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From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: [PATCH] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE
Date:   Tue, 13 Apr 2021 13:54:39 +0200
Message-Id: <20210413115439.1011560-1-schnelle@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

When PCI_IOBASE is not defined, it is set to 0 such that it is ignored
in calls to the readX/writeX primitives. While mathematically obvious
this triggers clang's -Wnull-pointer-arithmetic warning.

An additional complication is that PCI_IOBASE is explicitly typed as
"void __iomem *" which causes the type conversion that converts the
"unsigned long" port/addr parameters to the appropriate pointer type.
As non pointer types are used by drivers at the callsite since these are
dealing with I/O port numbers, changing the parameter type would cause
further warnings in drivers. Instead use "uintptr_t" for PCI_IOBASE
0 and explicitly cast to "void __iomem *" when calling readX/writeX.

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 include/asm-generic/io.h | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index c6af40ce03be..8eb00bdef7ad 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -441,7 +441,7 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 #endif /* CONFIG_64BIT */
 
 #ifndef PCI_IOBASE
-#define PCI_IOBASE ((void __iomem *)0)
+#define PCI_IOBASE ((uintptr_t)0)
 #endif
 
 #ifndef IO_SPACE_LIMIT
@@ -461,7 +461,7 @@ static inline u8 _inb(unsigned long addr)
 	u8 val;
 
 	__io_pbr();
-	val = __raw_readb(PCI_IOBASE + addr);
+	val = __raw_readb((void __iomem *)(PCI_IOBASE + addr));
 	__io_par(val);
 	return val;
 }
@@ -474,7 +474,7 @@ static inline u16 _inw(unsigned long addr)
 	u16 val;
 
 	__io_pbr();
-	val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
+	val = __le16_to_cpu((__le16 __force)__raw_readw((void __iomem *)(PCI_IOBASE + addr)));
 	__io_par(val);
 	return val;
 }
@@ -487,7 +487,7 @@ static inline u32 _inl(unsigned long addr)
 	u32 val;
 
 	__io_pbr();
-	val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
+	val = __le32_to_cpu((__le32 __force)__raw_readl((void __iomem *)(PCI_IOBASE + addr)));
 	__io_par(val);
 	return val;
 }
@@ -498,7 +498,7 @@ static inline u32 _inl(unsigned long addr)
 static inline void _outb(u8 value, unsigned long addr)
 {
 	__io_pbw();
-	__raw_writeb(value, PCI_IOBASE + addr);
+	__raw_writeb(value, (void __iomem *)(PCI_IOBASE + addr));
 	__io_paw();
 }
 #endif
@@ -508,7 +508,7 @@ static inline void _outb(u8 value, unsigned long addr)
 static inline void _outw(u16 value, unsigned long addr)
 {
 	__io_pbw();
-	__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
+	__raw_writew((u16 __force)cpu_to_le16(value), (void __iomem *)(PCI_IOBASE + addr));
 	__io_paw();
 }
 #endif
@@ -518,7 +518,7 @@ static inline void _outw(u16 value, unsigned long addr)
 static inline void _outl(u32 value, unsigned long addr)
 {
 	__io_pbw();
-	__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
+	__raw_writel((u32 __force)cpu_to_le32(value), (void __iomem *)(PCI_IOBASE + addr));
 	__io_paw();
 }
 #endif
@@ -606,7 +606,7 @@ static inline void outl_p(u32 value, unsigned long addr)
 #define insb insb
 static inline void insb(unsigned long addr, void *buffer, unsigned int count)
 {
-	readsb(PCI_IOBASE + addr, buffer, count);
+	readsb((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
@@ -614,7 +614,7 @@ static inline void insb(unsigned long addr, void *buffer, unsigned int count)
 #define insw insw
 static inline void insw(unsigned long addr, void *buffer, unsigned int count)
 {
-	readsw(PCI_IOBASE + addr, buffer, count);
+	readsw((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
@@ -622,7 +622,7 @@ static inline void insw(unsigned long addr, void *buffer, unsigned int count)
 #define insl insl
 static inline void insl(unsigned long addr, void *buffer, unsigned int count)
 {
-	readsl(PCI_IOBASE + addr, buffer, count);
+	readsl((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
@@ -631,7 +631,7 @@ static inline void insl(unsigned long addr, void *buffer, unsigned int count)
 static inline void outsb(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
-	writesb(PCI_IOBASE + addr, buffer, count);
+	writesb((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
@@ -640,7 +640,7 @@ static inline void outsb(unsigned long addr, const void *buffer,
 static inline void outsw(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
-	writesw(PCI_IOBASE + addr, buffer, count);
+	writesw((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
@@ -649,7 +649,7 @@ static inline void outsw(unsigned long addr, const void *buffer,
 static inline void outsl(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
-	writesl(PCI_IOBASE + addr, buffer, count);
+	writesl((void __iomem *)(PCI_IOBASE + addr), buffer, count);
 }
 #endif
 
-- 
2.25.1