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 /* 104 * Free current thread data structures etc.. 105 */ 106 void exit_thread(void) 107 { 108 exit_thread_runtime_instr(); 109 } 110 111 void flush_thread(void) 112 { 113 } 114 115 void release_thread(struct task_struct *dead_task) 116 { 117 } 118 119 int copy_thread(unsigned long clone_flags, unsigned long new_stackp, 120 unsigned long arg, 121 struct task_struct *p, struct pt_regs *regs) 122 { 123 struct thread_info *ti; 124 struct fake_frame 125 { 126 struct stack_frame sf; 127 struct pt_regs childregs; 128 } *frame; 129 130 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 131 p->thread.ksp = (unsigned long) frame; 132 /* Save access registers to new thread structure. */ 133 save_access_regs(&p->thread.acrs[0]); 134 /* start new process with ar4 pointing to the correct address space */ 135 p->thread.mm_segment = get_fs(); 136 /* Don't copy debug registers */ 137 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 138 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 139 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 140 clear_tsk_thread_flag(p, TIF_PER_TRAP); 141 /* Initialize per thread user and system timer values */ 142 ti = task_thread_info(p); 143 ti->user_timer = 0; 144 ti->system_timer = 0; 145 146 frame->sf.back_chain = 0; 147 /* new return point is ret_from_fork */ 148 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 149 /* fake return stack for resume(), don't go back to schedule */ 150 frame->sf.gprs[9] = (unsigned long) frame; 151 152 /* Store access registers to kernel stack of new process. */ 153 if (unlikely(!regs)) { 154 /* kernel thread */ 155 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 156 frame->childregs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | 157 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 158 frame->childregs.psw.addr = PSW_ADDR_AMODE | 159 (unsigned long) kernel_thread_starter; 160 frame->childregs.gprs[9] = new_stackp; /* function */ 161 frame->childregs.gprs[10] = arg; 162 frame->childregs.gprs[11] = (unsigned long) do_exit; 163 frame->childregs.orig_gpr2 = -1; 164 165 return 0; 166 } 167 frame->childregs = *regs; 168 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 169 frame->childregs.gprs[15] = new_stackp; 170 171 /* Don't copy runtime instrumentation info */ 172 p->thread.ri_cb = NULL; 173 p->thread.ri_signum = 0; 174 frame->childregs.psw.mask &= ~PSW_MASK_RI; 175 176 #ifndef CONFIG_64BIT 177 /* 178 * save fprs to current->thread.fp_regs to merge them with 179 * the emulated registers and then copy the result to the child. 180 */ 181 save_fp_regs(¤t->thread.fp_regs); 182 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs, 183 sizeof(s390_fp_regs)); 184 /* Set a new TLS ? */ 185 if (clone_flags & CLONE_SETTLS) 186 p->thread.acrs[0] = regs->gprs[6]; 187 #else /* CONFIG_64BIT */ 188 /* Save the fpu registers to new thread structure. */ 189 save_fp_regs(&p->thread.fp_regs); 190 /* Set a new TLS ? */ 191 if (clone_flags & CLONE_SETTLS) { 192 if (is_compat_task()) { 193 p->thread.acrs[0] = (unsigned int) regs->gprs[6]; 194 } else { 195 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32); 196 p->thread.acrs[1] = (unsigned int) regs->gprs[6]; 197 } 198 } 199 #endif /* CONFIG_64BIT */ 200 return 0; 201 } 202 203 SYSCALL_DEFINE0(fork) 204 { 205 struct pt_regs *regs = task_pt_regs(current); 206 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL); 207 } 208 209 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags, 210 int __user *, parent_tidptr, int __user *, child_tidptr) 211 { 212 struct pt_regs *regs = task_pt_regs(current); 213 214 if (!newsp) 215 newsp = regs->gprs[15]; 216 return do_fork(clone_flags, newsp, regs, 0, 217 parent_tidptr, child_tidptr); 218 } 219 220 /* 221 * This is trivial, and on the face of it looks like it 222 * could equally well be done in user mode. 223 * 224 * Not so, for quite unobvious reasons - register pressure. 225 * In user mode vfork() cannot have a stack frame, and if 226 * done by calling the "clone()" system call directly, you 227 * do not have enough call-clobbered registers to hold all 228 * the information you need. 229 */ 230 SYSCALL_DEFINE0(vfork) 231 { 232 struct pt_regs *regs = task_pt_regs(current); 233 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 234 regs->gprs[15], regs, 0, NULL, NULL); 235 } 236 237 asmlinkage void execve_tail(void) 238 { 239 current->thread.fp_regs.fpc = 0; 240 if (MACHINE_HAS_IEEE) 241 asm volatile("sfpc %0,%0" : : "d" (0)); 242 } 243 244 /* 245 * fill in the FPU structure for a core dump. 246 */ 247 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 248 { 249 #ifndef CONFIG_64BIT 250 /* 251 * save fprs to current->thread.fp_regs to merge them with 252 * the emulated registers and then copy the result to the dump. 253 */ 254 save_fp_regs(¤t->thread.fp_regs); 255 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs)); 256 #else /* CONFIG_64BIT */ 257 save_fp_regs(fpregs); 258 #endif /* CONFIG_64BIT */ 259 return 1; 260 } 261 EXPORT_SYMBOL(dump_fpu); 262 263 unsigned long get_wchan(struct task_struct *p) 264 { 265 struct stack_frame *sf, *low, *high; 266 unsigned long return_address; 267 int count; 268 269 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 270 return 0; 271 low = task_stack_page(p); 272 high = (struct stack_frame *) task_pt_regs(p); 273 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN); 274 if (sf <= low || sf > high) 275 return 0; 276 for (count = 0; count < 16; count++) { 277 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); 278 if (sf <= low || sf > high) 279 return 0; 280 return_address = sf->gprs[8] & PSW_ADDR_INSN; 281 if (!in_sched_functions(return_address)) 282 return return_address; 283 } 284 return 0; 285 } 286 287 unsigned long arch_align_stack(unsigned long sp) 288 { 289 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 290 sp -= get_random_int() & ~PAGE_MASK; 291 return sp & ~0xf; 292 } 293 294 static inline unsigned long brk_rnd(void) 295 { 296 /* 8MB for 32bit, 1GB for 64bit */ 297 if (is_32bit_task()) 298 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; 299 else 300 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT; 301 } 302 303 unsigned long arch_randomize_brk(struct mm_struct *mm) 304 { 305 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd()); 306 307 if (ret < mm->brk) 308 return mm->brk; 309 return ret; 310 } 311 312 unsigned long randomize_et_dyn(unsigned long base) 313 { 314 unsigned long ret = PAGE_ALIGN(base + brk_rnd()); 315 316 if (!(current->flags & PF_RANDOMIZE)) 317 return base; 318 if (ret < base) 319 return base; 320 return ret; 321 } 322