powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
The Powerpc clang builds failed due to following warnings / errors on the Linux next-20240416 tag.
Powerpc: - tqm8xx_defconfig + clang-17 - Failed - allnoconfig + clang-17 - Failed - tinyconfig + clang-17 - Failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log: -------- In file included from arch/powerpc/kernel/ptrace/ptrace.c:19: In file included from include/linux/syscalls.h:93: In file included from include/trace/syscall.h:7: In file included from include/linux/trace_events.h:9: In file included from include/linux/hardirq.h:11: In file included from arch/powerpc/include/asm/hardirq.h:6: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:14: In file included from arch/powerpc/include/asm/io.h:672: arch/powerpc/include/asm/io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] 43 | DEF_PCI_AC_NORET(insb, (unsigned long p, void *b, unsigned long c), | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 44 | (p, b, c), pio, p) | ~~~~~~~~~~~~~~~~~~
Links: - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240416/tes... - https://storage.tuxsuite.com/public/linaro/lkft/builds/2fAvI3mKJ0dTHcazPrLl2...
-- Linaro LKFT https://lkft.linaro.org
On Tue, Apr 16, 2024 at 03:02:52PM +0530, Naresh Kamboju wrote:
In file included from arch/powerpc/include/asm/io.h:672: arch/powerpc/include/asm/io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
It is not UB, but just undefined: the program is meaningless.
It is not a null pointer but even a null pointer constant here. It matters in places, including here.
It would help if the warnings were more correct :-(
Segher
From: Segher Boessenkool
Sent: 16 April 2024 11:38
On Tue, Apr 16, 2024 at 03:02:52PM +0530, Naresh Kamboju wrote:
In file included from arch/powerpc/include/asm/io.h:672: arch/powerpc/include/asm/io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
It is not UB, but just undefined: the program is meaningless.
It is not a null pointer but even a null pointer constant here. It matters in places, including here.
It would help if the warnings were more correct :-(
Isn't it only a problem because the NULL pointer isn't required to be the all-zero bit pattern?
So when do we get a warning from using memset() on a structure that contains pointers? Since it is equally buggy.
Has anyone ever seen a system where NULL wasn't 'all zeros'? I've used a system where the 'native' invalid pointer was 'all ones', but even there the C code used 'all zeros'.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Tue, Apr 16, 2024, at 11:32, Naresh Kamboju wrote:
The Powerpc clang builds failed due to following warnings / errors on the Linux next-20240416 tag.
Powerpc:
- tqm8xx_defconfig + clang-17 - Failed
- allnoconfig + clang-17 - Failed
- tinyconfig + clang-17 - Failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
I'm not sure why this showed up now, but there is a series from in progress that will avoid this in the future, as the same issue is present on a couple of other architectures.
The broken definitions are in the !CONFIG_PCI path of
#ifndef CONFIG_PCI #define _IO_BASE 0 #define _ISA_MEM_BASE 0 #define PCI_DRAM_OFFSET 0 #elif defined(CONFIG_PPC32) #define _IO_BASE isa_io_base #define _ISA_MEM_BASE isa_mem_base #define PCI_DRAM_OFFSET pci_dram_offset #else #define _IO_BASE pci_io_base #define _ISA_MEM_BASE isa_mem_base #define PCI_DRAM_OFFSET 0 #endif
Once the series is merged, the !PCI case can disable CONFIG_HAS_IOPORT and move all references to it into #ifdef sections, something like the (incomplete) patch below.
It looks like regardless of this, powerpc can also just set _IO_BASE to ISA_IO_BASE unconditionally, but I could be missing something there.
Arnd
--- diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h index 08c550ed49be..29e002b9316c 100644 --- a/arch/powerpc/include/asm/io.h +++ b/arch/powerpc/include/asm/io.h @@ -36,11 +36,8 @@ extern struct pci_dev *isa_bridge_pcidev; * bases. Most of this file only uses _IO_BASE though which we * define properly based on the platform */ -#ifndef CONFIG_PCI -#define _IO_BASE 0 -#define _ISA_MEM_BASE 0 -#define PCI_DRAM_OFFSET 0 -#elif defined(CONFIG_PPC32) +#ifdef CONFIG_HAS_IOPORT +#ifdef CONFIG_PPC32 #define _IO_BASE isa_io_base #define _ISA_MEM_BASE isa_mem_base #define PCI_DRAM_OFFSET pci_dram_offset @@ -486,8 +483,7 @@ static inline u64 __raw_rm_readq(volatile void __iomem *paddr) * to port it over */
-#ifdef CONFIG_PPC32 - +#if defined(CONFIG_PPC32) && defined(CONFIG_HAS_IOPORT) #define __do_in_asm(name, op) \ static inline unsigned int name(unsigned int port) \ { \ @@ -534,7 +530,7 @@ __do_out_asm(_rec_outb, "stbx") __do_out_asm(_rec_outw, "sthbrx") __do_out_asm(_rec_outl, "stwbrx")
-#endif /* CONFIG_PPC32 */ +#endif /* CONFIG_PPC32 && CONFIG_HAS_IOPORT */
/* The "__do_*" operations below provide the actual "base" implementation * for each of the defined accessors. Some of them use the out_* functions @@ -577,6 +573,7 @@ __do_out_asm(_rec_outl, "stwbrx") #define __do_readq_be(addr) in_be64(PCI_FIX_ADDR(addr)) #endif /* !defined(CONFIG_EEH) */
+#ifdef CONFIG_HAS_IOPORT #ifdef CONFIG_PPC32 #define __do_outb(val, port) _rec_outb(val, port) #define __do_outw(val, port) _rec_outw(val, port) @@ -592,6 +589,7 @@ __do_out_asm(_rec_outl, "stwbrx") #define __do_inw(port) readw((PCI_IO_ADDR)_IO_BASE + port); #define __do_inl(port) readl((PCI_IO_ADDR)_IO_BASE + port); #endif /* !CONFIG_PPC32 */ +#endif
#ifdef CONFIG_EEH #define __do_readsb(a, b, n) eeh_readsb(PCI_FIX_ADDR(a), (b), (n)) @@ -606,12 +604,14 @@ __do_out_asm(_rec_outl, "stwbrx") #define __do_writesw(a, b, n) _outsw(PCI_FIX_ADDR(a),(b),(n)) #define __do_writesl(a, b, n) _outsl(PCI_FIX_ADDR(a),(b),(n))
+#ifdef CONFIG_HAS_IOPORT #define __do_insb(p, b, n) readsb((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) #define __do_insw(p, b, n) readsw((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) #define __do_insl(p, b, n) readsl((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) #define __do_outsb(p, b, n) writesb((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) #define __do_outsw(p, b, n) writesw((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) #define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) +#endif
#define __do_memset_io(addr, c, n) \ _memset_io(PCI_FIX_ADDR(addr), c, n) @@ -689,6 +689,8 @@ static inline void name at \ #define writesb writesb #define writesw writesw #define writesl writesl + +#ifdef CONFIG_HAS_IOPORT #define inb inb #define inw inw #define inl inl @@ -701,6 +703,8 @@ static inline void name at \ #define outsb outsb #define outsw outsw #define outsl outsl +#endif + #ifdef __powerpc64__ #define readq readq #define writeq writeq
On Tue, Apr 16, 2024, at 13:01, Arnd Bergmann wrote:
On Tue, Apr 16, 2024, at 11:32, Naresh Kamboju wrote:
The Powerpc clang builds failed due to following warnings / errors on the Linux next-20240416 tag.
Powerpc:
- tqm8xx_defconfig + clang-17 - Failed
- allnoconfig + clang-17 - Failed
- tinyconfig + clang-17 - Failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
I'm not sure why this showed up now, but there is a series from in progress that will avoid this in the future, as the same issue is present on a couple of other architectures.
I see now, it was introduced by my patch to turn on -Wextra by default. I had tested that patch on all architectures with allmodconfig and defconfig, but I did not test any powerpc configs with PCI disabled.
Arnd
On Tue, Apr 16, 2024 at 01:55:57PM +0200, Arnd Bergmann wrote:
On Tue, Apr 16, 2024, at 13:01, Arnd Bergmann wrote:
On Tue, Apr 16, 2024, at 11:32, Naresh Kamboju wrote:
The Powerpc clang builds failed due to following warnings / errors on the Linux next-20240416 tag.
Powerpc:
- tqm8xx_defconfig + clang-17 - Failed
- allnoconfig + clang-17 - Failed
- tinyconfig + clang-17 - Failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
I'm not sure why this showed up now, but there is a series from in progress that will avoid this in the future, as the same issue is present on a couple of other architectures.
I see now, it was introduced by my patch to turn on -Wextra by default. I had tested that patch on all architectures with allmodconfig and defconfig, but I did not test any powerpc configs with PCI disabled.
I think this warning is clang specific as well... (Maybe clang was included in all architectures but I'm not sure).
regards, dan carpenter
On Tue, Apr 16, 2024, at 14:42, Dan Carpenter wrote:
On Tue, Apr 16, 2024 at 01:55:57PM +0200, Arnd Bergmann wrote:
On Tue, Apr 16, 2024, at 13:01, Arnd Bergmann wrote:
On Tue, Apr 16, 2024, at 11:32, Naresh Kamboju wrote:
The Powerpc clang builds failed due to following warnings / errors on the Linux next-20240416 tag.
Powerpc:
- tqm8xx_defconfig + clang-17 - Failed
- allnoconfig + clang-17 - Failed
- tinyconfig + clang-17 - Failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
I'm not sure why this showed up now, but there is a series from in progress that will avoid this in the future, as the same issue is present on a couple of other architectures.
I see now, it was introduced by my patch to turn on -Wextra by default. I had tested that patch on all architectures with allmodconfig and defconfig, but I did not test any powerpc configs with PCI disabled.
I think this warning is clang specific as well... (Maybe clang was included in all architectures but I'm not sure).
Yes, I did test with both gcc and clang where supported.
Arnd
-
Arnd Bergmann -
Dan Carpenter -
David Laight -
Naresh Kamboju -
Segher Boessenkool