asm-generic: kill <asm/segment.h> and improve nommu generic uaccess helpers

Christoph Hellwig writes:
 
   This is a series doing two somewhat interwinded things.  It improves
   the asm-generic nommu uaccess helper to optionally be entirely generic
   and not require any arch helpers for the actual uaccess.  For the
   generic uaccess.h to actually be generically useful I also had to kill
   off the mess we made of <asm/segment.h>, which really shouldn't exist
   on most architectures.
 
 Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Merge tag 'asm-generic-nommu' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull nommu generic uaccess updates from Arnd Bergmann:
 "asm-generic: kill <asm/segment.h> and improve nommu generic uaccess helpers

  Christoph Hellwig writes:

     This is a series doing two somewhat interwinded things. It improves
     the asm-generic nommu uaccess helper to optionally be entirely
     generic and not require any arch helpers for the actual uaccess.
     For the generic uaccess.h to actually be generically useful I also
     had to kill off the mess we made of <asm/segment.h>, which really
     shouldn't exist on most architectures"

* tag 'asm-generic-nommu' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  asm-generic: optimize generic uaccess for 8-byte loads and stores
  asm-generic: provide entirely generic nommu uaccess
  arch: mostly remove <asm/segment.h>
  asm-generic: don't include <asm/segment.h> from <asm/uaccess.h>

arch/alpha/include/asm/segment.h

@@ -1,6 +0,0 @@
-#ifndef __ALPHA_SEGMENT_H
-#define __ALPHA_SEGMENT_H
-
-/* Only here because we have some old header files that expect it.. */
-
-#endif

arch/alpha/kernel/smc37c669.c

@@ -10,7 +10,6 @@
 
 #include <asm/hwrpb.h>
 #include <asm/io.h>
-#include <asm/segment.h>
 
 #if 0
 # define DBG_DEVS(args)         printk args

arch/alpha/kernel/smc37c93x.c

@@ -11,7 +11,6 @@
 
 #include <asm/hwrpb.h>
 #include <asm/io.h>
-#include <asm/segment.h>
 
 #define SMC_DEBUG 0
 

arch/arc/include/asm/uaccess.h

@@ -742,6 +742,7 @@ extern long arc_strnlen_user_noinline(const char __user *src, long n);
 
 #endif
 
+#include <asm/segment.h>
 #include <asm-generic/uaccess.h>
 
 #endif

arch/arm/include/asm/Kbuild

@@ -14,7 +14,6 @@ generic-y += msi.h
 generic-y += parport.h
 generic-y += preempt.h
 generic-y += seccomp.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += simd.h
 generic-y += trace_clock.h

arch/arm64/include/asm/Kbuild

@@ -17,7 +17,6 @@ generic-y += mmiowb.h
 generic-y += msi.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += set_memory.h
 generic-y += switch_to.h

arch/c6x/include/asm/Kbuild

@@ -30,7 +30,6 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += pgalloc.h
 generic-y += preempt.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += shmparam.h
 generic-y += tlbflush.h

arch/h8300/Kconfig

@@ -23,6 +23,7 @@ config H8300
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_HASH
 	select CPU_NO_EFFICIENT_FFS
+	select UACCESS_MEMCPY
 
 config CPU_BIG_ENDIAN
 	def_bool y

arch/h8300/include/asm/Kbuild

@@ -47,6 +47,7 @@ generic-y += timex.h
 generic-y += tlbflush.h
 generic-y += topology.h
 generic-y += trace_clock.h
+generic-y += uaccess.h
 generic-y += unaligned.h
 generic-y += vga.h
 generic-y += word-at-a-time.h

arch/h8300/include/asm/uaccess.h

@@ -1,55 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_UACCESS_H
-#define _ASM_UACCESS_H
-
-#include <linux/string.h>
-
-static inline __must_check unsigned long
-raw_copy_from_user(void *to, const void __user * from, unsigned long n)
-{
-	if (__builtin_constant_p(n)) {
-		switch(n) {
-		case 1:
-			*(u8 *)to = *(u8 __force *)from;
-			return 0;
-		case 2:
-			*(u16 *)to = *(u16 __force *)from;
-			return 0;
-		case 4:
-			*(u32 *)to = *(u32 __force *)from;
-			return 0;
-		}
-	}
-
-	memcpy(to, (const void __force *)from, n);
-	return 0;
-}
-
-static inline __must_check unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long n)
-{
-	if (__builtin_constant_p(n)) {
-		switch(n) {
-		case 1:
-			*(u8 __force *)to = *(u8 *)from;
-			return 0;
-		case 2:
-			*(u16 __force *)to = *(u16 *)from;
-			return 0;
-		case 4:
-			*(u32 __force *)to = *(u32 *)from;
-			return 0;
-		default:
-			break;
-		}
-	}
-
-	memcpy((void __force *)to, from, n);
-	return 0;
-}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
-#include <asm-generic/uaccess.h>
-
-#endif

arch/hexagon/include/asm/Kbuild

@@ -29,7 +29,6 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += shmparam.h
 generic-y += topology.h

arch/hexagon/include/asm/uaccess.h

@@ -24,7 +24,6 @@
  * User space memory access functions
  */
 #include <linux/mm.h>
-#include <asm/segment.h>
 #include <asm/sections.h>
 
 /*

arch/ia64/include/asm/segment.h

@@ -1,6 +0,0 @@
-#ifndef _ASM_IA64_SEGMENT_H
-#define _ASM_IA64_SEGMENT_H
-
-/* Only here because we have some old header files that expect it.. */
-
-#endif /* _ASM_IA64_SEGMENT_H */

arch/mips/include/asm/Kbuild

@@ -19,7 +19,6 @@ generic-y += preempt.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += trace_clock.h
 generic-y += unaligned.h
 generic-y += user.h

arch/nds32/include/asm/Kbuild

@@ -37,7 +37,6 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += switch_to.h
 generic-y += timex.h

arch/nios2/include/asm/Kbuild

@@ -33,7 +33,6 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += spinlock.h
 generic-y += topology.h

arch/openrisc/include/asm/Kbuild

@@ -34,7 +34,6 @@ generic-y += qspinlock.h
 generic-y += qrwlock_types.h
 generic-y += qrwlock.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += shmparam.h
 generic-y += switch_to.h
 generic-y += topology.h

arch/openrisc/kernel/ptrace.c

@@ -30,7 +30,6 @@
 #include <linux/elf.h>
 
 #include <asm/thread_info.h>
-#include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 

arch/openrisc/kernel/setup.c

@@ -39,7 +39,6 @@
 #include <linux/device.h>
 
 #include <asm/sections.h>
-#include <asm/segment.h>
 #include <asm/pgtable.h>
 #include <asm/types.h>
 #include <asm/setup.h>

arch/openrisc/kernel/traps.c

@@ -35,7 +35,6 @@
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>
 
-#include <asm/segment.h>
 #include <asm/io.h>
 #include <asm/pgtable.h>
 #include <asm/unwinder.h>

arch/openrisc/mm/init.c

@@ -32,7 +32,6 @@
 #include <linux/blkdev.h>	/* for initrd_* */
 #include <linux/pagemap.h>
 
-#include <asm/segment.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/dma.h>

arch/openrisc/mm/tlb.c

@@ -26,7 +26,6 @@
 #include <linux/mm.h>
 #include <linux/init.h>
 
-#include <asm/segment.h>
 #include <asm/tlbflush.h>
 #include <asm/pgtable.h>
 #include <asm/mmu_context.h>

arch/parisc/include/asm/Kbuild

@@ -19,7 +19,6 @@ generic-y += mmiowb.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += seccomp.h
-generic-y += segment.h
 generic-y += trace_clock.h
 generic-y += user.h
 generic-y += vga.h

arch/s390/include/asm/segment.h

@@ -1,5 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_SEGMENT_H
-#define _ASM_SEGMENT_H
-
-#endif

arch/s390/kernel/ptrace.c

@@ -24,7 +24,6 @@
 #include <linux/seccomp.h>
 #include <linux/compat.h>
 #include <trace/syscall.h>
-#include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>

arch/unicore32/include/asm/Kbuild

@@ -28,7 +28,6 @@ generic-y += parport.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += sections.h
-generic-y += segment.h
 generic-y += serial.h
 generic-y += shmparam.h
 generic-y += syscalls.h

arch/xtensa/include/asm/segment.h

@@ -1,16 +0,0 @@
-/*
- * include/asm-xtensa/segment.h
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 2001 - 2005 Tensilica Inc.
- */
-
-#ifndef _XTENSA_SEGMENT_H
-#define _XTENSA_SEGMENT_H
-
-#include <linux/uaccess.h>
-
-#endif	/* _XTENSA_SEGEMENT_H */

include/asm-generic/segment.h

@@ -1,9 +0,0 @@
-#ifndef __ASM_GENERIC_SEGMENT_H
-#define __ASM_GENERIC_SEGMENT_H
-/*
- * Only here because we have some old header files that expect it...
- *
- * New architectures probably don't want to have their own version.
- */
-
-#endif /* __ASM_GENERIC_SEGMENT_H */

include/asm-generic/uaccess.h

@@ -9,7 +9,63 @@
  */
 #include <linux/string.h>
 
-#include <asm/segment.h>
+#ifdef CONFIG_UACCESS_MEMCPY
+static inline __must_check unsigned long
+raw_copy_from_user(void *to, const void __user * from, unsigned long n)
+{
+	if (__builtin_constant_p(n)) {
+		switch(n) {
+		case 1:
+			*(u8 *)to = *(u8 __force *)from;
+			return 0;
+		case 2:
+			*(u16 *)to = *(u16 __force *)from;
+			return 0;
+		case 4:
+			*(u32 *)to = *(u32 __force *)from;
+			return 0;
+#ifdef CONFIG_64BIT
+		case 8:
+			*(u64 *)to = *(u64 __force *)from;
+			return 0;
+#endif
+		}
+	}
+
+	memcpy(to, (const void __force *)from, n);
+	return 0;
+}
+
+static inline __must_check unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	if (__builtin_constant_p(n)) {
+		switch(n) {
+		case 1:
+			*(u8 __force *)to = *(u8 *)from;
+			return 0;
+		case 2:
+			*(u16 __force *)to = *(u16 *)from;
+			return 0;
+		case 4:
+			*(u32 __force *)to = *(u32 *)from;
+			return 0;
+#ifdef CONFIG_64BIT
+		case 8:
+			*(u64 __force *)to = *(u64 *)from;
+			return 0;
+#endif
+		default:
+			break;
+		}
+	}
+
+	memcpy((void __force *)to, from, n);
+	return 0;
+}
+#define INLINE_COPY_FROM_USER
+#define INLINE_COPY_TO_USER
+#endif /* CONFIG_UACCESS_MEMCPY */
 
 #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
 

lib/Kconfig

@@ -601,6 +601,10 @@ config ARCH_NO_SG_CHAIN
 config ARCH_HAS_PMEM_API
 	bool
 
+# use memcpy to implement user copies for nommu architectures
+config UACCESS_MEMCPY
+	bool
+
 config ARCH_HAS_UACCESS_FLUSHCACHE
 	bool