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/guarded_storage.h> 35 #include <asm/access-regs.h> 36 #include <asm/switch_to.h> 37 #include <asm/cpu_mf.h> 38 #include <asm/processor.h> 39 #include <asm/ptrace.h> 40 #include <asm/vtimer.h> 41 #include <asm/exec.h> 42 #include <asm/fpu.h> 43 #include <asm/irq.h> 44 #include <asm/nmi.h> 45 #include <asm/smp.h> 46 #include <asm/stacktrace.h> 47 #include <asm/runtime_instr.h> 48 #include <asm/unwind.h> 49 #include "entry.h" 50 51 void ret_from_fork(void) asm("ret_from_fork"); 52 53 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs) 54 { 55 void (*func)(void *arg); 56 57 schedule_tail(prev); 58 59 if (!user_mode(regs)) { 60 /* Kernel thread */ 61 func = (void *)regs->gprs[9]; 62 func((void *)regs->gprs[10]); 63 } 64 clear_pt_regs_flag(regs, PIF_SYSCALL); 65 syscall_exit_to_user_mode(regs); 66 } 67 68 void flush_thread(void) 69 { 70 } 71 72 void arch_setup_new_exec(void) 73 { 74 if (get_lowcore()->current_pid != current->pid) { 75 get_lowcore()->current_pid = current->pid; 76 if (test_facility(40)) 77 lpp(&get_lowcore()->lpp); 78 } 79 } 80 81 void arch_release_task_struct(struct task_struct *tsk) 82 { 83 runtime_instr_release(tsk); 84 guarded_storage_release(tsk); 85 } 86 87 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 88 { 89 save_user_fpu_regs(); 90 91 *dst = *src; 92 dst->thread.kfpu_flags = 0; 93 94 /* 95 * Don't transfer over the runtime instrumentation or the guarded 96 * storage control block pointers. These fields are cleared here instead 97 * of in copy_thread() to avoid premature freeing of associated memory 98 * on fork() failure. Wait to clear the RI flag because ->stack still 99 * refers to the source thread. 100 */ 101 dst->thread.ri_cb = NULL; 102 dst->thread.gs_cb = NULL; 103 dst->thread.gs_bc_cb = NULL; 104 105 return 0; 106 } 107 108 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 109 { 110 unsigned long clone_flags = args->flags; 111 unsigned long new_stackp = args->stack; 112 unsigned long tls = args->tls; 113 struct fake_frame 114 { 115 struct stack_frame sf; 116 struct pt_regs childregs; 117 } *frame; 118 119 frame = container_of(task_pt_regs(p), struct fake_frame, childregs); 120 p->thread.ksp = (unsigned long) frame; 121 /* Save access registers to new thread structure. */ 122 save_access_regs(&p->thread.acrs[0]); 123 /* start new process with ar4 pointing to the correct address space */ 124 /* Don't copy debug registers */ 125 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 126 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 127 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 128 p->thread.per_flags = 0; 129 /* Initialize per thread user and system timer values */ 130 p->thread.user_timer = 0; 131 p->thread.guest_timer = 0; 132 p->thread.system_timer = 0; 133 p->thread.hardirq_timer = 0; 134 p->thread.softirq_timer = 0; 135 p->thread.last_break = 1; 136 137 frame->sf.back_chain = 0; 138 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; 139 frame->sf.gprs[12 - 6] = (unsigned long)p; 140 /* new return point is ret_from_fork */ 141 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork; 142 /* fake return stack for resume(), don't go back to schedule */ 143 frame->sf.gprs[15 - 6] = (unsigned long)frame; 144 145 /* Store access registers to kernel stack of new process. */ 146 if (unlikely(args->fn)) { 147 /* kernel thread */ 148 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 149 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | 150 PSW_MASK_EXT | PSW_MASK_MCHECK; 151 frame->childregs.gprs[9] = (unsigned long)args->fn; 152 frame->childregs.gprs[10] = (unsigned long)args->fn_arg; 153 frame->childregs.orig_gpr2 = -1; 154 frame->childregs.last_break = 1; 155 return 0; 156 } 157 frame->childregs = *current_pt_regs(); 158 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ 159 frame->childregs.flags = 0; 160 if (new_stackp) 161 frame->childregs.gprs[15] = new_stackp; 162 /* 163 * Clear the runtime instrumentation flag after the above childregs 164 * copy. The CB pointer was already cleared in arch_dup_task_struct(). 165 */ 166 frame->childregs.psw.mask &= ~PSW_MASK_RI; 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 /* 178 * s390 stores the svc return address in arch_data when calling 179 * sigreturn()/restart_syscall() via vdso. 1 means no valid address 180 * stored. 181 */ 182 p->restart_block.arch_data = 1; 183 return 0; 184 } 185 186 void execve_tail(void) 187 { 188 current->thread.ufpu.fpc = 0; 189 fpu_sfpc(0); 190 } 191 192 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next) 193 { 194 save_user_fpu_regs(); 195 save_kernel_fpu_regs(&prev->thread); 196 save_access_regs(&prev->thread.acrs[0]); 197 save_ri_cb(prev->thread.ri_cb); 198 save_gs_cb(prev->thread.gs_cb); 199 update_cr_regs(next); 200 restore_kernel_fpu_regs(&next->thread); 201 restore_access_regs(&next->thread.acrs[0]); 202 restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb); 203 restore_gs_cb(next->thread.gs_cb); 204 return __switch_to_asm(prev, next); 205 } 206 207 unsigned long __get_wchan(struct task_struct *p) 208 { 209 struct unwind_state state; 210 unsigned long ip = 0; 211 212 if (!task_stack_page(p)) 213 return 0; 214 215 if (!try_get_task_stack(p)) 216 return 0; 217 218 unwind_for_each_frame(&state, p, NULL, 0) { 219 if (state.stack_info.type != STACK_TYPE_TASK) { 220 ip = 0; 221 break; 222 } 223 224 ip = unwind_get_return_address(&state); 225 if (!ip) 226 break; 227 228 if (!in_sched_functions(ip)) 229 break; 230 } 231 232 put_task_stack(p); 233 return ip; 234 } 235 236 unsigned long arch_align_stack(unsigned long sp) 237 { 238 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 239 sp -= get_random_u32_below(PAGE_SIZE); 240 return sp & ~0xf; 241 } 242 243 static inline unsigned long brk_rnd(void) 244 { 245 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT; 246 } 247 248 unsigned long arch_randomize_brk(struct mm_struct *mm) 249 { 250 unsigned long ret; 251 252 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 253 return (ret > mm->brk) ? ret : mm->brk; 254 } 255