[RFC PATCH v1 2/9] uaccess: Convert INLINE_COPY_{TO/FROM}_USER to kconfig and reduce ifdefery

Christophe Leroy (CS GROUP)
2026-04-27T17:17:33Z

Among the 21 architectures supported by the kernel, 16 define both
INLINE_COPY_TO_USER and INLINE_COPY_FROM_USER while the 5 other ones
don't define any of the two.

To simplify and reduce risk of mistakes, convert them to a single
kconfig item named CONFIG_ARCH_WANTS_NOINLINE_COPY which will be
selected by the 5 architectures that don't want inlined copy.

To minimise complication in a later patch, also remove
ifdefery and replace it with IS_ENABLED().

Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
---
arch/alpha/Kconfig | 1 +
arch/arc/include/asm/uaccess.h | 3 ---
arch/arm/include/asm/uaccess.h | 2 --
arch/arm64/include/asm/uaccess.h | 3 ---
arch/csky/Kconfig | 1 +
arch/hexagon/include/asm/uaccess.h | 3 ---
arch/loongarch/include/asm/uaccess.h | 3 ---
arch/m68k/include/asm/uaccess.h | 3 ---
arch/microblaze/include/asm/uaccess.h | 2 --
arch/mips/include/asm/uaccess.h | 3 ---
arch/nios2/include/asm/uaccess.h | 2 --
arch/openrisc/include/asm/uaccess.h | 2 --
arch/parisc/include/asm/uaccess.h | 3 ---
arch/powerpc/Kconfig | 1 +
arch/riscv/Kconfig | 1 +
arch/s390/include/asm/uaccess.h | 3 ---
arch/sh/include/asm/uaccess.h | 2 --
arch/sparc/include/asm/uaccess_32.h | 3 ---
arch/sparc/include/asm/uaccess_64.h | 2 --
arch/um/include/asm/uaccess.h | 3 ---
arch/x86/Kconfig | 1 +
arch/xtensa/include/asm/uaccess.h | 2 --
include/asm-generic/uaccess.h | 2 --
include/linux/uaccess.h | 32 ++++++++++++---------------
lib/Kconfig | 3 +++
lib/Makefile | 3 ++-
lib/usercopy.c | 4 ----
rust/helpers/uaccess.c | 2 +-
28 files changed, 25 insertions(+), 70 deletions(-)

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 7b7dafe7d9df..65e533cead6b 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -11,6 +11,7 @@ config ALPHA
select ARCH_NO_PREEMPT
select ARCH_NO_SG_CHAIN
select ARCH_USE_CMPXCHG_LOCKREF
+ select ARCH_WANTS_NOINLINE_COPY_USER
select FORCE_PCI
select PCI_DOMAINS if PCI
select PCI_SYSCALL if PCI
diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
index 1e8809ea000a..e8b161b37a03 100644
--- a/arch/arc/include/asm/uaccess.h
+++ b/arch/arc/include/asm/uaccess.h
@@ -628,9 +628,6 @@ static inline unsigned long __clear_user(void __user *to, unsigned long n)
return res;
}

-#define INLINE_COPY_TO_USER
-#define INLINE_COPY_FROM_USER
-
#define __clear_user __clear_user

#include <asm-generic/uaccess.h>
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index d6ae80b5df36..7280c162bb71 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -616,8 +616,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
}
#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
#endif
-#define INLINE_COPY_TO_USER
-#define INLINE_COPY_FROM_USER

static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index b0c83a08dda9..1e20ec91b56f 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -456,9 +456,6 @@ do { \
unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
} while (0)

-#define INLINE_COPY_TO_USER
-#define INLINE_COPY_FROM_USER
-
extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
{
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 4331313a42ff..d010d7eb47bf 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -40,6 +40,7 @@ config CSKY
select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_WANT_FRAME_POINTERS if !CPU_CK610 && $(cc-option,-mbacktrace)
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+ select ARCH_WANTS_NOINLINE_COPY_USER
select COMMON_CLK
select CLKSRC_MMIO
select CSKY_MPINTC if CPU_CK860
diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
index bff77efc0d9a..4bf863217636 100644
--- a/arch/hexagon/include/asm/uaccess.h
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -26,9 +26,6 @@ unsigned long raw_copy_from_user(void *to, const void __user *from,
unsigned long n);
unsigned long raw_copy_to_user(void __user *to, const void *from,
unsigned long n);
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
#define __clear_user(a, s) __clear_user_hexagon((a), (s))

diff --git a/arch/loongarch/include/asm/uaccess.h b/arch/loongarch/include/asm/uaccess.h
index 438269313e78..72a04ac88549 100644
--- a/arch/loongarch/include/asm/uaccess.h
+++ b/arch/loongarch/include/asm/uaccess.h
@@ -292,9 +292,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
return __copy_user((__force void *)to, from, n);
}

-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
/*
* __clear_user: - Zero a block of memory in user space, with less checking.
* @addr: Destination address, in user space.
diff --git a/arch/m68k/include/asm/uaccess.h b/arch/m68k/include/asm/uaccess.h
index 64914872a5c9..20e249a6ad07 100644
--- a/arch/m68k/include/asm/uaccess.h
+++ b/arch/m68k/include/asm/uaccess.h
@@ -377,9 +377,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
return __constant_copy_to_user(to, from, n);
return __generic_copy_to_user(to, from, n);
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
type *__gk_dst = (type *)(dst); \
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index 3aab2f17e046..3355f541e12a 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -250,8 +250,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
return __copy_tofrom_user(to, (__force const void __user *)from, n);
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

/*
* Copy a null terminated string from userspace.
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index c0cede273c7c..8714caefbac8 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -433,9 +433,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
return __cu_len_r;
}

-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
extern __kernel_size_t __bzero(void __user *addr, __kernel_size_t size);

/*
diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index 6ccc9a232c23..46d7312a1c96 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -57,8 +57,6 @@ extern unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n);
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

extern long strncpy_from_user(char *__to, const char __user *__from,
long __len);
diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
index d6500a374e18..c84effde867a 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -218,8 +218,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long size)
{
return __copy_tofrom_user((__force void *)to, from, size);
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

extern unsigned long __clear_user(void __user *addr, unsigned long size);

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 6c531d2c847e..1dd6a1dd653f 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -197,7 +197,4 @@ unsigned long __must_check raw_copy_to_user(void __user *dst, const void *src,
unsigned long len);
unsigned long __must_check raw_copy_from_user(void *dst, const void __user *src,
unsigned long len);
-#define INLINE_COPY_TO_USER
-#define INLINE_COPY_FROM_USER
-
#endif /* __PARISC_UACCESS_H */
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e93df95b79e7..6816f402fe3d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -187,6 +187,7 @@ config PPC
select ARCH_WANT_LD_ORPHAN_WARN
select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if PPC_RADIX_MMU
select ARCH_WANTS_MODULES_DATA_IN_VMALLOC if PPC_BOOK3S_32 || PPC_8xx
+ select ARCH_WANTS_NOINLINE_COPY_USER
select ARCH_WEAK_RELEASE_ACQUIRE
select AUDIT_ARCH_COMPAT_GENERIC
select BINFMT_ELF
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d235396c4514..492b920c1a51 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -88,6 +88,7 @@ config RISCV
select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
select ARCH_WANTS_NO_INSTR
+ select ARCH_WANTS_NOINLINE_COPY_USER if MMU
select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
select ARCH_WEAK_RELEASE_ACQUIRE if ARCH_USE_QUEUED_SPINLOCKS
select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index dff035372601..2e0472c20da0 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -30,9 +30,6 @@ void debug_user_asce(int exit);
#define uaccess_kmsan_or_inline __always_inline
#endif

-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
static uaccess_kmsan_or_inline __must_check unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long size)
{
diff --git a/arch/sh/include/asm/uaccess.h b/arch/sh/include/asm/uaccess.h
index a79609eb14be..0cd75308e6d3 100644
--- a/arch/sh/include/asm/uaccess.h
+++ b/arch/sh/include/asm/uaccess.h
@@ -95,8 +95,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
return __copy_user((__force void *)to, from, n);
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

/*
* Clear the area and return remaining number of bytes
diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
index 43284b6ec46a..e01f43c6421c 100644
--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -190,9 +190,6 @@ static inline unsigned long raw_copy_from_user(void *to, const void __user *from
return __copy_user((__force void __user *) to, from, n);
}

-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
static inline unsigned long __clear_user(void __user *addr, unsigned long size)
{
unsigned long ret;
diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
index b825a5dd0210..62ee0b074fec 100644
--- a/arch/sparc/include/asm/uaccess_64.h
+++ b/arch/sparc/include/asm/uaccess_64.h
@@ -231,8 +231,6 @@ unsigned long __must_check raw_copy_from_user(void *to,
unsigned long __must_check raw_copy_to_user(void __user *to,
const void *from,
unsigned long size);
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

unsigned long __must_check raw_copy_in_user(void __user *to,
const void __user *from,
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index 0df9ea4abda8..1e14260c7f0f 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -27,9 +27,6 @@ static inline int __access_ok(const void __user *ptr, unsigned long size);
#define __access_ok __access_ok
#define __clear_user __clear_user

-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
#include <asm-generic/uaccess.h>

static inline int __access_ok(const void __user *ptr, unsigned long size)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f3f7cb01d69d..c1e58d8c6864 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -143,6 +143,7 @@ config X86
select ARCH_WANTS_CLOCKSOURCE_READ_INLINE if X86_64
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
select ARCH_WANTS_NO_INSTR
+ select ARCH_WANTS_NOINLINE_COPY_USER
select ARCH_WANT_GENERAL_HUGETLB
select ARCH_WANT_HUGE_PMD_SHARE if X86_64
select ARCH_WANT_LD_ORPHAN_WARN
diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 56aec6d504fe..f9e1623a7be9 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -237,8 +237,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
prefetch(from);
return __xtensa_copy_user((__force void *)to, from, n);
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER

/*
* We need to return the number of bytes not cleared. Our memset()
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index b276f783494c..fb33a71fd24e 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -91,8 +91,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
memcpy((void __force *)to, from, n);
return 0;
}
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
#endif /* CONFIG_UACCESS_MEMCPY */

/*
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 56328601218c..bd1201c81d94 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -83,8 +83,8 @@
* with that. They should not be used directly; they are used to implement
* the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
* that are used instead. Out of those, __... ones are inlined. Plain
- * copy_{to,from}_user() might or might not be inlined. If you want them
- * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
+ * copy_{to,from}_user() might or might not be inlined. If you don't want them
+ * inlined, select CONFIG_ARCH_WANTS_NOINLINE_COPY_USER.
*
* NOTE: only copy_from_user() zero-pads the destination in case of short copy.
* Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
@@ -157,8 +157,8 @@ __copy_to_user(void __user *to, const void *from, unsigned long n)
}

/*
- * Architectures that #define INLINE_COPY_TO_USER use this function
- * directly in the normal copy_to/from_user(), the other ones go
+ * Architectures that don't select CONFIG_ARCH_WANTS_NOINLINE_COPY_USER use
+ * this function directly in the normal copy_to/from_user(), the other ones go
* through an extern _copy_to/from_user(), which expands the same code
* here.
*/
@@ -190,10 +190,9 @@ _inline_copy_from_user(void *to, const void __user *from, unsigned long n)
memset(to + (n - res), 0, res);
return res;
}
-#ifndef INLINE_COPY_FROM_USER
+
extern __must_check unsigned long
_copy_from_user(void *, const void __user *, unsigned long);
-#endif

static inline __must_check unsigned long
_inline_copy_to_user(void __user *to, const void *from, unsigned long n)
@@ -207,21 +206,19 @@ _inline_copy_to_user(void __user *to, const void *from, unsigned long n)
}
return n;
}
-#ifndef INLINE_COPY_TO_USER
+
extern __must_check unsigned long
_copy_to_user(void __user *, const void *, unsigned long);
-#endif

static __always_inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (!check_copy_size(to, n, false))
return n;
-#ifdef INLINE_COPY_FROM_USER
- return _inline_copy_from_user(to, from, n);
-#else
- return _copy_from_user(to, from, n);
-#endif
+ if (IS_ENABLED(ARCH_WANTS_NOINLINE_COPY_USER))
+ return _copy_from_user(to, from, n);
+ else
+ return _inline_copy_from_user(to, from, n);
}

static __always_inline unsigned long __must_check
@@ -230,11 +227,10 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
if (!check_copy_size(from, n, true))
return n;

-#ifdef INLINE_COPY_TO_USER
- return _inline_copy_to_user(to, from, n);
-#else
- return _copy_to_user(to, from, n);
-#endif
+ if (IS_ENABLED(ARCH_WANTS_NOINLINE_COPY_USER))
+ return _copy_to_user(to, from, n);
+ else
+ return _inline_copy_to_user(to, from, n);
}

#ifndef copy_mc_to_kernel
diff --git a/lib/Kconfig b/lib/Kconfig
index 00a9509636c1..a2e07d4dd2bf 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -68,6 +68,9 @@ config ARCH_HAS_STRNCPY_FROM_USER
config ARCH_HAS_STRNLEN_USER
bool

+config ARCH_WANTS_NOINLINE_COPY_USER
+ bool
+
config GENERIC_STRNCPY_FROM_USER
def_bool !ARCH_HAS_STRNCPY_FROM_USER

diff --git a/lib/Makefile b/lib/Makefile
index 7c0334d7675b..f4d577910671 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -57,9 +57,10 @@ obj-y += bcd.o sort.o parser.o debug_locks.o random32.o \
list_sort.o uuid.o iov_iter.o clz_ctz.o \
bsearch.o find_bit.o llist.o lwq.o memweight.o kfifo.o \
percpu-refcount.o rhashtable.o base64.o \
- once.o refcount.o rcuref.o usercopy.o errseq.o bucket_locks.o \
+ once.o refcount.o rcuref.o errseq.o bucket_locks.o \
generic-radix-tree.o bitmap-str.o
obj-y += usercheck.o
+obj-$(CONFIG_ARCH_WANTS_NOINLINE_COPY_USER) += usercopy.o
obj-y += string_helpers.o
obj-y += hexdump.o
obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
diff --git a/lib/usercopy.c b/lib/usercopy.c
index 7a93f56d81dd..d2deb4b0a3c5 100644
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -4,18 +4,14 @@

/* out-of-line parts */

-#if !defined(INLINE_COPY_FROM_USER)
unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
{
return _inline_copy_from_user(to, from, n);
}
EXPORT_SYMBOL(_copy_from_user);
-#endif

-#if !defined(INLINE_COPY_TO_USER)
unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
{
return _inline_copy_to_user(to, from, n);
}
EXPORT_SYMBOL(_copy_to_user);
-#endif
diff --git a/rust/helpers/uaccess.c b/rust/helpers/uaccess.c
index d9625b9ee046..01de4fbbcc84 100644
--- a/rust/helpers/uaccess.c
+++ b/rust/helpers/uaccess.c
@@ -14,7 +14,7 @@ rust_helper_copy_to_user(void __user *to, const void *from, unsigned long n)
return copy_to_user(to, from, n);
}

-#ifdef INLINE_COPY_FROM_USER
+#ifndef CONFIG_ARCH_WANTS_NOINLINE_COPY_USER
__rust_helper
unsigned long rust_helper__copy_from_user(void *to, const void __user *from, unsigned long n)
{
--
2.49.0