[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20201211184633.3213045-5-samitolvanen@google.com>
Date: Fri, 11 Dec 2020 10:46:21 -0800
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Will Deacon <will@...nel.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>,
Peter Zijlstra <peterz@...radead.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,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v9 04/16] kbuild: lto: limit inlining
This change limits function inlining across translation unit boundaries
in order to reduce the binary size with LTO. The -import-instr-limit
flag defines a size limit, as the number of LLVM IR instructions, for
importing functions from other TUs, defaulting to 100.
Based on testing with arm64 defconfig, we found that a limit of 5 is a
reasonable compromise between performance and binary size, reducing the
size of a stripped vmlinux by 11%.
Suggested-by: George Burgess IV <gbiv@...gle.com>
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index a07e3909e5d0..84c60f38ee3e 100644
--- a/Makefile
+++ b/Makefile
@@ -901,6 +901,9 @@ else
CC_FLAGS_LTO += -flto
endif
CC_FLAGS_LTO += -fvisibility=hidden
+
+# Limit inlining across translation units to reduce binary size
+KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
endif
ifdef CONFIG_LTO
--
2.29.2.576.ga3fc446d84-goog
Powered by blists - more mailing lists