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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 <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/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 <linux/io.h>
#include <asm/cpu_mf.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[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) {
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 -= 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;
}
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