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/cpu_mf.h> 33 #include <asm/io.h> 34 #include <asm/processor.h> 35 #include <asm/vtimer.h> 36 #include <asm/exec.h> 37 #include <asm/irq.h> 38 #include <asm/nmi.h> 39 #include <asm/smp.h> 40 #include <asm/stacktrace.h> 41 #include <asm/switch_to.h> 42 #include <asm/runtime_instr.h> 43 #include "entry.h" 44 45 asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); 46 47 extern void kernel_thread_starter(void); 48 49 void flush_thread(void) 50 { 51 } 52 53 void arch_setup_new_exec(void) 54 { 55 if (S390_lowcore.current_pid != current->pid) { 56 S390_lowcore.current_pid = current->pid; 57 if (test_facility(40)) 58 lpp(&S390_lowcore.lpp); 59 } 60 } 61 62 void arch_release_task_struct(struct task_struct *tsk) 63 { 64 runtime_instr_release(tsk); 65 guarded_storage_release(tsk); 66 } 67 68 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 69 { 70 /* 71 * Save the floating-point or vector register state of the current 72 * task and set the CIF_FPU flag to lazy restore the FPU register 73 * state when returning to user space. 74 */ 75 save_fpu_regs(); 76 77 memcpy(dst, src, arch_task_struct_size); 78 dst->thread.fpu.regs = dst->thread.fpu.fprs; 79 return 0; 80 } 81 82 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp, 83 unsigned long arg, struct task_struct *p, unsigned long tls) 84 { 85 struct fake_frame 86 { 87 struct stack_frame sf; 88 struct pt_regs childregs; 89 } *frame; 90 91 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 92 p->thread.ksp = (unsigned long) frame; 93 /* Save access registers to new thread structure. */ 94 save_access_regs(&p->thread.acrs[0]); 95 /* start new process with ar4 pointing to the correct address space */ 96 p->thread.mm_segment = get_fs(); 97 /* Don't copy debug registers */ 98 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 99 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 100 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 101 p->thread.per_flags = 0; 102 /* Initialize per thread user and system timer values */ 103 p->thread.user_timer = 0; 104 p->thread.guest_timer = 0; 105 p->thread.system_timer = 0; 106 p->thread.hardirq_timer = 0; 107 p->thread.softirq_timer = 0; 108 109 frame->sf.back_chain = 0; 110 /* new return point is ret_from_fork */ 111 frame->sf.gprs[8] = (unsigned long) ret_from_fork; 112 /* fake return stack for resume(), don't go back to schedule */ 113 frame->sf.gprs[9] = (unsigned long) frame; 114 115 /* Store access registers to kernel stack of new process. */ 116 if (unlikely(p->flags & PF_KTHREAD)) { 117 /* kernel thread */ 118 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 119 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | 120 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 121 frame->childregs.psw.addr = 122 (unsigned long) kernel_thread_starter; 123 frame->childregs.gprs[9] = new_stackp; /* function */ 124 frame->childregs.gprs[10] = arg; 125 frame->childregs.gprs[11] = (unsigned long) do_exit; 126 frame->childregs.orig_gpr2 = -1; 127 128 return 0; 129 } 130 frame->childregs = *current_pt_regs(); 131 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 132 frame->childregs.flags = 0; 133 if (new_stackp) 134 frame->childregs.gprs[15] = new_stackp; 135 136 /* Don't copy runtime instrumentation info */ 137 p->thread.ri_cb = NULL; 138 frame->childregs.psw.mask &= ~PSW_MASK_RI; 139 /* Don't copy guarded storage control block */ 140 p->thread.gs_cb = NULL; 141 p->thread.gs_bc_cb = NULL; 142 143 /* Set a new TLS ? */ 144 if (clone_flags & CLONE_SETTLS) { 145 if (is_compat_task()) { 146 p->thread.acrs[0] = (unsigned int)tls; 147 } else { 148 p->thread.acrs[0] = (unsigned int)(tls >> 32); 149 p->thread.acrs[1] = (unsigned int)tls; 150 } 151 } 152 return 0; 153 } 154 155 asmlinkage void execve_tail(void) 156 { 157 current->thread.fpu.fpc = 0; 158 asm volatile("sfpc %0" : : "d" (0)); 159 } 160 161 /* 162 * fill in the FPU structure for a core dump. 163 */ 164 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs) 165 { 166 save_fpu_regs(); 167 fpregs->fpc = current->thread.fpu.fpc; 168 fpregs->pad = 0; 169 if (MACHINE_HAS_VX) 170 convert_vx_to_fp((freg_t *)&fpregs->fprs, 171 current->thread.fpu.vxrs); 172 else 173 memcpy(&fpregs->fprs, current->thread.fpu.fprs, 174 sizeof(fpregs->fprs)); 175 return 1; 176 } 177 EXPORT_SYMBOL(dump_fpu); 178 179 unsigned long get_wchan(struct task_struct *p) 180 { 181 struct stack_frame *sf, *low, *high; 182 unsigned long return_address; 183 int count; 184 185 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) 186 return 0; 187 188 if (!try_get_task_stack(p)) 189 return 0; 190 191 low = task_stack_page(p); 192 high = (struct stack_frame *) task_pt_regs(p); 193 sf = (struct stack_frame *) p->thread.ksp; 194 if (sf <= low || sf > high) { 195 return_address = 0; 196 goto out; 197 } 198 for (count = 0; count < 16; count++) { 199 sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain); 200 if (sf <= low || sf > high) { 201 return_address = 0; 202 goto out; 203 } 204 return_address = READ_ONCE_NOCHECK(sf->gprs[8]); 205 if (!in_sched_functions(return_address)) 206 goto out; 207 } 208 out: 209 put_task_stack(p); 210 return return_address; 211 } 212 213 unsigned long arch_align_stack(unsigned long sp) 214 { 215 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 216 sp -= get_random_int() & ~PAGE_MASK; 217 return sp & ~0xf; 218 } 219 220 static inline unsigned long brk_rnd(void) 221 { 222 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT; 223 } 224 225 unsigned long arch_randomize_brk(struct mm_struct *mm) 226 { 227 unsigned long ret; 228 229 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 230 return (ret > mm->brk) ? ret : mm->brk; 231 } 232 233 void set_fs_fixup(void) 234 { 235 struct pt_regs *regs = current_pt_regs(); 236 static bool warned; 237 238 set_fs(USER_DS); 239 if (warned) 240 return; 241 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code); 242 show_registers(regs); 243 warned = true; 244 } 245