arch/riscv/kernel/hibernate.c:76:65: warning: array subscript -1 is outside array bounds of 'const void[]'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   06dc10eae55b5ceabfef287a7e5f16ceea204aa0
commit: c0317210012e3b985779ddd92a7c5db8424e1e97 RISC-V: Add arch functions to support hibernation/suspend-to-disk
date:   6 months ago
config: riscv-allyesconfig (https://download.01.org/0day-ci/archive/20231019/202310190159.mAUo9iEX-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231019/202310190159.mAUo9iEX-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310190159.mAUo9iEX-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/riscv/include/asm/page.h:12,
                    from arch/riscv/include/asm/thread_info.h:11,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/riscv/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:78,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/mm.h:7,
                    from arch/riscv/include/asm/cacheflush.h:9,
                    from arch/riscv/kernel/hibernate.c:11:
   arch/riscv/kernel/hibernate.c: In function 'pfn_is_nosave':
>> arch/riscv/kernel/hibernate.c:76:65: warning: array subscript -1 is outside array bounds of 'const void[]' [-Warray-bounds=]
      76 |         unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
   include/linux/pfn.h:22:43: note: in definition of macro 'PHYS_PFN'
      22 | #define PHYS_PFN(x)     ((unsigned long)((x) >> PAGE_SHIFT))
         |                                           ^
   arch/riscv/include/asm/page.h:172:33: note: in expansion of macro '__phys_to_pfn'
     172 | #define sym_to_pfn(x)           __phys_to_pfn(__pa_symbol(x))
         |                                 ^~~~~~~~~~~~~
   arch/riscv/include/asm/page.h:156:44: note: in expansion of macro 'RELOC_HIDE'
     156 | #define __pa_symbol(x)  __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
         |                                            ^~~~~~~~~~
   arch/riscv/include/asm/page.h:172:47: note: in expansion of macro '__pa_symbol'
     172 | #define sym_to_pfn(x)           __phys_to_pfn(__pa_symbol(x))
         |                                               ^~~~~~~~~~~
   arch/riscv/kernel/hibernate.c:76:40: note: in expansion of macro 'sym_to_pfn'
      76 |         unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
         |                                        ^~~~~~~~~~
   In file included from arch/riscv/include/asm/sections.h:8,
                    from include/linux/interrupt.h:21,
                    from include/linux/kernel_stat.h:9,
                    from include/linux/cgroup.h:26,
                    from include/linux/memcontrol.h:13,
                    from include/linux/swap.h:9,
                    from include/asm-generic/tlb.h:15,
                    from arch/riscv/include/asm/tlb.h:14,
                    from arch/riscv/include/asm/pgalloc.h:11,
                    from arch/riscv/kernel/hibernate.c:14:
   include/asm-generic/sections.h:59:45: note: at offset -1 into object '__nosave_end' of size [0, 9223372036854775807]
      59 | extern __visible const void __nosave_begin, __nosave_end;
         |                                             ^~~~~~~~~~~~


vim +76 arch/riscv/kernel/hibernate.c

    69	
    70	/*
    71	 * Check if the given pfn is in the 'nosave' section.
    72	 */
    73	int pfn_is_nosave(unsigned long pfn)
    74	{
    75		unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
  > 76		unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
    77	
    78		return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
    79	}
    80	

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