[ Upstream commit 05026ea01e95ffdeb0e5ac8fb7fb1b551e3a8726 ]
If execute_location()'s memcpy of do_nothing() gets inlined and unrolled
by the compiler, it copies one word at a time:
mov 0x0(%rip),%rax R_X86_64_PC32 .text+0x1374
mov %rax,0x38(%rbx)
mov 0x0(%rip),%rax R_X86_64_PC32 .text+0x136c
mov %rax,0x30(%rbx)
...
Those .text references point to the middle of the function, causing
objtool to complain about their lack of ENDBR.
Prevent that by resolving the function pointer at runtime rather than
build time. This fixes the following warning:
drivers/misc/lkdtm/lkdtm.o: warning: objtool: execute_location+0x23: relocation to !ENDBR: .text+0x1378
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/30b9abffbddeb43c4f6320b1270fa9b4d74c54ed.1742852847.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503191453.uFfxQy5R-lkp@intel.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
db437e9854