[davidhildenbrand:get_dummy 14/21] include/linux/pgtable.h:2351:6: error: call to undeclared function 'mm_pmd_folded'; ISO C99 and later do not support implicit function declarations

Hi Yeoreum,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://github.com/davidhildenbrand/linux get_dummy
head:   112a153a97494becabd764fe6257578ba908801f
commit: db92928e80f5332bbfca9a70beaef62d46a0c9de [14/21] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot()
config: arm-allnoconfig (https://download.01.org/0day-ci/archive/20260827/[email protected]/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260827/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:31:
>> include/linux/pgtable.h:2351:6: error: call to undeclared function 'mm_pmd_folded'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    2351 |         if (mm_pmd_folded(mm))
         |             ^
>> include/linux/pgtable.h:2353:6: error: call to undeclared function 'mm_pud_folded'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    2353 |         if (mm_pud_folded(mm))
         |             ^
>> include/linux/pgtable.h:2355:6: error: call to undeclared function 'mm_p4d_folded'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    2355 |         if (mm_p4d_folded(mm))
         |             ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:98:11: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
      98 |                 return (set->sig[3] | set->sig[2] |
         |                         ^        ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:98:25: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
      98 |                 return (set->sig[3] | set->sig[2] |
         |                                       ^        ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:114:11: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     114 |                 return  (set1->sig[3] == set2->sig[3]) &&
         |                          ^         ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:114:27: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     114 |                 return  (set1->sig[3] == set2->sig[3]) &&
         |                                          ^         ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:115:5: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     115 |                         (set1->sig[2] == set2->sig[2]) &&
         |                          ^         ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:115:21: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     115 |                         (set1->sig[2] == set2->sig[2]) &&
         |                                          ^         ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:157:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:138:8: note: expanded from macro '_SIG_SET_BINOP'
     138 |                 a3 = a->sig[3]; a2 = a->sig[2];                         \
         |                      ^      ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:157:1: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:138:24: note: expanded from macro '_SIG_SET_BINOP'
     138 |                 a3 = a->sig[3]; a2 = a->sig[2];                         \
         |                                      ^      ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm/kernel/asm-offsets.c:14:
   In file included from include/linux/mm.h:36:
   In file included from include/linux/rcuwait.h:6:
   In file included from include/linux/sched/signal.h:6:
   include/linux/signal.h:157:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:139:8: note: expanded from macro '_SIG_SET_BINOP'
     139 |                 b3 = b->sig[3]; b2 = b->sig[2];                         \
         |                      ^      ~
   arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
      17 |         unsigned long sig[_NSIG_WORDS];


vim +/mm_pmd_folded +2351 include/linux/pgtable.h

  2331	
  2332	/**
  2333	 * mm_first_pgtable_level - return the first non-folded page-table level
  2334	 * @mm: The mm structure.
  2335	 *
  2336	 * With runtime- or compile-time folded page tables, page-table walkers
  2337	 * effectively skip the folded top-level page tables, treating them as
  2338	 * always-present entries pointing to the next lower-level page table.
  2339	 *
  2340	 * Return the first page-table level in @mm that is not folded.
  2341	 *
  2342	 * Return: the first non-folded page-table level.
  2343	 */
  2344	static inline enum pgtable_level mm_first_pgtable_level(struct mm_struct *mm)
  2345	{
  2346		/*
  2347		 * "PMD folded" actually means "PMD is folded into PUD", and
  2348		 * pud_present() etc. are hard-coded to look like present page table
  2349		 * levels, whereby pmd_present() etc. contain real logic.
  2350		 */
> 2351		if (mm_pmd_folded(mm))
  2352			return PGTABLE_LEVEL_PMD;
> 2353		if (mm_pud_folded(mm))
  2354			return PGTABLE_LEVEL_PUD;
> 2355		if (mm_p4d_folded(mm))
  2356			return PGTABLE_LEVEL_P4D;
  2357		return PGTABLE_LEVEL_PGD;
  2358	}
  2359	

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