arch, mm: set high_memory in free_area_init()

high_memory defines upper bound on the directly mapped memory.  This bound
is defined by the beginning of ZONE_HIGHMEM when a system has high memory
and by the end of memory otherwise.

All this is known to generic memory management initialization code that
can set high_memory while initializing core mm structures.

Add a generic calculation of high_memory to free_area_init() and remove
per-architecture calculation except for the architectures that set and use
high_memory earlier than that.

Link: https://lkml.kernel.org/r/20250313135003.836600-11-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>	[x86]
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Guo Ren (csky) <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: rppt

arch/alpha/mm/init.c

@@ -276,7 +276,6 @@ srm_paging_stop (void)
 void __init
 mem_init(void)
 {
-	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 	memblock_free_all();
 }
 

arch/arc/mm/init.c

@@ -150,8 +150,6 @@ void __init setup_arch_memory(void)
 	 */
 	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;
 
-	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
-
 	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
 	kmap_init();
 #endif /* CONFIG_HIGHMEM */

arch/arm64/mm/init.c

@@ -309,8 +309,6 @@ void __init arm64_memblock_init(void)
 	}
 
 	early_init_fdt_scan_reserved_mem();
-
-	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 }
 
 void __init bootmem_init(void)

arch/csky/mm/init.c

@@ -47,7 +47,6 @@ void __init mem_init(void)
 #ifdef CONFIG_HIGHMEM
 	unsigned long tmp;
 #endif
-	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 
 	memblock_free_all();
 

arch/hexagon/mm/init.c

@@ -100,12 +100,6 @@ static void __init paging_init(void)
 	 * initial kernel segment table's physical address.
 	 */
 	init_mm.context.ptbase = __pa(init_mm.pgd);
-
-	/*
-	 * Start of high memory area.  Will probably need something more
-	 * fancy if we...  get more fancy.
-	 */
-	high_memory = (void *)((bootmem_lastpg + 1) << PAGE_SHIFT);
 }
 
 #ifndef DMA_RESERVE

arch/loongarch/kernel/numa.c

@@ -389,7 +389,6 @@ void __init paging_init(void)
 
 void __init mem_init(void)
 {
-	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 	memblock_free_all();
 }
 

arch/loongarch/mm/init.c

@@ -78,8 +78,6 @@ void __init paging_init(void)
 
 void __init mem_init(void)
 {
-	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
-
 	memblock_free_all();
 }
 #endif /* !CONFIG_NUMA */

arch/microblaze/mm/init.c

@@ -120,8 +120,6 @@ void __init setup_memory(void)
 
 void __init mem_init(void)
 {
-	high_memory = (void *)__va(memory_start + lowmem_size - 1);
-
 	/* this will put all memory onto the freelists */
 	memblock_free_all();
 #ifdef CONFIG_HIGHMEM

arch/mips/mm/init.c

@@ -417,7 +417,6 @@ void __init paging_init(void)
 		max_zone_pfns[ZONE_HIGHMEM] = max_low_pfn;
 	}
 #endif
-	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 
 	free_area_init(max_zone_pfns);
 }
@@ -469,7 +468,6 @@ void __init mem_init(void)
 #else  /* CONFIG_NUMA */
 void __init mem_init(void)
 {
-	high_memory = (void *) __va(get_num_physpages() << PAGE_SHIFT);
 	setup_zero_pages();	/* This comes from node 0 */
 	memblock_free_all();
 }

arch/nios2/mm/init.c

@@ -62,12 +62,6 @@ void __init paging_init(void)
 
 void __init mem_init(void)
 {
-	unsigned long end_mem   = memory_end; /* this must not include
-						kernel stack at top */
-
-	end_mem &= PAGE_MASK;
-	high_memory = __va(end_mem);
-
 	/* this will put all memory onto the freelists */
 	memblock_free_all();
 }