From: Alexander Lobakin <alobakin@pm.me>
To: Kees Cook <keescook@chromium.org>
Cc: Sami Tolvanen <samitolvanen@google.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Alexander Lobakin <alobakin@pm.me>,
kernel-hardening@lists.openwall.com,
linux-hardening@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH kspp-next] kbuild: prevent CC_FLAGS_LTO self-bloating on recursive rebuilds
Date: Thu, 21 Jan 2021 18:45:55 +0000 [thread overview]
Message-ID: <20210121184544.659998-1-alobakin@pm.me> (raw)
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 <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
--
2.30.0
next reply other threads:[~2021-01-21 19:53 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 18:45 Alexander Lobakin [this message]
2021-01-22 19:33 ` [PATCH kspp-next] kbuild: prevent CC_FLAGS_LTO self-bloating on recursive rebuilds Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210121184544.659998-1-alobakin@pm.me \
--to=alobakin@pm.me \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=michal.lkml@markovi.net \
--cc=samitolvanen@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).