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 <linux/entry-common.h> 33 #include <linux/io.h> 34 #include <asm/cpu_mf.h> 35 #include <asm/processor.h> 36 #include <asm/vtimer.h> 37 #include <asm/exec.h> 38 #include <asm/irq.h> 39 #include <asm/nmi.h> 40 #include <asm/smp.h> 41 #include <asm/stacktrace.h> 42 #include <asm/switch_to.h> 43 #include <asm/runtime_instr.h> 44 #include <asm/unwind.h> 45 #include "entry.h" 46 47 void ret_from_fork(void) asm("ret_from_fork"); 48 49 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs) 50 { 51 void (*func)(void *arg); 52 53 schedule_tail(prev); 54 55 if (!user_mode(regs)) { 56 /* Kernel thread */ 57 func = (void *)regs->gprs[9]; 58 func((void *)regs->gprs[10]); 59 } 60 clear_pt_regs_flag(regs, PIF_SYSCALL); 61 syscall_exit_to_user_mode(regs); 62 } 63 64 void flush_thread(void) 65 { 66 } 67 68 void arch_setup_new_exec(void) 69 { 70 if (S390_lowcore.current_pid != current->pid) { 71 S390_lowcore.current_pid = current->pid; 72 if (test_facility(40)) 73 lpp(&S390_lowcore.lpp); 74 } 75 } 76 77 void arch_release_task_struct(struct task_struct *tsk) 78 { 79 runtime_instr_release(tsk); 80 guarded_storage_release(tsk); 81 } 82 83 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 84 { 85 /* 86 * Save the floating-point or vector register state of the current 87 * task and set the CIF_FPU flag to lazy restore the FPU register 88 * state when returning to user space. 89 */ 90 save_fpu_regs(); 91 92 *dst = *src; 93 dst->thread.fpu.regs = dst->thread.fpu.fprs; 94 95 /* 96 * Don't transfer over the runtime instrumentation or the guarded 97 * storage control block pointers. These fields are cleared here instead 98 * of in copy_thread() to avoid premature freeing of associated memory 99 * on fork() failure. Wait to clear the RI flag because ->stack still 100 * refers to the source thread. 101 */ 102 dst->thread.ri_cb = NULL; 103 dst->thread.gs_cb = NULL; 104 dst->thread.gs_bc_cb = NULL; 105 106 return 0; 107 } 108 109 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 110 { 111 unsigned long clone_flags = args->flags; 112 unsigned long new_stackp = args->stack; 113 unsigned long tls = args->tls; 114 struct fake_frame 115 { 116 struct stack_frame sf; 117 struct pt_regs childregs; 118 } *frame; 119 120 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 121 p->thread.ksp = (unsigned long) frame; 122 /* Save access registers to new thread structure. */ 123 save_access_regs(&p->thread.acrs[0]); 124 /* start new process with ar4 pointing to the correct address space */ 125 /* Don't copy debug registers */ 126 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 127 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 128 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 129 p->thread.per_flags = 0; 130 /* Initialize per thread user and system timer values */ 131 p->thread.user_timer = 0; 132 p->thread.guest_timer = 0; 133 p->thread.system_timer = 0; 134 p->thread.hardirq_timer = 0; 135 p->thread.softirq_timer = 0; 136 p->thread.last_break = 1; 137 138 frame->sf.back_chain = 0; 139 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; 140 frame->sf.gprs[12 - 6] = (unsigned long)p; 141 /* new return point is ret_from_fork */ 142 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork; 143 /* fake return stack for resume(), don't go back to schedule */ 144 frame->sf.gprs[15 - 6] = (unsigned long)frame; 145 146 /* Store access registers to kernel stack of new process. */ 147 if (unlikely(args->fn)) { 148 /* kernel thread */ 149 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 150 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | 151 PSW_MASK_EXT | PSW_MASK_MCHECK; 152 frame->childregs.gprs[9] = (unsigned long)args->fn; 153 frame->childregs.gprs[10] = (unsigned long)args->fn_arg; 154 frame->childregs.orig_gpr2 = -1; 155 frame->childregs.last_break = 1; 156 return 0; 157 } 158 frame->childregs = *current_pt_regs(); 159 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 160 frame->childregs.flags = 0; 161 if (new_stackp) 162 frame->childregs.gprs[15] = new_stackp; 163 /* 164 * Clear the runtime instrumentation flag after the above childregs 165 * copy. The CB pointer was already cleared in arch_dup_task_struct(). 166 */ 167 frame->childregs.psw.mask &= ~PSW_MASK_RI; 168 169 /* Set a new TLS ? */ 170 if (clone_flags & CLONE_SETTLS) { 171 if (is_compat_task()) { 172 p->thread.acrs[0] = (unsigned int)tls; 173 } else { 174 p->thread.acrs[0] = (unsigned int)(tls >> 32); 175 p->thread.acrs[1] = (unsigned int)tls; 176 } 177 } 178 /* 179 * s390 stores the svc return address in arch_data when calling 180 * sigreturn()/restart_syscall() via vdso. 1 means no valid address 181 * stored. 182 */ 183 p->restart_block.arch_data = 1; 184 return 0; 185 } 186 187 void execve_tail(void) 188 { 189 current->thread.fpu.fpc = 0; 190 asm volatile("sfpc %0" : : "d" (0)); 191 } 192 193 unsigned long __get_wchan(struct task_struct *p) 194 { 195 struct unwind_state state; 196 unsigned long ip = 0; 197 198 if (!task_stack_page(p)) 199 return 0; 200 201 if (!try_get_task_stack(p)) 202 return 0; 203 204 unwind_for_each_frame(&state, p, NULL, 0) { 205 if (state.stack_info.type != STACK_TYPE_TASK) { 206 ip = 0; 207 break; 208 } 209 210 ip = unwind_get_return_address(&state); 211 if (!ip) 212 break; 213 214 if (!in_sched_functions(ip)) 215 break; 216 } 217 218 put_task_stack(p); 219 return ip; 220 } 221 222 unsigned long arch_align_stack(unsigned long sp) 223 { 224 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 225 sp -= get_random_u32_below(PAGE_SIZE); 226 return sp & ~0xf; 227 } 228 229 static inline unsigned long brk_rnd(void) 230 { 231 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT; 232 } 233 234 unsigned long arch_randomize_brk(struct mm_struct *mm) 235 { 236 unsigned long ret; 237 238 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 239 return (ret > mm->brk) ? ret : mm->brk; 240 } 241