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- // SPDX-License-Identifier: GPL-2.0
- /*
- * This file handles the architecture dependent parts of process handling.
- *
- * Copyright IBM Corp. 1999, 2009
- * Author(s): Martin Schwidefsky <[email protected]>,
- * Hartmut Penner <[email protected]>,
- * Denis Joseph Barrow,
- */
- #include <linux/elf-randomize.h>
- #include <linux/compiler.h>
- #include <linux/cpu.h>
- #include <linux/sched.h>
- #include <linux/sched/debug.h>
- #include <linux/sched/task.h>
- #include <linux/sched/task_stack.h>
- #include <linux/kernel.h>
- #include <linux/mm.h>
- #include <linux/elfcore.h>
- #include <linux/smp.h>
- #include <linux/slab.h>
- #include <linux/interrupt.h>
- #include <linux/tick.h>
- #include <linux/personality.h>
- #include <linux/syscalls.h>
- #include <linux/compat.h>
- #include <linux/kprobes.h>
- #include <linux/random.h>
- #include <linux/export.h>
- #include <linux/init_task.h>
- #include <linux/entry-common.h>
- #include <asm/cpu_mf.h>
- #include <asm/io.h>
- #include <asm/processor.h>
- #include <asm/vtimer.h>
- #include <asm/exec.h>
- #include <asm/irq.h>
- #include <asm/nmi.h>
- #include <asm/smp.h>
- #include <asm/stacktrace.h>
- #include <asm/switch_to.h>
- #include <asm/runtime_instr.h>
- #include <asm/unwind.h>
- #include "entry.h"
- void ret_from_fork(void) asm("ret_from_fork");
- void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
- {
- void (*func)(void *arg);
- schedule_tail(prev);
- if (!user_mode(regs)) {
- /* Kernel thread */
- func = (void *)regs->gprs[9];
- func((void *)regs->gprs[10]);
- }
- clear_pt_regs_flag(regs, PIF_SYSCALL);
- syscall_exit_to_user_mode(regs);
- }
- void flush_thread(void)
- {
- }
- void arch_setup_new_exec(void)
- {
- if (S390_lowcore.current_pid != current->pid) {
- S390_lowcore.current_pid = current->pid;
- if (test_facility(40))
- lpp(&S390_lowcore.lpp);
- }
- }
- void arch_release_task_struct(struct task_struct *tsk)
- {
- runtime_instr_release(tsk);
- guarded_storage_release(tsk);
- }
- int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
- {
- /*
- * Save the floating-point or vector register state of the current
- * task and set the CIF_FPU flag to lazy restore the FPU register
- * state when returning to user space.
- */
- save_fpu_regs();
- memcpy(dst, src, arch_task_struct_size);
- dst->thread.fpu.regs = dst->thread.fpu.fprs;
- /*
- * Don't transfer over the runtime instrumentation or the guarded
- * storage control block pointers. These fields are cleared here instead
- * of in copy_thread() to avoid premature freeing of associated memory
- * on fork() failure. Wait to clear the RI flag because ->stack still
- * refers to the source thread.
- */
- dst->thread.ri_cb = NULL;
- dst->thread.gs_cb = NULL;
- dst->thread.gs_bc_cb = NULL;
- return 0;
- }
- int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
- {
- unsigned long clone_flags = args->flags;
- unsigned long new_stackp = args->stack;
- unsigned long tls = args->tls;
- struct fake_frame
- {
- struct stack_frame sf;
- struct pt_regs childregs;
- } *frame;
- frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
- p->thread.ksp = (unsigned long) frame;
- /* Save access registers to new thread structure. */
- save_access_regs(&p->thread.acrs[0]);
- /* start new process with ar4 pointing to the correct address space */
- /* Don't copy debug registers */
- memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
- memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
- clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
- p->thread.per_flags = 0;
- /* Initialize per thread user and system timer values */
- p->thread.user_timer = 0;
- p->thread.guest_timer = 0;
- p->thread.system_timer = 0;
- p->thread.hardirq_timer = 0;
- p->thread.softirq_timer = 0;
- p->thread.last_break = 1;
- frame->sf.back_chain = 0;
- frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame);
- frame->sf.gprs[6] = (unsigned long)p;
- /* new return point is ret_from_fork */
- frame->sf.gprs[8] = (unsigned long)ret_from_fork;
- /* fake return stack for resume(), don't go back to schedule */
- frame->sf.gprs[9] = (unsigned long)frame;
- /* Store access registers to kernel stack of new process. */
- if (unlikely(args->fn)) {
- /* kernel thread */
- memset(&frame->childregs, 0, sizeof(struct pt_regs));
- frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
- PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
- frame->childregs.psw.addr =
- (unsigned long)__ret_from_fork;
- frame->childregs.gprs[9] = (unsigned long)args->fn;
- frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
- frame->childregs.orig_gpr2 = -1;
- frame->childregs.last_break = 1;
- return 0;
- }
- frame->childregs = *current_pt_regs();
- frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
- frame->childregs.flags = 0;
- if (new_stackp)
- frame->childregs.gprs[15] = new_stackp;
- /*
- * Clear the runtime instrumentation flag after the above childregs
- * copy. The CB pointer was already cleared in arch_dup_task_struct().
- */
- frame->childregs.psw.mask &= ~PSW_MASK_RI;
- /* Set a new TLS ? */
- if (clone_flags & CLONE_SETTLS) {
- if (is_compat_task()) {
- p->thread.acrs[0] = (unsigned int)tls;
- } else {
- p->thread.acrs[0] = (unsigned int)(tls >> 32);
- p->thread.acrs[1] = (unsigned int)tls;
- }
- }
- /*
- * s390 stores the svc return address in arch_data when calling
- * sigreturn()/restart_syscall() via vdso. 1 means no valid address
- * stored.
- */
- p->restart_block.arch_data = 1;
- return 0;
- }
- void execve_tail(void)
- {
- current->thread.fpu.fpc = 0;
- asm volatile("sfpc %0" : : "d" (0));
- }
- unsigned long __get_wchan(struct task_struct *p)
- {
- struct unwind_state state;
- unsigned long ip = 0;
- if (!task_stack_page(p))
- return 0;
- if (!try_get_task_stack(p))
- return 0;
- unwind_for_each_frame(&state, p, NULL, 0) {
- if (state.stack_info.type != STACK_TYPE_TASK) {
- ip = 0;
- break;
- }
- ip = unwind_get_return_address(&state);
- if (!ip)
- break;
- if (!in_sched_functions(ip))
- break;
- }
- put_task_stack(p);
- return ip;
- }
- unsigned long arch_align_stack(unsigned long sp)
- {
- if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
- sp -= prandom_u32_max(PAGE_SIZE);
- return sp & ~0xf;
- }
- static inline unsigned long brk_rnd(void)
- {
- return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
- }
- unsigned long arch_randomize_brk(struct mm_struct *mm)
- {
- unsigned long ret;
- ret = PAGE_ALIGN(mm->brk + brk_rnd());
- return (ret > mm->brk) ? ret : mm->brk;
- }
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