1 /* 2 * This file handles the architecture dependent parts of process handling. 3 * 4 * Copyright IBM Corp. 1999,2009 5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, 6 * Hartmut Penner <hp@de.ibm.com>, 7 * Denis Joseph Barrow, 8 */ 9 10 #include <linux/compiler.h> 11 #include <linux/cpu.h> 12 #include <linux/errno.h> 13 #include <linux/sched.h> 14 #include <linux/kernel.h> 15 #include <linux/mm.h> 16 #include <linux/fs.h> 17 #include <linux/smp.h> 18 #include <linux/stddef.h> 19 #include <linux/slab.h> 20 #include <linux/unistd.h> 21 #include <linux/ptrace.h> 22 #include <linux/vmalloc.h> 23 #include <linux/user.h> 24 #include <linux/interrupt.h> 25 #include <linux/delay.h> 26 #include <linux/reboot.h> 27 #include <linux/init.h> 28 #include <linux/module.h> 29 #include <linux/notifier.h> 30 #include <linux/tick.h> 31 #include <linux/elfcore.h> 32 #include <linux/kernel_stat.h> 33 #include <linux/syscalls.h> 34 #include <linux/compat.h> 35 #include <linux/kprobes.h> 36 #include <asm/compat.h> 37 #include <asm/uaccess.h> 38 #include <asm/pgtable.h> 39 #include <asm/system.h> 40 #include <asm/io.h> 41 #include <asm/processor.h> 42 #include <asm/irq.h> 43 #include <asm/timer.h> 44 #include <asm/nmi.h> 45 #include <asm/smp.h> 46 #include "entry.h" 47 48 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 49 50 /* 51 * Return saved PC of a blocked thread. used in kernel/sched. 52 * resume in entry.S does not create a new stack frame, it 53 * just stores the registers %r6-%r15 to the frame given by 54 * schedule. We want to return the address of the caller of 55 * schedule, so we have to walk the backchain one time to 56 * find the frame schedule() store its return address. 57 */ 58 unsigned long thread_saved_pc(struct task_struct *tsk) 59 { 60 struct stack_frame *sf, *low, *high; 61 62 if (!tsk || !task_stack_page(tsk)) 63 return 0; 64 low = task_stack_page(tsk); 65 high = (struct stack_frame *) task_pt_regs(tsk); 66 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 67 if (sf <= low || sf > high) 68 return 0; 69 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 70 if (sf <= low || sf > high) 71 return 0; 72 return sf->gprs[8]; 73 } 74 75 /* 76 * The idle loop on a S390... 77 */ 78 static void default_idle(void) 79 { 80 if (cpu_is_offline(smp_processor_id())) 81 cpu_die(); 82 local_irq_disable(); 83 if (need_resched()) { 84 local_irq_enable(); 85 return; 86 } 87 local_mcck_disable(); 88 if (test_thread_flag(TIF_MCCK_PENDING)) { 89 local_mcck_enable(); 90 local_irq_enable(); 91 s390_handle_mcck(); 92 return; 93 } 94 trace_hardirqs_on(); 95 /* Don't trace preempt off for idle. */ 96 stop_critical_timings(); 97 /* Stop virtual timer and halt the cpu. */ 98 vtime_stop_cpu(); 99 /* Reenable preemption tracer. */ 100 start_critical_timings(); 101 } 102 103 void cpu_idle(void) 104 { 105 for (;;) { 106 tick_nohz_stop_sched_tick(1); 107 while (!need_resched()) 108 default_idle(); 109 tick_nohz_restart_sched_tick(); 110 preempt_enable_no_resched(); 111 schedule(); 112 preempt_disable(); 113 } 114 } 115 116 extern void __kprobes kernel_thread_starter(void); 117 118 asm( 119 ".section .kprobes.text, \"ax\"\n" 120 ".global kernel_thread_starter\n" 121 "kernel_thread_starter:\n" 122 " la 2,0(10)\n" 123 " basr 14,9\n" 124 " la 2,0\n" 125 " br 11\n" 126 ".previous\n"); 127 128 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 129 { 130 struct pt_regs regs; 131 132 memset(®s, 0, sizeof(regs)); 133 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT; 134 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; 135 regs.gprs[9] = (unsigned long) fn; 136 regs.gprs[10] = (unsigned long) arg; 137 regs.gprs[11] = (unsigned long) do_exit; 138 regs.orig_gpr2 = -1; 139 140 /* Ok, create the new process.. */ 141 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 142 0, ®s, 0, NULL, NULL); 143 } 144 EXPORT_SYMBOL(kernel_thread); 145 146 /* 147 * Free current thread data structures etc.. 148 */ 149 void exit_thread(void) 150 { 151 } 152 153 void flush_thread(void) 154 { 155 } 156 157 void release_thread(struct task_struct *dead_task) 158 { 159 } 160 161 int copy_thread(unsigned long clone_flags, unsigned long new_stackp, 162 unsigned long unused, 163 struct task_struct *p, struct pt_regs *regs) 164 { 165 struct thread_info *ti; 166 struct fake_frame 167 { 168 struct stack_frame sf; 169 struct pt_regs childregs; 170 } *frame; 171 172 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 173 p->thread.ksp = (unsigned long) frame; 174 /* Store access registers to kernel stack of new process. */ 175 frame->childregs = *regs; 176 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 177 frame->childregs.gprs[15] = new_stackp; 178 frame->sf.back_chain = 0; 179 180 /* new return point is ret_from_fork */ 181 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 182 183 /* fake return stack for resume(), don't go back to schedule */ 184 frame->sf.gprs[9] = (unsigned long) frame; 185 186 /* Save access registers to new thread structure. */ 187 save_access_regs(&p->thread.acrs[0]); 188 189 #ifndef CONFIG_64BIT 190 /* 191 * save fprs to current->thread.fp_regs to merge them with 192 * the emulated registers and then copy the result to the child. 193 */ 194 save_fp_regs(¤t->thread.fp_regs); 195 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 196 sizeof(s390_fp_regs)); 197 /* Set a new TLS ? */ 198 if (clone_flags & CLONE_SETTLS) 199 p->thread.acrs[0] = regs->gprs[6]; 200 #else /* CONFIG_64BIT */ 201 /* Save the fpu registers to new thread structure. */ 202 save_fp_regs(&p->thread.fp_regs); 203 /* Set a new TLS ? */ 204 if (clone_flags & CLONE_SETTLS) { 205 if (is_compat_task()) { 206 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 207 } else { 208 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 209 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 210 } 211 } 212 #endif /* CONFIG_64BIT */ 213 /* start new process with ar4 pointing to the correct address space */ 214 p->thread.mm_segment = get_fs(); 215 /* Don't copy debug registers */ 216 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 217 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 218 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 219 clear_tsk_thread_flag(p, TIF_PER_TRAP); 220 /* Initialize per thread user and system timer values */ 221 ti = task_thread_info(p); 222 ti->user_timer = 0; 223 ti->system_timer = 0; 224 return 0; 225 } 226 227 SYSCALL_DEFINE0(fork) 228 { 229 struct pt_regs *regs = task_pt_regs(current); 230 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 231 } 232 233 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 234 int __user *, parent_tidptr, int __user *, child_tidptr) 235 { 236 struct pt_regs *regs = task_pt_regs(current); 237 238 if (!newsp) 239 newsp = regs->gprs[15]; 240 return do_fork(clone_flags, newsp, regs, 0, 241 parent_tidptr, child_tidptr); 242 } 243 244 /* 245 * This is trivial, and on the face of it looks like it 246 * could equally well be done in user mode. 247 * 248 * Not so, for quite unobvious reasons - register pressure. 249 * In user mode vfork() cannot have a stack frame, and if 250 * done by calling the "clone()" system call directly, you 251 * do not have enough call-clobbered registers to hold all 252 * the information you need. 253 */ 254 SYSCALL_DEFINE0(vfork) 255 { 256 struct pt_regs *regs = task_pt_regs(current); 257 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 258 regs->gprs[15], regs, 0, NULL, NULL); 259 } 260 261 asmlinkage void execve_tail(void) 262 { 263 current->thread.fp_regs.fpc = 0; 264 if (MACHINE_HAS_IEEE) 265 asm volatile("sfpc %0,%0" : : "d" (0)); 266 } 267 268 /* 269 * sys_execve() executes a new program. 270 */ 271 SYSCALL_DEFINE3(execve, const char __user *, name, 272 const char __user *const __user *, argv, 273 const char __user *const __user *, envp) 274 { 275 struct pt_regs *regs = task_pt_regs(current); 276 char *filename; 277 long rc; 278 279 filename = getname(name); 280 rc = PTR_ERR(filename); 281 if (IS_ERR(filename)) 282 return rc; 283 rc = do_execve(filename, argv, envp, regs); 284 if (rc) 285 goto out; 286 execve_tail(); 287 rc = regs->gprs[2]; 288 out: 289 putname(filename); 290 return rc; 291 } 292 293 /* 294 * fill in the FPU structure for a core dump. 295 */ 296 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 297 { 298 #ifndef CONFIG_64BIT 299 /* 300 * save fprs to current->thread.fp_regs to merge them with 301 * the emulated registers and then copy the result to the dump. 302 */ 303 save_fp_regs(¤t->thread.fp_regs); 304 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 305 #else /* CONFIG_64BIT */ 306 save_fp_regs(fpregs); 307 #endif /* CONFIG_64BIT */ 308 return 1; 309 } 310 EXPORT_SYMBOL(dump_fpu); 311 312 unsigned long get_wchan(struct task_struct *p) 313 { 314 struct stack_frame *sf, *low, *high; 315 unsigned long return_address; 316 int count; 317 318 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 319 return 0; 320 low = task_stack_page(p); 321 high = (struct stack_frame *) task_pt_regs(p); 322 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 323 if (sf <= low || sf > high) 324 return 0; 325 for (count = 0; count < 16; count++) { 326 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 327 if (sf <= low || sf > high) 328 return 0; 329 return_address = sf->gprs[8] & PSW_ADDR_INSN; 330 if (!in_sched_functions(return_address)) 331 return return_address; 332 } 333 return 0; 334 } 335