/* * linux/arch/i386/kernel/process.c * * Copyright (C) 1995 Linus Torvalds * * Pentium III FXSR, SSE support * Gareth Hughes , May 2000 */ /* * This file handles the architecture-dependent parts of process handling.. */ #define __KERNEL_SYSCALLS__ #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 #include asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); int hlt_counter; /* * Powermanagement idle function, if any.. */ void (*pm_idle)(void); /* * Power off function, if any */ void (*pm_power_off)(void); void disable_hlt(void) { hlt_counter++; } void enable_hlt(void) { hlt_counter--; } /* * 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) { extern int set_timeout_timer(void); /* Endless idle loop with no priority at all. */ init_idle(); current->nice = 20; current->counter = -100; for ( ; ; ) { while ( !current->need_resched ) { __cli(); if ( current->need_resched ) { /* The race-free check for events failed. */ __sti(); break; } else if ( set_timeout_timer() == 0 ) { /* NB. Blocking reenable events in a race-free manner. */ HYPERVISOR_block(); } else { /* No race here: yielding will get us the CPU again anyway. */ __sti(); HYPERVISOR_yield(); } } schedule(); check_pgt_cache(); } } void machine_restart(char * __unused) { HYPERVISOR_exit(); } void machine_halt(void) { HYPERVISOR_exit(); } void machine_power_off(void) { HYPERVISOR_exit(); } extern void show_trace(unsigned long* esp); void show_regs(struct pt_regs * regs) { printk("\n"); printk("Pid: %d, comm: %20s\n", current->pid, current->comm); printk("EIP: %04x:[<%08lx>] CPU: %d",0xffff & regs->xcs,regs->eip, smp_processor_id()); if (regs->xcs & 2) printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp); printk(" EFLAGS: %08lx %s\n",regs->eflags, print_tainted()); printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", regs->eax,regs->ebx,regs->ecx,regs->edx); printk("ESI: %08lx EDI: %08lx EBP: %08lx", regs->esi, regs->edi, regs->ebp); printk(" DS: %04x ES: %04x\n", 0xffff & regs->xds,0xffff & regs->xes); show_trace(®s->esp); } /* * Create a kernel thread */ int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) { long retval, d0; __asm__ __volatile__( "movl %%esp,%%esi\n\t" "int $0x80\n\t" /* Linux/i386 system call */ "cmpl %%esp,%%esi\n\t" /* child or parent? */ "je 1f\n\t" /* parent - jump */ /* Load the argument into eax, and push it. That way, it does * not matter whether the called function is compiled with * -mregparm or not. */ "movl %4,%%eax\n\t" "pushl %%eax\n\t" "call *%5\n\t" /* call fn */ "movl %3,%0\n\t" /* exit */ "int $0x80\n" "1:\t" :"=&a" (retval), "=&S" (d0) :"0" (__NR_clone), "i" (__NR_exit), "r" (arg), "r" (fn), "b" (flags | CLONE_VM) : "memory"); return retval; } /* * Free current thread data structures etc.. */ void exit_thread(void) { /* nothing to do ... */ } void flush_thread(void) { struct task_struct *tsk = current; memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); /* * Forget coprocessor state.. */ clear_fpu(tsk); tsk->used_math = 0; } void release_thread(struct task_struct *dead_task) { if (dead_task->mm) { // temporary debugging check if (dead_task->mm->context.size) { printk("WARNING: dead process %8s still has LDT? <%p/%p>\n", dead_task->comm, dead_task->mm->context.ldt, dead_task->mm->context.size); BUG(); } } //release_x86_irqs(dead_task); } /* * Save a segment. */ #define savesegment(seg,value) \ asm volatile("movl %%" #seg ",%0":"=m" (*(int *)&(value))) int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, unsigned long unused, struct task_struct * p, struct pt_regs * regs) { struct pt_regs * childregs; unsigned long eflags; childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p)) - 1; struct_cpy(childregs, regs); childregs->eax = 0; childregs->esp = esp; p->thread.esp = (unsigned long) childregs; p->thread.esp0 = (unsigned long) (childregs+1); p->thread.eip = (unsigned long) ret_from_fork; savesegment(fs,p->thread.fs); savesegment(gs,p->thread.gs); unlazy_fpu(current); struct_cpy(&p->thread.i387, ¤t->thread.i387); __asm__ __volatile__ ( "pushfl; popl %0" : "=r" (eflags) : ); p->thread.io_pl = (eflags >> 12) & 3; return 0; } /* * fill in the user structure for a core dump.. */ void dump_thread(struct pt_regs * regs, struct user * dump) { int i; /* changed the size calculations - should hopefully work better. lbt */ dump->magic = CMAGIC; dump->start_code = 0; dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; dump->u_dsize -= dump->u_tsize; dump->u_ssize = 0; for (i = 0; i < 8; i++) dump->u_debugreg[i] = current->thread.debugreg[i]; if (dump->start_stack < TASK_SIZE) dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; dump->regs.ebx = regs->ebx; dump->regs.ecx = regs->ecx; dump->regs.edx = regs->edx; dump->regs.esi = regs->esi; dump->regs.edi = regs->edi; dump->regs.ebp = regs->ebp; dump->regs.eax = regs->eax; dump->regs.ds = regs->xds; dump->regs.es = regs->xes; savesegment(fs,dump->regs.fs); savesegment(gs,dump->regs.gs); dump->regs.orig_eax = regs->orig_eax; dump->regs.eip = regs->eip; dump->regs.cs = regs->xcs; dump->regs.eflags = regs->eflags; dump->regs.esp = regs->esp; dump->regs.ss = regs->xss; dump->u_fpvalid = dump_fpu (regs, &dump->i387); } /* * 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. */ void __switch_to(struct task_struct *prev_p, struct task_struct *next_p) { struct thread_struct *next = &next_p->thread; __cli(); /* * We clobber FS and GS here so that we avoid a GPF when restoring previous * task's FS/GS values in Xen when the LDT is switched. If we don't do this * then we can end up erroneously re-flushing the page-update queue when * we 'execute_multicall_list'. */ __asm__ __volatile__ ( "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs" : : : "eax" ); MULTICALL_flush_page_update_queue(); /* * This is basically 'unlazy_fpu', except that we queue a multicall to * indicate FPU task switch, rather than synchronously trapping to Xen. */ if ( prev_p->flags & PF_USEDFPU ) { if ( cpu_has_fxsr ) asm volatile( "fxsave %0 ; fnclex" : "=m" (prev_p->thread.i387.fxsave) ); else asm volatile( "fnsave %0 ; fwait" : "=m" (prev_p->thread.i387.fsave) ); prev_p->flags &= ~PF_USEDFPU; queue_multicall0(__HYPERVISOR_fpu_taskswitch); } queue_multicall2(__HYPERVISOR_stack_switch, __KERNEL_DS, next->esp0); if ( start_info.flags & SIF_PRIVILEGED ) { dom0_op_t op; op.cmd = DOM0_IOPL; op.u.iopl.domain = DOMID_SELF; op.u.iopl.iopl = next->io_pl; queue_multicall1(__HYPERVISOR_dom0_op, (unsigned long)&op); } /* EXECUTE ALL TASK SWITCH XEN SYSCALLS AT THIS POINT. */ execute_multicall_list(); __sti(); /* * Restore %fs and %gs. */ loadsegment(fs, next->fs); loadsegment(gs, next->gs); /* * Now maybe reload the debug registers */ if ( next->debugreg[7] != 0 ) { HYPERVISOR_set_debugreg(0, next->debugreg[0]); HYPERVISOR_set_debugreg(1, next->debugreg[1]); HYPERVISOR_set_debugreg(2, next->debugreg[2]); HYPERVISOR_set_debugreg(3, next->debugreg[3]); /* no 4 and 5 */ HYPERVISOR_set_debugreg(6, next->debugreg[6]); HYPERVISOR_set_debugreg(7, next->debugreg[7]); } } asmlinkage int sys_fork(struct pt_regs regs) { return do_fork(SIGCHLD, regs.esp, ®s, 0); } asmlinkage int sys_clone(struct pt_regs regs) { unsigned long clone_flags; unsigned long newsp; clone_flags = regs.ebx; newsp = regs.ecx; if (!newsp) newsp = regs.esp; return do_fork(clone_flags, newsp, ®s, 0); } /* * 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.esp, ®s, 0); } /* * sys_execve() executes a new program. */ asmlinkage int sys_execve(struct pt_regs regs) { int error; char * filename; filename = getname((char *) regs.ebx); error = PTR_ERR(filename); if (IS_ERR(filename)) goto out; error = do_execve(filename, (char **) regs.ecx, (char **) regs.edx, ®s); if (error == 0) current->ptrace &= ~PT_DTRACE; putname(filename); out: return error; } /* * These bracket the sleeping functions.. */ extern void scheduling_functions_start_here(void); extern void scheduling_functions_end_here(void); #define first_sched ((unsigned long) scheduling_functions_start_here) #define last_sched ((unsigned long) scheduling_functions_end_here) unsigned long get_wchan(struct task_struct *p) { unsigned long ebp, esp, eip; unsigned long stack_page; int count = 0; if (!p || p == current || p->state == TASK_RUNNING) return 0; stack_page = (unsigned long)p; esp = p->thread.esp; if (!stack_page || esp < stack_page || esp > 8188+stack_page) return 0; /* include/asm-i386/system.h:switch_to() pushes ebp last. */ ebp = *(unsigned long *) esp; do { if (ebp < stack_page || ebp > 8184+stack_page) return 0; eip = *(unsigned long *) (ebp+4); if (eip < first_sched || eip >= last_sched) return eip; ebp = *(unsigned long *) ebp; } while (count++ < 16); return 0; } #undef last_sched #undef first_sched