Commit a3266bd4 authored Aug 17, 2018 by Luis R. Rodriguez Committed by Linus Torvalds Aug 17, 2018

mm: provide a fallback for PAGE_KERNEL_RO for architectures

Some architectures do not define certain PAGE_KERNEL_* flags, this is
either because:

 a) The way to implement some of these flags is *not yet ported*, or
 b) The architecture *has no way* to describe them

Over time we have accumulated a few PAGE_KERNEL_* fallback workarounds
for architectures in the kernel which do not define them using
*relatively safe* equivalents.  Move these scattered fallback hacks into
asm-generic.

We start off with PAGE_KERNEL_RO using PAGE_KERNEL as a fallback.  This
has been in place on the firmware loader for years.  Move the fallback
into the respective asm-generic header.

Link: http://lkml.kernel.org/r/20180510185507.2439-2-mcgrof@kernel.org


Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3172e5e6

drivers/base/firmware_loader/fallback.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -219,11 +219,6 @@ static ssize_t firmware_loading_show(struct device *dev,
		return sprintf(buf, "%d\n", loading);
		}

		/* Some architectures don't have PAGE_KERNEL_RO */
		#ifndef PAGE_KERNEL_RO
		#define PAGE_KERNEL_RO PAGE_KERNEL
		#endif

		/* one pages buffer should be mapped/unmapped only once */
		static int map_fw_priv_pages(struct fw_priv *fw_priv)
		{

include/asm-generic/pgtable.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -1095,6 +1095,20 @@ static inline bool arch_has_pfn_modify_check(void)
		}
		#endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */

		/*
		* Architecture PAGE_KERNEL_* fallbacks
		*
		* Some architectures don't define certain PAGE_KERNEL_* flags. This is either
		* because they really don't support them, or the port needs to be updated to
		* reflect the required functionality. Below are a set of relatively safe
		* fallbacks, as best effort, which we can count on in lieu of the architectures
		* not defining them on their own yet.
		*/

		#ifndef PAGE_KERNEL_RO
		# define PAGE_KERNEL_RO PAGE_KERNEL
		#endif

		#endif /* !__ASSEMBLY__ */

		#ifndef io_remap_pfn_range