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/slab.h> 20 #include <linux/unistd.h> 21 #include <linux/ptrace.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/tick.h> 31 #include <linux/elfcore.h> 32 #include <linux/kernel_stat.h> 33 #include <linux/syscalls.h> 34 #include <linux/compat.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 #ifdef CONFIG_HOTPLUG_CPU 80 if (cpu_is_offline(smp_processor_id())) { 81 preempt_enable_no_resched(); 82 cpu_die(); 83 } 84 #endif 85 local_irq_disable(); 86 if (need_resched()) { 87 local_irq_enable(); 88 return; 89 } 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 } 157 158 void release_thread(struct task_struct *dead_task) 159 { 160 } 161 162 int copy_thread(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 (is_compat_task()) { 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 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 219 /* Initialize per thread user and system timer values */ 220 ti = task_thread_info(p); 221 ti->user_timer = 0; 222 ti->system_timer = 0; 223 return 0; 224 } 225 226 SYSCALL_DEFINE0(fork) 227 { 228 struct pt_regs *regs = task_pt_regs(current); 229 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 230 } 231 232 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 233 int __user *, parent_tidptr, int __user *, child_tidptr) 234 { 235 struct pt_regs *regs = task_pt_regs(current); 236 237 if (!newsp) 238 newsp = regs->gprs[15]; 239 return do_fork(clone_flags, newsp, regs, 0, 240 parent_tidptr, child_tidptr); 241 } 242 243 /* 244 * This is trivial, and on the face of it looks like it 245 * could equally well be done in user mode. 246 * 247 * Not so, for quite unobvious reasons - register pressure. 248 * In user mode vfork() cannot have a stack frame, and if 249 * done by calling the "clone()" system call directly, you 250 * do not have enough call-clobbered registers to hold all 251 * the information you need. 252 */ 253 SYSCALL_DEFINE0(vfork) 254 { 255 struct pt_regs *regs = task_pt_regs(current); 256 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 257 regs->gprs[15], regs, 0, NULL, NULL); 258 } 259 260 asmlinkage void execve_tail(void) 261 { 262 current->thread.fp_regs.fpc = 0; 263 if (MACHINE_HAS_IEEE) 264 asm volatile("sfpc %0,%0" : : "d" (0)); 265 } 266 267 /* 268 * sys_execve() executes a new program. 269 */ 270 SYSCALL_DEFINE3(execve, const char __user *, name, 271 const char __user *const __user *, argv, 272 const char __user *const __user *, envp) 273 { 274 struct pt_regs *regs = task_pt_regs(current); 275 char *filename; 276 long rc; 277 278 filename = getname(name); 279 rc = PTR_ERR(filename); 280 if (IS_ERR(filename)) 281 return rc; 282 rc = do_execve(filename, argv, envp, regs); 283 if (rc) 284 goto out; 285 execve_tail(); 286 rc = regs->gprs[2]; 287 out: 288 putname(filename); 289 return rc; 290 } 291 292 /* 293 * fill in the FPU structure for a core dump. 294 */ 295 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 296 { 297 #ifndef CONFIG_64BIT 298 /* 299 * save fprs to current->thread.fp_regs to merge them with 300 * the emulated registers and then copy the result to the dump. 301 */ 302 save_fp_regs(¤t->thread.fp_regs); 303 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 304 #else /* CONFIG_64BIT */ 305 save_fp_regs(fpregs); 306 #endif /* CONFIG_64BIT */ 307 return 1; 308 } 309 EXPORT_SYMBOL(dump_fpu); 310 311 unsigned long get_wchan(struct task_struct *p) 312 { 313 struct stack_frame *sf, *low, *high; 314 unsigned long return_address; 315 int count; 316 317 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 318 return 0; 319 low = task_stack_page(p); 320 high = (struct stack_frame *) task_pt_regs(p); 321 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 322 if (sf <= low || sf > high) 323 return 0; 324 for (count = 0; count < 16; count++) { 325 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 326 if (sf <= low || sf > high) 327 return 0; 328 return_address = sf->gprs[8] & PSW_ADDR_INSN; 329 if (!in_sched_functions(return_address)) 330 return return_address; 331 } 332 return 0; 333 } 334