static void __init setup_lowcore_dat_off()

in kernel/setup.c [411:500]

• 68 lines of code
• 5 McCabe index (conditional complexity)

static void __init setup_lowcore_dat_off(void)
{
	unsigned long int_psw_mask = PSW_KERNEL_BITS;
	unsigned long mcck_stack;
	struct lowcore *lc;

	if (IS_ENABLED(CONFIG_KASAN))
		int_psw_mask |= PSW_MASK_DAT;

	/*
	 * Setup lowcore for boot cpu
	 */
	BUILD_BUG_ON(sizeof(struct lowcore) != LC_PAGES * PAGE_SIZE);
	lc = memblock_alloc_low(sizeof(*lc), sizeof(*lc));
	if (!lc)
		panic("%s: Failed to allocate %zu bytes align=%zx\n",
		      __func__, sizeof(*lc), sizeof(*lc));

	lc->restart_psw.mask = PSW_KERNEL_BITS;
	lc->restart_psw.addr = (unsigned long) restart_int_handler;
	lc->external_new_psw.mask = int_psw_mask | PSW_MASK_MCHECK;
	lc->external_new_psw.addr = (unsigned long) ext_int_handler;
	lc->svc_new_psw.mask = int_psw_mask | PSW_MASK_MCHECK;
	lc->svc_new_psw.addr = (unsigned long) system_call;
	lc->program_new_psw.mask = int_psw_mask | PSW_MASK_MCHECK;
	lc->program_new_psw.addr = (unsigned long) pgm_check_handler;
	lc->mcck_new_psw.mask = PSW_KERNEL_BITS;
	lc->mcck_new_psw.addr = (unsigned long) mcck_int_handler;
	lc->io_new_psw.mask = int_psw_mask | PSW_MASK_MCHECK;
	lc->io_new_psw.addr = (unsigned long) io_int_handler;
	lc->clock_comparator = clock_comparator_max;
	lc->nodat_stack = ((unsigned long) &init_thread_union)
		+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
	lc->current_task = (unsigned long)&init_task;
	lc->lpp = LPP_MAGIC;
	lc->machine_flags = S390_lowcore.machine_flags;
	lc->preempt_count = S390_lowcore.preempt_count;
	nmi_alloc_mcesa_early(&lc->mcesad);
	lc->sys_enter_timer = S390_lowcore.sys_enter_timer;
	lc->exit_timer = S390_lowcore.exit_timer;
	lc->user_timer = S390_lowcore.user_timer;
	lc->system_timer = S390_lowcore.system_timer;
	lc->steal_timer = S390_lowcore.steal_timer;
	lc->last_update_timer = S390_lowcore.last_update_timer;
	lc->last_update_clock = S390_lowcore.last_update_clock;

	/*
	 * Allocate the global restart stack which is the same for
	 * all CPUs in cast *one* of them does a PSW restart.
	 */
	restart_stack = memblock_alloc(THREAD_SIZE, THREAD_SIZE);
	if (!restart_stack)
		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
		      __func__, THREAD_SIZE, THREAD_SIZE);
	restart_stack += STACK_INIT_OFFSET;

	/*
	 * Set up PSW restart to call ipl.c:do_restart(). Copy the relevant
	 * restart data to the absolute zero lowcore. This is necessary if
	 * PSW restart is done on an offline CPU that has lowcore zero.
	 */
	lc->restart_stack = (unsigned long) restart_stack;
	lc->restart_fn = (unsigned long) do_restart;
	lc->restart_data = 0;
	lc->restart_source = -1U;

	mcck_stack = (unsigned long)memblock_alloc(THREAD_SIZE, THREAD_SIZE);
	if (!mcck_stack)
		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
		      __func__, THREAD_SIZE, THREAD_SIZE);
	lc->mcck_stack = mcck_stack + STACK_INIT_OFFSET;

	/* Setup absolute zero lowcore */
	mem_assign_absolute(S390_lowcore.restart_stack, lc->restart_stack);
	mem_assign_absolute(S390_lowcore.restart_fn, lc->restart_fn);
	mem_assign_absolute(S390_lowcore.restart_data, lc->restart_data);
	mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);
	mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);

	lc->spinlock_lockval = arch_spin_lockval(0);
	lc->spinlock_index = 0;
	arch_spin_lock_setup(0);
	lc->br_r1_trampoline = 0x07f1;	/* br %r1 */
	lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW);
	lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW);
	lc->preempt_count = PREEMPT_DISABLED;

	set_prefix((u32)(unsigned long) lc);
	lowcore_ptr[0] = lc;
}