[PATCH v5 0/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

[PATCH v5 0/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

[Niklas Schnelle]

Hi,

This is version 5 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.

This applies cleanly and was compile tested on top of v5.12 for the
previously broken ARC, nds32, h8300 and risc-v architecture. It also
applies cleanly on v5.13-rc1 for which I boot tested it on s390.

I did boot test this only on x86_64 and s390x the former implements
inb() itself while the latter would emit a WARN_ONCE() but no drivers
use inb().

Thanks,
Niklas

Changes since v4:
- Added Link to patch 4 (Arnd)
- Improved comment on RISC-V patch mentioning current brokeness (Arnd)

Changes since v3:
- Changed the subject of the last patch to better reflect the actual
  change i.e. the addition of WARN_ONCE() to the helpers not the
  silencing of the clang warning
- Added asm/bug.h to asm-generic/io.h so it doesn't have to be included
  previously by all arches to be available for the WARN_ONCE()
- Added patch for risc-v which defines PCI_IOBASE except when compiled
  for nommu

Changes since v2:
- Improved comment for SPARC PCI_IOBASE definition as suggested
  by David Laight
- Added a patch for ARC which is missing the asm/bug.h include for
  WARN_ONCE() (kernel test robot)
- Added ifdefs to ioport_map() and __pci_ioport_map() since apparently
  at least test configs enable CONFIG_HAS_IOPORT_MAP even on
  architectures which leave PCI_IOBASE unset (kernel test robot for
  nds32 and ARC).

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
  Bergmann)
Niklas Schnelle (3):
  sparc: explicitly set PCI_IOBASE to 0
  risc-v: Use generic io.h helpers for nommu
  asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

 arch/riscv/include/asm/io.h |  5 +--
 arch/sparc/include/asm/io.h |  8 +++++
 include/asm-generic/io.h    | 65 ++++++++++++++++++++++++++++++++++---
 3 files changed, 72 insertions(+), 6 deletions(-)

-- 
2.25.1

[PATCH v5 1/3] sparc: explicitly set PCI_IOBASE to 0

[Niklas Schnelle]

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/
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 arch/sparc/include/asm/io.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/sparc/include/asm/io.h b/arch/sparc/include/asm/io.h
index 2eefa526b38f..c019e50702c1 100644
--- a/arch/sparc/include/asm/io.h
+++ b/arch/sparc/include/asm/io.h
@@ -1,6 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef ___ASM_SPARC_IO_H
 #define ___ASM_SPARC_IO_H
+
+/*
+ * On LEON PCI addresses below 64k are converted to IO accesses.
+ * io_remap_xxx() returns a kernel virtual address in the PCI window so
+ * inb() doesn't need to add an offset.
+ */
+#define PCI_IOBASE ((void __iomem *)0)
+
 #if defined(__sparc__) && defined(__arch64__)
 #include <asm/io_64.h>
 #else
-- 
2.25.1

[PATCH v5 2/3] risc-v: Use generic io.h helpers for nommu

[Niklas Schnelle]

From: Niklas Schnelle <niklas@komani.de>

Without MMU support PCI_IOBASE is left undefined because PCI_IO_END is
VMEMMAP_START. Nevertheless the in*()/out*() helper macros are left
defined with uses of PCI_IOBASE.

At the moment this only compiles because asm-generic/io.h defines
PCI_IOBASE as 0 if it is undefined and so at macro expansion PCI_IOBASE
is defined. This leads to compilation errors when asm-generic/io.h is
changed to leave PCI_IOBASE undefined.  More importantly it is currently
broken at runtime, as accessing a fixed I/O port number of an ISA device
on NOMMU RISC-V would turn into a NULL pointer dereference.

Instead only define the in*()/out*() helper macros with MMU support and
fall back to the asm-generic/io.h helper stubs otherwise.

Signed-off-by: Niklas Schnelle <niklas@komani.de>
---
 arch/riscv/include/asm/io.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index c025a746a148..31a8b98c0f13 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -23,12 +23,12 @@
 #include <asm/mmio.h>
 
 /*
- *  I/O port access constants.
+ *  I/O port access constants. Without MMU support leave PCI_IOBASE undefined
+ *  and fall back to generic stubs for I/O access routines.
  */
 #ifdef CONFIG_MMU
 #define IO_SPACE_LIMIT		(PCI_IO_SIZE - 1)
 #define PCI_IOBASE		((void __iomem *)PCI_IO_START)
-#endif /* CONFIG_MMU */
 
 /*
  * Emulation routines for the port-mapped IO space used by some PCI drivers.
@@ -145,6 +145,7 @@ __io_writes_outs(writes, u64, q, __io_bw(), __io_aw())
 __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 #define outsq(addr, buffer, count) __outsq((void __iomem *)addr, buffer, count)
 #endif
+#endif /* CONFIG_MMU */
 
 #include <asm-generic/io.h>
 
-- 
2.25.1

[PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[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.

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.

Link: https://lore.kernel.org/lkml/20210421111759.2059976-1-schnelle@linux.ibm.com/
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 include/asm-generic/io.h | 65 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index e93375c710b9..7b523683c241 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -8,6 +8,7 @@
 #define __ASM_GENERIC_IO_H
 
 #include <asm/page.h> /* I/O is all done through memory accesses */
+#include <linux/bug.h>
 #include <linux/string.h> /* for memset() and memcpy() */
 #include <linux/types.h>
 
@@ -440,10 +441,6 @@ 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 +455,17 @@ 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 +473,17 @@ 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 +491,17 @@ 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 +509,13 @@ 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 +523,13 @@ 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 +537,13 @@ 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 +630,11 @@ 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 +642,11 @@ 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 +654,11 @@ 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 +667,11 @@ 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 +680,11 @@ 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 +693,11 @@ 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
 
@@ -1020,18 +1068,27 @@ 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 PCI_IOBASE
 	port &= IO_SPACE_LIMIT;
 	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+	return NULL;
+#endif
 }
 #define __pci_ioport_unmap __pci_ioport_unmap
 static inline void __pci_ioport_unmap(void __iomem *p)
 {
+#ifdef PCI_IOBASE
 	uintptr_t start = (uintptr_t) PCI_IOBASE;
 	uintptr_t addr = (uintptr_t) p;
 
 	if (addr >= start && addr < start + IO_SPACE_LIMIT)
 		return;
 	iounmap(p);
+#else
+	WARN_ONCE(1, "No I/O port support\n");
+#endif
 }
 #endif
 
-- 
2.25.1

Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 5347 bytes --]

Hi Niklas,

I love your patch! Perhaps something to improve:

[auto build test WARNING on soc/for-next]
[also build test WARNING on asm-generic/master v5.13-rc1 next-20210510]
[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/20210510-165435
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: h8300-randconfig-r035-20210510 (attached as .config)
compiler: h8300-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/fa75946a8988026bee808b5840438a3908f0a65b
        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/20210510-165435
        git checkout fa75946a8988026bee808b5840438a3908f0a65b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=h8300 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:10,
                    from drivers/media/rc/nuvoton-cir.c:25:
   include/linux/scatterlist.h: In function 'sg_set_buf':
   include/asm-generic/page.h:89:50: warning: ordered comparison of pointer with null pointer [-Wextra]
      89 | #define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
         |                                                  ^~
   include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
      78 | # define unlikely(x) __builtin_expect(!!(x), 0)
         |                                          ^
   include/linux/scatterlist.h:137:2: note: in expansion of macro 'BUG_ON'
     137 |  BUG_ON(!virt_addr_valid(buf));
         |  ^~~~~~
   include/linux/scatterlist.h:137:10: note: in expansion of macro 'virt_addr_valid'
     137 |  BUG_ON(!virt_addr_valid(buf));
         |          ^~~~~~~~~~~~~~~
   drivers/media/rc/nuvoton-cir.c: In function 'nvt_get_rx_ir_data':
>> drivers/media/rc/nuvoton-cir.c:761:15: warning: iteration 32 invokes undefined behavior [-Waggressive-loop-optimizations]
     761 |   nvt->buf[i] = nvt_cir_reg_read(nvt, CIR_SRXFIFO);
         |   ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/media/rc/nuvoton-cir.c:760:2: note: within this loop
     760 |  for (i = 0; i < fifocount; i++)
         |  ^~~


vim +761 drivers/media/rc/nuvoton-cir.c

fbdc781c6ba974 drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-08  747  
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  748  /* copy data from hardware rx fifo into driver buffer */
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  749  static void nvt_get_rx_ir_data(struct nvt_dev *nvt)
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  750  {
6db0168821fa4e drivers/media/rc/nuvoton-cir.c Heiner Kallweit 2016-08-02  751  	u8 fifocount;
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  752  	int i;
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  753  
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  754  	/* Get count of how many bytes to read from RX FIFO */
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  755  	fifocount = nvt_cir_reg_read(nvt, CIR_RXFCONT);
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  756  
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  757  	nvt_dbg("attempting to fetch %u bytes from hw rx fifo", fifocount);
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  758  
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  759  	/* Read fifocount bytes from CIR Sample RX FIFO register */
6db0168821fa4e drivers/media/rc/nuvoton-cir.c Heiner Kallweit 2016-08-02  760  	for (i = 0; i < fifocount; i++)
6db0168821fa4e drivers/media/rc/nuvoton-cir.c Heiner Kallweit 2016-08-02 @761  		nvt->buf[i] = nvt_cir_reg_read(nvt, CIR_SRXFIFO);
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  762  
bacf8351f23cfd drivers/media/rc/nuvoton-cir.c Heiner Kallweit 2016-08-02  763  	nvt->pkts = fifocount;
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  764  	nvt_dbg("%s: pkts now %d", __func__, nvt->pkts);
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  765  
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  766  	nvt_process_rx_ir_data(nvt);
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  767  }
6d2f5c27880c2c drivers/media/IR/nuvoton-cir.c Jarod Wilson    2010-10-07  768  

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

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 26536 bytes --]

Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 3345 bytes --]

Hi Niklas,

I love your patch! Perhaps something to improve:

[auto build test WARNING on soc/for-next]
[also build test WARNING on asm-generic/master v5.13-rc1 next-20210510]
[cannot apply to sparc-next/master]
[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/20210510-165435
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: openrisc-randconfig-r025-20210510 (attached as .config)
compiler: or1k-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/fa75946a8988026bee808b5840438a3908f0a65b
        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/20210510-165435
        git checkout fa75946a8988026bee808b5840438a3908f0a65b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:10,
                    from include/linux/list.h:9,
                    from include/linux/module.h:12,
                    from drivers/net/arcnet/com20020.c:31:
   drivers/net/arcnet/com20020.c: In function 'com20020_reset':
>> include/linux/compiler.h:70:32: warning: 'inbyte' is used uninitialized in this function [-Wuninitialized]
      70 |   (__if_trace.miss_hit[1]++,1) :  \
         |                                ^
   drivers/net/arcnet/com20020.c:286:9: note: 'inbyte' was declared here
     286 |  u_char inbyte;
         |         ^~~~~~


vim +/inbyte +70 include/linux/compiler.h

a15fd609ad53a6 Linus Torvalds 2019-03-20  59  
a15fd609ad53a6 Linus Torvalds 2019-03-20  60  #define __trace_if_value(cond) ({			\
2bcd521a684cc9 Steven Rostedt 2008-11-21  61  	static struct ftrace_branch_data		\
e04462fb82f8dd Miguel Ojeda   2018-09-03  62  		__aligned(4)				\
33def8498fdde1 Joe Perches    2020-10-21  63  		__section("_ftrace_branch")		\
a15fd609ad53a6 Linus Torvalds 2019-03-20  64  		__if_trace = {				\
2bcd521a684cc9 Steven Rostedt 2008-11-21  65  			.func = __func__,		\
2bcd521a684cc9 Steven Rostedt 2008-11-21  66  			.file = __FILE__,		\
2bcd521a684cc9 Steven Rostedt 2008-11-21  67  			.line = __LINE__,		\
2bcd521a684cc9 Steven Rostedt 2008-11-21  68  		};					\
a15fd609ad53a6 Linus Torvalds 2019-03-20  69  	(cond) ?					\
a15fd609ad53a6 Linus Torvalds 2019-03-20 @70  		(__if_trace.miss_hit[1]++,1) :		\
a15fd609ad53a6 Linus Torvalds 2019-03-20  71  		(__if_trace.miss_hit[0]++,0);		\
a15fd609ad53a6 Linus Torvalds 2019-03-20  72  })
a15fd609ad53a6 Linus Torvalds 2019-03-20  73  

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

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Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[Arnd Bergmann]

On Mon, May 10, 2021 at 3:30 PM kernel test robot <lkp@intel.com> wrote:
> All warnings (new ones prefixed by >>):
>
>    In file included from include/linux/kernel.h:10,
>                     from include/linux/list.h:9,
>                     from include/linux/module.h:12,
>                     from drivers/net/arcnet/com20020.c:31:
>    drivers/net/arcnet/com20020.c: In function 'com20020_reset':
> >> include/linux/compiler.h:70:32: warning: 'inbyte' is used uninitialized in this function [-Wuninitialized]
>       70 |   (__if_trace.miss_hit[1]++,1) :  \
>          |                                ^
>    drivers/net/arcnet/com20020.c:286:9: note: 'inbyte' was declared here
>      286 |  u_char inbyte;
>          |         ^~~~~~

This looks like a real problem with the patch: the insb()/insw()/insl() helpers
should memset(buffer, 0xff, size) to avoid using random stack data.

        Arnd

Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[Arnd Bergmann]

On Mon, May 10, 2021 at 3:08 PM kernel test robot <lkp@intel.com> wrote:
>
>    In file included from include/linux/kernel.h:10,
>                     from drivers/media/rc/nuvoton-cir.c:25:
>    include/linux/scatterlist.h: In function 'sg_set_buf':
>    include/asm-generic/page.h:89:50: warning: ordered comparison of pointer with null pointer [-Wextra]
>       89 | #define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
>          |                                                  ^~
>    include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
>       78 | # define unlikely(x) __builtin_expect(!!(x), 0)
>          |                                          ^
>    include/linux/scatterlist.h:137:2: note: in expansion of macro 'BUG_ON'
>      137 |  BUG_ON(!virt_addr_valid(buf));
>          |  ^~~~~~
>    include/linux/scatterlist.h:137:10: note: in expansion of macro 'virt_addr_valid'
>      137 |  BUG_ON(!virt_addr_valid(buf));
>          |          ^~~~~~~~~~~~~~~
>    drivers/media/rc/nuvoton-cir.c: In function 'nvt_get_rx_ir_data':
> >> drivers/media/rc/nuvoton-cir.c:761:15: warning: iteration 32 invokes undefined behavior [-Waggressive-loop-optimizations]
>      761 |   nvt->buf[i] = nvt_cir_reg_read(nvt, CIR_SRXFIFO);

I think you can ignore this one, it's a preexisting issue with this
driver that gets uncovered by your patch: if "fifocount" is read from
a broken device as 0xff, the loop causes a buffer overflow.

The code is already unreachable because the interrupt handler
will have aborted already, so the compiler's dead code elimination
should have shut up that warning, but adding a range check
before the loop would address this as well.

As far as I can tell, this warning only shows up when building with
"make W=1".

       Arnd

Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with undefined PCI_IOBASE

[Niklas Schnelle]

On Mon, 2021-05-10 at 15:43 +0200, Arnd Bergmann wrote:
> On Mon, May 10, 2021 at 3:30 PM kernel test robot <lkp@intel.com> wrote:
> > All warnings (new ones prefixed by >>):
> > 
> >    In file included from include/linux/kernel.h:10,
> >                     from include/linux/list.h:9,
> >                     from include/linux/module.h:12,
> >                     from drivers/net/arcnet/com20020.c:31:
> >    drivers/net/arcnet/com20020.c: In function 'com20020_reset':
> > > > include/linux/compiler.h:70:32: warning: 'inbyte' is used uninitialized in this function [-Wuninitialized]
> >       70 |   (__if_trace.miss_hit[1]++,1) :  \
> >          |                                ^
> >    drivers/net/arcnet/com20020.c:286:9: note: 'inbyte' was declared here
> >      286 |  u_char inbyte;
> >          |         ^~~~~~
> 
> This looks like a real problem with the patch: the insb()/insw()/insl() helpers
> should memset(buffer, 0xff, size) to avoid using random stack data.
> 
>         Arnd


Yes I agree, will send a v6 shortly. Thanks.