arch: consolidate existing CONFIG_PAGE_SIZE_*KB definitions

These four architectures define the same Kconfig symbols for configuring
the page size. Move the logic into a common place where it can be shared
with all other architectures.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 92 insertions, 2 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index a5af0edd3eb8..fd18b7db2c77 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1078,17 +1078,107 @@ config HAVE_ARCH_COMPAT_MMAP_BASES
 	  and vice-versa 32-bit applications to call 64-bit mmap().
 	  Required for applications doing different bitness syscalls.
 
+config HAVE_PAGE_SIZE_4KB
+	bool
+
+config HAVE_PAGE_SIZE_8KB
+	bool
+
+config HAVE_PAGE_SIZE_16KB
+	bool
+
+config HAVE_PAGE_SIZE_32KB
+	bool
+
+config HAVE_PAGE_SIZE_64KB
+	bool
+
+config HAVE_PAGE_SIZE_256KB
+	bool
+
+choice
+	prompt "MMU page size"
+
+config PAGE_SIZE_4KB
+	bool "4KiB pages"
+	depends on HAVE_PAGE_SIZE_4KB
+	help
+	  This option select the standard 4KiB Linux page size and the only
+	  available option on many architectures. Using 4KiB page size will
+	  minimize memory consumption and is therefore recommended for low
+	  memory systems.
+	  Some software that is written for x86 systems makes incorrect
+	  assumptions about the page size and only runs on 4KiB pages.
+
+config PAGE_SIZE_8KB
+	bool "8KiB pages"
+	depends on HAVE_PAGE_SIZE_8KB
+	help
+	  This option is the only supported page size on a few older
+	  processors, and can be slightly faster than 4KiB pages.
+
+config PAGE_SIZE_16KB
+	bool "16KiB pages"
+	depends on HAVE_PAGE_SIZE_16KB
+	help
+	  This option is usually a good compromise between memory
+	  consumption and performance for typical desktop and server
+	  workloads, often saving a level of page table lookups compared
+	  to 4KB pages as well as reducing TLB pressure and overhead of
+	  per-page operations in the kernel at the expense of a larger
+	  page cache.
+
+config PAGE_SIZE_32KB
+	bool "32KiB pages"
+	depends on HAVE_PAGE_SIZE_32KB
+	help
+	  Using 32KiB page size will result in slightly higher performance
+	  kernel at the price of higher memory consumption compared to
+	  16KiB pages.	This option is available only on cnMIPS cores.
+	  Note that you will need a suitable Linux distribution to
+	  support this.
+
+config PAGE_SIZE_64KB
+	bool "64KiB pages"
+	depends on HAVE_PAGE_SIZE_64KB
+	help
+	  Using 64KiB page size will result in slightly higher performance
+	  kernel at the price of much higher memory consumption compared to
+	  4KiB or 16KiB pages.
+	  This is not suitable for general-purpose workloads but the
+	  better performance may be worth the cost for certain types of
+	  supercomputing or database applications that work mostly with
+	  large in-memory data rather than small files.
+
+config PAGE_SIZE_256KB
+	bool "256KiB pages"
+	depends on HAVE_PAGE_SIZE_256KB
+	help
+	  256KiB pages have little practical value due to their extreme
+	  memory usage.  The kernel will only be able to run applications
+	  that have been compiled with '-zmax-page-size' set to 256KiB
+	  (the default is 64KiB or 4KiB on most architectures).
+
+endchoice
+
 config PAGE_SIZE_LESS_THAN_64KB
 	def_bool y
-	depends on !ARM64_64K_PAGES
 	depends on !PAGE_SIZE_64KB
-	depends on !PARISC_PAGE_SIZE_64KB
 	depends on PAGE_SIZE_LESS_THAN_256KB
 
 config PAGE_SIZE_LESS_THAN_256KB
 	def_bool y
 	depends on !PAGE_SIZE_256KB
 
+config PAGE_SHIFT
+	int
+	default 12 if PAGE_SIZE_4KB
+	default 13 if PAGE_SIZE_8KB
+	default 14 if PAGE_SIZE_16KB
+	default 15 if PAGE_SIZE_32KB
+	default 16 if PAGE_SIZE_64KB
+	default 18 if PAGE_SIZE_256KB
+
 # This allows to use a set of generic functions to determine mmap base
 # address by giving priority to top-down scheme only if the process
 # is not in legacy mode (compat task, unlimited stack size or