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Date: Fri, 18 Sep 2020 13:14:36 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>, Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Paul E. McKenney" <paulmck@...nel.org>,
Kees Cook <keescook@...omium.org>, Nick Desaulniers <ndesaulniers@...gle.com>,
clang-built-linux@...glegroups.com, kernel-hardening@...ts.openwall.com,
linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, x86@...nel.org,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v3 30/30] x86, build: allow LTO_CLANG and THINLTO to be selected
Pass code model and stack alignment to the linker as these are
not stored in LLVM bitcode, and allow both CONFIG_LTO_CLANG and
CONFIG_THINLTO to be selected.
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
arch/x86/Kconfig | 2 ++
arch/x86/Makefile | 5 +++++
2 files changed, 7 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6de2e5c0bdba..0a49008c2363 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -92,6 +92,8 @@ config X86
select ARCH_SUPPORTS_ACPI
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
+ select ARCH_SUPPORTS_LTO_CLANG if X86_64
+ select ARCH_SUPPORTS_THINLTO if X86_64
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 4346ffb2e39f..49e3b8674eb5 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -173,6 +173,11 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
endif
+ifdef CONFIG_LTO_CLANG
+KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \
+ -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
+endif
+
# Workaround for a gcc prelease that unfortunately was shipped in a suse release
KBUILD_CFLAGS += -Wno-sign-compare
#
--
2.28.0.681.g6f77f65b4e-goog
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