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/compat.h> 36 #include <asm/uaccess.h> 37 #include <asm/pgtable.h> 38 #include <asm/system.h> 39 #include <asm/io.h> 40 #include <asm/processor.h> 41 #include <asm/irq.h> 42 #include <asm/timer.h> 43 #include <asm/nmi.h> 44 #include "entry.h" 45 46 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 47 48 /* 49 * Return saved PC of a blocked thread. used in kernel/sched. 50 * resume in entry.S does not create a new stack frame, it 51 * just stores the registers %r6-%r15 to the frame given by 52 * schedule. We want to return the address of the caller of 53 * schedule, so we have to walk the backchain one time to 54 * find the frame schedule() store its return address. 55 */ 56 unsigned long thread_saved_pc(struct task_struct *tsk) 57 { 58 struct stack_frame *sf, *low, *high; 59 60 if (!tsk || !task_stack_page(tsk)) 61 return 0; 62 low = task_stack_page(tsk); 63 high = (struct stack_frame *) task_pt_regs(tsk); 64 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); 65 if (sf <= low || sf > high) 66 return 0; 67 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 68 if (sf <= low || sf > high) 69 return 0; 70 return sf->gprs[8]; 71 } 72 73 /* 74 * The idle loop on a S390... 75 */ 76 static void default_idle(void) 77 { 78 /* CPU is going idle. */ 79 local_irq_disable(); 80 if (need_resched()) { 81 local_irq_enable(); 82 return; 83 } 84 #ifdef CONFIG_HOTPLUG_CPU 85 if (cpu_is_offline(smp_processor_id())) { 86 preempt_enable_no_resched(); 87 cpu_die(); 88 } 89 #endif 90 local_mcck_disable(); 91 if (test_thread_flag(TIF_MCCK_PENDING)) { 92 local_mcck_enable(); 93 local_irq_enable(); 94 s390_handle_mcck(); 95 return; 96 } 97 trace_hardirqs_on(); 98 /* Don't trace preempt off for idle. */ 99 stop_critical_timings(); 100 /* Stop virtual timer and halt the cpu. */ 101 vtime_stop_cpu(); 102 /* Reenable preemption tracer. */ 103 start_critical_timings(); 104 } 105 106 void cpu_idle(void) 107 { 108 for (;;) { 109 tick_nohz_stop_sched_tick(1); 110 while (!need_resched()) 111 default_idle(); 112 tick_nohz_restart_sched_tick(); 113 preempt_enable_no_resched(); 114 schedule(); 115 preempt_disable(); 116 } 117 } 118 119 extern void kernel_thread_starter(void); 120 121 asm( 122 ".align 4\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"); 128 129 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 130 { 131 struct pt_regs regs; 132 133 memset(®s, 0, sizeof(regs)); 134 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT; 135 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE; 136 regs.gprs[9] = (unsigned long) fn; 137 regs.gprs[10] = (unsigned long) arg; 138 regs.gprs[11] = (unsigned long) do_exit; 139 regs.orig_gpr2 = -1; 140 141 /* Ok, create the new process.. */ 142 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 143 0, ®s, 0, NULL, NULL); 144 } 145 EXPORT_SYMBOL(kernel_thread); 146 147 /* 148 * Free current thread data structures etc.. 149 */ 150 void exit_thread(void) 151 { 152 } 153 154 void flush_thread(void) 155 { 156 clear_used_math(); 157 clear_tsk_thread_flag(current, TIF_USEDFPU); 158 } 159 160 void release_thread(struct task_struct *dead_task) 161 { 162 } 163 164 int copy_thread(unsigned long clone_flags, unsigned long new_stackp, 165 unsigned long unused, 166 struct task_struct *p, struct pt_regs *regs) 167 { 168 struct thread_info *ti; 169 struct fake_frame 170 { 171 struct stack_frame sf; 172 struct pt_regs childregs; 173 } *frame; 174 175 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 176 p->thread.ksp = (unsigned long) frame; 177 /* Store access registers to kernel stack of new process. */ 178 frame->childregs = *regs; 179 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 180 frame->childregs.gprs[15] = new_stackp; 181 frame->sf.back_chain = 0; 182 183 /* new return point is ret_from_fork */ 184 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 185 186 /* fake return stack for resume(), don't go back to schedule */ 187 frame->sf.gprs[9] = (unsigned long) frame; 188 189 /* Save access registers to new thread structure. */ 190 save_access_regs(&p->thread.acrs[0]); 191 192 #ifndef CONFIG_64BIT 193 /* 194 * save fprs to current->thread.fp_regs to merge them with 195 * the emulated registers and then copy the result to the child. 196 */ 197 save_fp_regs(¤t->thread.fp_regs); 198 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 199 sizeof(s390_fp_regs)); 200 /* Set a new TLS ? */ 201 if (clone_flags & CLONE_SETTLS) 202 p->thread.acrs[0] = regs->gprs[6]; 203 #else /* CONFIG_64BIT */ 204 /* Save the fpu registers to new thread structure. */ 205 save_fp_regs(&p->thread.fp_regs); 206 /* Set a new TLS ? */ 207 if (clone_flags & CLONE_SETTLS) { 208 if (is_compat_task()) { 209 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 210 } else { 211 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 212 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 213 } 214 } 215 #endif /* CONFIG_64BIT */ 216 /* start new process with ar4 pointing to the correct address space */ 217 p->thread.mm_segment = get_fs(); 218 /* Don't copy debug registers */ 219 memset(&p->thread.per_info, 0, sizeof(p->thread.per_info)); 220 /* Initialize per thread user and system timer values */ 221 ti = task_thread_info(p); 222 ti->user_timer = 0; 223 ti->system_timer = 0; 224 return 0; 225 } 226 227 SYSCALL_DEFINE0(fork) 228 { 229 struct pt_regs *regs = task_pt_regs(current); 230 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 231 } 232 233 SYSCALL_DEFINE0(clone) 234 { 235 struct pt_regs *regs = task_pt_regs(current); 236 unsigned long clone_flags; 237 unsigned long newsp; 238 int __user *parent_tidptr, *child_tidptr; 239 240 clone_flags = regs->gprs[3]; 241 newsp = regs->orig_gpr2; 242 parent_tidptr = (int __user *) regs->gprs[4]; 243 child_tidptr = (int __user *) regs->gprs[5]; 244 if (!newsp) 245 newsp = regs->gprs[15]; 246 return do_fork(clone_flags, newsp, regs, 0, 247 parent_tidptr, child_tidptr); 248 } 249 250 /* 251 * This is trivial, and on the face of it looks like it 252 * could equally well be done in user mode. 253 * 254 * Not so, for quite unobvious reasons - register pressure. 255 * In user mode vfork() cannot have a stack frame, and if 256 * done by calling the "clone()" system call directly, you 257 * do not have enough call-clobbered registers to hold all 258 * the information you need. 259 */ 260 SYSCALL_DEFINE0(vfork) 261 { 262 struct pt_regs *regs = task_pt_regs(current); 263 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 264 regs->gprs[15], regs, 0, NULL, NULL); 265 } 266 267 asmlinkage void execve_tail(void) 268 { 269 current->thread.fp_regs.fpc = 0; 270 if (MACHINE_HAS_IEEE) 271 asm volatile("sfpc %0,%0" : : "d" (0)); 272 } 273 274 /* 275 * sys_execve() executes a new program. 276 */ 277 SYSCALL_DEFINE0(execve) 278 { 279 struct pt_regs *regs = task_pt_regs(current); 280 char *filename; 281 unsigned long result; 282 int rc; 283 284 filename = getname((char __user *) regs->orig_gpr2); 285 if (IS_ERR(filename)) { 286 result = PTR_ERR(filename); 287 goto out; 288 } 289 rc = do_execve(filename, (char __user * __user *) regs->gprs[3], 290 (char __user * __user *) regs->gprs[4], regs); 291 if (rc) { 292 result = rc; 293 goto out_putname; 294 } 295 execve_tail(); 296 result = regs->gprs[2]; 297 out_putname: 298 putname(filename); 299 out: 300 return result; 301 } 302 303 /* 304 * fill in the FPU structure for a core dump. 305 */ 306 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 307 { 308 #ifndef CONFIG_64BIT 309 /* 310 * save fprs to current->thread.fp_regs to merge them with 311 * the emulated registers and then copy the result to the dump. 312 */ 313 save_fp_regs(¤t->thread.fp_regs); 314 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 315 #else /* CONFIG_64BIT */ 316 save_fp_regs(fpregs); 317 #endif /* CONFIG_64BIT */ 318 return 1; 319 } 320 EXPORT_SYMBOL(dump_fpu); 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