Re: [PATCH 5/6] mips: drop GENERIC_IOMAP wrapper

On Tue, Mar 18, 2025, at 21:39, Nathan Chancellor wrote:
> On Sat, Mar 15, 2025 at 11:59:06AM +0100, Arnd Bergmann wrote:
>> From: Arnd Bergmann <[email protected]>
>> diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h

>>  void __ioread64_copy(void *to, const void __iomem *from, size_t count);
>>  
>> +#ifdef CONFIG_PCI_DRIVERS_LEGACY
>> +struct pci_dev;
>> +void pci_iounmap(struct pci_dev *dev, void __iomem *addr);
>> +#define pci_iounmap pci_iounmap
>> +#endif
>> +
>>  #include <asm-generic/io.h>
>>  
>>  static inline void *isa_bus_to_virt(unsigned long address)
>> diff --git a/arch/mips/lib/iomap-pci.c b/arch/mips/lib/iomap-pci.c
>> index a9cb28813f0b..2f82c776c6d0 100644
>> --- a/arch/mips/lib/iomap-pci.c
>> +++ b/arch/mips/lib/iomap-pci.c
>> @@ -43,4 +43,13 @@ void __iomem *__pci_ioport_map(struct pci_dev *dev,
>>  	return (void __iomem *) (ctrl->io_map_base + port);
>>  }
>>  
>> +void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
>> +{
>> +	struct pci_controller *ctrl = dev->bus->sysdata;
>> +	void __iomem *base = (void __iomem *)ctrl->io_map_base;
>> +
>> +	if (addr < base || addr > (base + resource_size(ctrl->io_resource)))
>> +		iounmap(addr);
>> +}
>> +
>>  #endif /* CONFIG_PCI_DRIVERS_LEGACY */
>> -- 
>> 2.39.5
>> 
>
> This change as commit 976bf3aec388 ("mips: drop GENERIC_IOMAP wrapper") in
> -next introduces new instances of -Wnull-pointer-arithmetic when building
> certain mips configurations with clang.
>

Thanks for the report, I missed that the generic ioport_map() function
is missing the PCI_IOBASE macro, we should probably remove that from
the asm-generic/io.h header and require architectures to define it
themselves, since the NULL fallback is pretty much always wrong.

There is also a type mismatch between the MIPS
PCI_IOBASE/mips_io_port_base and the one that asm-generic/io.h
expects, so I had to add a couple of extra typecasts, which
makes it rather ugly, but the change below seems to work.

     Arnd

diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 1fe56d1870a6..78c6573f91f2 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -544,12 +544,16 @@ extern void (*_dma_cache_inv)(unsigned long start, unsigned long size);
 
 void __ioread64_copy(void *to, const void __iomem *from, size_t count);
 
-#ifdef CONFIG_PCI_DRIVERS_LEGACY
+#if defined(CONFIG_PCI) && defined(CONFIG_PCI_DRIVERS_LEGACY)
 struct pci_dev;
 void pci_iounmap(struct pci_dev *dev, void __iomem *addr);
 #define pci_iounmap pci_iounmap
 #endif
 
+#ifndef PCI_IOBASE
+#define PCI_IOBASE ((void __iomem *)mips_io_port_base)
+#endif
+
 #include <asm-generic/io.h>
 
 static inline void *isa_bus_to_virt(unsigned long address)
diff --git a/arch/mips/include/asm/mach-loongson64/spaces.h b/arch/mips/include/asm/mach-loongson64/spaces.h
index ce04e998a37b..dbd26db5f2c5 100644
--- a/arch/mips/include/asm/mach-loongson64/spaces.h
+++ b/arch/mips/include/asm/mach-loongson64/spaces.h
@@ -7,9 +7,10 @@
 #endif /* CONFIG_64BIT */
 
 /* Skip 128k to trap NULL pointer dereferences */
-#define PCI_IOBASE	_AC(0xc000000000000000 + SZ_128K, UL)
+#define PCI_PORT_BASE	_AC(0xc000000000000000 + SZ_128K, UL)
+#define PCI_IOBASE	(void __iomem *)PCI_PORT_BASE
 #define PCI_IOSIZE	SZ_16M
-#define MAP_BASE	(PCI_IOBASE + PCI_IOSIZE)
+#define MAP_BASE	(PCI_PORT_BASE + PCI_IOSIZE)
 
 #define IO_SPACE_LIMIT  (PCI_IOSIZE - 1)
 
diff --git a/arch/mips/include/asm/mach-ralink/spaces.h b/arch/mips/include/asm/mach-ralink/spaces.h
index a9f0570d0f04..a63d106c89c6 100644
--- a/arch/mips/include/asm/mach-ralink/spaces.h
+++ b/arch/mips/include/asm/mach-ralink/spaces.h
@@ -2,7 +2,7 @@
 #ifndef __ASM_MACH_RALINK_SPACES_H_
 #define __ASM_MACH_RALINK_SPACES_H_
 
-#define PCI_IOBASE	mips_io_port_base
+#define PCI_IOBASE	(void __iomem *)mips_io_port_base
 #define PCI_IOSIZE	SZ_64K
 #define IO_SPACE_LIMIT	(PCI_IOSIZE - 1)
 
diff --git a/arch/mips/loongson64/init.c b/arch/mips/loongson64/init.c
index a35dd7311795..b9f90f33fc9a 100644
--- a/arch/mips/loongson64/init.c
+++ b/arch/mips/loongson64/init.c
@@ -128,7 +128,7 @@ void __init prom_init(void)
 	}
 
 	/* init base address of io space */
-	set_io_port_base(PCI_IOBASE);
+	set_io_port_base((unsigned long)PCI_IOBASE);
 
 	if (loongson_sysconf.early_config)
 		loongson_sysconf.early_config();
@@ -178,7 +178,7 @@ static int __init add_legacy_isa_io(struct fwnode_handle *fwnode, resource_size_
 		return -EINVAL;
 	}
 
-	vaddr = PCI_IOBASE + range->io_start;
+	vaddr = (unsigned long)PCI_IOBASE + range->io_start;
 
 	vmap_page_range(vaddr, vaddr + size, hw_start, pgprot_device(PAGE_KERNEL));