sp, pc, &ra); #endif out: return pc; } /* * Don't forget that the stack pointer must be aligned on a 8 bytes * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. */ unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) sp -= get_random_int() & ~PAGE_MASK; return sp & ALMASK; }