[xlnx:master 1783/1831] arch/arm64/include/asm/io.h:54:2: warning: 'pmap' may be used uninitialized in this function

tree:   https://github.com/Xilinx/linux-xlnx master
head:   5a0f5d4c5b359939907b9cf874d3a9f8ad72d5e3
commit: 71696811cb3f3c1e8c1ab40ae8f2f72de89363ba [1783/1831] net: xilinx: axiethernet: Split AXIDMA implementation in separate file
config: arm64-allmodconfig (attached as .config)
compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 71696811cb3f3c1e8c1ab40ae8f2f72de89363ba
        # save the attached .config to linux build tree
        GCC_VERSION=7.2.0 make.cross ARCH=arm64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from include/linux/skbuff.h:35,
                    from include/linux/if_ether.h:23,
                    from include/uapi/linux/ethtool.h:19,
                    from include/linux/ethtool.h:18,
                    from include/linux/netdevice.h:41,
                    from drivers/net/ethernet/xilinx/xilinx_axienet.h:12,
                    from drivers/net/ethernet/xilinx/xilinx_tsn_switch.h:21,
                    from drivers/net/ethernet/xilinx/xilinx_tsn_switch.c:18:
   drivers/net/ethernet/xilinx/xilinx_tsn_switch.c: In function 'tsnswitch_probe':

quoted

arch/arm64/include/asm/io.h:54:2: warning: 'pmap' may be used uninitialized in this function [-Wmaybe-uninitialized]

     asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
     ^~~
   drivers/net/ethernet/xilinx/xilinx_tsn_switch.c:723:6: note: 'pmap' was declared here
     u32 pmap;
         ^~~~
--
   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from include/linux/skbuff.h:35,
                    from include/linux/if_ether.h:23,
                    from include/uapi/linux/ethtool.h:19,
                    from include/linux/ethtool.h:18,
                    from include/linux/netdevice.h:41,
                    from drivers/net//ethernet/xilinx/xilinx_axienet.h:12,
                    from drivers/net//ethernet/xilinx/xilinx_tsn_switch.h:21,
                    from drivers/net//ethernet/xilinx/xilinx_tsn_switch.c:18:
   drivers/net//ethernet/xilinx/xilinx_tsn_switch.c: In function 'tsnswitch_probe':

quoted

arch/arm64/include/asm/io.h:54:2: warning: 'pmap' may be used uninitialized in this function [-Wmaybe-uninitialized]

     asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
     ^~~
   drivers/net//ethernet/xilinx/xilinx_tsn_switch.c:723:6: note: 'pmap' was declared here
     u32 pmap;
         ^~~~

vim +/pmap +54 arch/arm64/include/asm/io.h

fc47897d Catalin Marinas 2012-03-05  50  
09a57239 Thierry Reding  2014-07-28  51  #define __raw_writel __raw_writel
fc47897d Catalin Marinas 2012-03-05  52  static inline void __raw_writel(u32 val, volatile void __iomem *addr)
fc47897d Catalin Marinas 2012-03-05  53  {
ee5e41b5 Robin Murphy    2016-09-08 @54  	asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
fc47897d Catalin Marinas 2012-03-05  55  }
fc47897d Catalin Marinas 2012-03-05  56  

:::::: The code at line 54 was first introduced by commit
:::::: ee5e41b5f21a5438664effce1ba5bdd11e03ee24 arm64/io: Allow I/O writes to use {W,X}ZR

:::::: TO: Robin Murphy [off-list ref]
:::::: CC: Will Deacon [off-list ref]

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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