/* * This file handles the architecture dependent parts of process handling. * * Copyright IBM Corp. 1999,2009 * Author(s): Martin Schwidefsky , * Hartmut Penner , * Denis Joseph Barrow, */ #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 #include #include #include #include #include "entry.h" asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); /* * Return saved PC of a blocked thread. used in kernel/sched. * resume in entry.S does not create a new stack frame, it * just stores the registers %r6-%r15 to the frame given by * schedule. We want to return the address of the caller of * schedule, so we have to walk the backchain one time to * find the frame schedule() store its return address. */ unsigned long thread_saved_pc(struct task_struct *tsk) { struct stack_frame *sf, *low, *high; if (!tsk || !task_stack_page(tsk)) return 0; low = task_stack_page(tsk); high = (struct stack_frame *) task_pt_regs(tsk); sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); if (sf <= low || sf > high) return 0; sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); if (sf <= low || sf > high) return 0; return sf->gprs[8]; } /* * The idle loop on a S390... */ static void default_idle(void) { if (cpu_is_offline(smp_processor_id())) cpu_die(); local_irq_disable(); if (need_resched()) { local_irq_enable(); return; } local_mcck_disable(); if (test_thread_flag(TIF_MCCK_PENDING)) { local_mcck_enable(); local_irq_enable(); s390_handle_mcck(); return; } trace_hardirqs_on(); /* Don't trace preempt off for idle. */ stop_critical_timings(); /* Stop virtual timer and halt the cpu. */ vtime_stop_cpu(); /* Reenable preemption tracer. */ start_critical_timings(); } void cpu_idle(void) { for (;;) { tick_nohz_stop_sched_tick(1); while (!need_resched()) default_idle(); tick_nohz_restart_sched_tick(); preempt_enable_no_resched(); schedule(); preempt_disable(); } } extern void __kprobes kernel_thread_starter(void); asm( ".section .kprobes.text, \"ax\"\n" ".global kernel_thread_starter\n" "kernel_thread_starter:\n" " la 2,0(10)\n" " basr 14,9\n" " la 2,0\n" " br 11\n" ".previous\n"); int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) { struct pt_regs regs; memset(®s, 0, sizeof(regs)); regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT; regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; regs.gprs[9] = (unsigned long) fn; regs.gprs[10] = (unsigned long) arg; regs.gprs[11] = (unsigned long) do_exit; regs.orig_gpr2 = -1; /* 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) { } void flush_thread(void) { } void release_thread(struct task_struct *dead_task) { } int copy_thread(unsigned long clone_flags, unsigned long new_stackp, unsigned long unused, struct task_struct *p, struct pt_regs *regs) { struct thread_info *ti; struct fake_frame { struct stack_frame sf; struct pt_regs childregs; } *frame; frame = container_of(task_pt_regs(p), struct fake_frame, childregs); p->thread.ksp = (unsigned long) frame; /* Store access registers to kernel stack of new process. */ frame->childregs = *regs; frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ frame->childregs.gprs[15] = new_stackp; frame->sf.back_chain = 0; /* new return point is ret_from_fork */ frame->sf.gprs[8] = (unsigned long) ret_from_fork; /* fake return stack for resume(), don't go back to schedule */ frame->sf.gprs[9] = (unsigned long) frame; /* Save access registers to new thread structure. */ save_access_regs(&p->thread.acrs[0]); #ifndef CONFIG_64BIT /* * save fprs to current->thread.fp_regs to merge them with * the emulated registers and then copy the result to the child. */ save_fp_regs(¤t->thread.fp_regs); memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); /* Set a new TLS ? */ if (clone_flags & CLONE_SETTLS) p->thread.acrs[0] = regs->gprs[6]; #else /* CONFIG_64BIT */ /* Save the fpu registers to new thread structure. */ save_fp_regs(&p->thread.fp_regs); /* Set a new TLS ? */ if (clone_flags & CLONE_SETTLS) { if (is_compat_task()) { p->thread.acrs[0] = (unsigned int) regs->gprs[6]; } else { p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); p->thread.acrs[1] = (unsigned int) regs->gprs[6]; } } #endif /* CONFIG_64BIT */ /* start new process with ar4 pointing to the correct address space */ p->thread.mm_segment = get_fs(); /* Don't copy debug registers */ memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); clear_tsk_thread_flag(p, TIF_SINGLE_STEP); clear_tsk_thread_flag(p, TIF_PER_TRAP); /* Initialize per thread user and system timer values */ ti = task_thread_info(p); ti->user_timer = 0; ti->system_timer = 0; return 0; } SYSCALL_DEFINE0(fork) { struct pt_regs *regs = task_pt_regs(current); return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); } SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, int __user *, parent_tidptr, int __user *, child_tidptr) { struct pt_regs *regs = task_pt_regs(current); if (!newsp) newsp = regs->gprs[15]; return do_fork(clone_flags, newsp, regs, 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. */ SYSCALL_DEFINE0(vfork) { struct pt_regs *regs = task_pt_regs(current); return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); } asmlinkage void execve_tail(void) { current->thread.fp_regs.fpc = 0; if (MACHINE_HAS_IEEE) asm volatile("sfpc %0,%0" : : "d" (0)); } /* * sys_execve() executes a new program. */ SYSCALL_DEFINE3(execve, const char __user *, name, const char __user *const __user *, argv, const char __user *const __user *, envp) { struct pt_regs *regs = task_pt_regs(current); char *filename; long rc; filename = getname(name); rc = PTR_ERR(filename); if (IS_ERR(filename)) return rc; rc = do_execve(filename, argv, envp, regs); if (rc) goto out; execve_tail(); rc = regs->gprs[2]; out: putname(filename); return rc; } /* * fill in the FPU structure for a core dump. */ int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) { #ifndef CONFIG_64BIT /* * save fprs to current->thread.fp_regs to merge them with * the emulated registers and then copy the result to the dump. */ save_fp_regs(¤t->thread.fp_regs); memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); #else /* CONFIG_64BIT */ save_fp_regs(fpregs); #endif /* CONFIG_64BIT */ return 1; } EXPORT_SYMBOL(dump_fpu); unsigned long get_wchan(struct task_struct *p) { struct stack_frame *sf, *low, *high; unsigned long return_address; int count; if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) return 0; low = task_stack_page(p); high = (struct stack_frame *) task_pt_regs(p); sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); if (sf <= low || sf > high) return 0; for (count = 0; count < 16; count++) { sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); if (sf <= low || sf > high) return 0; return_address = sf->gprs[8] & PSW_ADDR_INSN; if (!in_sched_functions(return_address)) return return_address; } return 0; }