From: Arnd Bergmann arnd@arndb.de
[ Upstream commit d5d469247264e56960705dc5ae7e1d014861fe40 ]
A lot of the tsan helpers are already excempt from the UACCESS warnings, but some more functions were added that need the same thing:
kernel/kcsan/core.o: warning: objtool: __tsan_volatile_read16+0x0: call to __tsan_unaligned_read16() with UACCESS enabled kernel/kcsan/core.o: warning: objtool: __tsan_volatile_write16+0x0: call to __tsan_unaligned_write16() with UACCESS enabled vmlinux.o: warning: objtool: __tsan_unaligned_volatile_read16+0x4: call to __tsan_unaligned_read16() with UACCESS enabled vmlinux.o: warning: objtool: __tsan_unaligned_volatile_write16+0x4: call to __tsan_unaligned_write16() with UACCESS enabled
As Marco points out, these functions don't even call each other explicitly but instead gcc (but not clang) notices the functions being identical and turns one symbol into a direct branch to the other.
Link: https://lkml.kernel.org/r/20230215130058.3836177-4-arnd@kernel.org Fixes: 75d75b7a4d54 ("kcsan: Support distinguishing volatile accesses") Signed-off-by: Arnd Bergmann arnd@arndb.de Acked-by: Marco Elver elver@google.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Josh Poimboeuf jpoimboe@kernel.org Cc: Kuan-Ying Lee Kuan-Ying.Lee@mediatek.com Cc: Peter Zijlstra (Intel) peterz@infradead.org Cc: Vincenzo Frascino vincenzo.frascino@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/check.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 3ef767284b3f0..2fc0270e3c1f7 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -908,6 +908,8 @@ static const char *uaccess_safe_builtin[] = { "__tsan_atomic64_compare_exchange_val", "__tsan_atomic_thread_fence", "__tsan_atomic_signal_fence", + "__tsan_unaligned_read16", + "__tsan_unaligned_write16", /* KCOV */ "write_comp_data", "check_kcov_mode",