diff mbox series

[2/2] kbuild: Disable GCOV for *.mod.o

Message ID 20230623001140.1111494-6-samitolvanen@google.com
State New
Headers
Series Fix CFI failures with GCOV_PROFILE_ALL |

Commit Message

Sami Tolvanen June 23, 2023, 12:11 a.m. UTC 
  With GCOV_PROFILE_ALL, Clang injects __llvm_gcov_* functions to each
object file, including the *.mod.o. As we filter out CC_FLAGS_CFI
for *.mod.o, the compiler won't generate type hashes for the
injected functions, and therefore indirectly calling them during
module loading trips indirect call checking.

Enabling CFI for *.mod.o isn't sufficient to fix this issue after
commit 0c3e806ec0f9 ("x86/cfi: Add boot time hash randomization"),
as *.mod.o aren't processed by objtool, which means any hashes
emitted there won't be randomized. Therefore, in addition to
disabling CFI for *.mod.o, also disable GCOV, as the object files
don't otherwise contain any executable code.

Fixes: cf68fffb66d6 ("add support for Clang CFI")
Reported-by: Joe Fradley <joefradley@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 scripts/Makefile.modfinal | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 4703f652c009..fc19f67039bd 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -23,7 +23,7 @@  modname = $(notdir $(@:.mod.o=))
 part-of-module = y
 
 quiet_cmd_cc_o_c = CC [M]  $@
-      cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI), $(c_flags)) -c -o $@ $<
+      cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI) $(CFLAGS_GCOV), $(c_flags)) -c -o $@ $<
 
 %.mod.o: %.mod.c FORCE
 	$(call if_changed_dep,cc_o_c)