linux-kernel - [PATCH] mm: Remove broken pfn_to_virt() on arch csky/hexagon/openrisc

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Date: Fri,  2 Feb 2024 22:05:50 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: arnd@...db.de,
	linus.walleij@...aro.org,
	guoren@...nel.org,
	bcain@...cinc.com,
	jonas@...thpole.se,
	stefan.kristiansson@...nalahti.fi,
	shorne@...il.com
Cc: linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-csky@...r.kernel.org,
	linux-hexagon@...r.kernel.org,
	linux-openrisc@...r.kernel.org,
	Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH] mm: Remove broken pfn_to_virt() on arch csky/hexagon/openrisc

Remove the broken pfn_to_virt() on architectures csky/hexagon/openrisc.

The pfn_to_virt() on those architectures takes PFN instead of PA as the
input to macro __va(), with PAGE_SHIFT applying to the converted VA, which
is not right, especially when there's a non-zero offset in __va(). [1]

The broken pfn_to_virt() was noticed when checking how page_to_virt() is
unfolded on x86. It turns out that the one in linux/mm.h instead of in
asm-generic/page.h is compiled for x86. However, page_to_virt() in
asm-generic/page.h is found out expanding to pfn_to_virt() with a bug
described above. The pfn_to_virt() is found out not right as well on
architectures csky/hexagon/openrisc.

Since there's no single caller on csky/hexagon/openrisc to pfn_to_virt()
and there are functions doing similar things as pfn_to_virt() --
- pfn_to_kaddr() in asm/page.h for csky,
- page_to_virt() in asm/page.h for hexagon, and
- page_to_virt() in linux/mm.h for openrisc,
just delete the pfn_to_virt() on those architectures.

The pfn_to_virt() in asm-generic/page.h is not touched in this patch as
it's referenced by page_to_virt() in that header while the whole header is
going to be removed as a whole due to no one including it.

Link:https://lore.kernel.org/all/20240131055159.2506-1-yan.y.zhao@intel.com [1]
Cc: Linus Walleij <linus.walleij@...aro.org>
Suggested-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 arch/csky/include/asm/page.h     | 5 -----
 arch/hexagon/include/asm/page.h  | 6 ------
 arch/openrisc/include/asm/page.h | 5 -----
 3 files changed, 16 deletions(-)

diff --git a/arch/csky/include/asm/page.h b/arch/csky/include/asm/page.h
index 4a0502e324a6..866855e1ab43 100644
--- a/arch/csky/include/asm/page.h
+++ b/arch/csky/include/asm/page.h
@@ -82,11 +82,6 @@ static inline unsigned long virt_to_pfn(const void *kaddr)
 	return __pa(kaddr) >> PAGE_SHIFT;
 }
 
-static inline void * pfn_to_virt(unsigned long pfn)
-{
-	return (void *)((unsigned long)__va(pfn) << PAGE_SHIFT);
-}
-
 #define MAP_NR(x)	PFN_DOWN((unsigned long)(x) - PAGE_OFFSET - \
 				 PHYS_OFFSET_OFFSET)
 #define virt_to_page(x)	(mem_map + MAP_NR(x))
diff --git a/arch/hexagon/include/asm/page.h b/arch/hexagon/include/asm/page.h
index 10f1bc07423c..32394b7e752e 100644
--- a/arch/hexagon/include/asm/page.h
+++ b/arch/hexagon/include/asm/page.h
@@ -133,12 +133,6 @@ static inline unsigned long virt_to_pfn(const void *kaddr)
 	return __pa(kaddr) >> PAGE_SHIFT;
 }
 
-static inline void *pfn_to_virt(unsigned long pfn)
-{
-	return (void *)((unsigned long)__va(pfn) << PAGE_SHIFT);
-}
-
-
 #define page_to_virt(page)	__va(page_to_phys(page))
 
 #include <asm/mem-layout.h>
diff --git a/arch/openrisc/include/asm/page.h b/arch/openrisc/include/asm/page.h
index 44fc1fd56717..de33ba10ee67 100644
--- a/arch/openrisc/include/asm/page.h
+++ b/arch/openrisc/include/asm/page.h
@@ -77,11 +77,6 @@ static inline unsigned long virt_to_pfn(const void *kaddr)
 	return __pa(kaddr) >> PAGE_SHIFT;
 }
 
-static inline void * pfn_to_virt(unsigned long pfn)
-{
-	return (void *)((unsigned long)__va(pfn) << PAGE_SHIFT);
-}
-
 #define virt_to_page(addr) \
 	(mem_map + (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT))
 

base-commit: 41bccc98fb7931d63d03f326a746ac4d429c1dd3
-- 
2.17.1