From a3266bd49c721e2e0a71f352d83713fbd60caadb Mon Sep 17 00:00:00 2001
From: "Luis R. Rodriguez" <mcgrof@kernel.org>
Date: Fri, 17 Aug 2018 15:46:29 -0700
Subject: [PATCH] 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>
---
drivers/base/firmware_loader/fallback.c | 5 -----
include/asm-generic/pgtable.h | 14 ++++++++++++++
2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 202324291542f..b5c865fe263b2 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -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)
{
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index a75cb371cd193..62bbd6f23c356 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
--
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