diff mbox series

[v2,28/28] x86, build: allow LTO_CLANG and THINLTO to be selected

Message ID 20200903203053.3411268-29-samitolvanen@google.com
State New
Headers show
Series Add support for Clang LTO | expand

Commit Message

Sami Tolvanen Sept. 3, 2020, 8:30 p.m. UTC
Allow CONFIG_LTO_CLANG and CONFIG_THINLTO to be enabled.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/x86/Kconfig  | 2 ++
 arch/x86/Makefile | 5 +++++
 2 files changed, 7 insertions(+)

Comments

Kees Cook Sept. 3, 2020, 10:48 p.m. UTC | #1
On Thu, Sep 03, 2020 at 01:30:53PM -0700, Sami Tolvanen wrote:
> Allow CONFIG_LTO_CLANG and CONFIG_THINLTO to be enabled.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

I think it might be worth detailing why these arguments aren't handled
in the normal fashion under Clang's LTO. Regardless, it's needed to make
it work, so:

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

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
 #