[v2,01/15] x86/efi: Drop EFI stub .bss from .data section

Message ID	20230912090051.4014114-18-ardb@google.com
State	New
Headers	show Return-Path: <linux-efi-owner@vger.kernel.org> Date: Tue, 12 Sep 2023 09:00:52 +0000 In-Reply-To: <20230912090051.4014114-17-ardb@google.com> Mime-Version: 1.0 References: <20230912090051.4014114-17-ardb@google.com> Message-ID: <20230912090051.4014114-18-ardb@google.com> Subject: [PATCH v2 01/15] x86/efi: Drop EFI stub .bss from .data section From: Ard Biesheuvel <ardb@google.com> To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>, Evgeniy Baskov <baskov@ispras.ru>, Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Peter Jones <pjones@redhat.com>, Matthew Garrett <mjg59@srcf.ucam.org>, Gerd Hoffmann <kraxel@redhat.com>, Kees Cook <keescook@chromium.org>, "H. Peter Anvin" <hpa@zytor.com> Content-Type: text/plain; charset="UTF-8" Precedence: bulk
Series	x86/boot: Rework PE header generation \| expand [v2,00/15] x86/boot: Rework PE header generation [v2,01/15] x86/efi: Drop EFI stub .bss from .data section [v2,02/15] x86/efi: Disregard setup header of loaded image [v2,03/15] x86/efi: Drop alignment flags from PE section headers [v2,04/15] x86/boot: Remove the 'bugger off' message [v2,05/15] x86/boot: Omit compression buffer from PE/COFF image memory footprint [v2,06/15] x86/boot: Drop redundant code setting the root device [v2,07/15] x86/boot: Grab kernel_info offset from zoffset header directly [v2,08/15] x86/boot: Drop references to startup_64 [v2,09/15] x86/boot: Set EFI handover offset directly in header asm [v2,10/15] x86/boot: Define setup size in linker script [v2,11/15] x86/boot: Derive file size from _edata symbol [v2,12/15] x86/boot: Construct PE/COFF .text section from assembler [v2,13/15] x86/boot: Drop PE/COFF .reloc section [v2,14/15] x86/boot: Split off PE/COFF .data section [v2,15/15] x86/boot: Increase section and file alignment to 4k/512

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20230912090051.4014114-18-ardb@google.com

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Date: Tue, 12 Sep 2023 09:00:52 +0000
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Subject: [PATCH v2 01/15] x86/efi: Drop EFI stub .bss from .data section
From: Ard Biesheuvel <ardb@google.com>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
        Evgeniy Baskov <baskov@ispras.ru>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Jones <pjones@redhat.com>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Series

x86/boot: Rework PE header generation | expand

Commit Message

Ard Biesheuvel Sept. 12, 2023, 9 a.m. UTC

From: Ard Biesheuvel <ardb@kernel.org>

Now that the EFI stub always zero inits its BSS section upon entry,
there is no longer a need to place the BSS symbols carried by the stub
into the .data section.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/boot/compressed/vmlinux.lds.S | 1 -
 drivers/firmware/efi/libstub/Makefile  | 7 -------
 2 files changed, 8 deletions(-)

diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index b22f34b8684a..4ff6ab1b67d9 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -47,7 +47,6 @@  SECTIONS
 		_data = . ;
 		*(.data)
 		*(.data.*)
-		*(.bss.efistub)
 		_edata = . ;
 	}
 	. = ALIGN(L1_CACHE_BYTES);
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index a1157c2a7170..ef4c12f0877b 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -108,13 +108,6 @@  lib-y				:= $(patsubst %.o,%.stub.o,$(lib-y))
 # https://bugs.llvm.org/show_bug.cgi?id=46480
 STUBCOPY_FLAGS-y		+= --remove-section=.note.gnu.property
 
-#
-# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
-# .bss section, so the .bss section of the EFI stub needs to be included in the
-# .data section of the compressed kernel to ensure initialization. Rename the
-# .bss section here so it's easy to pick out in the linker script.
-#
-STUBCOPY_FLAGS-$(CONFIG_X86)	+= --rename-section .bss=.bss.efistub,load,alloc
 STUBCOPY_RELOC-$(CONFIG_X86_32)	:= R_386_32
 STUBCOPY_RELOC-$(CONFIG_X86_64)	:= R_X86_64_64

[v2,01/15] x86/efi: Drop EFI stub .bss from .data section

Commit Message

Patch