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x86/boot: Split off PE/COFF .data section

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Describe the code and data of the decompressor binary using separate
.text and .data PE/COFF sections, so that we will be able to map them
using restricted permissions once we increase the section and file
alignment sufficiently. This avoids the need for memory mappings that
are writable and executable at the same time, which is something that
is best avoided for security reasons.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-17-ardb@google.com
This commit is contained in:
Ard Biesheuvel 2023-09-15 17:16:31 +00:00 committed by Ingo Molnar
parent fa5750521e
commit 34951f3c28
2 changed files with 16 additions and 5 deletions
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2
arch/x86/boot/Makefile
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@ -89,7 +89,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p'
sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p'
quiet_cmd_zoffset = ZOFFSET $@
cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@

19
arch/x86/boot/header.S
View File

@ -75,9 +75,9 @@ optional_header:
.byte 0x02 # MajorLinkerVersion
.byte 0x14 # MinorLinkerVersion
.long setup_size + ZO__end - 0x200 # SizeOfCode
.long ZO__data # SizeOfCode
.long 0 # SizeOfInitializedData
.long ZO__end - ZO__data # SizeOfInitializedData
.long 0 # SizeOfUninitializedData
.long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint
@ -178,9 +178,9 @@ section_table:
.byte 0
.byte 0
.byte 0
.long ZO__end
.long ZO__data
.long setup_size
.long ZO__edata # Size of initialized data
.long ZO__data # Size of initialized data
# on disk
.long setup_size
.long 0 # PointerToRelocations
@ -191,6 +191,17 @@ section_table:
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_EXECUTE # Characteristics
.ascii ".data\0\0\0"
.long ZO__end - ZO__data # VirtualSize
.long setup_size + ZO__data # VirtualAddress
.long ZO__edata - ZO__data # SizeOfRawData
.long setup_size + ZO__data # PointerToRawData
.long 0, 0, 0
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_WRITE # Characteristics
.set section_count, (. - section_table) / 40
#endif /* CONFIG_EFI_STUB */