Re: drivers/bluetooth/hci_vhci.o: error: objtool: vhci_coredump_hdr(): STT_FUNC at end of section

[Josh Poimboeuf]

On Sun, Apr 13, 2025 at 06:16:42AM +0800, kernel test robot wrote:
> :::::: 
> :::::: Manual check reason: "only suspicious fbc files changed"
> :::::: 
> 
> BCC: lkp@xxxxxxxxx
> CC: llvm@xxxxxxxxxxxxxxx
> CC: oe-kbuild-all@xxxxxxxxxxxxxxx
> CC: linux-kernel@xxxxxxxxxxxxxxx
> TO: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxxxxx>
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   b676ac484f847bbe5c7d29603f41475b64fefe55
> commit: 3e7be635937d19b91bab70695328214a3d789d51 objtool: Change "warning:" to "error: " for fatal errors
> date:   12 days ago
> :::::: branch date: 2 hours ago
> :::::: commit date: 12 days ago
> config: x86_64-buildonly-randconfig-001-20250413 (https://download.01.org/0day-ci/archive/20250413/202504130652.o7UWcPMe-lkp@xxxxxxxxx/config)
> compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
> rustc: rustc 1.78.0 (9b00956e5 2024-04-29)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250413/202504130652.o7UWcPMe-lkp@xxxxxxxxx/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@xxxxxxxxx>
> | Closes: https://lore.kernel.org/r/202504130652.o7UWcPMe-lkp@xxxxxxxxx/
> 
> All errors (new ones prefixed by >>):
> 
> >> drivers/bluetooth/hci_vhci.o: error: objtool: vhci_coredump_hdr(): STT_FUNC at end of section

Hi Nathan,

This is looking like a Clang bug to me.  .text.vhci_coredump_hdr has
zero bytes, and its zero-length vhci_coredump_hdr() function is
referenced by force_devcd_write() as a function pointer.  I wasn't able
to find any undefined behavior that might trigger that somehow.

-- 
Josh