arm-trusted-firmware/bl1/bl1.ld.S

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/*
* Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
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*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <platform_def.h>
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OUTPUT_FORMAT(PLATFORM_LINKER_FORMAT)
OUTPUT_ARCH(PLATFORM_LINKER_ARCH)
ENTRY(bl1_entrypoint)
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MEMORY {
ROM (rx): ORIGIN = BL1_RO_BASE, LENGTH = BL1_RO_LIMIT - BL1_RO_BASE
RAM (rwx): ORIGIN = BL1_RW_BASE, LENGTH = BL1_RW_LIMIT - BL1_RW_BASE
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}
SECTIONS
{
. = BL1_RO_BASE;
ASSERT(. == ALIGN(4096),
"BL1_RO_BASE address is not aligned on a page boundary.")
Introduce SEPARATE_CODE_AND_RODATA build flag At the moment, all BL images share a similar memory layout: they start with their code section, followed by their read-only data section. The two sections are contiguous in memory. Therefore, the end of the code section and the beginning of the read-only data one might share a memory page. This forces both to be mapped with the same memory attributes. As the code needs to be executable, this means that the read-only data stored on the same memory page as the code are executable as well. This could potentially be exploited as part of a security attack. This patch introduces a new build flag called SEPARATE_CODE_AND_RODATA, which isolates the code and read-only data on separate memory pages. This in turn allows independent control of the access permissions for the code and read-only data. This has an impact on memory footprint, as padding bytes need to be introduced between the code and read-only data to ensure the segragation of the two. To limit the memory cost, the memory layout of the read-only section has been changed in this case. - When SEPARATE_CODE_AND_RODATA=0, the layout is unchanged, i.e. the read-only section still looks like this (padding omitted): | ... | +-------------------+ | Exception vectors | +-------------------+ | Read-only data | +-------------------+ | Code | +-------------------+ BLx_BASE In this case, the linker script provides the limits of the whole read-only section. - When SEPARATE_CODE_AND_RODATA=1, the exception vectors and read-only data are swapped, such that the code and exception vectors are contiguous, followed by the read-only data. This gives the following new layout (padding omitted): | ... | +-------------------+ | Read-only data | +-------------------+ | Exception vectors | +-------------------+ | Code | +-------------------+ BLx_BASE In this case, the linker script now exports 2 sets of addresses instead: the limits of the code and the limits of the read-only data. Refer to the Firmware Design guide for more details. This provides platform code with a finer-grained view of the image layout and allows it to map these 2 regions with the appropriate access permissions. Note that SEPARATE_CODE_AND_RODATA applies to all BL images. Change-Id: I936cf80164f6b66b6ad52b8edacadc532c935a49
2016-07-08 14:37:40 +01:00
#if SEPARATE_CODE_AND_RODATA
.text . : {
__TEXT_START__ = .;
*bl1_entrypoint.o(.text*)
*(.text*)
*(.vectors)
. = NEXT(4096);
__TEXT_END__ = .;
} >ROM
.rodata . : {
__RODATA_START__ = .;
*(.rodata*)
/* Ensure 8-byte alignment for descriptors and ensure inclusion */
. = ALIGN(8);
__PARSER_LIB_DESCS_START__ = .;
KEEP(*(.img_parser_lib_descs))
__PARSER_LIB_DESCS_END__ = .;
/*
* Ensure 8-byte alignment for cpu_ops so that its fields are also
* aligned. Also ensure cpu_ops inclusion.
*/
. = ALIGN(8);
__CPU_OPS_START__ = .;
KEEP(*(cpu_ops))
__CPU_OPS_END__ = .;
/*
* No need to pad out the .rodata section to a page boundary. Next is
* the .data section, which can mapped in ROM with the same memory
* attributes as the .rodata section.
*/
__RODATA_END__ = .;
} >ROM
#else
ro . : {
__RO_START__ = .;
*bl1_entrypoint.o(.text*)
*(.text*)
*(.rodata*)
TBB: add authentication framework This patch adds the authentication framework that will be used as the base to implement Trusted Board Boot in the Trusted Firmware. The framework comprises the following modules: - Image Parser Module (IPM) This module is responsible for interpreting images, check their integrity and extract authentication information from them during Trusted Board Boot. The module currently supports three types of images i.e. raw binaries, X509v3 certificates and any type specific to a platform. An image parser library must be registered for each image type (the only exception is the raw image parser, which is included in the main module by default). Each parser library (if used) must export a structure in a specific linker section which contains function pointers to: 1. Initialize the library 2. Check the integrity of the image type supported by the library 3. Extract authentication information from the image - Cryptographic Module (CM) This module is responsible for verifying digital signatures and hashes. It relies on an external cryptographic library to perform the cryptographic operations. To register a cryptographic library, the library must use the REGISTER_CRYPTO_LIB macro, passing function pointers to: 1. Initialize the library 2. Verify a digital signature 3. Verify a hash Failing to register a cryptographic library will generate a build time error. - Authentication Module (AM) This module provides methods to authenticate an image, like hash comparison or digital signatures. It uses the image parser module to extract authentication parameters, the crypto module to perform cryptographic operations and the Chain of Trust to authenticate the images. The Chain of Trust (CoT) is a data structure that defines the dependencies between images and the authentication methods that must be followed to authenticate an image. The Chain of Trust, when added, must provide a header file named cot_def.h with the following definitions: - COT_MAX_VERIFIED_PARAMS Integer value indicating the maximum number of authentication parameters an image can present. This value will be used by the authentication module to allocate the memory required to load the parameters in the image descriptor. Change-Id: Ied11bd5cd410e1df8767a1df23bb720ce7e58178
2015-04-02 09:48:16 +01:00
/* Ensure 8-byte alignment for descriptors and ensure inclusion */
. = ALIGN(8);
__PARSER_LIB_DESCS_START__ = .;
KEEP(*(.img_parser_lib_descs))
__PARSER_LIB_DESCS_END__ = .;
/*
* Ensure 8-byte alignment for cpu_ops so that its fields are also
* aligned. Also ensure cpu_ops inclusion.
*/
. = ALIGN(8);
__CPU_OPS_START__ = .;
KEEP(*(cpu_ops))
__CPU_OPS_END__ = .;
*(.vectors)
__RO_END__ = .;
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} >ROM
Introduce SEPARATE_CODE_AND_RODATA build flag At the moment, all BL images share a similar memory layout: they start with their code section, followed by their read-only data section. The two sections are contiguous in memory. Therefore, the end of the code section and the beginning of the read-only data one might share a memory page. This forces both to be mapped with the same memory attributes. As the code needs to be executable, this means that the read-only data stored on the same memory page as the code are executable as well. This could potentially be exploited as part of a security attack. This patch introduces a new build flag called SEPARATE_CODE_AND_RODATA, which isolates the code and read-only data on separate memory pages. This in turn allows independent control of the access permissions for the code and read-only data. This has an impact on memory footprint, as padding bytes need to be introduced between the code and read-only data to ensure the segragation of the two. To limit the memory cost, the memory layout of the read-only section has been changed in this case. - When SEPARATE_CODE_AND_RODATA=0, the layout is unchanged, i.e. the read-only section still looks like this (padding omitted): | ... | +-------------------+ | Exception vectors | +-------------------+ | Read-only data | +-------------------+ | Code | +-------------------+ BLx_BASE In this case, the linker script provides the limits of the whole read-only section. - When SEPARATE_CODE_AND_RODATA=1, the exception vectors and read-only data are swapped, such that the code and exception vectors are contiguous, followed by the read-only data. This gives the following new layout (padding omitted): | ... | +-------------------+ | Read-only data | +-------------------+ | Exception vectors | +-------------------+ | Code | +-------------------+ BLx_BASE In this case, the linker script now exports 2 sets of addresses instead: the limits of the code and the limits of the read-only data. Refer to the Firmware Design guide for more details. This provides platform code with a finer-grained view of the image layout and allows it to map these 2 regions with the appropriate access permissions. Note that SEPARATE_CODE_AND_RODATA applies to all BL images. Change-Id: I936cf80164f6b66b6ad52b8edacadc532c935a49
2016-07-08 14:37:40 +01:00
#endif
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ASSERT(__CPU_OPS_END__ > __CPU_OPS_START__,
"cpu_ops not defined for this platform.")
/*
* The .data section gets copied from ROM to RAM at runtime.
* Its LMA must be 16-byte aligned.
* Its VMA must be page-aligned as it marks the first read/write page.
*/
. = BL1_RW_BASE;
ASSERT(. == ALIGN(4096),
"BL1_RW_BASE address is not aligned on a page boundary.")
.data . : ALIGN(16) {
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__DATA_RAM_START__ = .;
*(.data*)
__DATA_RAM_END__ = .;
} >RAM AT>ROM
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stacks . (NOLOAD) : {
__STACKS_START__ = .;
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*(tzfw_normal_stacks)
__STACKS_END__ = .;
} >RAM
/*
* The .bss section gets initialised to 0 at runtime.
* Its base address must be 16-byte aligned.
*/
.bss : ALIGN(16) {
__BSS_START__ = .;
*(.bss*)
*(COMMON)
__BSS_END__ = .;
} >RAM
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/*
* The xlat_table section is for full, aligned page tables (4K).
* Removing them from .bss avoids forcing 4K alignment on
* the .bss section and eliminates the unecessary zero init
*/
xlat_table (NOLOAD) : {
*(xlat_table)
} >RAM
#if USE_COHERENT_MEM
/*
* The base address of the coherent memory section must be page-aligned (4K)
* to guarantee that the coherent data are stored on their own pages and
* are not mixed with normal data. This is required to set up the correct
* memory attributes for the coherent data page tables.
*/
coherent_ram (NOLOAD) : ALIGN(4096) {
__COHERENT_RAM_START__ = .;
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*(tzfw_coherent_mem)
__COHERENT_RAM_END_UNALIGNED__ = .;
/*
* Memory page(s) mapped to this section will be marked
* as device memory. No other unexpected data must creep in.
* Ensure the rest of the current memory page is unused.
*/
. = NEXT(4096);
__COHERENT_RAM_END__ = .;
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} >RAM
#endif
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__BL1_RAM_START__ = ADDR(.data);
__BL1_RAM_END__ = .;
__DATA_ROM_START__ = LOADADDR(.data);
__DATA_SIZE__ = SIZEOF(.data);
/*
* The .data section is the last PROGBITS section so its end marks the end
* of BL1's actual content in Trusted ROM.
*/
__BL1_ROM_END__ = __DATA_ROM_START__ + __DATA_SIZE__;
ASSERT(__BL1_ROM_END__ <= BL1_RO_LIMIT,
"BL1's ROM content has exceeded its limit.")
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__BSS_SIZE__ = SIZEOF(.bss);
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#if USE_COHERENT_MEM
__COHERENT_RAM_UNALIGNED_SIZE__ =
__COHERENT_RAM_END_UNALIGNED__ - __COHERENT_RAM_START__;
#endif
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ASSERT(. <= BL1_RW_LIMIT, "BL1's RW section has exceeded its limit.")
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}