1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This file handles the architecture dependent parts of process handling. 4 * 5 * Copyright IBM Corp. 1999, 2009 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, 7 * Hartmut Penner <hp@de.ibm.com>, 8 * Denis Joseph Barrow, 9 */ 10 11 #include <linux/elf-randomize.h> 12 #include <linux/compiler.h> 13 #include <linux/cpu.h> 14 #include <linux/sched.h> 15 #include <linux/sched/debug.h> 16 #include <linux/sched/task.h> 17 #include <linux/sched/task_stack.h> 18 #include <linux/kernel.h> 19 #include <linux/mm.h> 20 #include <linux/elfcore.h> 21 #include <linux/smp.h> 22 #include <linux/slab.h> 23 #include <linux/interrupt.h> 24 #include <linux/tick.h> 25 #include <linux/personality.h> 26 #include <linux/syscalls.h> 27 #include <linux/compat.h> 28 #include <linux/kprobes.h> 29 #include <linux/random.h> 30 #include <linux/export.h> 31 #include <linux/init_task.h> 32 #include <asm/io.h> 33 #include <asm/processor.h> 34 #include <asm/vtimer.h> 35 #include <asm/exec.h> 36 #include <asm/irq.h> 37 #include <asm/nmi.h> 38 #include <asm/smp.h> 39 #include <asm/switch_to.h> 40 #include <asm/runtime_instr.h> 41 #include "entry.h" 42 43 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 44 45 extern void kernel_thread_starter(void); 46 47 /* 48 * Free current thread data structures etc.. 49 */ 50 void exit_thread(struct task_struct *tsk) 51 { 52 if (tsk == current) { 53 exit_thread_runtime_instr(); 54 exit_thread_gs(); 55 } 56 } 57 58 void flush_thread(void) 59 { 60 } 61 62 void release_thread(struct task_struct *dead_task) 63 { 64 } 65 66 void arch_release_task_struct(struct task_struct *tsk) 67 { 68 } 69 70 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 71 { 72 /* 73 * Save the floating-point or vector register state of the current 74 * task and set the CIF_FPU flag to lazy restore the FPU register 75 * state when returning to user space. 76 */ 77 save_fpu_regs(); 78 79 memcpy(dst, src, arch_task_struct_size); 80 dst->thread.fpu.regs = dst->thread.fpu.fprs; 81 return 0; 82 } 83 84 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp, 85 unsigned long arg, struct task_struct *p, unsigned long tls) 86 { 87 struct fake_frame 88 { 89 struct stack_frame sf; 90 struct pt_regs childregs; 91 } *frame; 92 93 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 94 p->thread.ksp = (unsigned long) frame; 95 /* Save access registers to new thread structure. */ 96 save_access_regs(&p->thread.acrs[0]); 97 /* start new process with ar4 pointing to the correct address space */ 98 p->thread.mm_segment = get_fs(); 99 /* Don't copy debug registers */ 100 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 101 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 102 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 103 /* Initialize per thread user and system timer values */ 104 p->thread.user_timer = 0; 105 p->thread.guest_timer = 0; 106 p->thread.system_timer = 0; 107 p->thread.hardirq_timer = 0; 108 p->thread.softirq_timer = 0; 109 110 frame->sf.back_chain = 0; 111 /* new return point is ret_from_fork */ 112 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 113 /* fake return stack for resume(), don't go back to schedule */ 114 frame->sf.gprs[9] = (unsigned long) frame; 115 116 /* Store access registers to kernel stack of new process. */ 117 if (unlikely(p->flags & PF_KTHREAD)) { 118 /* kernel thread */ 119 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 120 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | 121 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 122 frame->childregs.psw.addr = 123 (unsigned long) kernel_thread_starter; 124 frame->childregs.gprs[9] = new_stackp; /* function */ 125 frame->childregs.gprs[10] = arg; 126 frame->childregs.gprs[11] = (unsigned long) do_exit; 127 frame->childregs.orig_gpr2 = -1; 128 129 return 0; 130 } 131 frame->childregs = *current_pt_regs(); 132 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 133 frame->childregs.flags = 0; 134 if (new_stackp) 135 frame->childregs.gprs[15] = new_stackp; 136 137 /* Don't copy runtime instrumentation info */ 138 p->thread.ri_cb = NULL; 139 frame->childregs.psw.mask &= ~PSW_MASK_RI; 140 /* Don't copy guarded storage control block */ 141 p->thread.gs_cb = NULL; 142 p->thread.gs_bc_cb = NULL; 143 144 /* Set a new TLS ? */ 145 if (clone_flags & CLONE_SETTLS) { 146 if (is_compat_task()) { 147 p->thread.acrs[0] = (unsigned int)tls; 148 } else { 149 p->thread.acrs[0] = (unsigned int)(tls >> 32); 150 p->thread.acrs[1] = (unsigned int)tls; 151 } 152 } 153 return 0; 154 } 155 156 asmlinkage void execve_tail(void) 157 { 158 current->thread.fpu.fpc = 0; 159 asm volatile("sfpc %0" : : "d" (0)); 160 } 161 162 /* 163 * fill in the FPU structure for a core dump. 164 */ 165 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 166 { 167 save_fpu_regs(); 168 fpregs->fpc = current->thread.fpu.fpc; 169 fpregs->pad = 0; 170 if (MACHINE_HAS_VX) 171 convert_vx_to_fp((freg_t *)&fpregs->fprs, 172 current->thread.fpu.vxrs); 173 else 174 memcpy(&fpregs->fprs, current->thread.fpu.fprs, 175 sizeof(fpregs->fprs)); 176 return 1; 177 } 178 EXPORT_SYMBOL(dump_fpu); 179 180 unsigned long get_wchan(struct task_struct *p) 181 { 182 struct stack_frame *sf, *low, *high; 183 unsigned long return_address; 184 int count; 185 186 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 187 return 0; 188 low = task_stack_page(p); 189 high = (struct stack_frame *) task_pt_regs(p); 190 sf = (struct stack_frame *) p->thread.ksp; 191 if (sf <= low || sf > high) 192 return 0; 193 for (count = 0; count < 16; count++) { 194 sf = (struct stack_frame *) sf->back_chain; 195 if (sf <= low || sf > high) 196 return 0; 197 return_address = sf->gprs[8]; 198 if (!in_sched_functions(return_address)) 199 return return_address; 200 } 201 return 0; 202 } 203 204 unsigned long arch_align_stack(unsigned long sp) 205 { 206 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 207 sp -= get_random_int() & ~PAGE_MASK; 208 return sp & ~0xf; 209 } 210 211 static inline unsigned long brk_rnd(void) 212 { 213 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT; 214 } 215 216 unsigned long arch_randomize_brk(struct mm_struct *mm) 217 { 218 unsigned long ret; 219 220 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 221 return (ret > mm->brk) ? ret : mm->brk; 222 } 223 224 void set_fs_fixup(void) 225 { 226 struct pt_regs *regs = current_pt_regs(); 227 static bool warned; 228 229 set_fs(USER_DS); 230 if (warned) 231 return; 232 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code); 233 show_registers(regs); 234 warned = true; 235 } 236