Date:   Tue,  7 Feb 2017 13:10:16 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kees Cook <keescook@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Arnd Bergmann <arnd@...db.de>
Cc:     Laura Abbott <labbott@...hat.com>, x86@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [RFC][PATCH] treewide: Move set_memory_* functions away from cacheflush.h

The set_memory_* APIs came out of a desire to have a better way to
change memory attributes. Many of these attributes were linked to cache
functionality so the prototypes were put in cacheflush.h. These days,
the APIs have grown and have a much wider use than just cache APIs. To
support this growth, split off set_memory_* and friends into a separate
header file to avoid growing cacheflush.h for APIs that have nothing to
do with caches.

Signed-off-by: Laura Abbott <labbott@...hat.com>
---
This came out of a comment Russell made while reviewing RODATA test cases
http://lists.infradead.org/pipermail/linux-arm-kernel/2017-January/480855.html
While the final result of that series was the rodata code was refactored into
its own header file, the set_memory_* APIs are still out of place.

This is a simple attempt at moving all the API stubs to their own file.
Another idea I had was throwing set_memory_{x,nx,ro,rw} in an asm-generic
file since those are commonly used for module setting across all arches.

This is an RFC to see if this is actually beneficial. The diffstat is not
negative unfortunately due to header guards in newer files.
I have patches to convert call sites over to set_memory.h instead of
cacheflush.h if there is sufficient interest.
---
 arch/arm/include/asm/cacheflush.h   |  21 +-------
 arch/arm/include/asm/set_memory.h   |  32 ++++++++++++
 arch/arm64/include/asm/cacheflush.h |   6 +--
 arch/arm64/include/asm/set_memory.h |  26 ++++++++++
 arch/s390/include/asm/cacheflush.h  |   6 +--
 arch/s390/include/asm/set_memory.h  |   9 ++++
 arch/x86/include/asm/cacheflush.h   |  96 +---------------------------------
 arch/x86/include/asm/set_memory.h   | 100 ++++++++++++++++++++++++++++++++++++
 8 files changed, 171 insertions(+), 125 deletions(-)
 create mode 100644 arch/arm/include/asm/set_memory.h
 create mode 100644 arch/arm64/include/asm/set_memory.h
 create mode 100644 arch/s390/include/asm/set_memory.h
 create mode 100644 arch/x86/include/asm/set_memory.h

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 02454fa..1cb9d11 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -16,6 +16,7 @@
 #include <asm/shmparam.h>
 #include <asm/cachetype.h>
 #include <asm/outercache.h>
+#include <asm/set_memory.h>
 
 #define CACHE_COLOUR(vaddr)	((vaddr & (SHMLBA - 1)) >> PAGE_SHIFT)
 
@@ -478,26 +479,6 @@ static inline void __sync_cache_range_r(volatile void *p, size_t size)
 	: : : "r0","r1","r2","r3","r4","r5","r6","r7", \
 	      "r9","r10","lr","memory" )
 
-#ifdef CONFIG_MMU
-int set_memory_ro(unsigned long addr, int numpages);
-int set_memory_rw(unsigned long addr, int numpages);
-int set_memory_x(unsigned long addr, int numpages);
-int set_memory_nx(unsigned long addr, int numpages);
-#else
-static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
-static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
-static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
-static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
-#endif
-
-#ifdef CONFIG_STRICT_KERNEL_RWX
-void set_kernel_text_rw(void);
-void set_kernel_text_ro(void);
-#else
-static inline void set_kernel_text_rw(void) { }
-static inline void set_kernel_text_ro(void) { }
-#endif
-
 void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
 			     void *kaddr, unsigned long len);
 
diff --git a/arch/arm/include/asm/set_memory.h b/arch/arm/include/asm/set_memory.h
new file mode 100644
index 0000000..5aa4315
--- /dev/null
+++ b/arch/arm/include/asm/set_memory.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 1999-2002 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASMARM_SET_MEMORY_H
+#define _ASMARM_SET_MEMORY_H
+
+#ifdef CONFIG_MMU
+int set_memory_ro(unsigned long addr, int numpages);
+int set_memory_rw(unsigned long addr, int numpages);
+int set_memory_x(unsigned long addr, int numpages);
+int set_memory_nx(unsigned long addr, int numpages);
+#else
+static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
+static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
+static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
+static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
+#endif
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void set_kernel_text_rw(void);
+void set_kernel_text_ro(void);
+#else
+static inline void set_kernel_text_rw(void) { }
+static inline void set_kernel_text_ro(void) { }
+#endif
+
+#endif
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 5a2a6ee..7db6962 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -20,6 +20,7 @@
 #define __ASM_CACHEFLUSH_H
 
 #include <linux/mm.h>
+#include <asm/set_memory.h>
 
 /*
  * This flag is used to indicate that the page pointed to by a pte is clean
@@ -150,9 +151,4 @@ static inline void flush_cache_vunmap(unsigned long start, unsigned long end)
 {
 }
 
-int set_memory_ro(unsigned long addr, int numpages);
-int set_memory_rw(unsigned long addr, int numpages);
-int set_memory_x(unsigned long addr, int numpages);
-int set_memory_nx(unsigned long addr, int numpages);
-
 #endif
diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h
new file mode 100644
index 0000000..5b38ab80
--- /dev/null
+++ b/arch/arm64/include/asm/set_memory.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 1999-2002 Russell King.
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ARM64_ASM_SET_MEMORY_H
+#define __ARM64_ASM_SET_MEMORY_H
+
+int set_memory_ro(unsigned long addr, int numpages);
+int set_memory_rw(unsigned long addr, int numpages);
+int set_memory_x(unsigned long addr, int numpages);
+int set_memory_nx(unsigned long addr, int numpages);
+
+#endif
diff --git a/arch/s390/include/asm/cacheflush.h b/arch/s390/include/asm/cacheflush.h
index 58fae7d..afe2965 100644
--- a/arch/s390/include/asm/cacheflush.h
+++ b/arch/s390/include/asm/cacheflush.h
@@ -3,10 +3,6 @@
 
 /* Caches aren't brain-dead on the s390. */
 #include <asm-generic/cacheflush.h>
-
-int set_memory_ro(unsigned long addr, int numpages);
-int set_memory_rw(unsigned long addr, int numpages);
-int set_memory_nx(unsigned long addr, int numpages);
-int set_memory_x(unsigned long addr, int numpages);
+#include <asm/set_memory.h>
 
 #endif /* _S390_CACHEFLUSH_H */
diff --git a/arch/s390/include/asm/set_memory.h b/arch/s390/include/asm/set_memory.h
new file mode 100644
index 0000000..1bb61c5
--- /dev/null
+++ b/arch/s390/include/asm/set_memory.h
@@ -0,0 +1,9 @@
+#ifndef _S390_SET_MEMORY_H
+#define _S390_SET_MEMORY_H
+
+int set_memory_ro(unsigned long addr, int numpages);
+int set_memory_rw(unsigned long addr, int numpages);
+int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_x(unsigned long addr, int numpages);
+
+#endif /* _S390_SET_MEMORY_H */
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 872877d..3d7db6f 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -4,104 +4,10 @@
 /* Caches aren't brain-dead on the intel. */
 #include <asm-generic/cacheflush.h>
 #include <asm/special_insns.h>
-
-/*
- * The set_memory_* API can be used to change various attributes of a virtual
- * address range. The attributes include:
- * Cachability   : UnCached, WriteCombining, WriteThrough, WriteBack
- * Executability : eXeutable, NoteXecutable
- * Read/Write    : ReadOnly, ReadWrite
- * Presence      : NotPresent
- *
- * Within a category, the attributes are mutually exclusive.
- *
- * The implementation of this API will take care of various aspects that
- * are associated with changing such attributes, such as:
- * - Flushing TLBs
- * - Flushing CPU caches
- * - Making sure aliases of the memory behind the mapping don't violate
- *   coherency rules as defined by the CPU in the system.
- *
- * What this API does not do:
- * - Provide exclusion between various callers - including callers that
- *   operation on other mappings of the same physical page
- * - Restore default attributes when a page is freed
- * - Guarantee that mappings other than the requested one are
- *   in any state, other than that these do not violate rules for
- *   the CPU you have. Do not depend on any effects on other mappings,
- *   CPUs other than the one you have may have more relaxed rules.
- * The caller is required to take care of these.
- */
-
-int _set_memory_uc(unsigned long addr, int numpages);
-int _set_memory_wc(unsigned long addr, int numpages);
-int _set_memory_wt(unsigned long addr, int numpages);
-int _set_memory_wb(unsigned long addr, int numpages);
-int set_memory_uc(unsigned long addr, int numpages);
-int set_memory_wc(unsigned long addr, int numpages);
-int set_memory_wt(unsigned long addr, int numpages);
-int set_memory_wb(unsigned long addr, int numpages);
-int set_memory_x(unsigned long addr, int numpages);
-int set_memory_nx(unsigned long addr, int numpages);
-int set_memory_ro(unsigned long addr, int numpages);
-int set_memory_rw(unsigned long addr, int numpages);
-int set_memory_np(unsigned long addr, int numpages);
-int set_memory_4k(unsigned long addr, int numpages);
-
-int set_memory_array_uc(unsigned long *addr, int addrinarray);
-int set_memory_array_wc(unsigned long *addr, int addrinarray);
-int set_memory_array_wt(unsigned long *addr, int addrinarray);
-int set_memory_array_wb(unsigned long *addr, int addrinarray);
-
-int set_pages_array_uc(struct page **pages, int addrinarray);
-int set_pages_array_wc(struct page **pages, int addrinarray);
-int set_pages_array_wt(struct page **pages, int addrinarray);
-int set_pages_array_wb(struct page **pages, int addrinarray);
-
-/*
- * For legacy compatibility with the old APIs, a few functions
- * are provided that work on a "struct page".
- * These functions operate ONLY on the 1:1 kernel mapping of the
- * memory that the struct page represents, and internally just
- * call the set_memory_* function. See the description of the
- * set_memory_* function for more details on conventions.
- *
- * These APIs should be considered *deprecated* and are likely going to
- * be removed in the future.
- * The reason for this is the implicit operation on the 1:1 mapping only,
- * making this not a generally useful API.
- *
- * Specifically, many users of the old APIs had a virtual address,
- * called virt_to_page() or vmalloc_to_page() on that address to
- * get a struct page* that the old API required.
- * To convert these cases, use set_memory_*() on the original
- * virtual address, do not use these functions.
- */
-
-int set_pages_uc(struct page *page, int numpages);
-int set_pages_wb(struct page *page, int numpages);
-int set_pages_x(struct page *page, int numpages);
-int set_pages_nx(struct page *page, int numpages);
-int set_pages_ro(struct page *page, int numpages);
-int set_pages_rw(struct page *page, int numpages);
-
+#include <asm/set_memory.h>
 
 void clflush_cache_range(void *addr, unsigned int size);
 
 #define mmio_flush_range(addr, size) clflush_cache_range(addr, size)
 
-extern const int rodata_test_data;
-extern int kernel_set_to_readonly;
-void set_kernel_text_rw(void);
-void set_kernel_text_ro(void);
-
-#ifdef CONFIG_DEBUG_RODATA_TEST
-int rodata_test(void);
-#else
-static inline int rodata_test(void)
-{
-	return 0;
-}
-#endif
-
 #endif /* _ASM_X86_CACHEFLUSH_H */
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
new file mode 100644
index 0000000..d9f3f87
--- /dev/null
+++ b/arch/x86/include/asm/set_memory.h
@@ -0,0 +1,100 @@
+#ifndef _ASM_X86_SET_MEMORY_H
+#define _ASM_X86_SET_MEMORY_H
+
+#include <asm/page.h>
+
+/*
+ * The set_memory_* API can be used to change various attributes of a virtual
+ * address range. The attributes include:
+ * Cachability   : UnCached, WriteCombining, WriteThrough, WriteBack
+ * Executability : eXeutable, NoteXecutable
+ * Read/Write    : ReadOnly, ReadWrite
+ * Presence      : NotPresent
+ *
+ * Within a category, the attributes are mutually exclusive.
+ *
+ * The implementation of this API will take care of various aspects that
+ * are associated with changing such attributes, such as:
+ * - Flushing TLBs
+ * - Flushing CPU caches
+ * - Making sure aliases of the memory behind the mapping don't violate
+ *   coherency rules as defined by the CPU in the system.
+ *
+ * What this API does not do:
+ * - Provide exclusion between various callers - including callers that
+ *   operation on other mappings of the same physical page
+ * - Restore default attributes when a page is freed
+ * - Guarantee that mappings other than the requested one are
+ *   in any state, other than that these do not violate rules for
+ *   the CPU you have. Do not depend on any effects on other mappings,
+ *   CPUs other than the one you have may have more relaxed rules.
+ * The caller is required to take care of these.
+ */
+
+int _set_memory_uc(unsigned long addr, int numpages);
+int _set_memory_wc(unsigned long addr, int numpages);
+int _set_memory_wt(unsigned long addr, int numpages);
+int _set_memory_wb(unsigned long addr, int numpages);
+int set_memory_uc(unsigned long addr, int numpages);
+int set_memory_wc(unsigned long addr, int numpages);
+int set_memory_wt(unsigned long addr, int numpages);
+int set_memory_wb(unsigned long addr, int numpages);
+int set_memory_x(unsigned long addr, int numpages);
+int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_ro(unsigned long addr, int numpages);
+int set_memory_rw(unsigned long addr, int numpages);
+int set_memory_np(unsigned long addr, int numpages);
+int set_memory_4k(unsigned long addr, int numpages);
+
+int set_memory_array_uc(unsigned long *addr, int addrinarray);
+int set_memory_array_wc(unsigned long *addr, int addrinarray);
+int set_memory_array_wt(unsigned long *addr, int addrinarray);
+int set_memory_array_wb(unsigned long *addr, int addrinarray);
+
+int set_pages_array_uc(struct page **pages, int addrinarray);
+int set_pages_array_wc(struct page **pages, int addrinarray);
+int set_pages_array_wt(struct page **pages, int addrinarray);
+int set_pages_array_wb(struct page **pages, int addrinarray);
+
+/*
+ * For legacy compatibility with the old APIs, a few functions
+ * are provided that work on a "struct page".
+ * These functions operate ONLY on the 1:1 kernel mapping of the
+ * memory that the struct page represents, and internally just
+ * call the set_memory_* function. See the description of the
+ * set_memory_* function for more details on conventions.
+ *
+ * These APIs should be considered *deprecated* and are likely going to
+ * be removed in the future.
+ * The reason for this is the implicit operation on the 1:1 mapping only,
+ * making this not a generally useful API.
+ *
+ * Specifically, many users of the old APIs had a virtual address,
+ * called virt_to_page() or vmalloc_to_page() on that address to
+ * get a struct page* that the old API required.
+ * To convert these cases, use set_memory_*() on the original
+ * virtual address, do not use these functions.
+ */
+
+int set_pages_uc(struct page *page, int numpages);
+int set_pages_wb(struct page *page, int numpages);
+int set_pages_x(struct page *page, int numpages);
+int set_pages_nx(struct page *page, int numpages);
+int set_pages_ro(struct page *page, int numpages);
+int set_pages_rw(struct page *page, int numpages);
+
+extern const int rodata_test_data;
+extern int kernel_set_to_readonly;
+void set_kernel_text_rw(void);
+void set_kernel_text_ro(void);
+
+#ifdef CONFIG_DEBUG_RODATA_TEST
+int rodata_test(void);
+#else
+static inline int rodata_test(void)
+{
+	return 0;
+}
+#endif
+
+#endif /* _ASM_X86_SET_MEMORY_H */
-- 
2.7.4

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