Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 18 Sep 2020 13:14:21 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>, Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.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, x86@...nel.org, 
	Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v3 15/30] kbuild: lto: merge module sections

LLD always splits sections with LTO, which increases module sizes. This
change adds linker script rules to merge the split sections in the final
module.

Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
 scripts/module.lds.S | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 69b9b71a6a47..037120173a22 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -25,5 +25,33 @@ SECTIONS {
 	__jump_table		0 : ALIGN(8) { KEEP(*(__jump_table)) }
 }
 
+#ifdef CONFIG_LTO_CLANG
+/*
+ * With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and
+ * -ffunction-sections, which increases the size of the final module.
+ * Merge the split sections in the final binary.
+ */
+SECTIONS {
+	__patchable_function_entries : { *(__patchable_function_entries) }
+
+	.bss : {
+		*(.bss .bss.[0-9a-zA-Z_]*)
+		*(.bss..L*)
+	}
+
+	.data : {
+		*(.data .data.[0-9a-zA-Z_]*)
+		*(.data..L*)
+	}
+
+	.rodata : {
+		*(.rodata .rodata.[0-9a-zA-Z_]*)
+		*(.rodata..L*)
+	}
+
+	.text : { *(.text .text.[0-9a-zA-Z_]*) }
+}
+#endif
+
 /* bring in arch-specific sections */
 #include <asm/module.lds.h>
-- 
2.28.0.681.g6f77f65b4e-goog

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.