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/kprobes.h> 28 #include <linux/random.h> 29 #include <linux/init_task.h> 30 #include <linux/entry-common.h> 31 #include <linux/io.h> 32 #include <asm/guarded_storage.h> 33 #include <asm/access-regs.h> 34 #include <asm/switch_to.h> 35 #include <asm/cpu_mf.h> 36 #include <asm/processor.h> 37 #include <asm/ptrace.h> 38 #include <asm/vtimer.h> 39 #include <asm/exec.h> 40 #include <asm/fpu.h> 41 #include <asm/irq.h> 42 #include <asm/nmi.h> 43 #include <asm/smp.h> 44 #include <asm/stacktrace.h> 45 #include <asm/runtime_instr.h> 46 #include <asm/unwind.h> 47 #include "entry.h" 48 49 void ret_from_fork(void) asm("ret_from_fork"); 50 51 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs) 52 { 53 void (*func)(void *arg); 54 55 schedule_tail(prev); 56 57 if (!user_mode(regs)) { 58 /* Kernel thread */ 59 func = (void *)regs->gprs[9]; 60 func((void *)regs->gprs[10]); 61 } 62 clear_pt_regs_flag(regs, PIF_SYSCALL); 63 syscall_exit_to_user_mode(regs); 64 } 65 66 void flush_thread(void) 67 { 68 } 69 70 void arch_setup_new_exec(void) 71 { 72 if (get_lowcore()->current_pid != current->pid) { 73 get_lowcore()->current_pid = current->pid; 74 if (test_facility(40)) 75 lpp(&get_lowcore()->lpp); 76 } 77 } 78 79 void arch_release_task_struct(struct task_struct *tsk) 80 { 81 runtime_instr_release(tsk); 82 guarded_storage_release(tsk); 83 } 84 85 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 86 { 87 save_user_fpu_regs(); 88 89 *dst = *src; 90 dst->thread.kfpu_flags = 0; 91 92 /* 93 * Don't transfer over the runtime instrumentation or the guarded 94 * storage control block pointers. These fields are cleared here instead 95 * of in copy_thread() to avoid premature freeing of associated memory 96 * on fork() failure. Wait to clear the RI flag because ->stack still 97 * refers to the source thread. 98 */ 99 dst->thread.ri_cb = NULL; 100 dst->thread.gs_cb = NULL; 101 dst->thread.gs_bc_cb = NULL; 102 103 return 0; 104 } 105 106 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 107 { 108 u64 clone_flags = args->flags; 109 unsigned long new_stackp = args->stack; 110 unsigned long tls = args->tls; 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 /* Don't copy debug registers */ 123 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); 124 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); 125 clear_tsk_thread_flag(p, TIF_SINGLE_STEP); 126 p->thread.per_flags = 0; 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 p->thread.last_break = 1; 134 135 frame->sf.back_chain = 0; 136 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; 137 frame->sf.gprs[12 - 6] = (unsigned long)p; 138 /* new return point is ret_from_fork */ 139 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork; 140 /* fake return stack for resume(), don't go back to schedule */ 141 frame->sf.gprs[15 - 6] = (unsigned long)frame; 142 143 /* Store access registers to kernel stack of new process. */ 144 if (unlikely(args->fn)) { 145 /* kernel thread */ 146 memset(&frame->childregs, 0, sizeof(struct pt_regs)); 147 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | 148 PSW_MASK_EXT | PSW_MASK_MCHECK; 149 frame->childregs.gprs[9] = (unsigned long)args->fn; 150 frame->childregs.gprs[10] = (unsigned long)args->fn_arg; 151 frame->childregs.orig_gpr2 = -1; 152 frame->childregs.last_break = 1; 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 * Clear the runtime instrumentation flag after the above childregs 162 * copy. The CB pointer was already cleared in arch_dup_task_struct(). 163 */ 164 frame->childregs.psw.mask &= ~PSW_MASK_RI; 165 166 /* Set a new TLS ? */ 167 if (clone_flags & CLONE_SETTLS) { 168 p->thread.acrs[0] = (unsigned int)(tls >> 32); 169 p->thread.acrs[1] = (unsigned int)tls; 170 } 171 /* 172 * s390 stores the svc return address in arch_data when calling 173 * sigreturn()/restart_syscall() via vdso. 1 means no valid address 174 * stored. 175 */ 176 p->restart_block.arch_data = 1; 177 return 0; 178 } 179 180 void execve_tail(void) 181 { 182 current->thread.ufpu.fpc = 0; 183 fpu_sfpc(0); 184 } 185 186 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next) 187 { 188 save_user_fpu_regs(); 189 save_kernel_fpu_regs(&prev->thread); 190 save_access_regs(&prev->thread.acrs[0]); 191 save_ri_cb(prev->thread.ri_cb); 192 save_gs_cb(prev->thread.gs_cb); 193 update_cr_regs(next); 194 restore_kernel_fpu_regs(&next->thread); 195 restore_access_regs(&next->thread.acrs[0]); 196 restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb); 197 restore_gs_cb(next->thread.gs_cb); 198 return __switch_to_asm(prev, next); 199 } 200 201 unsigned long __get_wchan(struct task_struct *p) 202 { 203 struct unwind_state state; 204 unsigned long ip = 0; 205 206 if (!task_stack_page(p)) 207 return 0; 208 209 if (!try_get_task_stack(p)) 210 return 0; 211 212 unwind_for_each_frame(&state, p, NULL, 0) { 213 if (state.stack_info.type != STACK_TYPE_TASK) { 214 ip = 0; 215 break; 216 } 217 218 ip = unwind_get_return_address(&state); 219 if (!ip) 220 break; 221 222 if (!in_sched_functions(ip)) 223 break; 224 } 225 226 put_task_stack(p); 227 return ip; 228 } 229 230 unsigned long arch_align_stack(unsigned long sp) 231 { 232 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 233 sp -= get_random_u32_below(PAGE_SIZE); 234 return sp & ~0xf; 235 } 236 237 static inline unsigned long brk_rnd(void) 238 { 239 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT; 240 } 241 242 unsigned long arch_randomize_brk(struct mm_struct *mm) 243 { 244 unsigned long ret; 245 246 ret = PAGE_ALIGN(mm->brk + brk_rnd()); 247 return (ret > mm->brk) ? ret : mm->brk; 248 } 249