From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit 10b4c4bce3f5541f54bcc2039720b11d2bc96d79 ]
If SAVE and RESTORE unwind hints are in different basic blocks, and objtool sees the RESTORE before the SAVE, it errors out with:
vmlinux.o: warning: objtool: vmw_port_hb_in+0x242: objtool isn't smart enough to handle this CFI save/restore combo
In such a case, defer following the RESTORE block until the straight-line path gets followed later.
Fixes: 8faea26e6111 ("objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}") Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202402240702.zJFNmahW-lkp@intel.com/ Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Link: https://lore.kernel.org/r/20240227073527.avcm5naavbv3cj5s@treble Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/check.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 548ec3cd7c00c..c4c2f75eadfd9 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3620,6 +3620,18 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, }
if (!save_insn->visited) { + /* + * If the restore hint insn is at the + * beginning of a basic block and was + * branched to from elsewhere, and the + * save insn hasn't been visited yet, + * defer following this branch for now. + * It will be seen later via the + * straight-line path. + */ + if (!prev_insn) + return 0; + WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo"); return 1; }