/* * Copyright (C) 1995 Linus Torvalds * * Pentium III FXSR, SSE support * Gareth Hughes <gareth@valinux.com>, May 2000 */ /* * This file handles the architecture-dependent parts of process handling.. */ #include <stdarg.h> #include <linux/cpu.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/elfcore.h> #include <linux/smp.h> #include <linux/stddef.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/user.h> #include <linux/interrupt.h> #include <linux/utsname.h> #include <linux/delay.h> #include <linux/reboot.h> #include <linux/init.h> #include <linux/mc146818rtc.h> #include <linux/module.h> #include <linux/kallsyms.h> #include <linux/ptrace.h> #include <linux/random.h> #include <linux/personality.h> #include <linux/tick.h> #include <linux/percpu.h> #include <linux/prctl.h> #include <asm/uaccess.h> #include <asm/pgtable.h> #include <asm/system.h> #include <asm/io.h> #include <asm/ldt.h> #include <asm/processor.h> #include <asm/i387.h> #include <asm/desc.h> #ifdef CONFIG_MATH_EMULATION #include <asm/math_emu.h> #endif #include <linux/err.h> #include <asm/tlbflush.h> #include <asm/cpu.h> #include <asm/kdebug.h> asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; EXPORT_PER_CPU_SYMBOL(current_task); DEFINE_PER_CPU(int, cpu_number); EXPORT_PER_CPU_SYMBOL(cpu_number); /* * Return saved PC of a blocked thread. */ unsigned long thread_saved_pc(struct task_struct *tsk) { return ((unsigned long *)tsk->thread.sp)[3]; } #ifdef CONFIG_HOTPLUG_CPU #include <asm/nmi.h> static void cpu_exit_clear(void) { int cpu = raw_smp_processor_id(); idle_task_exit(); cpu_uninit(); irq_ctx_exit(cpu); cpu_clear(cpu, cpu_callout_map); cpu_clear(cpu, cpu_callin_map); numa_remove_cpu(cpu); } /* We don't actually take CPU down, just spin without interrupts. */ static inline void play_dead(void) { /* This must be done before dead CPU ack */ cpu_exit_clear(); mb(); /* Ack it */ __get_cpu_var(cpu_state) = CPU_DEAD; /* * With physical CPU hotplug, we should halt the cpu */ local_irq_disable(); /* mask all interrupts, flush any and all caches, and halt */ wbinvd_halt(); } #else static inline void play_dead(void) { BUG(); } #endif /* CONFIG_HOTPLUG_CPU */ /* * 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 cpu_idle(void) { int cpu = smp_processor_id(); current_thread_info()->status |= TS_POLLING; /* endless idle loop with no priority at all */ while (1) { tick_nohz_stop_sched_tick(1); while (!need_resched()) { check_pgt_cache(); rmb(); if (rcu_pending(cpu)) rcu_check_callbacks(cpu, 0); if (cpu_is_offline(cpu)) play_dead(); local_irq_disable(); __get_cpu_var(irq_stat).idle_timestamp = jiffies; /* Don't trace irqs off for idle */ stop_critical_timings(); pm_idle(); start_critical_timings(); } tick_nohz_restart_sched_tick(); preempt_enable_no_resched(); schedule(); preempt_disable(); } } void __show_registers(struct pt_regs *regs, int all) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; unsigned long d0, d1, d2, d3, d6, d7; unsigned long sp; unsigned short ss, gs; if (user_mode_vm(regs)) { sp = regs->sp; ss = regs->ss & 0xffff; savesegment(gs, gs); } else { sp = (unsigned long) (®s->sp); savesegment(ss, ss); savesegment(gs, gs); } printk("\n"); printk("Pid: %d, comm: %s %s (%s %.*s)\n", task_pid_nr(current), current->comm, print_tainted(), init_utsname()->release, (int)strcspn(init_utsname()->version, " "), init_utsname()->version); printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n", (u16)regs->cs, regs->ip, regs->flags, smp_processor_id()); print_symbol("EIP is at %s\n", regs->ip); printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", regs->ax, regs->bx, regs->cx, regs->dx); printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", regs->si, regs->di, regs->bp, sp); printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n", (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss); if (!all) return; cr0 = read_cr0(); cr2 = read_cr2(); cr3 = read_cr3(); cr4 = read_cr4_safe(); printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4); get_debugreg(d0, 0); get_debugreg(d1, 1); get_debugreg(d2, 2); get_debugreg(d3, 3); printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", d0, d1, d2, d3); get_debugreg(d6, 6); get_debugreg(d7, 7); printk("DR6: %08lx DR7: %08lx\n", d6, d7); } void show_regs(struct pt_regs *regs) { __show_registers(regs, 1); show_trace(NULL, regs, ®s->sp, regs->bp); } /* * This gets run with %bx containing the * function to call, and %dx containing * the "args". */ extern void kernel_thread_helper(void); /* * Create a kernel thread */ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) { struct pt_regs regs; memset(®s, 0, sizeof(regs)); regs.bx = (unsigned long) fn; regs.dx = (unsigned long) arg; regs.ds = __USER_DS; regs.es = __USER_DS; regs.fs = __KERNEL_PERCPU; regs.orig_ax = -1; regs.ip = (unsigned long) kernel_thread_helper; regs.cs = __KERNEL_CS | get_kernel_rpl(); regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; /* Ok, create the new process.. */ return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); } EXPORT_SYMBOL(kernel_thread); /* * Free current thread data structures etc.. */ void exit_thread(void) { /* The process may have allocated an io port bitmap... nuke it. */ if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { struct task_struct *tsk = current; struct thread_struct *t = &tsk->thread; int cpu = get_cpu(); struct tss_struct *tss = &per_cpu(init_tss, cpu); kfree(t->io_bitmap_ptr); t->io_bitmap_ptr = NULL; clear_thread_flag(TIF_IO_BITMAP); /* * Careful, clear this in the TSS too: */ memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); t->io_bitmap_max = 0; tss->io_bitmap_owner = NULL; tss->io_bitmap_max = 0; tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; put_cpu(); } } void flush_thread(void) { struct task_struct *tsk = current; tsk->thread.debugreg0 = 0; tsk->thread.debugreg1 = 0; tsk->thread.debugreg2 = 0; tsk->thread.debugreg3 = 0; tsk->thread.debugreg6 = 0; tsk->thread.debugreg7 = 0; memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); clear_tsk_thread_flag(tsk, TIF_DEBUG); /* * Forget coprocessor state.. */ tsk->fpu_counter = 0; clear_fpu(tsk); clear_used_math(); } void release_thread(struct task_struct *dead_task) { BUG_ON(dead_task->mm); release_vm86_irqs(dead_task); } /* * This gets called before we allocate a new thread and copy * the current task into it. */ void prepare_to_copy(struct task_struct *tsk) { unlazy_fpu(tsk); } int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, unsigned long unused, struct task_struct * p, struct pt_regs * regs) { struct pt_regs * childregs; struct task_struct *tsk; int err; childregs = task_pt_regs(p); *childregs = *regs; childregs->ax = 0; childregs->sp = sp; p->thread.sp = (unsigned long) childregs; p->thread.sp0 = (unsigned long) (childregs+1); p->thread.ip = (unsigned long) ret_from_fork; savesegment(gs, p->thread.gs); tsk = current; if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, IO_BITMAP_BYTES, GFP_KERNEL); if (!p->thread.io_bitmap_ptr) { p->thread.io_bitmap_max = 0; return -ENOMEM; } set_tsk_thread_flag(p, TIF_IO_BITMAP); } err = 0; /* * Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) err = do_set_thread_area(p, -1, (struct user_desc __user *)childregs->si, 0); if (err && p->thread.io_bitmap_ptr) { kfree(p->thread.io_bitmap_ptr); p->thread.io_bitmap_max = 0; } return err; } void start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) { __asm__("movl %0, %%gs" :: "r"(0)); regs->fs = 0; set_fs(USER_DS); regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; regs->ip = new_ip; regs->sp = new_sp; /* * Free the old FP and other extended state */ free_thread_xstate(current); } EXPORT_SYMBOL_GPL(start_thread); static void hard_disable_TSC(void) { write_cr4(read_cr4() | X86_CR4_TSD); } void disable_TSC(void) { preempt_disable(); if (!test_and_set_thread_flag(TIF_NOTSC)) /* * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ hard_disable_TSC(); preempt_enable(); } static void hard_enable_TSC(void) { write_cr4(read_cr4() & ~X86_CR4_TSD); } static void enable_TSC(void) { preempt_disable(); if (test_and_clear_thread_flag(TIF_NOTSC)) /* * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ hard_enable_TSC(); preempt_enable(); } int get_tsc_mode(unsigned long adr) { unsigned int val; if (test_thread_flag(TIF_NOTSC)) val = PR_TSC_SIGSEGV; else val = PR_TSC_ENABLE; return put_user(val, (unsigned int __user *)adr); } int set_tsc_mode(unsigned int val) { if (val == PR_TSC_SIGSEGV) disable_TSC(); else if (val == PR_TSC_ENABLE) enable_TSC(); else return -EINVAL; return 0; } static noinline void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, struct tss_struct *tss) { struct thread_struct *prev, *next; unsigned long debugctl; prev = &prev_p->thread; next = &next_p->thread; debugctl = prev->debugctlmsr; if (next->ds_area_msr != prev->ds_area_msr) { /* we clear debugctl to make sure DS * is not in use when we change it */ debugctl = 0; update_debugctlmsr(0); wrmsr(MSR_IA32_DS_AREA, next->ds_area_msr, 0); } if (next->debugctlmsr != debugctl) update_debugctlmsr(next->debugctlmsr); if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { set_debugreg(next->debugreg0, 0); set_debugreg(next->debugreg1, 1); set_debugreg(next->debugreg2, 2); set_debugreg(next->debugreg3, 3); /* no 4 and 5 */ set_debugreg(next->debugreg6, 6); set_debugreg(next->debugreg7, 7); } if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ test_tsk_thread_flag(next_p, TIF_NOTSC)) { /* prev and next are different */ if (test_tsk_thread_flag(next_p, TIF_NOTSC)) hard_disable_TSC(); else hard_enable_TSC(); } #ifdef X86_BTS if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS)) ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS); if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS)) ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES); #endif if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { /* * Disable the bitmap via an invalid offset. We still cache * the previous bitmap owner and the IO bitmap contents: */ tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; return; } if (likely(next == tss->io_bitmap_owner)) { /* * Previous owner of the bitmap (hence the bitmap content) * matches the next task, we dont have to do anything but * to set a valid offset in the TSS: */ tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET; return; } /* * Lazy TSS's I/O bitmap copy. We set an invalid offset here * and we let the task to get a GPF in case an I/O instruction * is performed. The handler of the GPF will verify that the * faulting task has a valid I/O bitmap and, it true, does the * real copy and restart the instruction. This will save us * redundant copies when the currently switched task does not * perform any I/O during its timeslice. */ tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; } /* * switch_to(x,yn) should switch tasks from x to y. * * We fsave/fwait so that an exception goes off at the right time * (as a call from the fsave or fwait in effect) rather than to * the wrong process. Lazy FP saving no longer makes any sense * with modern CPU's, and this simplifies a lot of things (SMP * and UP become the same). * * NOTE! We used to use the x86 hardware context switching. The * reason for not using it any more becomes apparent when you * try to recover gracefully from saved state that is no longer * valid (stale segment register values in particular). With the * hardware task-switch, there is no way to fix up bad state in * a reasonable manner. * * The fact that Intel documents the hardware task-switching to * be slow is a fairly red herring - this code is not noticeably * faster. However, there _is_ some room for improvement here, * so the performance issues may eventually be a valid point. * More important, however, is the fact that this allows us much * more flexibility. * * The return value (in %ax) will be the "prev" task after * the task-switch, and shows up in ret_from_fork in entry.S, * for example. */ struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) { struct thread_struct *prev = &prev_p->thread, *next = &next_p->thread; int cpu = smp_processor_id(); struct tss_struct *tss = &per_cpu(init_tss, cpu); /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ __unlazy_fpu(prev_p); /* we're going to use this soon, after a few expensive things */ if (next_p->fpu_counter > 5) prefetch(next->xstate); /* * Reload esp0. */ load_sp0(tss, next); /* * Save away %gs. No need to save %fs, as it was saved on the * stack on entry. No need to save %es and %ds, as those are * always kernel segments while inside the kernel. Doing this * before setting the new TLS descriptors avoids the situation * where we temporarily have non-reloadable segments in %fs * and %gs. This could be an issue if the NMI handler ever * used %fs or %gs (it does not today), or if the kernel is * running inside of a hypervisor layer. */ savesegment(gs, prev->gs); /* * Load the per-thread Thread-Local Storage descriptor. */ load_TLS(next, cpu); /* * Restore IOPL if needed. In normal use, the flags restore * in the switch assembly will handle this. But if the kernel * is running virtualized at a non-zero CPL, the popf will * not restore flags, so it must be done in a separate step. */ if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) set_iopl_mask(next->iopl); /* * Now maybe handle debug registers and/or IO bitmaps */ if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) __switch_to_xtra(prev_p, next_p, tss); /* * Leave lazy mode, flushing any hypercalls made here. * This must be done before restoring TLS segments so * the GDT and LDT are properly updated, and must be * done before math_state_restore, so the TS bit is up * to date. */ arch_leave_lazy_cpu_mode(); /* If the task has used fpu the last 5 timeslices, just do a full * restore of the math state immediately to avoid the trap; the * chances of needing FPU soon are obviously high now * * tsk_used_math() checks prevent calling math_state_restore(), * which can sleep in the case of !tsk_used_math() */ if (tsk_used_math(next_p) && next_p->fpu_counter > 5) math_state_restore(); /* * Restore %gs if needed (which is common) */ if (prev->gs | next->gs) loadsegment(gs, next->gs); x86_write_percpu(current_task, next_p); return prev_p; } asmlinkage int sys_fork(struct pt_regs regs) { return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL); } asmlinkage int sys_clone(struct pt_regs regs) { unsigned long clone_flags; unsigned long newsp; int __user *parent_tidptr, *child_tidptr; clone_flags = regs.bx; newsp = regs.cx; parent_tidptr = (int __user *)regs.dx; child_tidptr = (int __user *)regs.di; if (!newsp) newsp = regs.sp; return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); } /* * This is trivial, and on the face of it looks like it * could equally well be done in user mode. * * Not so, for quite unobvious reasons - register pressure. * In user mode vfork() cannot have a stack frame, and if * done by calling the "clone()" system call directly, you * do not have enough call-clobbered registers to hold all * the information you need. */ asmlinkage int sys_vfork(struct pt_regs regs) { return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL); } /* * sys_execve() executes a new program. */ asmlinkage int sys_execve(struct pt_regs regs) { int error; char * filename; filename = getname((char __user *) regs.bx); error = PTR_ERR(filename); if (IS_ERR(filename)) goto out; error = do_execve(filename, (char __user * __user *) regs.cx, (char __user * __user *) regs.dx, ®s); if (error == 0) { /* Make sure we don't return using sysenter.. */ set_thread_flag(TIF_IRET); } putname(filename); out: return error; } #define top_esp (THREAD_SIZE - sizeof(unsigned long)) #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) unsigned long get_wchan(struct task_struct *p) { unsigned long bp, sp, ip; unsigned long stack_page; int count = 0; if (!p || p == current || p->state == TASK_RUNNING) return 0; stack_page = (unsigned long)task_stack_page(p); sp = p->thread.sp; if (!stack_page || sp < stack_page || sp > top_esp+stack_page) return 0; /* include/asm-i386/system.h:switch_to() pushes bp last. */ bp = *(unsigned long *) sp; do { if (bp < stack_page || bp > top_ebp+stack_page) return 0; ip = *(unsigned long *) (bp+4); if (!in_sched_functions(ip)) return ip; bp = *(unsigned long *) bp; } while (count++ < 16); return 0; } unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) sp -= get_random_int() % 8192; return sp & ~0xf; } unsigned long arch_randomize_brk(struct mm_struct *mm) { unsigned long range_end = mm->brk + 0x02000000; return randomize_range(mm->brk, range_end, 0) ? : mm->brk; }