linux-kernel - [PATCH] efi/libstub: avoid linking libstub/lib-ksyms.o into vmlinux

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Message-Id: <20200305055047.6097-1-masahiroy@kernel.org>
Date:   Thu,  5 Mar 2020 14:50:47 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Masahiro Yamada <masahiroy@...nel.org>
Subject: [PATCH] efi/libstub: avoid linking libstub/lib-ksyms.o into vmlinux

drivers/firmware/efi/libstub/Makefile is supposed to create a static
library, which is not directly linked to vmlinux.

Since commit 7f2084fa55e6 ("[kbuild] handle exports in lib-y objects
reliably"), any Makefile using lib-y generates lib-ksyms.o which is
linked into vmlinux.

In this case, the following garbage object is linked into vmlinux.

  drivers/firmware/efi/libstub/lib-ksyms.o

We do not want to link anything from libstub/ directly to vmlinux,
so using subdir-y instead of obj-y is the correct way to descend into
this directory.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 drivers/firmware/efi/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 554d795270d9..4fd2fa02f549 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -19,7 +19,7 @@ obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
 obj-$(CONFIG_UEFI_CPER)			+= cper.o
 obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o
 obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o
-obj-$(CONFIG_EFI_STUB)			+= libstub/
+subdir-$(CONFIG_EFI_STUB)		+= libstub
 obj-$(CONFIG_EFI_FAKE_MEMMAP)		+= fake_map.o
 obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o
 obj-$(CONFIG_EFI_TEST)			+= test/
-- 
2.17.1