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