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Date:   Tue, 29 Sep 2020 14:46:26 -0700
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Subject: [PATCH v4 24/29] arm64: vdso: disable LTO
From:   Sami Tolvanen <samitolvanen@google.com>
To:     Masahiro Yamada <masahiroy@kernel.org>,
        Will Deacon <will@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com,
        kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        x86@kernel.org, Sami Tolvanen <samitolvanen@google.com>
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Precedence: bulk

Disable LTO for the vDSO by filtering out CC_FLAGS_LTO, as there's no
point in using link-time optimization for the small about of C code.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 arch/arm64/kernel/vdso/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index e836e300440f..aa47070a3ccf 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -30,7 +30,8 @@ ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv	\
 ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
 ccflags-y += -DDISABLE_BRANCH_PROFILING
 
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS)
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) \
+				$(CC_FLAGS_LTO)
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
 OBJECT_FILES_NON_STANDARD	:= y
-- 
2.28.0.709.gb0816b6eb0-goog