[PATCH v11 0/4] Replace fallback for IO memcpy and IO memset

[PATCH v11 0/4] Replace fallback for IO memcpy and IO memset

[Julian Vetter]

Thank you Arnd for your feedback and no problem. I should have asked
before, to clarify what you meant. I have now addressed what you
proposed. I have kept the iomem_copy.c and only made the minimal changes
to asm-generic/io.h and kept them in place just modifiying the content.
Not sure though about the commit message of patch 1. Let me know if I
should rephrase it.

Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
---
Changes for v11:
- Restored iomem_copy.c
- Updated asm-generic/io.h to just contain the changes suggested by Arnd

Changes for v10:
- Removed libs/iomem_copy.c again
- Replaced the three functions in asm-generic/io.h directly
- Updated description for the first patch to clarify the matter
- Slightly updated description in patches 2 to 4

Changes for v9:
- Moved functions into a new file iomem_copy.c which is built
  unconditionally
- Guard prototypes with '#ifndef memcpy_fromio', etc.
- Dropped patches 5 to 14 for now. I will send some of the changes in
  separate patches or patchsets to the appropriate mailinglists
- Added proper reviewed-by and acked-by to arm64 and csky patches

Changes for v8:
- Dropped the arch/um patch that adds dummy implementations for IO
  memcpy functions
- Added 3 new patches that fix the dependency problem for UM (added
  dependencies on HAS_IOMEM || INDIRECT_IOMEM)
- Added new patch for s390 to internally call the zpci_memcpy functions
  and not the generic ones from libs/iomap_copy.c
- Addressed reviewer comments and replaced 2 or 3 shifts by
  'qc *= ~0UL / 0xff;'
- Addressed reviewer comments on pasrisc (masking the int value)
- Addressed reviewer comments on alpha (masking the int value)

Changes for v7:
- Added dummy implementations for memcpy_{to,from}io and memset_io on um
  architecture so drivers that use these functions build for um
- Replaced all accesses and checks by long type
- Added function prototypes as extern to asm-generic/io.h
- Removed '__' from the 3 new function names
- Some archs implement their own version of these IO functions with
  slightly different prototypes. So, I added 3 new patches to align
  prototypes with new ones in iomap_copy.c + io.h

Changes for v6:
- Added include of linux/align.h to fix build on arm arch
- Replaced compile-time check by ifdef for the CONFIG_64BIT otherwise we
  get a warning for the 'qc << 32' for archs with 32bit int types
- Suffixed arch commits by arch name

Changes for v5:
- Added functions to iomap_copy.c as proposed by Arndt
- Removed again the new io_copy.c and related objects
- Removed GENERIC_IO_COPY symbol and instead rely on the existing
  HAS_IOMEM symbol
- Added prototypes of __memcpy_{to,from}io and __memset_io functions to
  asm-generic/io.h

Changes for v4:
- Replaced memcpy/memset in asm-generic/io.h by the new
  __memcpy_{to,from}io and __memset_io, so individual architectures can
  use it instead of using their own implementation.

Changes for v3:
- Replaced again 'if(IS_ENABLED(CONFIG_64BIT))' by '#ifdef CONFIG_64BIT'
  because on 32bit architectures (e.g., csky), __raw_{read,write}q are
  not defined. So, it leads to compilation errors

Changes for v2:
- Renamed io.c -> io_copy.c
- Updated flag to 'GENERIC_IO_COPY'
- Replaced pointer dereferences by 'put_unaligned()'/'get_unaligned()'
- Replaced '#ifdef CONFIG_64BIT' by 'if(IS_ENABLED(CONFIG_64BIT))'
- Removed '__raw_{read,write}_native' and replaced by
  'if(IS_ENABLED(CONFIG_64BIT))' -> '__raw_write{l,q}'
---
Julian Vetter (4):
  New implementation for IO memcpy and IO memset
  arm64: Use new fallback IO memcpy/memset
  csky: Use new fallback IO memcpy/memset
  loongarch: Use new fallback IO memcpy/memset

 arch/arm64/include/asm/io.h     |  11 ---
 arch/arm64/kernel/io.c          |  87 --------------------
 arch/csky/include/asm/io.h      |  11 ---
 arch/csky/kernel/Makefile       |   2 +-
 arch/csky/kernel/io.c           |  91 ---------------------
 arch/loongarch/include/asm/io.h |  10 ---
 arch/loongarch/kernel/Makefile  |   2 +-
 arch/loongarch/kernel/io.c      |  94 ----------------------
 include/asm-generic/io.h        |  22 +-----
 lib/Makefile                    |   2 +-
 lib/iomem_copy.c                | 136 ++++++++++++++++++++++++++++++++
 11 files changed, 142 insertions(+), 326 deletions(-)
 delete mode 100644 arch/csky/kernel/io.c
 delete mode 100644 arch/loongarch/kernel/io.c
 create mode 100644 lib/iomem_copy.c

-- 
2.34.1

[PATCH v11 1/4] New implementation for IO memcpy and IO memset

[Julian Vetter]

The IO memcpy and IO memset functions in asm-generic/io.h simply call
memcpy and memset. This can lead to alignment problems or faults on
architectures that do not define their own version and fall back to
these defaults.
This patch introduces new implementations for IO memcpy and IO memset,
that use read{l,q} accessor functions, align accesses to machine word
size, and resort to byte accesses when the target memory is not aligned.
For new architectures and existing ones that were using the old
fallbacks these functions are save to use, because IO memory constraints
are taken into account. Moreover, architectures with similar
implementations can now use these new versions, not needing to implement
their own.

Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
---
Changes for v11:
- Updated asm-generic/io.h to just contain the changes suggested by Arnd
- Restored iomem_copy.c
  - Re-ordered functions to match the order in asm-generic/io.h
  - Aligned variable names (e.g., src and dst instead of to and from)
    with the ones from asm-generic/io.h
---
 include/asm-generic/io.h |  22 +------
 lib/Makefile             |   2 +-
 lib/iomem_copy.c         | 136 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 20 deletions(-)
 create mode 100644 lib/iomem_copy.c

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 80de699bf6af..7004c2e5e8f1 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1151,7 +1151,6 @@ static inline void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
 #endif
 
 #ifndef memset_io
-#define memset_io memset_io
 /**
  * memset_io	Set a range of I/O memory to a constant value
  * @addr:	The beginning of the I/O-memory range to set
@@ -1160,15 +1159,10 @@ static inline void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  *
  * Set a range of I/O memory to a given value.
  */
-static inline void memset_io(volatile void __iomem *addr, int value,
-			     size_t size)
-{
-	memset(__io_virt(addr), value, size);
-}
+void memset_io(volatile void __iomem *addr, int val, size_t count);
 #endif
 
 #ifndef memcpy_fromio
-#define memcpy_fromio memcpy_fromio
 /**
  * memcpy_fromio	Copy a block of data from I/O memory
  * @dst:		The (RAM) destination for the copy
@@ -1177,16 +1171,10 @@ static inline void memset_io(volatile void __iomem *addr, int value,
  *
  * Copy a block of data from I/O memory.
  */
-static inline void memcpy_fromio(void *buffer,
-				 const volatile void __iomem *addr,
-				 size_t size)
-{
-	memcpy(buffer, __io_virt(addr), size);
-}
+void memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count);
 #endif
 
 #ifndef memcpy_toio
-#define memcpy_toio memcpy_toio
 /**
  * memcpy_toio		Copy a block of data into I/O memory
  * @dst:		The (I/O memory) destination for the copy
@@ -1195,11 +1183,7 @@ static inline void memcpy_fromio(void *buffer,
  *
  * Copy a block of data to I/O memory.
  */
-static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer,
-			       size_t size)
-{
-	memcpy(__io_virt(addr), buffer, size);
-}
+void memcpy_toio(volatile void __iomem *dst, const void *src, size_t count);
 #endif
 
 extern int devmem_is_allowed(unsigned long pfn);
diff --git a/lib/Makefile b/lib/Makefile
index 773adf88af41..db4717538fad 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -35,7 +35,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
 	 earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
 	 nmi_backtrace.o win_minmax.o memcat_p.o \
-	 buildid.o objpool.o union_find.o
+	 buildid.o objpool.o union_find.o iomem_copy.o
 
 lib-$(CONFIG_PRINTK) += dump_stack.o
 lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/iomem_copy.c b/lib/iomem_copy.c
new file mode 100644
index 000000000000..24c2b59a0ad2
--- /dev/null
+++ b/lib/iomem_copy.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2024 Kalray, Inc.  All Rights Reserved.
+ */
+
+#include <linux/align.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+
+#ifndef memset_io
+/**
+ * memset_io		Set a range of I/O memory to a constant value
+ * @addr:		The beginning of the I/O-memory range to set
+ * @val:		The value to set the memory to
+ * @count:		The number of bytes to set
+ *
+ * Set a range of I/O memory to a given value.
+ */
+void memset_io(volatile void __iomem *addr, int val, size_t count)
+{
+	long qc = (u8)val;
+
+	qc *= ~0UL / 0xff;
+
+	while (count && !IS_ALIGNED((long)addr, sizeof(long))) {
+		__raw_writeb(val, addr);
+		addr++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+#ifdef CONFIG_64BIT
+		__raw_writeq(qc, addr);
+#else
+		__raw_writel(qc, addr);
+#endif
+
+		addr += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		__raw_writeb(val, addr);
+		addr++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memset_io);
+#endif
+
+#ifndef memcpy_fromio
+/**
+ * memcpy_fromio	Copy a block of data from I/O memory
+ * @dst:		The (RAM) destination for the copy
+ * @src:		The (I/O memory) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data from I/O memory.
+ */
+void memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count)
+{
+	while (count && !IS_ALIGNED((long)src, sizeof(long))) {
+		*(u8 *)dst = __raw_readb(src);
+		src++;
+		dst++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+#ifdef CONFIG_64BIT
+		long val = __raw_readq(src);
+#else
+		long val = __raw_readl(src);
+#endif
+		put_unaligned(val, (long *)dst);
+
+
+		src += sizeof(long);
+		dst += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		*(u8 *)dst = __raw_readb(src);
+		src++;
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_fromio);
+#endif
+
+#ifndef memcpy_toio
+/**
+ * memcpy_toio		Copy a block of data into I/O memory
+ * @dst:		The (I/O memory) destination for the copy
+ * @src:		The (RAM) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data to I/O memory.
+ */
+void memcpy_toio(volatile void __iomem *dst, const void *src, size_t count)
+{
+	while (count && !IS_ALIGNED((long)dst, sizeof(long))) {
+		__raw_writeb(*(u8 *)src, dst);
+		src++;
+		dst++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+		long val = get_unaligned((long *)src);
+#ifdef CONFIG_64BIT
+		__raw_writeq(val, dst);
+#else
+		__raw_writel(val, dst);
+#endif
+
+		src += sizeof(long);
+		dst += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		__raw_writeb(*(u8 *)src, dst);
+		src++;
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_toio);
+#endif
+
+
-- 
2.34.1

[PATCH v11 2/4] arm64: Use new fallback IO memcpy/memset

[Julian Vetter]

Use the new fallback memcpy_{from,to}io and memset_io functions from
lib/iomem_copy.c on the arm64 processor architecture.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
---
Changes for v11:
- Updated commit message
---
 arch/arm64/include/asm/io.h | 11 -----
 arch/arm64/kernel/io.c      | 87 -------------------------------------
 2 files changed, 98 deletions(-)

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 1ada23a6ec19..463067bffdfd 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -128,17 +128,6 @@ static __always_inline u64 __raw_readq(const volatile void __iomem *addr)
 #define IO_SPACE_LIMIT		(PCI_IO_SIZE - 1)
 #define PCI_IOBASE		((void __iomem *)PCI_IO_START)
 
-/*
- * String version of I/O memory access operations.
- */
-extern void __memcpy_fromio(void *, const volatile void __iomem *, size_t);
-extern void __memcpy_toio(volatile void __iomem *, const void *, size_t);
-extern void __memset_io(volatile void __iomem *, int, size_t);
-
-#define memset_io(c,v,l)	__memset_io((c),(v),(l))
-#define memcpy_fromio(a,c,l)	__memcpy_fromio((a),(c),(l))
-#define memcpy_toio(c,a,l)	__memcpy_toio((c),(a),(l))
-
 /*
  * The ARM64 iowrite implementation is intended to support drivers that want to
  * use write combining. For instance PCI drivers using write combining with a 64
diff --git a/arch/arm64/kernel/io.c b/arch/arm64/kernel/io.c
index ef48089fbfe1..fe86ada23c7d 100644
--- a/arch/arm64/kernel/io.c
+++ b/arch/arm64/kernel/io.c
@@ -9,34 +9,6 @@
 #include <linux/types.h>
 #include <linux/io.h>
 
-/*
- * Copy data from IO memory space to "real" memory space.
- */
-void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)from, 8)) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 8) {
-		*(u64 *)to = __raw_readq(from);
-		from += 8;
-		to += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_fromio);
-
 /*
  * This generates a memcpy that works on a from/to address which is aligned to
  * bits. Count is in terms of the number of bits sized quantities to copy. It
@@ -78,62 +50,3 @@ void __iowrite32_copy_full(void __iomem *to, const void *from, size_t count)
 	dgh();
 }
 EXPORT_SYMBOL(__iowrite32_copy_full);
-
-/*
- * Copy data from "real" memory space to IO memory space.
- */
-void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)to, 8)) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 8) {
-		__raw_writeq(*(u64 *)from, to);
-		from += 8;
-		to += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_toio);
-
-/*
- * "memset" on IO memory space.
- */
-void __memset_io(volatile void __iomem *dst, int c, size_t count)
-{
-	u64 qc = (u8)c;
-
-	qc |= qc << 8;
-	qc |= qc << 16;
-	qc |= qc << 32;
-
-	while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-
-	while (count >= 8) {
-		__raw_writeq(qc, dst);
-		dst += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memset_io);
-- 
2.34.1

[PATCH v11 3/4] csky: Use new fallback IO memcpy/memset

[Julian Vetter]

Use the new fallback memcpy_{from,to}io and memset_io functions from
lib/iomem_copy.c on the csky processor architecture.

Acked-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
---
Changes for v11:
- Updated commit message
---
 arch/csky/include/asm/io.h | 11 -----
 arch/csky/kernel/Makefile  |  2 +-
 arch/csky/kernel/io.c      | 91 --------------------------------------
 3 files changed, 1 insertion(+), 103 deletions(-)
 delete mode 100644 arch/csky/kernel/io.c

diff --git a/arch/csky/include/asm/io.h b/arch/csky/include/asm/io.h
index 4725bb977b0f..ed53f0b47388 100644
--- a/arch/csky/include/asm/io.h
+++ b/arch/csky/include/asm/io.h
@@ -31,17 +31,6 @@
 #define writel(v,c)		({ wmb(); writel_relaxed((v),(c)); mb(); })
 #endif
 
-/*
- * String version of I/O memory access operations.
- */
-extern void __memcpy_fromio(void *, const volatile void __iomem *, size_t);
-extern void __memcpy_toio(volatile void __iomem *, const void *, size_t);
-extern void __memset_io(volatile void __iomem *, int, size_t);
-
-#define memset_io(c,v,l)        __memset_io((c),(v),(l))
-#define memcpy_fromio(a,c,l)    __memcpy_fromio((a),(c),(l))
-#define memcpy_toio(c,a,l)      __memcpy_toio((c),(a),(l))
-
 /*
  * I/O memory mapping functions.
  */
diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index 8a868316b912..de1c3472e8f0 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -2,7 +2,7 @@
 extra-y := vmlinux.lds
 
 obj-y += head.o entry.o atomic.o signal.o traps.o irq.o time.o vdso.o vdso/
-obj-y += power.o syscall.o syscall_table.o setup.o io.o
+obj-y += power.o syscall.o syscall_table.o setup.o
 obj-y += process.o cpu-probe.o ptrace.o stacktrace.o
 obj-y += probes/
 
diff --git a/arch/csky/kernel/io.c b/arch/csky/kernel/io.c
deleted file mode 100644
index 5883f13fa2b1..000000000000
--- a/arch/csky/kernel/io.c
+++ /dev/null
@@ -1,91 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include <linux/export.h>
-#include <linux/types.h>
-#include <linux/io.h>
-
-/*
- * Copy data from IO memory space to "real" memory space.
- */
-void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)from, 4)) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 4) {
-		*(u32 *)to = __raw_readl(from);
-		from += 4;
-		to += 4;
-		count -= 4;
-	}
-
-	while (count) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_fromio);
-
-/*
- * Copy data from "real" memory space to IO memory space.
- */
-void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)to, 4)) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 4) {
-		__raw_writel(*(u32 *)from, to);
-		from += 4;
-		to += 4;
-		count -= 4;
-	}
-
-	while (count) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_toio);
-
-/*
- * "memset" on IO memory space.
- */
-void __memset_io(volatile void __iomem *dst, int c, size_t count)
-{
-	u32 qc = (u8)c;
-
-	qc |= qc << 8;
-	qc |= qc << 16;
-
-	while (count && !IS_ALIGNED((unsigned long)dst, 4)) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-
-	while (count >= 4) {
-		__raw_writel(qc, dst);
-		dst += 4;
-		count -= 4;
-	}
-
-	while (count) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memset_io);
-- 
2.34.1

[PATCH v11 4/4] loongarch: Use new fallback IO memcpy/memset

[Julian Vetter]

Use the new fallback memcpy_{from,to}io and memset_io functions from
lib/iomem_copy.c on the loongarch processor architecture.

Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
---
Changes for v11:
- Updated commit message
---
 arch/loongarch/include/asm/io.h | 10 ----
 arch/loongarch/kernel/Makefile  |  2 +-
 arch/loongarch/kernel/io.c      | 94 ---------------------------------
 3 files changed, 1 insertion(+), 105 deletions(-)
 delete mode 100644 arch/loongarch/kernel/io.c

diff --git a/arch/loongarch/include/asm/io.h b/arch/loongarch/include/asm/io.h
index 5e95a60df180..e77a56eaf906 100644
--- a/arch/loongarch/include/asm/io.h
+++ b/arch/loongarch/include/asm/io.h
@@ -62,16 +62,6 @@ static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
 
 #define mmiowb() wmb()
 
-/*
- * String version of I/O memory access operations.
- */
-extern void __memset_io(volatile void __iomem *dst, int c, size_t count);
-extern void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count);
-extern void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count);
-#define memset_io(c, v, l)     __memset_io((c), (v), (l))
-#define memcpy_fromio(a, c, l) __memcpy_fromio((a), (c), (l))
-#define memcpy_toio(c, a, l)   __memcpy_toio((c), (a), (l))
-
 #define __io_aw() mmiowb()
 
 #ifdef CONFIG_KFENCE
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index c9bfeda89e40..9497968ee158 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -8,7 +8,7 @@ OBJECT_FILES_NON_STANDARD_head.o := y
 extra-y		:= vmlinux.lds
 
 obj-y		+= head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
-		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
+		   traps.o irq.o idle.o process.o dma.o mem.o reset.o switch.o \
 		   elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
 		   alternative.o unwind.o
 
diff --git a/arch/loongarch/kernel/io.c b/arch/loongarch/kernel/io.c
deleted file mode 100644
index cb85bda5a6ad..000000000000
--- a/arch/loongarch/kernel/io.c
+++ /dev/null
@@ -1,94 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
- */
-#include <linux/export.h>
-#include <linux/types.h>
-#include <linux/io.h>
-
-/*
- * Copy data from IO memory space to "real" memory space.
- */
-void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)from, 8)) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 8) {
-		*(u64 *)to = __raw_readq(from);
-		from += 8;
-		to += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		*(u8 *)to = __raw_readb(from);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_fromio);
-
-/*
- * Copy data from "real" memory space to IO memory space.
- */
-void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
-{
-	while (count && !IS_ALIGNED((unsigned long)to, 8)) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-
-	while (count >= 8) {
-		__raw_writeq(*(u64 *)from, to);
-		from += 8;
-		to += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		__raw_writeb(*(u8 *)from, to);
-		from++;
-		to++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memcpy_toio);
-
-/*
- * "memset" on IO memory space.
- */
-void __memset_io(volatile void __iomem *dst, int c, size_t count)
-{
-	u64 qc = (u8)c;
-
-	qc |= qc << 8;
-	qc |= qc << 16;
-	qc |= qc << 32;
-
-	while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-
-	while (count >= 8) {
-		__raw_writeq(qc, dst);
-		dst += 8;
-		count -= 8;
-	}
-
-	while (count) {
-		__raw_writeb(c, dst);
-		dst++;
-		count--;
-	}
-}
-EXPORT_SYMBOL(__memset_io);
-- 
2.34.1

Re: [PATCH v11 0/4] Replace fallback for IO memcpy and IO memset

[Arnd Bergmann]

On Mon, Oct 28, 2024, at 13:42, Julian Vetter wrote:
> Thank you Arnd for your feedback and no problem. I should have asked
> before, to clarify what you meant. I have now addressed what you
> proposed. I have kept the iomem_copy.c and only made the minimal changes
> to asm-generic/io.h and kept them in place just modifiying the content.
> Not sure though about the commit message of patch 1. Let me know if I
> should rephrase it.
>
> Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
> ---
> Changes for v11:
> - Restored iomem_copy.c
> - Updated asm-generic/io.h to just contain the changes suggested by Arnd

I've applied it to the asm-generic tree now.

It's always possible to improve the commit messages, but I'll
call this good enough, as it's more important to give this some
time testing in linux-next.

Thanks for your work work on this!

     Arnd