arch/s390/kernel/ctlreg.c

Source file repositories/reference/linux-study-clean/arch/s390/kernel/ctlreg.c

File Facts

System
Linux kernel
Corpus path
arch/s390/kernel/ctlreg.c
Extension
.c
Size
2662 bytes
Lines
123
Domain
Architecture Layer
Bucket
arch/s390
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ctlreg_parms {
	unsigned long andval;
	unsigned long orval;
	unsigned long val;
	int request;
	int cr;
};

static void ctlreg_callback(void *info)
{
	struct ctlreg_parms *pp = info;
	struct ctlreg regs[16];

	__local_ctl_store(0, 15, regs);
	if (pp->request == CTLREG_LOAD) {
		regs[pp->cr].val = pp->val;
	} else {
		regs[pp->cr].val &= pp->andval;
		regs[pp->cr].val |= pp->orval;
	}
	__local_ctl_load(0, 15, regs);
}

static void system_ctlreg_update(void *info)
{
	unsigned long flags;

	if (system_state == SYSTEM_BOOTING) {
		/*
		 * For very early calls do not call on_each_cpu()
		 * since not everything might be setup.
		 */
		local_irq_save(flags);
		ctlreg_callback(info);
		local_irq_restore(flags);
	} else {
		on_each_cpu(ctlreg_callback, info, 1);
	}
}

void system_ctlreg_modify(unsigned int cr, unsigned long data, int request)
{
	struct ctlreg_parms pp = { .cr = cr, .request = request, };
	struct lowcore *abs_lc;

	switch (request) {
	case CTLREG_SET_BIT:
		pp.orval  = 1UL << data;
		pp.andval = -1UL;
		break;
	case CTLREG_CLEAR_BIT:
		pp.orval  = 0;
		pp.andval = ~(1UL << data);
		break;
	case CTLREG_LOAD:
		pp.val = data;
		break;
	}
	if (system_ctlreg_area_init) {
		system_ctlreg_lock();
		abs_lc = get_abs_lowcore();
		if (request == CTLREG_LOAD) {
			abs_lc->cregs_save_area[cr].val = pp.val;
		} else {
			abs_lc->cregs_save_area[cr].val &= pp.andval;
			abs_lc->cregs_save_area[cr].val |= pp.orval;
		}
		put_abs_lowcore(abs_lc);
		system_ctlreg_update(&pp);
		system_ctlreg_unlock();
	} else {
		system_ctlreg_update(&pp);
	}
}
EXPORT_SYMBOL(system_ctlreg_modify);

Annotation

Implementation Notes