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/elf-randomize.h> 11 #include <linux/compiler.h> 12 #include <linux/cpu.h> 13 #include <linux/sched.h> 14 #include <linux/sched/debug.h> 15 #include <linux/sched/task.h> 16 #include <linux/sched/task_stack.h> 17 #include <linux/kernel.h> 18 #include <linux/mm.h> 19 #include <linux/elfcore.h> 20 #include <linux/smp.h> 21 #include <linux/slab.h> 22 #include <linux/interrupt.h> 23 #include <linux/tick.h> 24 #include <linux/personality.h> 25 #include <linux/syscalls.h> 26 #include <linux/compat.h> 27 #include <linux/kprobes.h> 28 #include <linux/random.h> 29 #include <linux/export.h> 30 #include <linux/init_task.h> 31 #include <asm/io.h> 32 #include <asm/processor.h> 33 #include <asm/vtimer.h> 34 #include <asm/exec.h> 35 #include <asm/irq.h> 36 #include <asm/nmi.h> 37 #include <asm/smp.h> 38 #include <asm/switch_to.h> 39 #include <asm/runtime_instr.h> 40 #include "entry.h" 41 42 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 43 44 /* 45 * Return saved PC of a blocked thread. used in kernel/sched. 46 * resume in entry.S does not create a new stack frame, it 47 * just stores the registers %r6-%r15 to the frame given by 48 * schedule. We want to return the address of the caller of 49 * schedule, so we have to walk the backchain one time to 50 * find the frame schedule() store its return address. 51 */ 52 unsigned long thread_saved_pc(struct task_struct *tsk) 53 { 54 struct stack_frame *sf, *low, *high; 55 56 if (!tsk || !task_stack_page(tsk)) 57 return 0; 58 low = task_stack_page(tsk); 59 high = (struct stack_frame *) task_pt_regs(tsk); 60 sf = (struct stack_frame *) tsk->thread.ksp; 61 if (sf <= low || sf > high) 62 return 0; 63 sf = (struct stack_frame *) sf->back_chain; 64 if (sf <= low || sf > high) 65 return 0; 66 return sf->gprs[8]; 67 } 68 69 extern void kernel_thread_starter(void); 70 71 /* 72 * Free current thread data structures etc.. 73 */ 74 void exit_thread(struct task_struct *tsk) 75 { 76 if (tsk == current) 77 exit_thread_runtime_instr(); 78 } 79 80 void flush_thread(void) 81 { 82 } 83 84 void release_thread(struct task_struct *dead_task) 85 { 86 } 87 88 void arch_release_task_struct(struct task_struct *tsk) 89 { 90 } 91 92 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 93 { 94 /* 95 * Save the floating-point or vector register state of the current 96 * task and set the CIF_FPU flag to lazy restore the FPU register 97 * state when returning to user space. 98 */ 99 save_fpu_regs(); 100 101 memcpy(dst, src, arch_task_struct_size); 102 dst->thread.fpu.regs = dst->thread.fpu.fprs; 103 return 0; 104 } 105 106 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp, 107 unsigned long arg, struct task_struct *p, unsigned long tls) 108 { 109 struct fake_frame 110 { 111 struct stack_frame sf; 112 struct pt_regs childregs; 113 } *frame; 114 115 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 116 p->thread.ksp = (unsigned long) frame; 117 /* Save access registers to new thread structure. */ 118 save_access_regs(&p->thread.acrs[0]); 119 /* start new process with ar4 pointing to the correct address space */ 120 p->thread.mm_segment = get_fs(); 121 /* Don't copy debug registers */ 122 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 123 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 124 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 125 /* Initialize per thread user and system timer values */ 126 p->thread.user_timer = 0; 127 p->thread.system_timer = 0; 128 129 frame->sf.back_chain = 0; 130 /* new return point is ret_from_fork */ 131 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 132 /* fake return stack for resume(), don't go back to schedule */ 133 frame->sf.gprs[9] = (unsigned long) frame; 134 135 /* Store access registers to kernel stack of new process. */ 136 if (unlikely(p->flags & PF_KTHREAD)) { 137 /* kernel thread */ 138 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 139 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | 140 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 141 frame->childregs.psw.addr = 142 (unsigned long) kernel_thread_starter; 143 frame->childregs.gprs[9] = new_stackp; /* function */ 144 frame->childregs.gprs[10] = arg; 145 frame->childregs.gprs[11] = (unsigned long) do_exit; 146 frame->childregs.orig_gpr2 = -1; 147 148 return 0; 149 } 150 frame->childregs = *current_pt_regs(); 151 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 152 frame->childregs.flags = 0; 153 if (new_stackp) 154 frame->childregs.gprs[15] = new_stackp; 155 156 /* Don't copy runtime instrumentation info */ 157 p->thread.ri_cb = NULL; 158 frame->childregs.psw.mask &= ~PSW_MASK_RI; 159 160 /* Set a new TLS ? */ 161 if (clone_flags & CLONE_SETTLS) { 162 if (is_compat_task()) { 163 p->thread.acrs[0] = (unsigned int)tls; 164 } else { 165 p->thread.acrs[0] = (unsigned int)(tls >> 32); 166 p->thread.acrs[1] = (unsigned int)tls; 167 } 168 } 169 return 0; 170 } 171 172 asmlinkage void execve_tail(void) 173 { 174 current->thread.fpu.fpc = 0; 175 asm volatile("sfpc %0" : : "d" (0)); 176 } 177 178 /* 179 * fill in the FPU structure for a core dump. 180 */ 181 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 182 { 183 save_fpu_regs(); 184 fpregs->fpc = current->thread.fpu.fpc; 185 fpregs->pad = 0; 186 if (MACHINE_HAS_VX) 187 convert_vx_to_fp((freg_t *)&fpregs->fprs, 188 current->thread.fpu.vxrs); 189 else 190 memcpy(&fpregs->fprs, current->thread.fpu.fprs, 191 sizeof(fpregs->fprs)); 192 return 1; 193 } 194 EXPORT_SYMBOL(dump_fpu); 195 196 unsigned long get_wchan(struct task_struct *p) 197 { 198 struct stack_frame *sf, *low, *high; 199 unsigned long return_address; 200 int count; 201 202 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 203 return 0; 204 low = task_stack_page(p); 205 high = (struct stack_frame *) task_pt_regs(p); 206 sf = (struct stack_frame *) p->thread.ksp; 207 if (sf <= low || sf > high) 208 return 0; 209 for (count = 0; count < 16; count++) { 210 sf = (struct stack_frame *) sf->back_chain; 211 if (sf <= low || sf > high) 212 return 0; 213 return_address = sf->gprs[8]; 214 if (!in_sched_functions(return_address)) 215 return return_address; 216 } 217 return 0; 218 } 219 220 unsigned long arch_align_stack(unsigned long sp) 221 { 222 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 223 sp -= get_random_int() & ~PAGE_MASK; 224 return sp & ~0xf; 225 } 226 227 static inline unsigned long brk_rnd(void) 228 { 229 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT; 230 } 231 232 unsigned long arch_randomize_brk(struct mm_struct *mm) 233 { 234 unsigned long ret; 235 236 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 237 return (ret > mm->brk) ? ret : mm->brk; 238 } 239 240 void set_fs_fixup(void) 241 { 242 struct pt_regs *regs = current_pt_regs(); 243 static bool warned; 244 245 set_fs(USER_DS); 246 if (warned) 247 return; 248 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code); 249 show_registers(regs); 250 warned = true; 251 } 252