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/[email protected]
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
Acked-by: Dave Hansen <[email protected]>	[x86]
Tested-by: Mark Brown <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Andreas Larsson <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Betkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Guo Ren (csky) <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiaxun Yang <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: John Paul Adrian Glaubitz <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Russel King <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Thomas Gleinxer <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 30 insertions, 0 deletions

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 7fd48d2d5064..bd7071c32a44 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -45,6 +45,13 @@ struct page *mem_map;
 EXPORT_SYMBOL(mem_map);
 #endif
 
+/*
+ * high_memory defines the upper bound on direct map memory, then end
+ * of ZONE_NORMAL.
+ */
+void *high_memory;
+EXPORT_SYMBOL(high_memory);
+
 #ifdef CONFIG_DEBUG_MEMORY_INIT
 int __meminitdata mminit_loglevel;
 
@@ -1778,6 +1785,27 @@ static bool arch_has_descending_max_zone_pfns(void)
 	return IS_ENABLED(CONFIG_ARC) && !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
 }
 
+static void set_high_memory(void)
+{
+	phys_addr_t highmem = memblock_end_of_DRAM();
+
+	/*
+	 * Some architectures (e.g. ARM) set high_memory very early and
+	 * use it in arch setup code.
+	 * If an architecture already set high_memory don't overwrite it
+	 */
+	if (high_memory)
+		return;
+
+#ifdef CONFIG_HIGHMEM
+	if (arch_has_descending_max_zone_pfns() ||
+	    highmem > PFN_PHYS(arch_zone_lowest_possible_pfn[ZONE_HIGHMEM]))
+		highmem = PFN_PHYS(arch_zone_lowest_possible_pfn[ZONE_HIGHMEM]);
+#endif
+
+	high_memory = phys_to_virt(highmem - 1) + 1;
+}
+
 /**
  * free_area_init - Initialise all pg_data_t and zone data
  * @max_zone_pfn: an array of max PFNs for each zone
@@ -1900,6 +1928,8 @@ void __init free_area_init(unsigned long *max_zone_pfn)
 
 	/* disable hash distribution for systems with a single node */
 	fixup_hashdist();
+
+	set_high_memory();
 }
 
 /**