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/exec.h> 30 #include <asm/irq.h> 31 #include <asm/nmi.h> 32 #include <asm/smp.h> 33 #include <asm/switch_to.h> 34 #include <asm/runtime_instr.h> 35 #include "entry.h" 36 37 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 38 39 /* 40 * Return saved PC of a blocked thread. used in kernel/sched. 41 * resume in entry.S does not create a new stack frame, it 42 * just stores the registers %r6-%r15 to the frame given by 43 * schedule. We want to return the address of the caller of 44 * schedule, so we have to walk the backchain one time to 45 * find the frame schedule() store its return address. 46 */ 47 unsigned long thread_saved_pc(struct task_struct *tsk) 48 { 49 struct stack_frame *sf, *low, *high; 50 51 if (!tsk || !task_stack_page(tsk)) 52 return 0; 53 low = task_stack_page(tsk); 54 high = (struct stack_frame *) task_pt_regs(tsk); 55 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 56 if (sf <= low || sf > high) 57 return 0; 58 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 59 if (sf <= low || sf > high) 60 return 0; 61 return sf->gprs[8]; 62 } 63 64 /* 65 * The idle loop on a S390... 66 */ 67 static void default_idle(void) 68 { 69 if (cpu_is_offline(smp_processor_id())) 70 cpu_die(); 71 local_irq_disable(); 72 if (need_resched()) { 73 local_irq_enable(); 74 return; 75 } 76 local_mcck_disable(); 77 if (test_thread_flag(TIF_MCCK_PENDING)) { 78 local_mcck_enable(); 79 local_irq_enable(); 80 return; 81 } 82 /* Halt the cpu and keep track of cpu time accounting. */ 83 vtime_stop_cpu(); 84 } 85 86 void cpu_idle(void) 87 { 88 for (;;) { 89 tick_nohz_idle_enter(); 90 rcu_idle_enter(); 91 while (!need_resched() && !test_thread_flag(TIF_MCCK_PENDING)) 92 default_idle(); 93 rcu_idle_exit(); 94 tick_nohz_idle_exit(); 95 if (test_thread_flag(TIF_MCCK_PENDING)) 96 s390_handle_mcck(); 97 schedule_preempt_disabled(); 98 } 99 } 100 101 extern void __kprobes kernel_thread_starter(void); 102 103 asm( 104 ".section .kprobes.text, \"ax\"\n" 105 ".global kernel_thread_starter\n" 106 "kernel_thread_starter:\n" 107 " la 2,0(10)\n" 108 " basr 14,9\n" 109 " la 2,0\n" 110 " br 11\n" 111 ".previous\n"); 112 113 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 114 { 115 struct pt_regs regs; 116 117 memset(®s, 0, sizeof(regs)); 118 regs.psw.mask = psw_kernel_bits | 119 PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 120 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; 121 regs.gprs[9] = (unsigned long) fn; 122 regs.gprs[10] = (unsigned long) arg; 123 regs.gprs[11] = (unsigned long) do_exit; 124 regs.orig_gpr2 = -1; 125 126 /* Ok, create the new process.. */ 127 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 128 0, ®s, 0, NULL, NULL); 129 } 130 EXPORT_SYMBOL(kernel_thread); 131 132 /* 133 * Free current thread data structures etc.. 134 */ 135 void exit_thread(void) 136 { 137 exit_thread_runtime_instr(); 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 /* Don't copy runtime instrumentation info */ 177 p->thread.ri_cb = NULL; 178 p->thread.ri_signum = 0; 179 frame->childregs.psw.mask &= ~PSW_MASK_RI; 180 181 #ifndef CONFIG_64BIT 182 /* 183 * save fprs to current->thread.fp_regs to merge them with 184 * the emulated registers and then copy the result to the child. 185 */ 186 save_fp_regs(¤t->thread.fp_regs); 187 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 188 sizeof(s390_fp_regs)); 189 /* Set a new TLS ? */ 190 if (clone_flags & CLONE_SETTLS) 191 p->thread.acrs[0] = regs->gprs[6]; 192 #else /* CONFIG_64BIT */ 193 /* Save the fpu registers to new thread structure. */ 194 save_fp_regs(&p->thread.fp_regs); 195 /* Set a new TLS ? */ 196 if (clone_flags & CLONE_SETTLS) { 197 if (is_compat_task()) { 198 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 199 } else { 200 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 201 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 202 } 203 } 204 #endif /* CONFIG_64BIT */ 205 /* start new process with ar4 pointing to the correct address space */ 206 p->thread.mm_segment = get_fs(); 207 /* Don't copy debug registers */ 208 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 209 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 210 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 211 clear_tsk_thread_flag(p, TIF_PER_TRAP); 212 /* Initialize per thread user and system timer values */ 213 ti = task_thread_info(p); 214 ti->user_timer = 0; 215 ti->system_timer = 0; 216 return 0; 217 } 218 219 SYSCALL_DEFINE0(fork) 220 { 221 struct pt_regs *regs = task_pt_regs(current); 222 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 223 } 224 225 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 226 int __user *, parent_tidptr, int __user *, child_tidptr) 227 { 228 struct pt_regs *regs = task_pt_regs(current); 229 230 if (!newsp) 231 newsp = regs->gprs[15]; 232 return do_fork(clone_flags, newsp, regs, 0, 233 parent_tidptr, child_tidptr); 234 } 235 236 /* 237 * This is trivial, and on the face of it looks like it 238 * could equally well be done in user mode. 239 * 240 * Not so, for quite unobvious reasons - register pressure. 241 * In user mode vfork() cannot have a stack frame, and if 242 * done by calling the "clone()" system call directly, you 243 * do not have enough call-clobbered registers to hold all 244 * the information you need. 245 */ 246 SYSCALL_DEFINE0(vfork) 247 { 248 struct pt_regs *regs = task_pt_regs(current); 249 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 250 regs->gprs[15], regs, 0, NULL, NULL); 251 } 252 253 asmlinkage void execve_tail(void) 254 { 255 current->thread.fp_regs.fpc = 0; 256 if (MACHINE_HAS_IEEE) 257 asm volatile("sfpc %0,%0" : : "d" (0)); 258 } 259 260 /* 261 * sys_execve() executes a new program. 262 */ 263 SYSCALL_DEFINE3(execve, const char __user *, name, 264 const char __user *const __user *, argv, 265 const char __user *const __user *, envp) 266 { 267 struct pt_regs *regs = task_pt_regs(current); 268 char *filename; 269 long rc; 270 271 filename = getname(name); 272 rc = PTR_ERR(filename); 273 if (IS_ERR(filename)) 274 return rc; 275 rc = do_execve(filename, argv, envp, regs); 276 if (rc) 277 goto out; 278 execve_tail(); 279 rc = regs->gprs[2]; 280 out: 281 putname(filename); 282 return rc; 283 } 284 285 /* 286 * fill in the FPU structure for a core dump. 287 */ 288 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 289 { 290 #ifndef CONFIG_64BIT 291 /* 292 * save fprs to current->thread.fp_regs to merge them with 293 * the emulated registers and then copy the result to the dump. 294 */ 295 save_fp_regs(¤t->thread.fp_regs); 296 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 297 #else /* CONFIG_64BIT */ 298 save_fp_regs(fpregs); 299 #endif /* CONFIG_64BIT */ 300 return 1; 301 } 302 EXPORT_SYMBOL(dump_fpu); 303 304 unsigned long get_wchan(struct task_struct *p) 305 { 306 struct stack_frame *sf, *low, *high; 307 unsigned long return_address; 308 int count; 309 310 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 311 return 0; 312 low = task_stack_page(p); 313 high = (struct stack_frame *) task_pt_regs(p); 314 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 315 if (sf <= low || sf > high) 316 return 0; 317 for (count = 0; count < 16; count++) { 318 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 319 if (sf <= low || sf > high) 320 return 0; 321 return_address = sf->gprs[8] & PSW_ADDR_INSN; 322 if (!in_sched_functions(return_address)) 323 return return_address; 324 } 325 return 0; 326 } 327 328 unsigned long arch_align_stack(unsigned long sp) 329 { 330 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 331 sp -= get_random_int() & ~PAGE_MASK; 332 return sp & ~0xf; 333 } 334 335 static inline unsigned long brk_rnd(void) 336 { 337 /* 8MB for 32bit, 1GB for 64bit */ 338 if (is_32bit_task()) 339 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; 340 else 341 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT; 342 } 343 344 unsigned long arch_randomize_brk(struct mm_struct *mm) 345 { 346 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); 347 348 if (ret < mm->brk) 349 return mm->brk; 350 return ret; 351 } 352 353 unsigned long randomize_et_dyn(unsigned long base) 354 { 355 unsigned long ret = PAGE_ALIGN(base + brk_rnd()); 356 357 if (!(current->flags & PF_RANDOMIZE)) 358 return base; 359 if (ret < base) 360 return base; 361 return ret; 362 } 363