Commit 2b868952 authored by Alexander Lobakin's avatar Alexander Lobakin Committed by Kees Cook
Browse files

kbuild: prevent CC_FLAGS_LTO self-bloating on recursive rebuilds 



CC_FLAGS_LTO gets initialized only via +=, never with := or =.
When building with CONFIG_TRIM_UNUSED_KSYMS, Kbuild may perform
several kernel rebuilds to satisfy symbol dependencies. In this
case, value of CC_FLAGS_LTO is concatenated each time, which
triggers a full rebuild.
Initialize it with := to fix this.

Fixes: dc5723b0 ("kbuild: add support for Clang LTO")
Signed-off-by: default avatarAlexander Lobakin <alobakin@pm.me>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210121184544.659998-1-alobakin@pm.me
parent 112b6a8e

Makefile

+2 −2
Original line number Diff line number Diff line
@@ -895,10 +895,10 @@ endif 


ifdef CONFIG_LTO_CLANG

ifdef CONFIG_LTO_CLANG_THIN

CC_FLAGS_LTO	+= -flto=thin -fsplit-lto-unit

CC_FLAGS_LTO	:= -flto=thin -fsplit-lto-unit

KBUILD_LDFLAGS	+= --thinlto-cache-dir=$(extmod-prefix).thinlto-cache

else

CC_FLAGS_LTO	+= -flto

CC_FLAGS_LTO	:= -flto

endif

CC_FLAGS_LTO	+= -fvisibility=hidden