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/unistd.h> 20 #include <linux/ptrace.h> 21 #include <linux/slab.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/utsname.h> 31 #include <linux/tick.h> 32 #include <linux/elfcore.h> 33 #include <linux/kernel_stat.h> 34 #include <linux/syscalls.h> 35 #include <asm/uaccess.h> 36 #include <asm/pgtable.h> 37 #include <asm/system.h> 38 #include <asm/io.h> 39 #include <asm/processor.h> 40 #include <asm/irq.h> 41 #include <asm/timer.h> 42 #include <asm/nmi.h> 43 #include "entry.h" 44 45 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 46 47 /* 48 * Return saved PC of a blocked thread. used in kernel/sched. 49 * resume in entry.S does not create a new stack frame, it 50 * just stores the registers %r6-%r15 to the frame given by 51 * schedule. We want to return the address of the caller of 52 * schedule, so we have to walk the backchain one time to 53 * find the frame schedule() store its return address. 54 */ 55 unsigned long thread_saved_pc(struct task_struct *tsk) 56 { 57 struct stack_frame *sf, *low, *high; 58 59 if (!tsk || !task_stack_page(tsk)) 60 return 0; 61 low = task_stack_page(tsk); 62 high = (struct stack_frame *) task_pt_regs(tsk); 63 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 64 if (sf <= low || sf > high) 65 return 0; 66 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 67 if (sf <= low || sf > high) 68 return 0; 69 return sf->gprs[8]; 70 } 71 72 /* 73 * The idle loop on a S390... 74 */ 75 static void default_idle(void) 76 { 77 /* CPU is going idle. */ 78 local_irq_disable(); 79 if (need_resched()) { 80 local_irq_enable(); 81 return; 82 } 83 #ifdef CONFIG_HOTPLUG_CPU 84 if (cpu_is_offline(smp_processor_id())) { 85 preempt_enable_no_resched(); 86 cpu_die(); 87 } 88 #endif 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 kernel_thread_starter(void); 119 120 asm( 121 ".align 4\n" 122 "kernel_thread_starter:\n" 123 " la 2,0(10)\n" 124 " basr 14,9\n" 125 " la 2,0\n" 126 " br 11\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 } 144 145 /* 146 * Free current thread data structures etc.. 147 */ 148 void exit_thread(void) 149 { 150 } 151 152 void flush_thread(void) 153 { 154 clear_used_math(); 155 clear_tsk_thread_flag(current, TIF_USEDFPU); 156 } 157 158 void release_thread(struct task_struct *dead_task) 159 { 160 } 161 162 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp, 163 unsigned long unused, 164 struct task_struct *p, struct pt_regs *regs) 165 { 166 struct thread_info *ti; 167 struct fake_frame 168 { 169 struct stack_frame sf; 170 struct pt_regs childregs; 171 } *frame; 172 173 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 174 p->thread.ksp = (unsigned long) frame; 175 /* Store access registers to kernel stack of new process. */ 176 frame->childregs = *regs; 177 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 178 frame->childregs.gprs[15] = new_stackp; 179 frame->sf.back_chain = 0; 180 181 /* new return point is ret_from_fork */ 182 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 183 184 /* fake return stack for resume(), don't go back to schedule */ 185 frame->sf.gprs[9] = (unsigned long) frame; 186 187 /* Save access registers to new thread structure. */ 188 save_access_regs(&p->thread.acrs[0]); 189 190 #ifndef CONFIG_64BIT 191 /* 192 * save fprs to current->thread.fp_regs to merge them with 193 * the emulated registers and then copy the result to the child. 194 */ 195 save_fp_regs(¤t->thread.fp_regs); 196 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 197 sizeof(s390_fp_regs)); 198 /* Set a new TLS ? */ 199 if (clone_flags & CLONE_SETTLS) 200 p->thread.acrs[0] = regs->gprs[6]; 201 #else /* CONFIG_64BIT */ 202 /* Save the fpu registers to new thread structure. */ 203 save_fp_regs(&p->thread.fp_regs); 204 /* Set a new TLS ? */ 205 if (clone_flags & CLONE_SETTLS) { 206 if (test_thread_flag(TIF_31BIT)) { 207 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 208 } else { 209 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 210 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 211 } 212 } 213 #endif /* CONFIG_64BIT */ 214 /* start new process with ar4 pointing to the correct address space */ 215 p->thread.mm_segment = get_fs(); 216 /* Don't copy debug registers */ 217 memset(&p->thread.per_info, 0, sizeof(p->thread.per_info)); 218 /* Initialize per thread user and system timer values */ 219 ti = task_thread_info(p); 220 ti->user_timer = 0; 221 ti->system_timer = 0; 222 return 0; 223 } 224 225 SYSCALL_DEFINE0(fork) 226 { 227 struct pt_regs *regs = task_pt_regs(current); 228 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 229 } 230 231 SYSCALL_DEFINE0(clone) 232 { 233 struct pt_regs *regs = task_pt_regs(current); 234 unsigned long clone_flags; 235 unsigned long newsp; 236 int __user *parent_tidptr, *child_tidptr; 237 238 clone_flags = regs->gprs[3]; 239 newsp = regs->orig_gpr2; 240 parent_tidptr = (int __user *) regs->gprs[4]; 241 child_tidptr = (int __user *) regs->gprs[5]; 242 if (!newsp) 243 newsp = regs->gprs[15]; 244 return do_fork(clone_flags, newsp, regs, 0, 245 parent_tidptr, child_tidptr); 246 } 247 248 /* 249 * This is trivial, and on the face of it looks like it 250 * could equally well be done in user mode. 251 * 252 * Not so, for quite unobvious reasons - register pressure. 253 * In user mode vfork() cannot have a stack frame, and if 254 * done by calling the "clone()" system call directly, you 255 * do not have enough call-clobbered registers to hold all 256 * the information you need. 257 */ 258 SYSCALL_DEFINE0(vfork) 259 { 260 struct pt_regs *regs = task_pt_regs(current); 261 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 262 regs->gprs[15], regs, 0, NULL, NULL); 263 } 264 265 asmlinkage void execve_tail(void) 266 { 267 task_lock(current); 268 current->ptrace &= ~PT_DTRACE; 269 task_unlock(current); 270 current->thread.fp_regs.fpc = 0; 271 if (MACHINE_HAS_IEEE) 272 asm volatile("sfpc %0,%0" : : "d" (0)); 273 } 274 275 /* 276 * sys_execve() executes a new program. 277 */ 278 SYSCALL_DEFINE0(execve) 279 { 280 struct pt_regs *regs = task_pt_regs(current); 281 char *filename; 282 unsigned long result; 283 int rc; 284 285 filename = getname((char __user *) regs->orig_gpr2); 286 if (IS_ERR(filename)) { 287 result = PTR_ERR(filename); 288 goto out; 289 } 290 rc = do_execve(filename, (char __user * __user *) regs->gprs[3], 291 (char __user * __user *) regs->gprs[4], regs); 292 if (rc) { 293 result = rc; 294 goto out_putname; 295 } 296 execve_tail(); 297 result = regs->gprs[2]; 298 out_putname: 299 putname(filename); 300 out: 301 return result; 302 } 303 304 /* 305 * fill in the FPU structure for a core dump. 306 */ 307 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 308 { 309 #ifndef CONFIG_64BIT 310 /* 311 * save fprs to current->thread.fp_regs to merge them with 312 * the emulated registers and then copy the result to the dump. 313 */ 314 save_fp_regs(¤t->thread.fp_regs); 315 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 316 #else /* CONFIG_64BIT */ 317 save_fp_regs(fpregs); 318 #endif /* CONFIG_64BIT */ 319 return 1; 320 } 321 322 unsigned long get_wchan(struct task_struct *p) 323 { 324 struct stack_frame *sf, *low, *high; 325 unsigned long return_address; 326 int count; 327 328 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 329 return 0; 330 low = task_stack_page(p); 331 high = (struct stack_frame *) task_pt_regs(p); 332 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 333 if (sf <= low || sf > high) 334 return 0; 335 for (count = 0; count < 16; count++) { 336 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 337 if (sf <= low || sf > high) 338 return 0; 339 return_address = sf->gprs[8] & PSW_ADDR_INSN; 340 if (!in_sched_functions(return_address)) 341 return return_address; 342 } 343 return 0; 344 } 345