From 2b8689520520175075ca97bc4eaf51ff3f7253aa Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Thu, 21 Jan 2021 18:45:55 +0000 Subject: [PATCH] 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: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Alexander Lobakin Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210121184544.659998-1-alobakin@pm.me --- Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 668909e7a460..2233951666f7 100644 --- a/Makefile +++ b/Makefile @@ -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