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From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: arnd@arndb.de
Cc: gregkh@linuxfoundation.org, willy@infradead.org,
	geert@linux-m68k.org, linux-m68k@lists.linux-m68k.org,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	"Luis R. Rodriguez" <mcgrof@kernel.org>
Subject: [PATCH v3 1/2] mm: provide a fallback for PAGE_KERNEL_RO for architectures
Date: Thu, 10 May 2018 11:55:06 -0700	[thread overview]
Message-ID: <20180510185507.2439-2-mcgrof@kernel.org> (raw)
In-Reply-To: <20180510185507.2439-1-mcgrof@kernel.org>

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 work arounds
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.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.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 358354148dec..36f016b753e0 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 f59639afaa39..4e310e543fc8 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1083,6 +1083,20 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
 static inline void init_espfix_bsp(void) { }
 #endif
 
+/*
+ * 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
-- 
2.17.0

  reply	other threads:[~2018-05-10 18:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-10 18:55 [PATCH v3 0/2] mm: PAGE_KERNEL_* fallbacks Luis R. Rodriguez
2018-05-10 18:55 ` Luis R. Rodriguez [this message]
2018-05-10 18:55 ` [PATCH v3 2/2] mm: provide a fallback for PAGE_KERNEL_EXEC for architectures Luis R. Rodriguez
2018-05-16 16:44 ` [PATCH v3 0/2] mm: PAGE_KERNEL_* fallbacks Luis R. Rodriguez
2018-05-23 21:35   ` Luis R. Rodriguez
2018-05-30 19:55     ` Luis R. Rodriguez
2018-05-30 20:06       ` Greg KH
2018-05-30 20:21         ` Luis R. Rodriguez

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