[PATCHv6 11/13] arm64/kexec: Select KEXEC_BPF to support UEFI-style kernel image

[PATCHv6 11/13] arm64/kexec: Select KEXEC_BPF to support UEFI-style kernel image

[Pingfan Liu]

Now everything is ready for kexec PE image parser. Select it on arm64
for zboot and UKI image support.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 93173f0a09c7d..922d58abbbd67 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1587,6 +1587,7 @@ config ARCH_SELECTS_KEXEC_FILE
 	def_bool y
 	depends on KEXEC_FILE
 	select HAVE_IMA_KEXEC if IMA
+	select KEXEC_BPF if DEBUG_INFO_BTF && BPF_SYSCALL
 
 config ARCH_SUPPORTS_KEXEC_SIG
 	def_bool y
-- 
2.49.0

Re: [PATCHv6 11/13] arm64/kexec: Select KEXEC_BPF to support UEFI-style kernel image

[kernel test robot]

Hi Pingfan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/net]
[also build test WARNING on bpf-next/master bpf/master akpm-mm/mm-nonmm-unstable linus/master v6.19-rc6 next-20260116]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pingfan-Liu/bpf-Introduce-kfuncs-to-parser-buffer-content/20260119-112939
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git net
patch link:    https://lore.kernel.org/r/20260119032424.10781-12-piliu%40redhat.com
patch subject: [PATCHv6 11/13] arm64/kexec: Select KEXEC_BPF to support UEFI-style kernel image
config: arm64-randconfig-004-20260119 (https://download.01.org/0day-ci/archive/20260119/202601191626.CUD61tIS-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260119/202601191626.CUD61tIS-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/202601191626.CUD61tIS-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/kexec_bpf_loader.c:103:22: warning: unknown attribute 'optimize' ignored [-Wunknown-attributes]
     103 | __attribute__((used, optimize("O0"))) void kexec_image_parser_anchor(
         |                      ^~~~~~~~~~~~~~
   1 warning generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for KEXEC_BPF
   Depends on [n]: KEXEC_FILE [=y] && DEBUG_INFO_BTF [=y] && BPF_SYSCALL [=y] && KEEP_DECOMPRESSOR [=n]
   Selected by [y]:
   - ARCH_SELECTS_KEXEC_FILE [=y] && KEXEC_FILE [=y] && DEBUG_INFO_BTF [=y] && BPF_SYSCALL [=y]


vim +/optimize +103 kernel/kexec_bpf_loader.c

e683ae405ea0458 Pingfan Liu 2026-01-19   93  
e683ae405ea0458 Pingfan Liu 2026-01-19   94  void kexec_image_parser_anchor(struct kexec_context *context,
e683ae405ea0458 Pingfan Liu 2026-01-19   95  		unsigned long parser_id);
e683ae405ea0458 Pingfan Liu 2026-01-19   96  
e683ae405ea0458 Pingfan Liu 2026-01-19   97  /*
e683ae405ea0458 Pingfan Liu 2026-01-19   98   * optimize("O0") prevents inline, compiler constant propagation
e683ae405ea0458 Pingfan Liu 2026-01-19   99   *
e683ae405ea0458 Pingfan Liu 2026-01-19  100   * Let bpf be the program context pointer so that it will not be spilled into
e683ae405ea0458 Pingfan Liu 2026-01-19  101   * stack.
e683ae405ea0458 Pingfan Liu 2026-01-19  102   */
e683ae405ea0458 Pingfan Liu 2026-01-19 @103  __attribute__((used, optimize("O0"))) void kexec_image_parser_anchor(
e683ae405ea0458 Pingfan Liu 2026-01-19  104  		struct kexec_context *context,
e683ae405ea0458 Pingfan Liu 2026-01-19  105  		unsigned long parser_id)
e683ae405ea0458 Pingfan Liu 2026-01-19  106  {
e683ae405ea0458 Pingfan Liu 2026-01-19  107  	/*
e683ae405ea0458 Pingfan Liu 2026-01-19  108  	 * To prevent linker from Identical Code Folding (ICF) with kexec_image_parser_anchor,
e683ae405ea0458 Pingfan Liu 2026-01-19  109  	 * making them have different code.
e683ae405ea0458 Pingfan Liu 2026-01-19  110  	 */
e683ae405ea0458 Pingfan Liu 2026-01-19  111  	volatile int dummy = 0;
e683ae405ea0458 Pingfan Liu 2026-01-19  112  
e683ae405ea0458 Pingfan Liu 2026-01-19  113  	dummy += 1;
e683ae405ea0458 Pingfan Liu 2026-01-19  114  }
e683ae405ea0458 Pingfan Liu 2026-01-19  115  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCHv6 11/13] arm64/kexec: Select KEXEC_BPF to support UEFI-style kernel image

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 1100 bytes --]

> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 93173f0a09c7..922d58abbbd6 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1587,6 +1587,7 @@ config ARCH_SELECTS_KEXEC_FILE
>  	def_bool y
>  	depends on KEXEC_FILE
>  	select HAVE_IMA_KEXEC if IMA
> +	select KEXEC_BPF if DEBUG_INFO_BTF && BPF_SYSCALL
                          ^^^

Should this condition also include KEEP_DECOMPRESSOR?

In kernel/Kconfig.kexec, KEXEC_BPF has:

    depends on DEBUG_INFO_BTF && BPF_SYSCALL && KEEP_DECOMPRESSOR

Since Kconfig's select statement forces a symbol's value without visiting
the dependencies, this select will enable KEXEC_BPF even when
KEEP_DECOMPRESSOR is not set, creating an inconsistent configuration.

KEEP_DECOMPRESSOR defaults to n and nothing selects it, so this appears
to be a missing condition in the select statement.


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21147860407