Re: [RFC PATCH v5 18/18] arm64: mm: Batch kpkeys level switches

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

Hi Kevin,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on 8f5ae30d69d7543eee0d70083daf4de8fe15d585]

url:    https://github.com/intel-lab-lkp/linux/commits/Kevin-Brodsky/mm-Introduce-kpkeys/20250815-165820
base:   8f5ae30d69d7543eee0d70083daf4de8fe15d585
patch link:    https://lore.kernel.org/r/20250815085512.2182322-19-kevin.brodsky%40arm.com
patch subject: [RFC PATCH v5 18/18] arm64: mm: Batch kpkeys level switches
config: arm64-randconfig-004-20250816 (https://download.01.org/0day-ci/archive/20250816/202508160646.pIunjEB7-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 93d24b6b7b148c47a2fa228a4ef31524fa1d9f3f)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250816/202508160646.pIunjEB7-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/202508160646.pIunjEB7-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:10:
   In file included from include/linux/trace_recursion.h:5:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/arm64/include/asm/hardirq.h:17:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:12:
   In file included from arch/arm64/include/asm/io.h:12:
   In file included from include/linux/pgtable.h:6:
>> arch/arm64/include/asm/pgtable.h:57:37: error: call to undeclared function 'kpkeys_set_level'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      57 |         current->thread.por_el1_lazy_mmu = kpkeys_set_level(KPKEYS_LVL_PGTABLES);
         |                                            ^
>> arch/arm64/include/asm/pgtable.h:75:3: error: call to undeclared function '__kpkeys_set_pkey_reg_nosync'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      75 |                 __kpkeys_set_pkey_reg_nosync(saved_por_el1);
         |                 ^
>> arch/arm64/include/asm/pgtable.h:77:3: error: call to undeclared function 'arch_kpkeys_restore_pkey_reg'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      77 |                 arch_kpkeys_restore_pkey_reg(saved_por_el1);
         |                 ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:454:22: warning: array index 3 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     454 |         case 4: v.sig[7] = (set->sig[3] >> 32); v.sig[6] = set->sig[3];
         |                             ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:454:10: warning: array index 7 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     454 |         case 4: v.sig[7] = (set->sig[3] >> 32); v.sig[6] = set->sig[3];
         |                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:454:42: warning: array index 6 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     454 |         case 4: v.sig[7] = (set->sig[3] >> 32); v.sig[6] = set->sig[3];
         |                                                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:454:53: warning: array index 3 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     454 |         case 4: v.sig[7] = (set->sig[3] >> 32); v.sig[6] = set->sig[3];
         |                                                            ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:456:22: warning: array index 2 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     456 |         case 3: v.sig[5] = (set->sig[2] >> 32); v.sig[4] = set->sig[2];
         |                             ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:456:10: warning: array index 5 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     456 |         case 3: v.sig[5] = (set->sig[2] >> 32); v.sig[4] = set->sig[2];
         |                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:456:42: warning: array index 4 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     456 |         case 3: v.sig[5] = (set->sig[2] >> 32); v.sig[4] = set->sig[2];
         |                                                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:456:53: warning: array index 2 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     456 |         case 3: v.sig[5] = (set->sig[2] >> 32); v.sig[4] = set->sig[2];
         |                                                            ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:458:22: warning: array index 1 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     458 |         case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
         |                             ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/arm64/kernel/asm-offsets.c:12:
   In file included from include/linux/ftrace.h:23:
   In file included from arch/arm64/include/asm/ftrace.h:41:
   include/linux/compat.h:458:10: warning: array index 3 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     458 |         case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
         |                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:458:42: warning: array index 2 is past the end of the array (that has type 'compat_sigset_word[2]' (aka 'unsigned int[2]')) [-Warray-bounds]
     458 |         case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
         |                                                 ^     ~
   include/linux/compat.h:130:2: note: array 'sig' declared here
     130 |         compat_sigset_word      sig[_COMPAT_NSIG_WORDS];
         |         ^
   include/linux/compat.h:458:53: warning: array index 1 is past the end of the array (that has type 'const unsigned long[1]') [-Warray-bounds]
     458 |         case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
         |                                                            ^        ~
   include/uapi/asm-generic/signal.h:62:2: note: array 'sig' declared here
      62 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   12 warnings and 3 errors generated.
   make[3]: *** [scripts/Makefile.build:182: arch/arm64/kernel/asm-offsets.s] Error 1 shuffle=2934569318
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1282: prepare0] Error 2 shuffle=2934569318
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2 shuffle=2934569318
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2 shuffle=2934569318


vim +/kpkeys_set_level +57 arch/arm64/include/asm/pgtable.h

    51	
    52	static void kpkeys_lazy_mmu_enter(void)
    53	{
    54		if (!kpkeys_hardened_pgtables_enabled())
    55			return;
    56	
  > 57		current->thread.por_el1_lazy_mmu = kpkeys_set_level(KPKEYS_LVL_PGTABLES);
    58	}
    59	
    60	static void kpkeys_lazy_mmu_exit(void)
    61	{
    62		u64 saved_por_el1;
    63	
    64		if (!kpkeys_hardened_pgtables_enabled())
    65			return;
    66	
    67		saved_por_el1 = current->thread.por_el1_lazy_mmu;
    68	
    69		/*
    70		 * We skip any barrier if TIF_LAZY_MMU_PENDING is set:
    71		 * emit_pte_barriers() will issue an ISB just after this function
    72		 * returns.
    73		 */
    74		if (test_thread_flag(TIF_LAZY_MMU_PENDING))
  > 75			__kpkeys_set_pkey_reg_nosync(saved_por_el1);
    76		else
  > 77			arch_kpkeys_restore_pkey_reg(saved_por_el1);
    78	}
    79	

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