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arm: separate .data and .text sections of EFI binaries

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EFI binaries should not contain sections that are both writable and
executable. Separate the RX .text section from the RW .data section.

We currently don't created relocation sections (.rel.*) for our EFI
binaries. Anyway these would have to be converted to PE/COFF relocations.
Enumerate them under DISCARD and add a comment.

Correct the characteristics of the sections.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
This commit is contained in:
Heinrich Schuchardt 2024-02-26 22:24:08 +01:00
parent 3b3d61df3b
commit 97da9aea78
2 changed files with 52 additions and 16 deletions
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40
arch/arm/lib/crt0_arm_efi.S
View file

@ -23,7 +23,7 @@ pe_header:
.long IMAGE_NT_SIGNATURE /* 'PE' */
coff_header:
.short IMAGE_FILE_MACHINE_THUMB /* Mixed ARM/Thumb */
.short 2 /* nr_sections */
.short 3 /* nr_sections */
.long 0 /* TimeDateStamp */
.long 0 /* PointerToSymbolTable */
.long 0 /* NumberOfSymbols */
@ -102,22 +102,44 @@ section_table:
.long 0 /* PointerToLineNumbers */
.short 0 /* NumberOfRelocations */
.short 0 /* NumberOfLineNumbers */
.long 0x42100040 /* Characteristics (section flags) */
/* Characteristics (section flags) */
.long (IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_DISCARDABLE | \
IMAGE_SCN_CNT_INITIALIZED_DATA)
.ascii ".text"
.byte 0
.byte 0
.byte 0 /* end of 0 padding of section name */
.long _edata - _start /* VirtualSize */
.long _text_size /* VirtualSize */
.long _start - image_base /* VirtualAddress */
.long _edata - _start /* SizeOfRawData */
.long _text_size /* SizeOfRawData */
.long _start - image_base /* PointerToRawData */
.long 0 /* PointerToRelocations */
.long 0 /* PointerToLineNumbers */
.short 0 /* NumberOfRelocations */
.short 0 /* NumberOfLineNumbers */
/* Characteristics (section flags) */
.long (IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_EXECUTE | \
IMAGE_SCN_CNT_CODE)
.long 0 /* PointerToRelocations (0 for executables) */
.long 0 /* PointerToLineNumbers (0 for executables) */
.short 0 /* NumberOfRelocations (0 for executables) */
.short 0 /* NumberOfLineNumbers (0 for executables) */
.long 0xe0500020 /* Characteristics (section flags) */
.ascii ".data"
.byte 0
.byte 0
.byte 0 /* end of 0 padding of section name */
.long _data_size /* VirtualSize */
.long _data - image_base /* VirtualAddress */
.long _data_size /* SizeOfRawData */
.long _data - image_base /* PointerToRawData */
.long 0 /* PointerToRelocations */
.long 0 /* PointerToLineNumbers */
.short 0 /* NumberOfRelocations */
.short 0 /* NumberOfLineNumbers */
/* Characteristics (section flags) */
.long (IMAGE_SCN_MEM_WRITE | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_CNT_INITIALIZED_DATA)
.align 12
_start:

28
arch/arm/lib/elf_arm_efi.lds
View file

@ -7,6 +7,12 @@
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
PHDRS
{
data PT_LOAD FLAGS(3); /* PF_W | PF_X */
}
ENTRY(_start)
SECTIONS
{
@ -18,11 +24,13 @@ SECTIONS
*(.gnu.linkonce.t.*)
*(.srodata)
*(.rodata*)
. = ALIGN(16);
*(.dynamic);
. = ALIGN(512);
}
_etext = .;
_text_size = . - _text;
.dynamic : { *(.dynamic) }
. = ALIGN(4096);
.data : {
_data = .;
*(.sdata)
@ -47,14 +55,20 @@ SECTIONS
. = ALIGN(512);
_bss_end = .;
_edata = .;
}
.rel.dyn : { *(.rel.dyn) }
.rel.plt : { *(.rel.plt) }
.rel.got : { *(.rel.got) }
.rel.data : { *(.rel.data) *(.rel.data*) }
_data_size = . - _etext;
} :data
_data_size = . - _data;
/DISCARD/ : {
/*
* We don't support relocations. These would have to be
* translated from ELF to PE format and added to the .reloc
* section.
*/
*(.rel.dyn)
*(.rel.plt)
*(.rel.got)
*(.rel.data)
*(.rel.data*)
*(.rel.reloc)
*(.eh_frame)
*(.note.GNU-stack)