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/sched.h> 13 #include <linux/kernel.h> 14 #include <linux/mm.h> 15 #include <linux/smp.h> 16 #include <linux/slab.h> 17 #include <linux/interrupt.h> 18 #include <linux/tick.h> 19 #include <linux/personality.h> 20 #include <linux/syscalls.h> 21 #include <linux/compat.h> 22 #include <linux/kprobes.h> 23 #include <linux/random.h> 24 #include <linux/module.h> 25 #include <asm/system.h> 26 #include <asm/io.h> 27 #include <asm/processor.h> 28 #include <asm/irq.h> 29 #include <asm/timer.h> 30 #include <asm/nmi.h> 31 #include <asm/compat.h> 32 #include <asm/smp.h> 33 #include "entry.h" 34 35 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 36 37 /* 38 * Return saved PC of a blocked thread. used in kernel/sched. 39 * resume in entry.S does not create a new stack frame, it 40 * just stores the registers %r6-%r15 to the frame given by 41 * schedule. We want to return the address of the caller of 42 * schedule, so we have to walk the backchain one time to 43 * find the frame schedule() store its return address. 44 */ 45 unsigned long thread_saved_pc(struct task_struct *tsk) 46 { 47 struct stack_frame *sf, *low, *high; 48 49 if (!tsk || !task_stack_page(tsk)) 50 return 0; 51 low = task_stack_page(tsk); 52 high = (struct stack_frame *) task_pt_regs(tsk); 53 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 54 if (sf <= low || sf > high) 55 return 0; 56 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 57 if (sf <= low || sf > high) 58 return 0; 59 return sf->gprs[8]; 60 } 61 62 /* 63 * The idle loop on a S390... 64 */ 65 static void default_idle(void) 66 { 67 if (cpu_is_offline(smp_processor_id())) 68 cpu_die(); 69 local_irq_disable(); 70 if (need_resched()) { 71 local_irq_enable(); 72 return; 73 } 74 local_mcck_disable(); 75 if (test_thread_flag(TIF_MCCK_PENDING)) { 76 local_mcck_enable(); 77 local_irq_enable(); 78 s390_handle_mcck(); 79 return; 80 } 81 trace_hardirqs_on(); 82 /* Don't trace preempt off for idle. */ 83 stop_critical_timings(); 84 /* Stop virtual timer and halt the cpu. */ 85 vtime_stop_cpu(); 86 /* Reenable preemption tracer. */ 87 start_critical_timings(); 88 } 89 90 void cpu_idle(void) 91 { 92 for (;;) { 93 tick_nohz_stop_sched_tick(1); 94 while (!need_resched()) 95 default_idle(); 96 tick_nohz_restart_sched_tick(); 97 preempt_enable_no_resched(); 98 schedule(); 99 preempt_disable(); 100 } 101 } 102 103 extern void __kprobes kernel_thread_starter(void); 104 105 asm( 106 ".section .kprobes.text, \"ax\"\n" 107 ".global kernel_thread_starter\n" 108 "kernel_thread_starter:\n" 109 " la 2,0(10)\n" 110 " basr 14,9\n" 111 " la 2,0\n" 112 " br 11\n" 113 ".previous\n"); 114 115 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 116 { 117 struct pt_regs regs; 118 119 memset(®s, 0, sizeof(regs)); 120 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT; 121 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; 122 regs.gprs[9] = (unsigned long) fn; 123 regs.gprs[10] = (unsigned long) arg; 124 regs.gprs[11] = (unsigned long) do_exit; 125 regs.orig_gpr2 = -1; 126 127 /* Ok, create the new process.. */ 128 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 129 0, ®s, 0, NULL, NULL); 130 } 131 EXPORT_SYMBOL(kernel_thread); 132 133 /* 134 * Free current thread data structures etc.. 135 */ 136 void exit_thread(void) 137 { 138 } 139 140 void flush_thread(void) 141 { 142 } 143 144 void release_thread(struct task_struct *dead_task) 145 { 146 } 147 148 int copy_thread(unsigned long clone_flags, unsigned long new_stackp, 149 unsigned long unused, 150 struct task_struct *p, struct pt_regs *regs) 151 { 152 struct thread_info *ti; 153 struct fake_frame 154 { 155 struct stack_frame sf; 156 struct pt_regs childregs; 157 } *frame; 158 159 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 160 p->thread.ksp = (unsigned long) frame; 161 /* Store access registers to kernel stack of new process. */ 162 frame->childregs = *regs; 163 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 164 frame->childregs.gprs[15] = new_stackp; 165 frame->sf.back_chain = 0; 166 167 /* new return point is ret_from_fork */ 168 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 169 170 /* fake return stack for resume(), don't go back to schedule */ 171 frame->sf.gprs[9] = (unsigned long) frame; 172 173 /* Save access registers to new thread structure. */ 174 save_access_regs(&p->thread.acrs[0]); 175 176 #ifndef CONFIG_64BIT 177 /* 178 * save fprs to current->thread.fp_regs to merge them with 179 * the emulated registers and then copy the result to the child. 180 */ 181 save_fp_regs(¤t->thread.fp_regs); 182 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 183 sizeof(s390_fp_regs)); 184 /* Set a new TLS ? */ 185 if (clone_flags & CLONE_SETTLS) 186 p->thread.acrs[0] = regs->gprs[6]; 187 #else /* CONFIG_64BIT */ 188 /* Save the fpu registers to new thread structure. */ 189 save_fp_regs(&p->thread.fp_regs); 190 /* Set a new TLS ? */ 191 if (clone_flags & CLONE_SETTLS) { 192 if (is_compat_task()) { 193 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 194 } else { 195 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 196 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 197 } 198 } 199 #endif /* CONFIG_64BIT */ 200 /* start new process with ar4 pointing to the correct address space */ 201 p->thread.mm_segment = get_fs(); 202 /* Don't copy debug registers */ 203 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 204 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 205 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 206 clear_tsk_thread_flag(p, TIF_PER_TRAP); 207 /* Initialize per thread user and system timer values */ 208 ti = task_thread_info(p); 209 ti->user_timer = 0; 210 ti->system_timer = 0; 211 return 0; 212 } 213 214 SYSCALL_DEFINE0(fork) 215 { 216 struct pt_regs *regs = task_pt_regs(current); 217 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 218 } 219 220 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 221 int __user *, parent_tidptr, int __user *, child_tidptr) 222 { 223 struct pt_regs *regs = task_pt_regs(current); 224 225 if (!newsp) 226 newsp = regs->gprs[15]; 227 return do_fork(clone_flags, newsp, regs, 0, 228 parent_tidptr, child_tidptr); 229 } 230 231 /* 232 * This is trivial, and on the face of it looks like it 233 * could equally well be done in user mode. 234 * 235 * Not so, for quite unobvious reasons - register pressure. 236 * In user mode vfork() cannot have a stack frame, and if 237 * done by calling the "clone()" system call directly, you 238 * do not have enough call-clobbered registers to hold all 239 * the information you need. 240 */ 241 SYSCALL_DEFINE0(vfork) 242 { 243 struct pt_regs *regs = task_pt_regs(current); 244 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 245 regs->gprs[15], regs, 0, NULL, NULL); 246 } 247 248 asmlinkage void execve_tail(void) 249 { 250 current->thread.fp_regs.fpc = 0; 251 if (MACHINE_HAS_IEEE) 252 asm volatile("sfpc %0,%0" : : "d" (0)); 253 } 254 255 /* 256 * sys_execve() executes a new program. 257 */ 258 SYSCALL_DEFINE3(execve, const char __user *, name, 259 const char __user *const __user *, argv, 260 const char __user *const __user *, envp) 261 { 262 struct pt_regs *regs = task_pt_regs(current); 263 char *filename; 264 long rc; 265 266 filename = getname(name); 267 rc = PTR_ERR(filename); 268 if (IS_ERR(filename)) 269 return rc; 270 rc = do_execve(filename, argv, envp, regs); 271 if (rc) 272 goto out; 273 execve_tail(); 274 rc = regs->gprs[2]; 275 out: 276 putname(filename); 277 return rc; 278 } 279 280 /* 281 * fill in the FPU structure for a core dump. 282 */ 283 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 284 { 285 #ifndef CONFIG_64BIT 286 /* 287 * save fprs to current->thread.fp_regs to merge them with 288 * the emulated registers and then copy the result to the dump. 289 */ 290 save_fp_regs(¤t->thread.fp_regs); 291 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 292 #else /* CONFIG_64BIT */ 293 save_fp_regs(fpregs); 294 #endif /* CONFIG_64BIT */ 295 return 1; 296 } 297 EXPORT_SYMBOL(dump_fpu); 298 299 unsigned long get_wchan(struct task_struct *p) 300 { 301 struct stack_frame *sf, *low, *high; 302 unsigned long return_address; 303 int count; 304 305 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 306 return 0; 307 low = task_stack_page(p); 308 high = (struct stack_frame *) task_pt_regs(p); 309 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 310 if (sf <= low || sf > high) 311 return 0; 312 for (count = 0; count < 16; count++) { 313 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 314 if (sf <= low || sf > high) 315 return 0; 316 return_address = sf->gprs[8] & PSW_ADDR_INSN; 317 if (!in_sched_functions(return_address)) 318 return return_address; 319 } 320 return 0; 321 } 322 323 unsigned long arch_align_stack(unsigned long sp) 324 { 325 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 326 sp -= get_random_int() & ~PAGE_MASK; 327 return sp & ~0xf; 328 } 329 330 static inline unsigned long brk_rnd(void) 331 { 332 /* 8MB for 32bit, 1GB for 64bit */ 333 if (is_32bit_task()) 334 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; 335 else 336 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT; 337 } 338 339 unsigned long arch_randomize_brk(struct mm_struct *mm) 340 { 341 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); 342 343 if (ret < mm->brk) 344 return mm->brk; 345 return ret; 346 } 347 348 unsigned long randomize_et_dyn(unsigned long base) 349 { 350 unsigned long ret = PAGE_ALIGN(base + brk_rnd()); 351 352 if (!(current->flags & PF_RANDOMIZE)) 353 return base; 354 if (ret < base) 355 return base; 356 return ret; 357 } 358