Commit f495054b authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool/klp: Fix unexported static call key access for manually built livepatch modules 



Enabling CONFIG_MEM_ALLOC_PROFILING_DEBUG with CONFIG_SAMPLE_LIVEPATCH
results in the following error:

  samples/livepatch/livepatch-shadow-fix1.o: error: objtool: static_call: can't find static_call_key symbol: __SCK__WARN_trap

This is caused an extra file->klp sanity check which was added by commit
164c9201 ("objtool: Add base objtool support for livepatch
modules").  That check was intended to ensure that livepatch modules
built with klp-build always have full access to their static call keys.

However, it failed to account for the fact that manually built livepatch
modules (i.e., not built with klp-build) might need access to unexported
static call keys, for which read-only access is typically allowed for
modules.

While the livepatch-shadow-fix1 module doesn't explicitly use any static
calls, it does have a memory allocation, which can cause
CONFIG_MEM_ALLOC_PROFILING_DEBUG to insert a WARN() call.  And WARN() is
now an unexported static call as of commit 860238af ("x86_64/bug:
Inline the UD1").

Fix it by removing the overzealous file->klp check, restoring the
original behavior for manually built livepatch modules.

Fixes: 164c9201 ("objtool: Add base objtool support for livepatch modules")
Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarSong Liu <song@kernel.org>
Tested-by: default avatarArnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/0bd3ae9a53c3d743417fe842b740a7720e2bcd1c.1770058775.git.jpoimboe@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 18328546

tools/objtool/check.c

+1 −1
Original line number Diff line number Diff line
@@ -682,7 +682,7 @@ static int create_static_call_sections(struct objtool_file *file) 


		key_sym = find_symbol_by_name(file->elf, tmp);

		if (!key_sym) {

			if (!opts.module || file->klp) {

			if (!opts.module) {

				ERROR("static_call: can't find static_call_key symbol: %s", tmp);

				return -1;

			}