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[PATCH v2 1/2] openrisc: Add text patching API support

ChenMiao posted 2 patches 2 months ago
[PATCH v2 1/2] openrisc: Add text patching API support
Posted by ChenMiao 2 months ago 
From: chenmiao <chenmiao.ku@gmail.com>

We need a text patching mechanism to ensure that in the subsequent
implementation of jump_label, the code can be modified to the correct
location. Therefore, FIX_TEXT_POKE0 has been added as a mapping area.

And, I create a new file named insn-def.h to define the or1k insn macro
size and more define in the future.

Among these changes, we implement patch_map and support the
patch_insn_write API for single instruction writing.

- V2: We modify the patch_insn_write(void *addr, const void *insn) API to
patch_insn_write(void *addr, u32 insn), derectly support a single u32
instruction write to map memory.

Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t

Signed-off-by: chenmiao <chenmiao.ku@gmail.com>
---
 arch/openrisc/include/asm/Kbuild          |  1 -
 arch/openrisc/include/asm/fixmap.h        |  1 +
 arch/openrisc/include/asm/insn-def.h      | 12 ++++
 arch/openrisc/include/asm/text-patching.h | 13 ++++
 arch/openrisc/kernel/Makefile             |  1 +
 arch/openrisc/kernel/patching.c           | 79 +++++++++++++++++++++++
 arch/openrisc/mm/init.c                   |  2 +-
 7 files changed, 107 insertions(+), 2 deletions(-)
 create mode 100644 arch/openrisc/include/asm/insn-def.h
 create mode 100644 arch/openrisc/include/asm/text-patching.h
 create mode 100644 arch/openrisc/kernel/patching.c

diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index 2b1a6b00cdac..cef49d60d74c 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -9,4 +9,3 @@ generic-y += spinlock.h
 generic-y += qrwlock_types.h
 generic-y += qrwlock.h
 generic-y += user.h
-generic-y += text-patching.h
diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm/fixmap.h
index aaa6a26a3e92..74000215064d 100644
--- a/arch/openrisc/include/asm/fixmap.h
+++ b/arch/openrisc/include/asm/fixmap.h
@@ -28,6 +28,7 @@
 
 enum fixed_addresses {
 	FIX_EARLYCON_MEM_BASE,
+	FIX_TEXT_POKE0,
 	__end_of_fixed_addresses
 };
 
diff --git a/arch/openrisc/include/asm/insn-def.h b/arch/openrisc/include/asm/insn-def.h
new file mode 100644
index 000000000000..dc8d16db1579
--- /dev/null
+++ b/arch/openrisc/include/asm/insn-def.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2025 Chen Miao
+ */
+
+#ifndef __ASM_INSN_DEF_H
+#define __ASM_INSN_DEF_H
+
+/* or1k instructions are always 32 bits. */
+#define	OPENRISC_INSN_SIZE		4
+
+#endif /* __ASM_INSN_DEF_H */
diff --git a/arch/openrisc/include/asm/text-patching.h b/arch/openrisc/include/asm/text-patching.h
new file mode 100644
index 000000000000..bffe828288c3
--- /dev/null
+++ b/arch/openrisc/include/asm/text-patching.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2025 Chen Miao
+ */
+
+#ifndef _ASM_PATCHING_H_
+#define _ASM_PATCHING_H_
+
+#include <linux/types.h>
+
+int patch_insn_write(void *addr, u32 insn);
+
+#endif /* _ASM_PATCHING_H_ */
diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
index 58e6a1b525b7..f0957ce16d6b 100644
--- a/arch/openrisc/kernel/Makefile
+++ b/arch/openrisc/kernel/Makefile
@@ -13,5 +13,6 @@ obj-$(CONFIG_SMP)		+= smp.o sync-timer.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= module.o
 obj-$(CONFIG_OF)		+= prom.o
+obj-y	+= patching.o
 
 clean:
diff --git a/arch/openrisc/kernel/patching.c b/arch/openrisc/kernel/patching.c
new file mode 100644
index 000000000000..c9a30f0d1193
--- /dev/null
+++ b/arch/openrisc/kernel/patching.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2020 SiFive
+ * Copyright (C) 2025 Chen Miao
+ */
+
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+
+#include <asm/insn-def.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+#include <asm/fixmap.h>
+#include <asm/text-patching.h>
+#include <asm/sections.h>
+
+static DEFINE_RAW_SPINLOCK(patch_lock);
+
+static inline bool is_exit_text(uintptr_t addr)
+{
+	/* Now Have NO Mechanism to do */
+	return true;
+}
+
+static __always_inline void *patch_map(void *addr, int fixmap)
+{
+	uintptr_t uaddr = (uintptr_t) addr;
+	phys_addr_t phys;
+
+	if (core_kernel_text(uaddr) || is_exit_text(uaddr)) {
+		phys = __pa_symbol(addr);
+	} else {
+		struct page *page = vmalloc_to_page(addr);
+		BUG_ON(!page);
+		phys = page_to_phys(page) + offset_in_page(addr);
+	}
+
+	return (void *)set_fixmap_offset(fixmap, phys);
+}
+
+static void patch_unmap(int fixmap)
+{
+	clear_fixmap(fixmap);
+}
+
+static int __patch_insn_write(void *addr, u32 insn)
+{
+	void *waddr = addr;
+	unsigned long flags = 0;
+	int ret;
+
+	raw_spin_lock_irqsave(&patch_lock, flags);
+
+	waddr = patch_map(addr, FIX_TEXT_POKE0);
+
+	ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
+	local_icache_range_inv((unsigned long)waddr,
+			       (unsigned long)waddr + OPENRISC_INSN_SIZE);
+
+	patch_unmap(FIX_TEXT_POKE0);
+
+	raw_spin_unlock_irqrestore(&patch_lock, flags);
+
+	return ret;
+}
+
+int patch_insn_write(void *addr, u32 insn)
+{
+	u32 *tp = addr;
+	int ret;
+
+	if ((uintptr_t) tp & 0x3)
+		return -EINVAL;
+
+	ret = __patch_insn_write(tp, insn);
+
+	return ret;
+}
diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
index e4904ca6f0a0..b5925710f954 100644
--- a/arch/openrisc/mm/init.c
+++ b/arch/openrisc/mm/init.c
@@ -226,7 +226,7 @@ static int __init map_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
 	return 0;
 }
 
-void __init __set_fixmap(enum fixed_addresses idx,
+void __set_fixmap(enum fixed_addresses idx,
 			 phys_addr_t phys, pgprot_t prot)
 {
 	unsigned long address = __fix_to_virt(idx);
-- 
2.45.2
Re: [PATCH v2 1/2] openrisc: Add text patching API support
Posted by Stafford Horne 1 month, 3 weeks ago 
On Wed, Aug 06, 2025 at 02:05:03AM +0000, ChenMiao wrote:
> From: chenmiao <chenmiao.ku@gmail.com>
> 
> We need a text patching mechanism to ensure that in the subsequent
> implementation of jump_label, the code can be modified to the correct
> location. Therefore, FIX_TEXT_POKE0 has been added as a mapping area.
> 
> And, I create a new file named insn-def.h to define the or1k insn macro
> size and more define in the future.
> 
> Among these changes, we implement patch_map and support the
> patch_insn_write API for single instruction writing.
> 
> - V2: We modify the patch_insn_write(void *addr, const void *insn) API to
> patch_insn_write(void *addr, u32 insn), derectly support a single u32
> instruction write to map memory.
> 
> Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t
> 
> Signed-off-by: chenmiao <chenmiao.ku@gmail.com>
> ---

The v2, notes should go in this part of the patch (after ---), this way
it does not show up when I queue the patches.

>  arch/openrisc/include/asm/Kbuild          |  1 -
>  arch/openrisc/include/asm/fixmap.h        |  1 +
>  arch/openrisc/include/asm/insn-def.h      | 12 ++++
>  arch/openrisc/include/asm/text-patching.h | 13 ++++
>  arch/openrisc/kernel/Makefile             |  1 +
>  arch/openrisc/kernel/patching.c           | 79 +++++++++++++++++++++++
>  arch/openrisc/mm/init.c                   |  2 +-
>  7 files changed, 107 insertions(+), 2 deletions(-)
>  create mode 100644 arch/openrisc/include/asm/insn-def.h
>  create mode 100644 arch/openrisc/include/asm/text-patching.h
>  create mode 100644 arch/openrisc/kernel/patching.c
> 
> diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
> index 2b1a6b00cdac..cef49d60d74c 100644
> --- a/arch/openrisc/include/asm/Kbuild
> +++ b/arch/openrisc/include/asm/Kbuild
> @@ -9,4 +9,3 @@ generic-y += spinlock.h
>  generic-y += qrwlock_types.h
>  generic-y += qrwlock.h
>  generic-y += user.h
> -generic-y += text-patching.h
> diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm/fixmap.h
> index aaa6a26a3e92..74000215064d 100644
> --- a/arch/openrisc/include/asm/fixmap.h
> +++ b/arch/openrisc/include/asm/fixmap.h
> @@ -28,6 +28,7 @@
>  
>  enum fixed_addresses {
>  	FIX_EARLYCON_MEM_BASE,
> +	FIX_TEXT_POKE0,
>  	__end_of_fixed_addresses
>  };
>  
> diff --git a/arch/openrisc/include/asm/insn-def.h b/arch/openrisc/include/asm/insn-def.h
> new file mode 100644
> index 000000000000..dc8d16db1579
> --- /dev/null
> +++ b/arch/openrisc/include/asm/insn-def.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2025 Chen Miao
> + */
> +
> +#ifndef __ASM_INSN_DEF_H
> +#define __ASM_INSN_DEF_H
> +
> +/* or1k instructions are always 32 bits. */
> +#define	OPENRISC_INSN_SIZE		4

Is this used outside of the usage below?  Why do we need a header for it?

> +#endif /* __ASM_INSN_DEF_H */
> diff --git a/arch/openrisc/include/asm/text-patching.h b/arch/openrisc/include/asm/text-patching.h
> new file mode 100644
> index 000000000000..bffe828288c3
> --- /dev/null
> +++ b/arch/openrisc/include/asm/text-patching.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2025 Chen Miao
> + */
> +
> +#ifndef _ASM_PATCHING_H_
> +#define _ASM_PATCHING_H_
> +
> +#include <linux/types.h>
> +
> +int patch_insn_write(void *addr, u32 insn);
> +
> +#endif /* _ASM_PATCHING_H_ */
> diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
> index 58e6a1b525b7..f0957ce16d6b 100644
> --- a/arch/openrisc/kernel/Makefile
> +++ b/arch/openrisc/kernel/Makefile
> @@ -13,5 +13,6 @@ obj-$(CONFIG_SMP)		+= smp.o sync-timer.o
>  obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
>  obj-$(CONFIG_MODULES)		+= module.o
>  obj-$(CONFIG_OF)		+= prom.o
> +obj-y	+= patching.o
>  
>  clean:
> diff --git a/arch/openrisc/kernel/patching.c b/arch/openrisc/kernel/patching.c
> new file mode 100644
> index 000000000000..c9a30f0d1193
> --- /dev/null
> +++ b/arch/openrisc/kernel/patching.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (C) 2020 SiFive
> + * Copyright (C) 2025 Chen Miao
> + */
> +
> +#include <linux/mm.h>
> +#include <linux/kernel.h>
> +#include <linux/spinlock.h>
> +#include <linux/uaccess.h>
> +
> +#include <asm/insn-def.h>
> +#include <asm/cacheflush.h>
> +#include <asm/page.h>
> +#include <asm/fixmap.h>
> +#include <asm/text-patching.h>
> +#include <asm/sections.h>
> +
> +static DEFINE_RAW_SPINLOCK(patch_lock);
> +
> +static inline bool is_exit_text(uintptr_t addr)
> +{
> +	/* Now Have NO Mechanism to do */
> +	return true;
> +}

Is this needed?  OpenRISC doesn't seem to have any sections to support __exit
annotated cleanup functions.

  Ref: https://kernelnewbies.org/FAQ/InitExitMacros

Returning true here means that all of the patch_map calls will be treated as
kernel pages below though, which is wrong, please remove this.

> +
> +static __always_inline void *patch_map(void *addr, int fixmap)
> +{
> +	uintptr_t uaddr = (uintptr_t) addr;
> +	phys_addr_t phys;
> +
> +	if (core_kernel_text(uaddr) || is_exit_text(uaddr)) {
> +		phys = __pa_symbol(addr);
> +	} else {
> +		struct page *page = vmalloc_to_page(addr);
> +		BUG_ON(!page);
> +		phys = page_to_phys(page) + offset_in_page(addr);
> +	}
> +
> +	return (void *)set_fixmap_offset(fixmap, phys);
> +}
> +
> +static void patch_unmap(int fixmap)
> +{
> +	clear_fixmap(fixmap);
> +}
> +
> +static int __patch_insn_write(void *addr, u32 insn)
> +{
> +	void *waddr = addr;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	raw_spin_lock_irqsave(&patch_lock, flags);
> +
> +	waddr = patch_map(addr, FIX_TEXT_POKE0);
> +
> +	ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
> +	local_icache_range_inv((unsigned long)waddr,
> +			       (unsigned long)waddr + OPENRISC_INSN_SIZE);

Instead of OPENRISC_INSN_SIZE, can you use sizeof(insn)?

> +	patch_unmap(FIX_TEXT_POKE0);
> +
> +	raw_spin_unlock_irqrestore(&patch_lock, flags);
> +
> +	return ret;
> +}
> +
> +int patch_insn_write(void *addr, u32 insn)
> +{
> +	u32 *tp = addr;
> +	int ret;
> +
> +	if ((uintptr_t) tp & 0x3)
> +		return -EINVAL;
> +
> +	ret = __patch_insn_write(tp, insn);
> +
> +	return ret;
> +}
> diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
> index e4904ca6f0a0..b5925710f954 100644
> --- a/arch/openrisc/mm/init.c
> +++ b/arch/openrisc/mm/init.c
> @@ -226,7 +226,7 @@ static int __init map_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
>  	return 0;
>  }
>  
> -void __init __set_fixmap(enum fixed_addresses idx,
> +void __set_fixmap(enum fixed_addresses idx,

Can you put a comment about this bit in the commit description?

>  			 phys_addr_t phys, pgprot_t prot)
>  {
>  	unsigned long address = __fix_to_virt(idx);
> -- 
> 2.45.2

-Stafford
Re: [PATCH v2 1/2] openrisc: Add text patching API support
Posted by Miao Chen 1 month, 3 weeks ago 
Stafford Horne <shorne@gmail.com> 于2025年8月9日周六 16:25写道：
>
> On Wed, Aug 06, 2025 at 02:05:03AM +0000, ChenMiao wrote:
> > From: chenmiao <chenmiao.ku@gmail.com>
> >
> > We need a text patching mechanism to ensure that in the subsequent
> > implementation of jump_label, the code can be modified to the correct
> > location. Therefore, FIX_TEXT_POKE0 has been added as a mapping area.
> >
> > And, I create a new file named insn-def.h to define the or1k insn macro
> > size and more define in the future.
> >
> > Among these changes, we implement patch_map and support the
> > patch_insn_write API for single instruction writing.
> >
> > - V2: We modify the patch_insn_write(void *addr, const void *insn) API to
> > patch_insn_write(void *addr, u32 insn), derectly support a single u32
> > instruction write to map memory.
> >
> > Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t
> >
> > Signed-off-by: chenmiao <chenmiao.ku@gmail.com>
> > ---
>
> The v2, notes should go in this part of the patch (after ---), this way
> it does not show up when I queue the patches.

well, I'll be care of the next version

>
> >  arch/openrisc/include/asm/Kbuild          |  1 -
> >  arch/openrisc/include/asm/fixmap.h        |  1 +
> >  arch/openrisc/include/asm/insn-def.h      | 12 ++++
> >  arch/openrisc/include/asm/text-patching.h | 13 ++++
> >  arch/openrisc/kernel/Makefile             |  1 +
> >  arch/openrisc/kernel/patching.c           | 79 +++++++++++++++++++++++
> >  arch/openrisc/mm/init.c                   |  2 +-
> >  7 files changed, 107 insertions(+), 2 deletions(-)
> >  create mode 100644 arch/openrisc/include/asm/insn-def.h
> >  create mode 100644 arch/openrisc/include/asm/text-patching.h
> >  create mode 100644 arch/openrisc/kernel/patching.c
> >
> > diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
> > index 2b1a6b00cdac..cef49d60d74c 100644
> > --- a/arch/openrisc/include/asm/Kbuild
> > +++ b/arch/openrisc/include/asm/Kbuild
> > @@ -9,4 +9,3 @@ generic-y += spinlock.h
> >  generic-y += qrwlock_types.h
> >  generic-y += qrwlock.h
> >  generic-y += user.h
> > -generic-y += text-patching.h
> > diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm/fixmap.h
> > index aaa6a26a3e92..74000215064d 100644
> > --- a/arch/openrisc/include/asm/fixmap.h
> > +++ b/arch/openrisc/include/asm/fixmap.h
> > @@ -28,6 +28,7 @@
> >
> >  enum fixed_addresses {
> >       FIX_EARLYCON_MEM_BASE,
> > +     FIX_TEXT_POKE0,
> >       __end_of_fixed_addresses
> >  };
> >
> > diff --git a/arch/openrisc/include/asm/insn-def.h b/arch/openrisc/include/asm/insn-def.h
> > new file mode 100644
> > index 000000000000..dc8d16db1579
> > --- /dev/null
> > +++ b/arch/openrisc/include/asm/insn-def.h
> > @@ -0,0 +1,12 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2025 Chen Miao
> > + */
> > +
> > +#ifndef __ASM_INSN_DEF_H
> > +#define __ASM_INSN_DEF_H
> > +
> > +/* or1k instructions are always 32 bits. */
> > +#define      OPENRISC_INSN_SIZE              4
>
> Is this used outside of the usage below?  Why do we need a header for it?

I think we need the header, although it seems redundant. Although we
only added one line here, I think as development progresses, we might
need more macro definitions related to the instruction set, possibly
including jump_label, ftrace, and potentially bpf.

>
> > +#endif /* __ASM_INSN_DEF_H */
> > diff --git a/arch/openrisc/include/asm/text-patching.h b/arch/openrisc/include/asm/text-patching.h
> > new file mode 100644
> > index 000000000000..bffe828288c3
> > --- /dev/null
> > +++ b/arch/openrisc/include/asm/text-patching.h
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2025 Chen Miao
> > + */
> > +
> > +#ifndef _ASM_PATCHING_H_
> > +#define _ASM_PATCHING_H_
> > +
> > +#include <linux/types.h>
> > +
> > +int patch_insn_write(void *addr, u32 insn);
> > +
> > +#endif /* _ASM_PATCHING_H_ */
> > diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
> > index 58e6a1b525b7..f0957ce16d6b 100644
> > --- a/arch/openrisc/kernel/Makefile
> > +++ b/arch/openrisc/kernel/Makefile
> > @@ -13,5 +13,6 @@ obj-$(CONFIG_SMP)           += smp.o sync-timer.o
> >  obj-$(CONFIG_STACKTRACE)     += stacktrace.o
> >  obj-$(CONFIG_MODULES)                += module.o
> >  obj-$(CONFIG_OF)             += prom.o
> > +obj-y        += patching.o
> >
> >  clean:
> > diff --git a/arch/openrisc/kernel/patching.c b/arch/openrisc/kernel/patching.c
> > new file mode 100644
> > index 000000000000..c9a30f0d1193
> > --- /dev/null
> > +++ b/arch/openrisc/kernel/patching.c
> > @@ -0,0 +1,79 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/* Copyright (C) 2020 SiFive
> > + * Copyright (C) 2025 Chen Miao
> > + */
> > +
> > +#include <linux/mm.h>
> > +#include <linux/kernel.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/uaccess.h>
> > +
> > +#include <asm/insn-def.h>
> > +#include <asm/cacheflush.h>
> > +#include <asm/page.h>
> > +#include <asm/fixmap.h>
> > +#include <asm/text-patching.h>
> > +#include <asm/sections.h>
> > +
> > +static DEFINE_RAW_SPINLOCK(patch_lock);
> > +
> > +static inline bool is_exit_text(uintptr_t addr)
> > +{
> > +     /* Now Have NO Mechanism to do */
> > +     return true;
> > +}
>
> Is this needed?  OpenRISC doesn't seem to have any sections to support __exit
> annotated cleanup functions.
>
>   Ref: https://kernelnewbies.org/FAQ/InitExitMacros
>
> Returning true here means that all of the patch_map calls will be treated as
> kernel pages below though, which is wrong, please remove this.
>

I'll remove it.

> > +
> > +static __always_inline void *patch_map(void *addr, int fixmap)
> > +{
> > +     uintptr_t uaddr = (uintptr_t) addr;
> > +     phys_addr_t phys;
> > +
> > +     if (core_kernel_text(uaddr) || is_exit_text(uaddr)) {
> > +             phys = __pa_symbol(addr);
> > +     } else {
> > +             struct page *page = vmalloc_to_page(addr);
> > +             BUG_ON(!page);
> > +             phys = page_to_phys(page) + offset_in_page(addr);
> > +     }
> > +
> > +     return (void *)set_fixmap_offset(fixmap, phys);
> > +}
> > +
> > +static void patch_unmap(int fixmap)
> > +{
> > +     clear_fixmap(fixmap);
> > +}
> > +
> > +static int __patch_insn_write(void *addr, u32 insn)
> > +{
> > +     void *waddr = addr;
> > +     unsigned long flags = 0;
> > +     int ret;
> > +
> > +     raw_spin_lock_irqsave(&patch_lock, flags);
> > +
> > +     waddr = patch_map(addr, FIX_TEXT_POKE0);
> > +
> > +     ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
> > +     local_icache_range_inv((unsigned long)waddr,
> > +                            (unsigned long)waddr + OPENRISC_INSN_SIZE);
>
> Instead of OPENRISC_INSN_SIZE, can you use sizeof(insn)?

I think not using sizeof(insn)here would be better. In fact, using the
OPENRISC_INSN_SIZE macro might be more appropriate.

Here we are modifying a single instruction, so it must be 4 bytes—the
length of one OPENRISC INSN.

>
> > +     patch_unmap(FIX_TEXT_POKE0);
> > +
> > +     raw_spin_unlock_irqrestore(&patch_lock, flags);
> > +
> > +     return ret;
> > +}
> > +
> > +int patch_insn_write(void *addr, u32 insn)
> > +{
> > +     u32 *tp = addr;
> > +     int ret;
> > +
> > +     if ((uintptr_t) tp & 0x3)
> > +             return -EINVAL;
> > +
> > +     ret = __patch_insn_write(tp, insn);
> > +
> > +     return ret;
> > +}
> > diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
> > index e4904ca6f0a0..b5925710f954 100644
> > --- a/arch/openrisc/mm/init.c
> > +++ b/arch/openrisc/mm/init.c
> > @@ -226,7 +226,7 @@ static int __init map_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
> >       return 0;
> >  }
> >
> > -void __init __set_fixmap(enum fixed_addresses idx,
> > +void __set_fixmap(enum fixed_addresses idx,
>
> Can you put a comment about this bit in the commit description?

I'll do the next version

>
> >                        phys_addr_t phys, pgprot_t prot)
> >  {
> >       unsigned long address = __fix_to_virt(idx);
> > --
> > 2.45.2
>
> -Stafford
>

Patchew 2.1-devel-b67e4c2

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