// 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 <schwidefsky@de.ibm.com>, *		 Hartmut Penner <hp@de.ibm.com>, *		 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/kprobes.h>#include <linux/random.h>#include <linux/init_task.h>#include <linux/entry-common.h>#include <linux/io.h>#include <asm/guarded_storage.h>#include <asm/access-regs.h>#include <asm/switch_to.h>#include <asm/cpu_mf.h>#include <asm/processor.h>#include <asm/ptrace.h>#include <asm/vtimer.h>#include <asm/exec.h>#include <asm/fpu.h>#include <asm/irq.h>#include <asm/nmi.h>#include <asm/smp.h>#include <asm/stacktrace.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){	int (*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 (get_lowcore()->current_pid != current->pid) {		get_lowcore()->current_pid = current->pid;		if (test_facility(40))			lpp(&get_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_user_fpu_regs(); 	*dst = *src;	dst->thread.kfpu_flags = 0; 	/*	 * 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){	u64 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[11 - 6] = (unsigned long)&frame->childregs;	frame->sf.gprs[12 - 6] = (unsigned long)p;	/* new return point is ret_from_fork */	frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;	/* fake return stack for resume(), don't go back to schedule */	frame->sf.gprs[15 - 6] = (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_IO |					    PSW_MASK_EXT | PSW_MASK_MCHECK;		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) {		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.ufpu.fpc = 0;	fpu_sfpc(0);} struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next){	save_user_fpu_regs();	save_kernel_fpu_regs(&prev->thread);	save_access_regs(&prev->thread.acrs[0]);	save_ri_cb(prev->thread.ri_cb);	save_gs_cb(prev->thread.gs_cb);	update_cr_regs(next);	restore_kernel_fpu_regs(&next->thread);	restore_access_regs(&next->thread.acrs[0]);	restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);	restore_gs_cb(next->thread.gs_cb);	return __switch_to_asm(prev, next);} unsigned long __get_wchan(struct task_struct *p){	struct unwind_state state;	unsigned long ip = 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 -= get_random_u32_below(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;}