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Message-ID: <20230912090051.4014114-30-ardb@google.com>
Date: Tue, 12 Sep 2023 09:01:04 +0000
From: Ard Biesheuvel <ardb@...gle.com>
To: linux-efi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
Evgeniy Baskov <baskov@...ras.ru>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Jones <pjones@...hat.com>,
Matthew Garrett <mjg59@...f.ucam.org>,
Gerd Hoffmann <kraxel@...hat.com>,
Kees Cook <keescook@...omium.org>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v2 13/15] x86/boot: Drop PE/COFF .reloc section
From: Ard Biesheuvel <ardb@...nel.org>
Ancient buggy EFI loaders may have required a .reloc section to be
present at some point in time, but this has not been true for a long
time so the .reloc section can just be dropped.
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
arch/x86/boot/header.S | 20 ------------
arch/x86/boot/setup.ld | 4 +--
arch/x86/boot/tools/build.c | 34 +++-----------------
3 files changed, 7 insertions(+), 51 deletions(-)
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 2b07bc596c39..9e9641e220a7 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -155,26 +155,6 @@ section_table:
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_EXECUTE # Characteristics
- #
- # The EFI application loader requires a relocation section
- # because EFI applications must be relocatable. The .reloc
- # offset & size fields are filled in by build.c.
- #
- .ascii ".reloc"
- .byte 0
- .byte 0
- .long 0
- .long 0
- .long 0 # SizeOfRawData
- .long 0 # PointerToRawData
- .long 0 # PointerToRelocations
- .long 0 # PointerToLineNumbers
- .word 0 # NumberOfRelocations
- .word 0 # NumberOfLineNumbers
- .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
- IMAGE_SCN_MEM_READ | \
- IMAGE_SCN_MEM_DISCARDABLE # Characteristics
-
#ifdef CONFIG_EFI_MIXED
#
# The offset & size fields are filled in by build.c.
diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index ae2b5046a0db..9b551eacffa8 100644
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -40,8 +40,8 @@ SECTIONS
setup_sig = .;
LONG(0x5a5aaa55)
- /* reserve some extra space for the reloc and compat sections */
- setup_size = ABSOLUTE(ALIGN(. + 64, 512));
+ /* reserve some extra space for the compat section */
+ setup_size = ABSOLUTE(ALIGN(. + 32, 512));
setup_sects = ABSOLUTE(setup_size / 512);
}
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index 9712f27e32c1..faccff9743a3 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -47,7 +47,6 @@ typedef unsigned int u32;
/* This must be large enough to hold the entire setup */
u8 buf[SETUP_SECT_MAX*512];
-#define PECOFF_RELOC_RESERVE 0x20
#define PECOFF_COMPAT_RESERVE 0x20
static unsigned long efi32_pe_entry;
@@ -180,24 +179,13 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
update_pecoff_section_header_fields(section_name, offset, size, size, offset);
}
-static void update_pecoff_setup_and_reloc(unsigned int size)
+static void update_pecoff_setup(unsigned int size)
{
u32 setup_offset = 0x200;
- u32 reloc_offset = size - PECOFF_RELOC_RESERVE - PECOFF_COMPAT_RESERVE;
-#ifdef CONFIG_EFI_MIXED
- u32 compat_offset = reloc_offset + PECOFF_RELOC_RESERVE;
-#endif
- u32 setup_size = reloc_offset - setup_offset;
+ u32 compat_offset = size - PECOFF_COMPAT_RESERVE;
+ u32 setup_size = compat_offset - setup_offset;
update_pecoff_section_header(".setup", setup_offset, setup_size);
- update_pecoff_section_header(".reloc", reloc_offset, PECOFF_RELOC_RESERVE);
-
- /*
- * Modify .reloc section contents with a single entry. The
- * relocation is applied to offset 10 of the relocation section.
- */
- put_unaligned_le32(reloc_offset + 10, &buf[reloc_offset]);
- put_unaligned_le32(10, &buf[reloc_offset + 4]);
#ifdef CONFIG_EFI_MIXED
update_pecoff_section_header(".compat", compat_offset, PECOFF_COMPAT_RESERVE);
@@ -214,21 +202,10 @@ static void update_pecoff_setup_and_reloc(unsigned int size)
#endif
}
-static int reserve_pecoff_reloc_section(int c)
-{
- /* Reserve 0x20 bytes for .reloc section */
- memset(buf+c, 0, PECOFF_RELOC_RESERVE);
- return PECOFF_RELOC_RESERVE;
-}
-
#else
-static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
+static inline void update_pecoff_setup(unsigned int size) {}
-static inline int reserve_pecoff_reloc_section(int c)
-{
- return 0;
-}
#endif /* CONFIG_EFI_STUB */
static int reserve_pecoff_compat_section(int c)
@@ -307,7 +284,6 @@ int main(int argc, char ** argv)
fclose(file);
c += reserve_pecoff_compat_section(c);
- c += reserve_pecoff_reloc_section(c);
/* Pad unused space with zeros */
setup_sectors = (c + 511) / 512;
@@ -316,7 +292,7 @@ int main(int argc, char ** argv)
i = setup_sectors*512;
memset(buf+c, 0, i-c);
- update_pecoff_setup_and_reloc(i);
+ update_pecoff_setup(i);
/* Open and stat the kernel file */
fd = open(argv[2], O_RDONLY);
--
2.42.0.283.g2d96d420d3-goog
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