s390/mm: get rid of VMEM_MAX_PHYS macro

VMEM_MAX_PHYS is supposed to be the highest physical
address that can be added to the identity mapping.
It should match ident_map_size, which has the same
meaning. However, unlike ident_map_size it is not
adjusted against various limiting factors (see the
comment to setup_ident_map_size() function). That
renders all checks against VMEM_MAX_PHYS invalid.

Further, VMEM_MAX_PHYS is currently set to vmemmap,
which is an address in virtual memory space. However,
it gets compared against physical addresses in various
locations. That works, because both address spaces
are the same on s390, but otherwise it is wrong.

Instead of fixing VMEM_MAX_PHYS misuse and semantics
just remove it.

Acked-by: Heiko Carstens <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>

Author: Alexander Gordeev

arch/s390/boot/startup.c

@@ -220,7 +220,6 @@ static unsigned long setup_kernel_memory_layout(void)
 	pages = SECTION_ALIGN_UP(pages);
 	/* keep vmemmap_start aligned to a top level region table entry */
 	vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
-	/* vmemmap_start is the future VMEM_MAX_PHYS, make sure it is within MAX_PHYSMEM */
 	vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
 	/* make sure identity map doesn't overlay with vmemmap */
 	ident_map_size = min(ident_map_size, vmemmap_start);

arch/s390/include/asm/pgtable.h

@@ -89,8 +89,6 @@ extern unsigned long __bootdata_preserved(VMALLOC_END);
 extern struct page *__bootdata_preserved(vmemmap);
 extern unsigned long __bootdata_preserved(vmemmap_size);
 
-#define VMEM_MAX_PHYS ((unsigned long) vmemmap)
-
 extern unsigned long __bootdata_preserved(MODULES_VADDR);
 extern unsigned long __bootdata_preserved(MODULES_END);
 #define MODULES_VADDR	MODULES_VADDR

arch/s390/mm/extmem.c

@@ -642,7 +642,7 @@ void segment_warning(int rc, char *seg_name)
 		break;
 	case -ERANGE:
 		pr_err("DCSS %s exceeds the kernel mapping range (%lu) "
-		       "and cannot be loaded\n", seg_name, VMEM_MAX_PHYS);
+		       "and cannot be loaded\n", seg_name, ident_map_size);
 		break;
 	default:
 		break;

arch/s390/mm/vmem.c

@@ -529,7 +529,7 @@ struct range arch_get_mappable_range(void)
 	struct range mhp_range;
 
 	mhp_range.start = 0;
-	mhp_range.end =  VMEM_MAX_PHYS - 1;
+	mhp_range.end = ident_map_size - 1;
 	return mhp_range;
 }
 

drivers/s390/char/sclp_cmd.c

@@ -392,10 +392,10 @@ static void __init add_memory_merged(u16 rn)
 		goto skip_add;
 	start = rn2addr(first_rn);
 	size = (unsigned long long) num * sclp.rzm;
-	if (start >= VMEM_MAX_PHYS)
+	if (start >= ident_map_size)
 		goto skip_add;
-	if (start + size > VMEM_MAX_PHYS)
-		size = VMEM_MAX_PHYS - start;
+	if (start + size > ident_map_size)
+		size = ident_map_size - start;
 	if (start >= ident_map_size)
 		goto skip_add;
 	if (start + size > ident_map_size)