Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Arnd Bergmann <arnd@arndb.de>, Vineet Gupta <vgupta@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>
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,
        linux-snps-arc@lists.infradead.org, sparclinux@vger.kernel.org
Subject: [PATCH v3 3/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE
Date:   Wed, 21 Apr 2021 13:17:59 +0200
Message-Id: <20210421111759.2059976-4-schnelle@linux.ibm.com>
In-Reply-To: <20210421111759.2059976-1-schnelle@linux.ibm.com>
References: <20210421111759.2059976-1-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. This triggers clang's
-Wnull-pointer-arithmetic warning and will result in illegal accesses on
platforms that do not support I/O ports if drivers do still attempt to
access them.

Make things explicit and silence the warning by letting inb() and
friends fail with WARN_ONCE() and a 0xff... return in case PCI_IOBASE is
not defined.

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
v2 -> v3:
- Added ifdefs to ioport_map() and __pci_ioport_map() since apparently at least
  test configs enable CONFIG_HAS_IOPORT_MAP even on architectures which leave
  PCI_IOBASE unset (kernel test robot for nds32 and ARC).
v1 -> v2:
- Instead of working around the warning with a uintptr_t PCI_IOBASE make inb()
  and friends explicitly WARN_ONCE() and return 0xff... (Arnd)
 include/asm-generic/io.h | 64 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 60 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index c6af40ce03be..aabb0a8186ee 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -440,10 +440,6 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 #endif
 #endif /* CONFIG_64BIT */
 
-#ifndef PCI_IOBASE
-#define PCI_IOBASE ((void __iomem *)0)
-#endif
-
 #ifndef IO_SPACE_LIMIT
 #define IO_SPACE_LIMIT 0xffff
 #endif
@@ -458,12 +454,17 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 #define _inb _inb
 static inline u8 _inb(unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	u8 val;
 
 	__io_pbr();
 	val = __raw_readb(PCI_IOBASE + addr);
 	__io_par(val);
 	return val;
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+	return ~0;
+#endif
 }
 #endif
 
@@ -471,12 +472,17 @@ static inline u8 _inb(unsigned long addr)
 #define _inw _inw
 static inline u16 _inw(unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	u16 val;
 
 	__io_pbr();
 	val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
 	__io_par(val);
 	return val;
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+	return ~0;
+#endif
 }
 #endif
 
@@ -484,12 +490,17 @@ static inline u16 _inw(unsigned long addr)
 #define _inl _inl
 static inline u32 _inl(unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	u32 val;
 
 	__io_pbr();
 	val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
 	__io_par(val);
 	return val;
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+	return ~0;
+#endif
 }
 #endif
 
@@ -497,9 +508,13 @@ static inline u32 _inl(unsigned long addr)
 #define _outb _outb
 static inline void _outb(u8 value, unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	__io_pbw();
 	__raw_writeb(value, PCI_IOBASE + addr);
 	__io_paw();
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -507,9 +522,13 @@ static inline void _outb(u8 value, unsigned long addr)
 #define _outw _outw
 static inline void _outw(u16 value, unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	__io_pbw();
 	__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
 	__io_paw();
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -517,9 +536,13 @@ static inline void _outw(u16 value, unsigned long addr)
 #define _outl _outl
 static inline void _outl(u32 value, unsigned long addr)
 {
+#ifdef PCI_IOBASE
 	__io_pbw();
 	__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
 	__io_paw();
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -606,7 +629,11 @@ 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)
 {
+#ifdef PCI_IOBASE
 	readsb(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -614,7 +641,11 @@ 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)
 {
+#ifdef PCI_IOBASE
 	readsw(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -622,7 +653,11 @@ 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)
 {
+#ifdef PCI_IOBASE
 	readsl(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -631,7 +666,11 @@ 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)
 {
+#ifdef PCI_IOBASE
 	writesb(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -640,7 +679,11 @@ static inline void outsb(unsigned long addr, const void *buffer,
 static inline void outsw(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
+#ifdef PCI_IOBASE
 	writesw(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -649,7 +692,11 @@ static inline void outsw(unsigned long addr, const void *buffer,
 static inline void outsl(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
+#ifdef PCI_IOBASE
 	writesl(PCI_IOBASE + addr, buffer, count);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
@@ -1001,18 +1048,27 @@ static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
 #define ioport_map ioport_map
 static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
 {
+#ifdef PCI_IOBASE
 	port &= IO_SPACE_LIMIT;
 	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+	return NULL;
+#endif
 }
 #define __pci_ioport_unmap __pci_ioport_unmap
 static inline void __pci_ioport_unmap(void __iomem *p)
 {
+#ifdef PCI_IOBASE
 	uintptr_t start = (uintptr_t) PCI_IOBASE;
 	uintptr_t addr = (uintptr_t) p;
 
 	if (addr >= start && addr < start + IO_SPACE_LIMIT)
 		return;
 	iounmap(p);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
-- 
2.25.1