s390/mm: allocate Absolute Lowcore Area in decompressor

Move Absolute Lowcore Area allocation to the decompressor.
As result, get_abs_lowcore() and put_abs_lowcore() access
brackets become really straight and do not require complex
execution context analysis and LAP and interrupts tackling.

Reviewed-by: Heiko Carstens <[e-mail]>
Signed-off-by: Alexander Gordeev <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/boot/boot.h

···
 extern struct vmlinux_info _vmlinux_info;
 #define vmlinux _vmlinux_info
 
+#define __abs_lowcore_pa(x)	(((unsigned long)(x) - __abs_lowcore) % sizeof(struct lowcore))
+
 #endif /* __ASSEMBLY__ */
 #endif /* BOOT_BOOT_H */

arch/s390/boot/vmem.c

···
 #include <asm/sections.h>
 #include <asm/mem_detect.h>
 #include <asm/maccess.h>
+#include <asm/abs_lowcore.h>
 #include "decompressor.h"
 #include "boot.h"
 
···
 enum populate_mode {
 	POPULATE_NONE,
 	POPULATE_ONE2ONE,
+	POPULATE_ABS_LOWCORE,
 };
 
 static void boot_check_oom(void)
···
 		return -1;
 	case POPULATE_ONE2ONE:
 		return addr;
+	case POPULATE_ABS_LOWCORE:
+		return __abs_lowcore_pa(addr);
 	default:
 		return -1;
 	}
···
 	pgtable_populate_begin(online_end);
 	pgtable_populate(0, sizeof(struct lowcore), POPULATE_ONE2ONE);
 	pgtable_populate(0, online_end, POPULATE_ONE2ONE);
+	pgtable_populate(__abs_lowcore, __abs_lowcore + sizeof(struct lowcore),
+			 POPULATE_ABS_LOWCORE);
 	pgtable_populate(__memcpy_real_area, __memcpy_real_area + PAGE_SIZE,
 			 POPULATE_NONE);
 	memcpy_real_ptep = __virt_to_kpte(__memcpy_real_area);

arch/s390/include/asm/abs_lowcore.h

···
 #define ABS_LOWCORE_MAP_SIZE	(NR_CPUS * sizeof(struct lowcore))
 
 extern unsigned long __abs_lowcore;
-extern bool abs_lowcore_mapped;
 
-struct lowcore *get_abs_lowcore(unsigned long *flags);
-void put_abs_lowcore(struct lowcore *lc, unsigned long flags);
 int abs_lowcore_map(int cpu, struct lowcore *lc, bool alloc);
 void abs_lowcore_unmap(int cpu);
+
+static inline struct lowcore *get_abs_lowcore(void)
+{
+	int cpu;
+
+	cpu = get_cpu();
+	return ((struct lowcore *)__abs_lowcore) + cpu;
+}
+
+static inline void put_abs_lowcore(struct lowcore *lc)
+{
+	put_cpu();
+}
 
 #endif /* _ASM_S390_ABS_LOWCORE_H */

arch/s390/kernel/abs_lowcore.c

···
 #include <linux/pgtable.h>
 #include <asm/abs_lowcore.h>
 
-#define ABS_LOWCORE_UNMAPPED	1
-#define ABS_LOWCORE_LAP_ON	2
-#define ABS_LOWCORE_IRQS_ON	4
-
 unsigned long __bootdata_preserved(__abs_lowcore);
-bool __ro_after_init abs_lowcore_mapped;
 
 int abs_lowcore_map(int cpu, struct lowcore *lc, bool alloc)
 {
···
 		vmem_unmap_4k_page(addr);
 		addr += PAGE_SIZE;
 	}
-}
-
-struct lowcore *get_abs_lowcore(unsigned long *flags)
-{
-	unsigned long irq_flags;
-	union ctlreg0 cr0;
-	int cpu;
-
-	*flags = 0;
-	cpu = get_cpu();
-	if (abs_lowcore_mapped) {
-		return ((struct lowcore *)__abs_lowcore) + cpu;
-	} else {
-		if (cpu != 0)
-			panic("Invalid unmapped absolute lowcore access\n");
-		local_irq_save(irq_flags);
-		if (!irqs_disabled_flags(irq_flags))
-			*flags |= ABS_LOWCORE_IRQS_ON;
-		__ctl_store(cr0.val, 0, 0);
-		if (cr0.lap) {
-			*flags |= ABS_LOWCORE_LAP_ON;
-			__ctl_clear_bit(0, 28);
-		}
-		*flags |= ABS_LOWCORE_UNMAPPED;
-		return lowcore_ptr[0];
-	}
-}
-
-void put_abs_lowcore(struct lowcore *lc, unsigned long flags)
-{
-	if (abs_lowcore_mapped) {
-		if (flags)
-			panic("Invalid mapped absolute lowcore release\n");
-	} else {
-		if (smp_processor_id() != 0)
-			panic("Invalid mapped absolute lowcore access\n");
-		if (!(flags & ABS_LOWCORE_UNMAPPED))
-			panic("Invalid unmapped absolute lowcore release\n");
-		if (flags & ABS_LOWCORE_LAP_ON)
-			__ctl_set_bit(0, 28);
-		if (flags & ABS_LOWCORE_IRQS_ON)
-			local_irq_enable();
-	}
-	put_cpu();
 }

arch/s390/kernel/ipl.c

···
 {
 	unsigned long ipib = (unsigned long) reipl_block_actual;
 	struct lowcore *abs_lc;
-	unsigned long flags;
 	unsigned int csum;
 
 	csum = (__force unsigned int)
 	       csum_partial(reipl_block_actual, reipl_block_actual->hdr.len, 0);
-	abs_lc = get_abs_lowcore(&flags);
+	abs_lc = get_abs_lowcore();
 	abs_lc->ipib = ipib;
 	abs_lc->ipib_checksum = csum;
-	put_abs_lowcore(abs_lc, flags);
+	put_abs_lowcore(abs_lc);
 	dump_run(trigger);
 }
 

arch/s390/kernel/machine_kexec.c

···
 void arch_crash_save_vmcoreinfo(void)
 {
 	struct lowcore *abs_lc;
-	unsigned long flags;
 
 	VMCOREINFO_SYMBOL(lowcore_ptr);
 	VMCOREINFO_SYMBOL(high_memory);
···
 	vmcoreinfo_append_str("SAMODE31=%lx\n", __samode31);
 	vmcoreinfo_append_str("EAMODE31=%lx\n", __eamode31);
 	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
-	abs_lc = get_abs_lowcore(&flags);
+	abs_lc = get_abs_lowcore();
 	abs_lc->vmcore_info = paddr_vmcoreinfo_note();
-	put_abs_lowcore(abs_lc, flags);
+	put_abs_lowcore(abs_lc);
 }
 
 void machine_shutdown(void)

arch/s390/kernel/os_info.c

···
 void __init os_info_init(void)
 {
 	struct lowcore *abs_lc;
-	unsigned long flags;
 
 	os_info.version_major = OS_INFO_VERSION_MAJOR;
 	os_info.version_minor = OS_INFO_VERSION_MINOR;
 	os_info.magic = OS_INFO_MAGIC;
 	os_info.csum = os_info_csum(&os_info);
-	abs_lc = get_abs_lowcore(&flags);
+	abs_lc = get_abs_lowcore();
 	abs_lc->os_info = __pa(&os_info);
-	put_abs_lowcore(abs_lc, flags);
+	put_abs_lowcore(abs_lc);
 }
 
 #ifdef CONFIG_CRASH_DUMP

arch/s390/kernel/setup.c

···
 {
 	struct lowcore *lc, *abs_lc;
 	unsigned long mcck_stack;
-	unsigned long flags;
 
 	/*
 	 * Setup lowcore for boot cpu
···
 	lc->kernel_asce = S390_lowcore.kernel_asce;
 	lc->user_asce = S390_lowcore.user_asce;
 
-	abs_lc = get_abs_lowcore(&flags);
+	abs_lc = get_abs_lowcore();
 	abs_lc->restart_stack = lc->restart_stack;
 	abs_lc->restart_fn = lc->restart_fn;
 	abs_lc->restart_data = lc->restart_data;
···
 	memcpy(abs_lc->cregs_save_area, lc->cregs_save_area, sizeof(abs_lc->cregs_save_area));
 	abs_lc->program_new_psw = lc->program_new_psw;
 	abs_lc->mcesad = lc->mcesad;
-	put_abs_lowcore(abs_lc, flags);
+	put_abs_lowcore(abs_lc);
 
 	set_prefix(__pa(lc));
 	lowcore_ptr[0] = lc;
-	if (abs_lowcore_map(0, lowcore_ptr[0], true))
+	if (abs_lowcore_map(0, lowcore_ptr[0], false))
 		panic("Couldn't setup absolute lowcore");
-	abs_lowcore_mapped = true;
 }
 
 static struct resource code_resource = {

arch/s390/kernel/smp.c

···
 {
 	struct lowcore *lc, *abs_lc;
 	unsigned int source_cpu;
-	unsigned long flags;
 
 	lc = lowcore_ptr[pcpu - pcpu_devices];
 	source_cpu = stap();
···
 		lc->restart_data = (unsigned long)data;
 		lc->restart_source = source_cpu;
 	} else {
-		abs_lc = get_abs_lowcore(&flags);
+		abs_lc = get_abs_lowcore();
 		abs_lc->restart_stack = stack;
 		abs_lc->restart_fn = (unsigned long)func;
 		abs_lc->restart_data = (unsigned long)data;
 		abs_lc->restart_source = source_cpu;
-		put_abs_lowcore(abs_lc, flags);
+		put_abs_lowcore(abs_lc);
 	}
 	__bpon();
 	asm volatile(
···
 {
 	struct ec_creg_mask_parms parms = { .cr = cr, };
 	struct lowcore *abs_lc;
-	unsigned long flags;
 	u64 ctlreg;
 
 	if (set) {
···
 		parms.andval = ~(1UL << bit);
 	}
 	spin_lock(&ctl_lock);
-	abs_lc = get_abs_lowcore(&flags);
+	abs_lc = get_abs_lowcore();
 	ctlreg = abs_lc->cregs_save_area[cr];
 	ctlreg = (ctlreg & parms.andval) | parms.orval;
 	abs_lc->cregs_save_area[cr] = ctlreg;
-	put_abs_lowcore(abs_lc, flags);
+	put_abs_lowcore(abs_lc);
 	spin_unlock(&ctl_lock);
 	on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 }

arch/s390/mm/maccess.c

···
 	void *ptr = phys_to_virt(addr);
 	void *bounce = ptr;
 	struct lowcore *abs_lc;
-	unsigned long flags;
 	unsigned long size;
 	int this_cpu, cpu;
 
···
 		goto out;
 	size = PAGE_SIZE - (addr & ~PAGE_MASK);
 	if (addr < sizeof(struct lowcore)) {
-		abs_lc = get_abs_lowcore(&flags);
+		abs_lc = get_abs_lowcore();
 		ptr = (void *)abs_lc + addr;
 		memcpy(bounce, ptr, size);
-		put_abs_lowcore(abs_lc, flags);
+		put_abs_lowcore(abs_lc);
 	} else if (cpu == this_cpu) {
 		ptr = (void *)(addr - virt_to_phys(lowcore_ptr[cpu]));
 		memcpy(bounce, ptr, size);