/* * Copyright (C) 1995 Linus Torvalds * * Pentium III FXSR, SSE support * Gareth Hughes , May 2000 */ /* * This file handles the architecture-dependent parts of process handling.. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_MATH_EMULATION #include #endif #include #include #include #include #include #include #include asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread"); /* * Return saved PC of a blocked thread. */ unsigned long thread_saved_pc(struct task_struct *tsk) { return ((unsigned long *)tsk->thread.sp)[3]; } void __show_regs(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(regs)) { sp = regs->sp; ss = regs->ss & 0xffff; gs = get_user_gs(regs); } else { sp = kernel_stack_pointer(regs); savesegment(ss, ss); savesegment(gs, gs); } printk(KERN_DEFAULT "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(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", regs->ax, regs->bx, regs->cx, regs->dx); printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", regs->si, regs->di, regs->bp, sp); printk(KERN_DEFAULT " 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(KERN_DEFAULT "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); get_debugreg(d6, 6); get_debugreg(d7, 7); /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && (d6 == DR6_RESERVED) && (d7 == 0x400)) return; printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", d0, d1, d2, d3); printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n", d6, d7); } void release_thread(struct task_struct *dead_task) { BUG_ON(dead_task->mm); release_vm86_irqs(dead_task); } int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p) { struct pt_regs *childregs = task_pt_regs(p); struct task_struct *tsk; int err; p->thread.sp = (unsigned long) childregs; p->thread.sp0 = (unsigned long) (childregs+1); memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); if (unlikely(p->flags & PF_KTHREAD)) { /* kernel thread */ memset(childregs, 0, sizeof(struct pt_regs)); p->thread.ip = (unsigned long) ret_from_kernel_thread; task_user_gs(p) = __KERNEL_STACK_CANARY; childregs->ds = __USER_DS; childregs->es = __USER_DS; childregs->fs = __KERNEL_PERCPU; childregs->bx = sp; /* function */ childregs->bp = arg; childregs->orig_ax = -1; childregs->cs = __KERNEL_CS | get_kernel_rpl(); childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED; p->thread.io_bitmap_ptr = NULL; return 0; } *childregs = *current_pt_regs(); childregs->ax = 0; if (sp) childregs->sp = sp; p->thread.ip = (unsigned long) ret_from_fork; task_user_gs(p) = get_user_gs(current_pt_regs()); p->thread.io_bitmap_ptr = NULL; tsk = current; err = -ENOMEM; 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) { set_user_gs(regs, 0); regs->fs = 0; regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; regs->ip = new_ip; regs->sp = new_sp; regs->flags = X86_EFLAGS_IF; force_iret(); } EXPORT_SYMBOL_GPL(start_thread); /* * switch_to(x,y) 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. */ __visible __notrace_funcgraph 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(cpu_tss, cpu); fpu_switch_t fpu; /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ fpu = switch_fpu_prepare(prev_p, next_p, cpu); /* * 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. */ lazy_save_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); /* * If it were not for PREEMPT_ACTIVE we could guarantee that the * preempt_count of all tasks was equal here and this would not be * needed. */ task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count); this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count); /* * 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_end_context_switch(next_p); /* * Reload esp0, kernel_stack, and current_top_of_stack. This changes * current_thread_info(). */ load_sp0(tss, next); this_cpu_write(kernel_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); this_cpu_write(cpu_current_top_of_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); /* * Restore %gs if needed (which is common) */ if (prev->gs | next->gs) lazy_load_gs(next->gs); switch_fpu_finish(next_p, fpu); this_cpu_write(current_task, next_p); return prev_p; } #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; }