[PATCH] m68knommu: switch to using asm-generic/uaccess.h

Greg Ungerer
2020-09-09T02:18:51Z

Switch to using the asm-generic/uaccess functions for non-MMU builds.
Remove all the m68knommu local specific uaccess defines and macros.

There is nothing so special about the m68knommu targets that they cannot
use all of the asm-generic uaccess support. Using the asm-generic
uaccess definitions also resolves some of the existing problems with
missing __user annotations in the m68knommu specific functions.

The elimination of all of the contents of uaccess_no.h means we can fold
the uaccess_mm.h back into uaccess.h - and just have the single file
now.

The resulting generated code ends up being slightly smaller (by a few
hundred bytes) due to the compilers ability to better optimize load
and stores without forcing its hand with asm statements.

Specifically trivial cases like this contrived example:

get_user(x, ptr);
x++;
put_user(x, ptr);

end up now being optimized to a single instruction on m68k. More
generally the compiler can avoid using a temporary register in many
cases as well.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
---
arch/m68k/Kconfig | 1 +
.../include/asm/{uaccess_mm.h => uaccess.h} | 7 +
arch/m68k/include/asm/uaccess_no.h | 160 ------------------
3 files changed, 8 insertions(+), 160 deletions(-)
rename arch/m68k/include/asm/{uaccess_mm.h => uaccess.h} (98%)
delete mode 100644 arch/m68k/include/asm/uaccess_no.h

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 6f2f38d05772..aefffebc0afa 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -24,6 +24,7 @@ config M68K
select GENERIC_IOMAP
select GENERIC_STRNCPY_FROM_USER if MMU
select GENERIC_STRNLEN_USER if MMU
+ select UACCESS_MEMCPY if !MMU
select ARCH_WANT_IPC_PARSE_VERSION
select HAVE_FUTEX_CMPXCHG if MMU && FUTEX
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/arch/m68k/include/asm/uaccess_mm.h b/arch/m68k/include/asm/uaccess.h
similarity index 98%
rename from arch/m68k/include/asm/uaccess_mm.h
rename to arch/m68k/include/asm/uaccess.h
index 9ae9f8d05925..f98208ccbbcd 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess.h
@@ -2,12 +2,15 @@
#ifndef __M68K_UACCESS_H
#define __M68K_UACCESS_H

+#ifdef CONFIG_MMU
+
/*
* User space memory access functions
*/
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/segment.h>
+#include <asm/extable.h>

/* We let the MMU do all checking */
static inline int access_ok(const void __user *addr,
@@ -387,4 +390,8 @@ unsigned long __clear_user(void __user *to, unsigned long n);

#define clear_user __clear_user

+#else /* !CONFIG_MMU */
+#include <asm-generic/uaccess.h>
+#endif
+
#endif /* _M68K_UACCESS_H */
diff --git a/arch/m68k/include/asm/uaccess_no.h b/arch/m68k/include/asm/uaccess_no.h
deleted file mode 100644
index dcfb69361408..000000000000
--- a/arch/m68k/include/asm/uaccess_no.h
+++ /dev/null
@@ -1,160 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __M68KNOMMU_UACCESS_H
-#define __M68KNOMMU_UACCESS_H
-
-/*
- * User space memory access functions
- */
-#include <linux/string.h>
-
-#include <asm/segment.h>
-
-#define access_ok(addr,size) _access_ok((unsigned long)(addr),(size))
-
-/*
- * It is not enough to just have access_ok check for a real RAM address.
- * This would disallow the case of code/ro-data running XIP in flash/rom.
- * Ideally we would check the possible flash ranges too, but that is
- * currently not so easy.
- */
-static inline int _access_ok(unsigned long addr, unsigned long size)
-{
- return 1;
-}
-
-/*
- * These are the main single-value transfer routines. They automatically
- * use the right size if we just have the right pointer type.
- */
-
-#define put_user(x, ptr) \
-({ \
- int __pu_err = 0; \
- typeof(*(ptr)) __pu_val = (x); \
- switch (sizeof (*(ptr))) { \
- case 1: \
- __put_user_asm(__pu_err, __pu_val, ptr, b); \
- break; \
- case 2: \
- __put_user_asm(__pu_err, __pu_val, ptr, w); \
- break; \
- case 4: \
- __put_user_asm(__pu_err, __pu_val, ptr, l); \
- break; \
- case 8: \
- memcpy((void __force *)ptr, &__pu_val, sizeof(*(ptr))); \
- break; \
- default: \
- __pu_err = __put_user_bad(); \
- break; \
- } \
- __pu_err; \
-})
-#define __put_user(x, ptr) put_user(x, ptr)
-
-extern int __put_user_bad(void);
-
-/*
- * Tell gcc we read from memory instead of writing: this is because
- * we do not write to any memory gcc knows about, so there are no
- * aliasing issues.
- */
-
-#define __ptr(x) ((unsigned long __user *)(x))
-
-#define __put_user_asm(err,x,ptr,bwl) \
- __asm__ ("move" #bwl " %0,%1" \
- : /* no outputs */ \
- :"d" (x),"m" (*__ptr(ptr)) : "memory")
-
-#define get_user(x, ptr) \
-({ \
- int __gu_err = 0; \
- switch (sizeof(*(ptr))) { \
- case 1: \
- __get_user_asm(__gu_err, x, ptr, b, "=d"); \
- break; \
- case 2: \
- __get_user_asm(__gu_err, x, ptr, w, "=r"); \
- break; \
- case 4: \
- __get_user_asm(__gu_err, x, ptr, l, "=r"); \
- break; \
- case 8: { \
- union { \
- u64 l; \
- __typeof__(*(ptr)) t; \
- } __gu_val; \
- memcpy(&__gu_val.l, (const void __force *)ptr, sizeof(__gu_val.l)); \
- (x) = __gu_val.t; \
- break; \
- } \
- default: \
- __gu_err = __get_user_bad(); \
- break; \
- } \
- __gu_err; \
-})
-#define __get_user(x, ptr) get_user(x, ptr)
-
-extern int __get_user_bad(void);
-
-#define __get_user_asm(err,x,ptr,bwl,reg) \
- __asm__ ("move" #bwl " %1,%0" \
- : "=d" (x) \
- : "m" (*__ptr(ptr)))
-
-static inline unsigned long
-raw_copy_from_user(void *to, const void __user *from, unsigned long n)
-{
- memcpy(to, (__force const void *)from, n);
- return 0;
-}
-
-static inline unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long n)
-{
- memcpy((__force void *)to, from, n);
- return 0;
-}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
-/*
- * Copy a null terminated string from userspace.
- */
-
-static inline long
-strncpy_from_user(char *dst, const char *src, long count)
-{
- char *tmp;
- strncpy(dst, src, count);
- for (tmp = dst; *tmp && count > 0; tmp++, count--)
- ;
- return(tmp - dst); /* DAVIDM should we count a NUL ? check getname */
-}
-
-/*
- * Return the size of a string (including the ending 0)
- *
- * Return 0 on exception, a value greater than N if too long
- */
-static inline long strnlen_user(const char *src, long n)
-{
- return(strlen(src) + 1); /* DAVIDM make safer */
-}
-
-/*
- * Zero Userspace
- */
-
-static inline unsigned long
-__clear_user(void *to, unsigned long n)
-{
- memset(to, 0, n);
- return 0;
-}
-
-#define clear_user(to,n) __clear_user(to,n)
-
-#endif /* _M68KNOMMU_UACCESS_H */
--
2.25.1