[PATCH v4 1/3] riscv: io: avoid null-pointer arithmetic in PIO helpers

[Yunhui Cui]

The RISC-V PIO helpers derive I/O addresses from PCI_IOBASE in ins*(),
outs*(), and ioport_map().

Under configurations where I/O port support is not available, these
expressions can still be formed during compilation and trigger
-Wnull-pointer-arithmetic warnings from clang.

Introduce a helper for the address calculation and guard the PIO-only
helpers with CONFIG_HAS_IOPORT so unsupported configurations do not
construct these PIO address expressions.

Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
---
 arch/riscv/include/asm/io.h | 26 ++++++++++++++++++--------
 include/asm-generic/io.h    |  4 ++++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 09bb5f57a9d34..6f5d70313c83e 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -56,6 +56,8 @@
 #define __io_pbw()	RISCV_FENCE(iow, o)
 #define __io_paw()	RISCV_FENCE(o, io)
 
+#define PCI_IO_ADDR(addr)	((void __iomem *)((unsigned long)PCI_IOBASE + (addr)))
+
 /*
  * Accesses from a single hart to a single I/O address must be ordered.  This
  * allows us to use the raw read macros, but we still need to fence before and
@@ -102,12 +104,14 @@ __io_reads_ins(reads, u32, l, __io_br(), __io_ar(addr))
 #define readsw(addr, buffer, count) __readsw(addr, buffer, count)
 #define readsl(addr, buffer, count) __readsl(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_reads_ins(ins,  u8, b, __io_pbr(), __io_par(addr))
 __io_reads_ins(ins, u16, w, __io_pbr(), __io_par(addr))
 __io_reads_ins(ins, u32, l, __io_pbr(), __io_par(addr))
-#define insb(addr, buffer, count) __insb(PCI_IOBASE + (addr), buffer, count)
-#define insw(addr, buffer, count) __insw(PCI_IOBASE + (addr), buffer, count)
-#define insl(addr, buffer, count) __insl(PCI_IOBASE + (addr), buffer, count)
+#define insb(addr, buffer, count) __insb(PCI_IO_ADDR(addr), buffer, count)
+#define insw(addr, buffer, count) __insw(PCI_IO_ADDR(addr), buffer, count)
+#define insl(addr, buffer, count) __insl(PCI_IO_ADDR(addr), buffer, count)
+#endif
 
 __io_writes_outs(writes,  u8, b, __io_bw(), __io_aw())
 __io_writes_outs(writes, u16, w, __io_bw(), __io_aw())
@@ -116,25 +120,31 @@ __io_writes_outs(writes, u32, l, __io_bw(), __io_aw())
 #define writesw(addr, buffer, count) __writesw(addr, buffer, count)
 #define writesl(addr, buffer, count) __writesl(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_writes_outs(outs,  u8, b, __io_pbw(), __io_paw())
 __io_writes_outs(outs, u16, w, __io_pbw(), __io_paw())
 __io_writes_outs(outs, u32, l, __io_pbw(), __io_paw())
-#define outsb(addr, buffer, count) __outsb(PCI_IOBASE + (addr), buffer, count)
-#define outsw(addr, buffer, count) __outsw(PCI_IOBASE + (addr), buffer, count)
-#define outsl(addr, buffer, count) __outsl(PCI_IOBASE + (addr), buffer, count)
+#define outsb(addr, buffer, count) __outsb(PCI_IO_ADDR(addr), buffer, count)
+#define outsw(addr, buffer, count) __outsw(PCI_IO_ADDR(addr), buffer, count)
+#define outsl(addr, buffer, count) __outsl(PCI_IO_ADDR(addr), buffer, count)
+#endif
 
 #ifdef CONFIG_64BIT
 __io_reads_ins(reads, u64, q, __io_br(), __io_ar(addr))
 #define readsq(addr, buffer, count) __readsq(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_reads_ins(ins, u64, q, __io_pbr(), __io_par(addr))
-#define insq(addr, buffer, count) __insq(PCI_IOBASE + (addr), buffer, count)
+#define insq(addr, buffer, count) __insq(PCI_IO_ADDR(addr), buffer, count)
+#endif
 
 __io_writes_outs(writes, u64, q, __io_bw(), __io_aw())
 #define writesq(addr, buffer, count) __writesq(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
-#define outsq(addr, buffer, count) __outsq(PCI_IOBASE + (addr), buffer, count)
+#define outsq(addr, buffer, count) __outsq(PCI_IO_ADDR(addr), buffer, count)
+#endif
 #endif
 
 #include <asm-generic/io.h>
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index ca5a1ce6f0f89..d799e5ccc9437 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1205,8 +1205,12 @@ static inline void __iomem *ioremap_np(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 CONFIG_HAS_IOPORT
 	port &= IO_SPACE_LIMIT;
 	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
+#else
+	return NULL;
+#endif
 }
 #define ARCH_HAS_GENERIC_IOPORT_MAP
 #endif
-- 
2.39.5