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 exit_thread_gs(); 79 } 80 } 81 82 void flush_thread(void) 83 { 84 } 85 86 void release_thread(struct task_struct *dead_task) 87 { 88 } 89 90 void arch_release_task_struct(struct task_struct *tsk) 91 { 92 } 93 94 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 95 { 96 /* 97 * Save the floating-point or vector register state of the current 98 * task and set the CIF_FPU flag to lazy restore the FPU register 99 * state when returning to user space. 100 */ 101 save_fpu_regs(); 102 103 memcpy(dst, src, arch_task_struct_size); 104 dst->thread.fpu.regs = dst->thread.fpu.fprs; 105 return 0; 106 } 107 108 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp, 109 unsigned long arg, struct task_struct *p, unsigned long tls) 110 { 111 struct fake_frame 112 { 113 struct stack_frame sf; 114 struct pt_regs childregs; 115 } *frame; 116 117 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 118 p->thread.ksp = (unsigned long) frame; 119 /* Save access registers to new thread structure. */ 120 save_access_regs(&p->thread.acrs[0]); 121 /* start new process with ar4 pointing to the correct address space */ 122 p->thread.mm_segment = get_fs(); 123 /* Don't copy debug registers */ 124 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 125 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 126 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 127 /* Initialize per thread user and system timer values */ 128 p->thread.user_timer = 0; 129 p->thread.guest_timer = 0; 130 p->thread.system_timer = 0; 131 p->thread.hardirq_timer = 0; 132 p->thread.softirq_timer = 0; 133 134 frame->sf.back_chain = 0; 135 /* new return point is ret_from_fork */ 136 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 137 /* fake return stack for resume(), don't go back to schedule */ 138 frame->sf.gprs[9] = (unsigned long) frame; 139 140 /* Store access registers to kernel stack of new process. */ 141 if (unlikely(p->flags & PF_KTHREAD)) { 142 /* kernel thread */ 143 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 144 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | 145 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 146 frame->childregs.psw.addr = 147 (unsigned long) kernel_thread_starter; 148 frame->childregs.gprs[9] = new_stackp; /* function */ 149 frame->childregs.gprs[10] = arg; 150 frame->childregs.gprs[11] = (unsigned long) do_exit; 151 frame->childregs.orig_gpr2 = -1; 152 153 return 0; 154 } 155 frame->childregs = *current_pt_regs(); 156 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 157 frame->childregs.flags = 0; 158 if (new_stackp) 159 frame->childregs.gprs[15] = new_stackp; 160 161 /* Don't copy runtime instrumentation info */ 162 p->thread.ri_cb = NULL; 163 frame->childregs.psw.mask &= ~PSW_MASK_RI; 164 /* Don't copy guarded storage control block */ 165 p->thread.gs_cb = NULL; 166 p->thread.gs_bc_cb = NULL; 167 168 /* Set a new TLS ? */ 169 if (clone_flags & CLONE_SETTLS) { 170 if (is_compat_task()) { 171 p->thread.acrs[0] = (unsigned int)tls; 172 } else { 173 p->thread.acrs[0] = (unsigned int)(tls >> 32); 174 p->thread.acrs[1] = (unsigned int)tls; 175 } 176 } 177 return 0; 178 } 179 180 asmlinkage void execve_tail(void) 181 { 182 current->thread.fpu.fpc = 0; 183 asm volatile("sfpc %0" : : "d" (0)); 184 } 185 186 /* 187 * fill in the FPU structure for a core dump. 188 */ 189 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 190 { 191 save_fpu_regs(); 192 fpregs->fpc = current->thread.fpu.fpc; 193 fpregs->pad = 0; 194 if (MACHINE_HAS_VX) 195 convert_vx_to_fp((freg_t *)&fpregs->fprs, 196 current->thread.fpu.vxrs); 197 else 198 memcpy(&fpregs->fprs, current->thread.fpu.fprs, 199 sizeof(fpregs->fprs)); 200 return 1; 201 } 202 EXPORT_SYMBOL(dump_fpu); 203 204 unsigned long get_wchan(struct task_struct *p) 205 { 206 struct stack_frame *sf, *low, *high; 207 unsigned long return_address; 208 int count; 209 210 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 211 return 0; 212 low = task_stack_page(p); 213 high = (struct stack_frame *) task_pt_regs(p); 214 sf = (struct stack_frame *) p->thread.ksp; 215 if (sf <= low || sf > high) 216 return 0; 217 for (count = 0; count < 16; count++) { 218 sf = (struct stack_frame *) sf->back_chain; 219 if (sf <= low || sf > high) 220 return 0; 221 return_address = sf->gprs[8]; 222 if (!in_sched_functions(return_address)) 223 return return_address; 224 } 225 return 0; 226 } 227 228 unsigned long arch_align_stack(unsigned long sp) 229 { 230 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 231 sp -= get_random_int() & ~PAGE_MASK; 232 return sp & ~0xf; 233 } 234 235 static inline unsigned long brk_rnd(void) 236 { 237 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT; 238 } 239 240 unsigned long arch_randomize_brk(struct mm_struct *mm) 241 { 242 unsigned long ret; 243 244 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 245 return (ret > mm->brk) ? ret : mm->brk; 246 } 247 248 void set_fs_fixup(void) 249 { 250 struct pt_regs *regs = current_pt_regs(); 251 static bool warned; 252 253 set_fs(USER_DS); 254 if (warned) 255 return; 256 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code); 257 show_registers(regs); 258 warned = true; 259 } 260