linux-kernel - [PATCH v2 1/3] efi/arm: Remove __efistub

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Message-Id: <20200416151227.3360778-2-nivedita@alum.mit.edu>
Date:   Thu, 16 Apr 2020 11:12:25 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] efi/arm: Remove __efistub_global annotation

Instead of using __efistub_global to force variables into the .data
section, leave them in the .bss but pull the EFI stub's .bss section
into .data in the linker script for the compressed kernel.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
Reviewed-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm/boot/compressed/vmlinux.lds.S | 2 +-
 drivers/firmware/efi/libstub/Makefile  | 7 ++++---
 drivers/firmware/efi/libstub/efistub.h | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
index b247f399de71..b6793c7932a9 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.S
+++ b/arch/arm/boot/compressed/vmlinux.lds.S
@@ -78,7 +78,7 @@ SECTIONS
      * The EFI stub always executes from RAM, and runs strictly before the
      * decompressor, so we can make an exception for its r/w data, and keep it
      */
-    *(.data.efistub)
+    *(.data.efistub .bss.efistub)
     __pecoff_data_end = .;
 
     /*
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 094eabdecfe6..45ffe0822df1 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -100,8 +100,9 @@ quiet_cmd_stubcopy = STUBCPY $@
 
 #
 # ARM discards the .data section because it disallows r/w data in the
-# decompressor. So move our .data to .data.efistub, which is preserved
-# explicitly by the decompressor linker script.
+# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
+# which are preserved explicitly by the decompressor linker script.
 #
-STUBCOPY_FLAGS-$(CONFIG_ARM)	+= --rename-section .data=.data.efistub
+STUBCOPY_FLAGS-$(CONFIG_ARM)	+= --rename-section .data=.data.efistub	\
+				   --rename-section .bss=.bss.efistub,load,alloc
 STUBCOPY_RELOC-$(CONFIG_ARM)	:= R_ARM_ABS
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index bd0b86b63936..a92d42ffd9f7 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -25,7 +25,7 @@
 #define EFI_ALLOC_ALIGN		EFI_PAGE_SIZE
 #endif
 
-#if defined(CONFIG_ARM) || defined(CONFIG_X86)
+#if defined(CONFIG_X86)
 #define __efistub_global	__section(.data)
 #else
 #define __efistub_global
-- 
2.25.3