asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

PATCH Superseded Niklas Schnelle 3 participants 6 messages Apr 15, 2021

Subsystems (3)

s390 Generic include/asm header files SPARC + UltraSPARC (sparc/sparc64)

lore

Share & tools

lore

Niklas Schnelle

author

2021-04-15 12:37 UTC #0 lore raw

v2 cover asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

Hi,

This is version 2 of my attempt to get rid of a clang -Wnull-pointer-arithmetic warning for the use of PCI_IOBASE in asm-generic/io.h. This was originally found on s390 but should apply to all platforms leaving PCI_IOBASE undefined while making use of the inb() and friends helpers from asm-generic/io.h.

Thanks,
Niklas

Changes since v1:
- Added patch to explicitly set PCI_IOBASE to 0 on sparc as suggested by Arnd Bergmann
- Instead of working around the warning with a uintptr_t PCI_IOBASE make inb() and friends explicitly WARN_ONCE() and return 0xff... (Arnd)

Niklas Schnelle (2):
sparc: explicitly set PCI_IOBASE to 0 asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on
PCI_IOBASE

 arch/sparc/include/asm/io.h |  4 +++
 include/asm-generic/io.h    | 55 ++++++++++++++++++++++++++++++++++---
 2 files changed, 55 insertions(+), 4 deletions(-)

Signature · 1 line

2.25.1

Niklas Schnelle

author

2021-04-15 12:37 UTC #1 lore raw

PATCH v2 1/2 sparc: explicitly set PCI_IOBASE to 0

Instead of relying on the fallback in asm-generic/io.h which sets PCI_IOBASE 0 if it is not defined set it explicitly.

Link https://lore.kernel.org/lkml/CAK8P3a3PK9zyeP4ymELtc2ZYnymECoACiigw9Za+pvSJpCk5=g@mail.gmail.com/ open here

Signed-off-by Niklas Schnelle <[email protected]>

---
 arch/sparc/include/asm/io.h | 4 ++++
 1 file changed, 4 insertions(+)

arch/sparc/include/asm/io.h +4 -0

index 2eefa526b38f..100992ba1317 100644
@@ -1,6 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef ___ASM_SPARC_IO_H
 #define ___ASM_SPARC_IO_H
+
+/* On LEON I/O Space is accessed through low iomem */
+#define PCI_IOBASE ((void __iomem *)0)
+
 #if defined(__sparc__) && defined(__arch64__)
 #include <asm/io_64.h>
 #else

Signature · 1 line

2.25.1

David Laight

2021-04-15 16:10 UTC #2 lore raw

RE: [PATCH v2 1/2] sparc: explicitly set PCI_IOBASE to 0

From: Niklas Schnelle

Quoted 27 lines

Sent: 15 April 2021 13:37
Instead of relying on the fallback in asm-generic/io.h which sets PCI_IOBASE 0 if it is not defined set it explicitly.
Link https://lore.kernel.org/lkml/CAK8P3a3PK9zyeP4ymELtc2ZYnymECoACiigw9Za+pvSJpCk5=g@mail.gmail.com/ open here
Signed-off-by Niklas Schnelle <[email protected]>
---
 arch/sparc/include/asm/io.h | 4 ++++
 1 file changed, 4 insertions(+)
arch/sparc/include/asm/io.h +4 -1
index 2eefa526b38f..100992ba1317 100644
@@ -1,6 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef ___ASM_SPARC_IO_H
 #define ___ASM_SPARC_IO_H
+
+/* On LEON I/O Space is accessed through low iomem */
+#define PCI_IOBASE ((void __iomem *)0)
+
 #if defined(__sparc__) && defined(__arch64__)
 #include <asm/io_64.h>
 #else
--

Quoted 1 line

2.25.1

Not sure the comment is informative enough.
Maybe something like:

/*
* On LEON PCI addresses below 64k are converted to IO accesses.
* io_remap_xxx() (whatever is it called) returns a kernel virtual
* address in the PCI window so inb() doesn't need to add an offset. */

That'll save the next person doing a lot of digging.

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)

Niklas Schnelle

author

2021-04-15 12:37 UTC #3 lore raw

PATCH v2 2/2 asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

In reply to Niklas Schnelle

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 <[email protected]>

---
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 | 55 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 4 deletions(-)

include/asm-generic/io.h +51 -4

index c6af40ce03be..e6c549b678c4 100644
@@ -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

Signature · 1 line

2.25.1

kernel test robot

build bot

2021-04-15 15:45 UTC #4 lore raw

I love your patch! Yet something to improve:

Hi Niklas,

I love your patch! Yet something to improve:

[auto build test ERROR on soc/for-next]
[also build test ERROR on sparc/master asm-generic/master sparc-next/master v5.12-rc7 next-20210415] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Niklas-Schnelle/asm-generic-io-h-Silence-Wnull-pointer-arithmetic-warning-on-PCI_IOBASE/20210415-203919
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: nds32-allnoconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0

reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/f0394115b166f960f12fc7bc48362d0d19f67883
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Niklas-Schnelle/asm-generic-io-h-Silence-Wnull-pointer-arithmetic-warning-on-PCI_IOBASE/20210415-203919 git checkout f0394115b166f960f12fc7bc48362d0d19f67883
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=nds32

If you fix the issue, kindly add following tag as appropriate

Reported-by kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

In file included from arch/nds32/include/asm/io.h:82,
from arch/nds32/kernel/vdso/gettimeofday.c:7:
include/asm-generic/io.h: In function 'ioport_map':

>> include/asm-generic/io.h:1071:44: error: 'PCI_IOBASE' undeclared (first use in this function)
    1071 |  return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
         |                                            ^~~~~~~~~~
   include/asm-generic/io.h:1071:44: note: each undeclared identifier is reported only once for each function it appears in
   include/asm-generic/io.h: In function '__pci_ioport_unmap':
   include/asm-generic/io.h:1076:32: error: 'PCI_IOBASE' undeclared (first use in this function)
    1076 |  uintptr_t start = (uintptr_t) PCI_IOBASE;
         |                                ^~~~~~~~~~

arch/nds32/kernel/vdso/gettimeofday.c: At top level:
arch/nds32/kernel/vdso/gettimeofday.c:158:13: warning: no previous prototype for '__vdso_clock_gettime' [-Wmissing-prototypes]
158 | notrace int __vdso_clock_gettime(clockid_t clkid, struct __kernel_old_timespec *ts)
| ^~~~~~~~~~~~~~~~~~~~
arch/nds32/kernel/vdso/gettimeofday.c:206:13: warning: no previous prototype for '__vdso_clock_getres' [-Wmissing-prototypes]
206 | notrace int __vdso_clock_getres(clockid_t clk_id, struct __kernel_old_timespec *res)
| ^~~~~~~~~~~~~~~~~~~
arch/nds32/kernel/vdso/gettimeofday.c:246:13: warning: no previous prototype for '__vdso_gettimeofday' [-Wmissing-prototypes]
246 | notrace int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
| ^~~~~~~~~~~~~~~~~~~
--
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
In file included from arch/nds32/include/asm/io.h:82,
from arch/nds32/kernel/vdso/gettimeofday.c:7:
include/asm-generic/io.h: In function 'ioport_map':

>> include/asm-generic/io.h:1071:44: error: 'PCI_IOBASE' undeclared (first use in this function)
    1071 |  return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
         |                                            ^~~~~~~~~~
   include/asm-generic/io.h:1071:44: note: each undeclared identifier is reported only once for each function it appears in
   include/asm-generic/io.h: In function '__pci_ioport_unmap':
   include/asm-generic/io.h:1076:32: error: 'PCI_IOBASE' undeclared (first use in this function)
    1076 |  uintptr_t start = (uintptr_t) PCI_IOBASE;
         |                                ^~~~~~~~~~

arch/nds32/kernel/vdso/gettimeofday.c: At top level:
arch/nds32/kernel/vdso/gettimeofday.c:158:13: warning: no previous prototype for '__vdso_clock_gettime' [-Wmissing-prototypes]
158 | notrace int __vdso_clock_gettime(clockid_t clkid, struct __kernel_old_timespec *ts)
| ^~~~~~~~~~~~~~~~~~~~
arch/nds32/kernel/vdso/gettimeofday.c:206:13: warning: no previous prototype for '__vdso_clock_getres' [-Wmissing-prototypes]
206 | notrace int __vdso_clock_getres(clockid_t clk_id, struct __kernel_old_timespec *res)
| ^~~~~~~~~~~~~~~~~~~
arch/nds32/kernel/vdso/gettimeofday.c:246:13: warning: no previous prototype for '__vdso_gettimeofday' [-Wmissing-prototypes]
246 | notrace int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
| ^~~~~~~~~~~~~~~~~~~
make[2]: *** [scripts/Makefile.build:271: arch/nds32/kernel/vdso/gettimeofday.o] Error 1
make[2]: Target 'include/generated/vdso-offsets.h' not remade because of errors.
make[1]: *** [arch/nds32/Makefile:63: vdso_prepare] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:215: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.

vim +/PCI_IOBASE +1071 include/asm-generic/io.h

7c566bb5e4d5fb0 Hector Martin 2021-02-11 1063
ce816fa88cca083 Uwe Kleine-König 2014-04-07 1064 #ifdef CONFIG_HAS_IOPORT_MAP

3f7e212df82ca04 Arnd Bergmann     2009-05-13  1065  #ifndef CONFIG_GENERIC_IOMAP
9216efafc52ff99 Thierry Reding    2014-10-01  1066  #ifndef ioport_map
9216efafc52ff99 Thierry Reding    2014-10-01  1067  #define ioport_map ioport_map
3f7e212df82ca04 Arnd Bergmann     2009-05-13  1068  static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
3f7e212df82ca04 Arnd Bergmann     2009-05-13  1069  {
500dd232449e7c0 Andrew Murray     2018-09-13  1070  	port &= IO_SPACE_LIMIT;
500dd232449e7c0 Andrew Murray     2018-09-13 @1071  	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
3f7e212df82ca04 Arnd Bergmann     2009-05-13  1072  }
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1073  #define __pci_ioport_unmap __pci_ioport_unmap
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1074  static inline void __pci_ioport_unmap(void __iomem *p)
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1075  {
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1076  	uintptr_t start = (uintptr_t) PCI_IOBASE;
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1077  	uintptr_t addr = (uintptr_t) p;
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1078  
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1079  	if (addr >= start && addr < start + IO_SPACE_LIMIT)
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1080  		return;
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1081  	iounmap(p);
f5810e5c329238b Lorenzo Pieralisi 2020-09-16  1082  }
9216efafc52ff99 Thierry Reding    2014-10-01  1083  #endif
3f7e212df82ca04 Arnd Bergmann     2009-05-13  1084

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

kernel test robot

build bot

2021-04-15 16:26 UTC #5 lore raw

In reply to Niklas Schnelle

I love your patch! Yet something to improve:

Hi Niklas,

I love your patch! Yet something to improve:

[auto build test ERROR on soc/for-next]
[also build test ERROR on sparc/master asm-generic/master v5.12-rc7 next-20210415] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Niklas-Schnelle/asm-generic-io-h-Silence-Wnull-pointer-arithmetic-warning-on-PCI_IOBASE/20210415-203919
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: arc-randconfig-s031-20210415 (attached as .config)
compiler: arc-elf-gcc (GCC) 9.3.0

reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.3-280-g2cd6d34e-dirty
# https://github.com/0day-ci/linux/commit/f0394115b166f960f12fc7bc48362d0d19f67883
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Niklas-Schnelle/asm-generic-io-h-Silence-Wnull-pointer-arithmetic-warning-on-PCI_IOBASE/20210415-203919 git checkout f0394115b166f960f12fc7bc48362d0d19f67883
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=arc

If you fix the issue, kindly add following tag as appropriate

Reported-by kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

In file included from arch/arc/include/asm/io.h:233,

                    from drivers/w1/w1_io.c:6:
   include/asm-generic/io.h: In function '_inb':
>> include/asm-generic/io.h:465:2: error: implicit declaration of function 'WARN_ONCE' [-Werror=implicit-function-declaration]
     465 |  WARN_ONCE(1, "No I/O port support\n");
         |  ^~~~~~~~~

cc1: some warnings being treated as errors

vim +/WARN_ONCE +465 include/asm-generic/io.h

446
447 /*
448 * {in,out}{b,w,l}() access little endian I/O. {in,out}{b,w,l}_p() can be
449 * implemented on hardware that needs an additional delay for I/O accesses to
450 * take effect.
451 */
452
453 #if !defined(inb) && !defined(_inb)
454 #define _inb _inb
455 static inline u8 _inb(unsigned long addr)
456 {
457 #ifdef PCI_IOBASE
458 u8 val;
459
460 __io_pbr();
461 val = __raw_readb(PCI_IOBASE + addr);
462 __io_par(val);
463 return val;
464 #else

 > 465		WARN_ONCE(1, "No I/O port support\n");

466 return ~0;
467 #endif
468 }
469 #endif
470

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org