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authorLuis R. Rodriguez <mcgrof@kernel.org>2018-08-17 15:46:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-17 16:20:29 -0700
commita3266bd49c721e2e0a71f352d83713fbd60caadb (patch)
tree2a1fd45483467ffd8687f60e06c9b497dc40aee0 /include
parent3172e5e61c8a78f690c50f221fdeedce35d0b1e4 (diff)
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>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/pgtable.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index a75cb371cd19..62bbd6f23c35 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -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