Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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 >> > >> > 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
Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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 > > > > 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
Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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 > > 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
RE: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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)
Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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
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_BASE0
#define _ISA_MEM_BASE 0
#define PCI_DRAM_OFFSET 0
#elif defined(CONFIG_PPC32)
#define _IO_BASEisa_io_base
#define _ISA_MEM_BASE isa_mem_base
#define PCI_DRAM_OFFSET pci_dram_offset
#else
#define _IO_BASEpci_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_OFFSETpci_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
Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
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
