Re: Remaining randconfig objtool warnings, linux-next-20200428

[Josh Poimboeuf]

On Tue, Apr 28, 2020 at 11:10:44AM -0500, Josh Poimboeuf wrote:
> > ==> build/x86/0x2EA4CE4F_defconfig/log <==
> > kernel/kcov.o: warning: objtool: write_comp_data()+0x1b: call to check_kcov_mode() with UACCESS enabled
> > kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0x15: call to check_kcov_mode() with UACCESS enabled

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Subject: [PATCH] objtool: Add check_kcov_mode() to the uaccess safelist

check_kcov_mode() is called by write_comp_data() and
__sanitizer_cov_trace_pc(), which are already on the uaccess safe list.
Might as well add check_kcov_mode() to the party.

This fixes the following warnings:

  kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0x15: call to check_kcov_mode() with UACCESS enabled
  kernel/kcov.o: warning: objtool: write_comp_data()+0x1b: call to check_kcov_mode() with UACCESS enabled

Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 tools/objtool/check.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0c732d586924..fec890547e04 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -516,6 +516,7 @@ static const char *uaccess_safe_builtin[] = {
 	"__tsan_write16",
 	/* KCOV */
 	"write_comp_data",
+	"check_kcov_mode",
 	"__sanitizer_cov_trace_pc",
 	"__sanitizer_cov_trace_const_cmp1",
 	"__sanitizer_cov_trace_const_cmp2",
-- 
2.21.1