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/personality.h> 34 #include <linux/syscalls.h> 35 #include <linux/compat.h> 36 #include <linux/kprobes.h> 37 #include <linux/random.h> 38 #include <asm/compat.h> 39 #include <asm/uaccess.h> 40 #include <asm/pgtable.h> 41 #include <asm/system.h> 42 #include <asm/io.h> 43 #include <asm/processor.h> 44 #include <asm/irq.h> 45 #include <asm/timer.h> 46 #include <asm/nmi.h> 47 #include <asm/smp.h> 48 #include "entry.h" 49 50 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 51 52 /* 53 * Return saved PC of a blocked thread. used in kernel/sched. 54 * resume in entry.S does not create a new stack frame, it 55 * just stores the registers %r6-%r15 to the frame given by 56 * schedule. We want to return the address of the caller of 57 * schedule, so we have to walk the backchain one time to 58 * find the frame schedule() store its return address. 59 */ 60 unsigned long thread_saved_pc(struct task_struct *tsk) 61 { 62 struct stack_frame *sf, *low, *high; 63 64 if (!tsk || !task_stack_page(tsk)) 65 return 0; 66 low = task_stack_page(tsk); 67 high = (struct stack_frame *) task_pt_regs(tsk); 68 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 69 if (sf <= low || sf > high) 70 return 0; 71 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 72 if (sf <= low || sf > high) 73 return 0; 74 return sf->gprs[8]; 75 } 76 77 /* 78 * The idle loop on a S390... 79 */ 80 static void default_idle(void) 81 { 82 if (cpu_is_offline(smp_processor_id())) 83 cpu_die(); 84 local_irq_disable(); 85 if (need_resched()) { 86 local_irq_enable(); 87 return; 88 } 89 local_mcck_disable(); 90 if (test_thread_flag(TIF_MCCK_PENDING)) { 91 local_mcck_enable(); 92 local_irq_enable(); 93 s390_handle_mcck(); 94 return; 95 } 96 trace_hardirqs_on(); 97 /* Don't trace preempt off for idle. */ 98 stop_critical_timings(); 99 /* Stop virtual timer and halt the cpu. */ 100 vtime_stop_cpu(); 101 /* Reenable preemption tracer. */ 102 start_critical_timings(); 103 } 104 105 void cpu_idle(void) 106 { 107 for (;;) { 108 tick_nohz_stop_sched_tick(1); 109 while (!need_resched()) 110 default_idle(); 111 tick_nohz_restart_sched_tick(); 112 preempt_enable_no_resched(); 113 schedule(); 114 preempt_disable(); 115 } 116 } 117 118 extern void __kprobes kernel_thread_starter(void); 119 120 asm( 121 ".section .kprobes.text, \"ax\"\n" 122 ".global kernel_thread_starter\n" 123 "kernel_thread_starter:\n" 124 " la 2,0(10)\n" 125 " basr 14,9\n" 126 " la 2,0\n" 127 " br 11\n" 128 ".previous\n"); 129 130 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 131 { 132 struct pt_regs regs; 133 134 memset(®s, 0, sizeof(regs)); 135 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT; 136 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; 137 regs.gprs[9] = (unsigned long) fn; 138 regs.gprs[10] = (unsigned long) arg; 139 regs.gprs[11] = (unsigned long) do_exit; 140 regs.orig_gpr2 = -1; 141 142 /* Ok, create the new process.. */ 143 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 144 0, ®s, 0, NULL, NULL); 145 } 146 EXPORT_SYMBOL(kernel_thread); 147 148 /* 149 * Free current thread data structures etc.. 150 */ 151 void exit_thread(void) 152 { 153 } 154 155 void flush_thread(void) 156 { 157 } 158 159 void release_thread(struct task_struct *dead_task) 160 { 161 } 162 163 int copy_thread(unsigned long clone_flags, unsigned long new_stackp, 164 unsigned long unused, 165 struct task_struct *p, struct pt_regs *regs) 166 { 167 struct thread_info *ti; 168 struct fake_frame 169 { 170 struct stack_frame sf; 171 struct pt_regs childregs; 172 } *frame; 173 174 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 175 p->thread.ksp = (unsigned long) frame; 176 /* Store access registers to kernel stack of new process. */ 177 frame->childregs = *regs; 178 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 179 frame->childregs.gprs[15] = new_stackp; 180 frame->sf.back_chain = 0; 181 182 /* new return point is ret_from_fork */ 183 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 184 185 /* fake return stack for resume(), don't go back to schedule */ 186 frame->sf.gprs[9] = (unsigned long) frame; 187 188 /* Save access registers to new thread structure. */ 189 save_access_regs(&p->thread.acrs[0]); 190 191 #ifndef CONFIG_64BIT 192 /* 193 * save fprs to current->thread.fp_regs to merge them with 194 * the emulated registers and then copy the result to the child. 195 */ 196 save_fp_regs(¤t->thread.fp_regs); 197 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 198 sizeof(s390_fp_regs)); 199 /* Set a new TLS ? */ 200 if (clone_flags & CLONE_SETTLS) 201 p->thread.acrs[0] = regs->gprs[6]; 202 #else /* CONFIG_64BIT */ 203 /* Save the fpu registers to new thread structure. */ 204 save_fp_regs(&p->thread.fp_regs); 205 /* Set a new TLS ? */ 206 if (clone_flags & CLONE_SETTLS) { 207 if (is_compat_task()) { 208 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 209 } else { 210 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 211 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 212 } 213 } 214 #endif /* CONFIG_64BIT */ 215 /* start new process with ar4 pointing to the correct address space */ 216 p->thread.mm_segment = get_fs(); 217 /* Don't copy debug registers */ 218 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 219 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 220 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 221 clear_tsk_thread_flag(p, TIF_PER_TRAP); 222 /* Initialize per thread user and system timer values */ 223 ti = task_thread_info(p); 224 ti->user_timer = 0; 225 ti->system_timer = 0; 226 return 0; 227 } 228 229 SYSCALL_DEFINE0(fork) 230 { 231 struct pt_regs *regs = task_pt_regs(current); 232 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 233 } 234 235 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 236 int __user *, parent_tidptr, int __user *, child_tidptr) 237 { 238 struct pt_regs *regs = task_pt_regs(current); 239 240 if (!newsp) 241 newsp = regs->gprs[15]; 242 return do_fork(clone_flags, newsp, regs, 0, 243 parent_tidptr, child_tidptr); 244 } 245 246 /* 247 * This is trivial, and on the face of it looks like it 248 * could equally well be done in user mode. 249 * 250 * Not so, for quite unobvious reasons - register pressure. 251 * In user mode vfork() cannot have a stack frame, and if 252 * done by calling the "clone()" system call directly, you 253 * do not have enough call-clobbered registers to hold all 254 * the information you need. 255 */ 256 SYSCALL_DEFINE0(vfork) 257 { 258 struct pt_regs *regs = task_pt_regs(current); 259 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 260 regs->gprs[15], regs, 0, NULL, NULL); 261 } 262 263 asmlinkage void execve_tail(void) 264 { 265 current->thread.fp_regs.fpc = 0; 266 if (MACHINE_HAS_IEEE) 267 asm volatile("sfpc %0,%0" : : "d" (0)); 268 } 269 270 /* 271 * sys_execve() executes a new program. 272 */ 273 SYSCALL_DEFINE3(execve, const char __user *, name, 274 const char __user *const __user *, argv, 275 const char __user *const __user *, envp) 276 { 277 struct pt_regs *regs = task_pt_regs(current); 278 char *filename; 279 long rc; 280 281 filename = getname(name); 282 rc = PTR_ERR(filename); 283 if (IS_ERR(filename)) 284 return rc; 285 rc = do_execve(filename, argv, envp, regs); 286 if (rc) 287 goto out; 288 execve_tail(); 289 rc = regs->gprs[2]; 290 out: 291 putname(filename); 292 return rc; 293 } 294 295 /* 296 * fill in the FPU structure for a core dump. 297 */ 298 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 299 { 300 #ifndef CONFIG_64BIT 301 /* 302 * save fprs to current->thread.fp_regs to merge them with 303 * the emulated registers and then copy the result to the dump. 304 */ 305 save_fp_regs(¤t->thread.fp_regs); 306 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 307 #else /* CONFIG_64BIT */ 308 save_fp_regs(fpregs); 309 #endif /* CONFIG_64BIT */ 310 return 1; 311 } 312 EXPORT_SYMBOL(dump_fpu); 313 314 unsigned long get_wchan(struct task_struct *p) 315 { 316 struct stack_frame *sf, *low, *high; 317 unsigned long return_address; 318 int count; 319 320 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 321 return 0; 322 low = task_stack_page(p); 323 high = (struct stack_frame *) task_pt_regs(p); 324 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 325 if (sf <= low || sf > high) 326 return 0; 327 for (count = 0; count < 16; count++) { 328 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 329 if (sf <= low || sf > high) 330 return 0; 331 return_address = sf->gprs[8] & PSW_ADDR_INSN; 332 if (!in_sched_functions(return_address)) 333 return return_address; 334 } 335 return 0; 336 } 337 338 unsigned long arch_align_stack(unsigned long sp) 339 { 340 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 341 sp -= get_random_int() & ~PAGE_MASK; 342 return sp & ~0xf; 343 } 344 345 static inline unsigned long brk_rnd(void) 346 { 347 /* 8MB for 32bit, 1GB for 64bit */ 348 if (is_32bit_task()) 349 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; 350 else 351 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT; 352 } 353 354 unsigned long arch_randomize_brk(struct mm_struct *mm) 355 { 356 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); 357 358 if (ret < mm->brk) 359 return mm->brk; 360 return ret; 361 } 362 363 unsigned long randomize_et_dyn(unsigned long base) 364 { 365 unsigned long ret = PAGE_ALIGN(base + brk_rnd()); 366 367 if (!(current->flags & PF_RANDOMIZE)) 368 return base; 369 if (ret < base) 370 return base; 371 return ret; 372 } 373