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BL1: Add linker symbol identifying end of ROM content
This patch adds a new linker symbol in BL1's linker script named '__BL1_ROM_END__', which marks the end of BL1's ROM content. This covers BL1's code, read-only data and read-write data to relocate in Trusted SRAM. The address of this new linker symbol is exported to C code through the 'BL1_ROM_END' macro. The section related to linker symbols in the Firmware Design guide has been updated and improved. Change-Id: I5c442ff497c78d865ffba1d7d044511c134e11c7
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Sandrine Bailleux
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b9161469fa
commit
c02fcc4a38
10
bl1/bl1.ld.S
10
bl1/bl1.ld.S
@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
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* Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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@ -139,12 +139,14 @@ SECTIONS
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__DATA_ROM_START__ = LOADADDR(.data);
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__DATA_SIZE__ = SIZEOF(.data);
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/*
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* The .data section is the last PROGBITS section so its end marks the end
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* of the read-only part of BL1's binary.
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* of BL1's actual content in Trusted ROM.
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*/
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ASSERT(__DATA_ROM_START__ + __DATA_SIZE__ <= BL1_RO_LIMIT,
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"BL1's RO section has exceeded its limit.")
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__BL1_ROM_END__ = __DATA_ROM_START__ + __DATA_SIZE__;
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ASSERT(__BL1_ROM_END__ <= BL1_RO_LIMIT,
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"BL1's ROM content has exceeded its limit.")
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__BSS_SIZE__ = SIZEOF(.bss);
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
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* Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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@ -35,8 +35,11 @@
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/*******************************************************************************
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* Declarations of linker defined symbols which will tell us where BL1 lives
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* in Trusted RAM
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* in Trusted ROM and RAM
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******************************************************************************/
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extern uint64_t __BL1_ROM_END__;
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#define BL1_ROM_END (uint64_t)(&__BL1_ROM_END__)
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extern uint64_t __BL1_RAM_START__;
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extern uint64_t __BL1_RAM_END__;
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#define BL1_RAM_BASE (uint64_t)(&__BL1_RAM_START__)
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@ -1052,10 +1052,10 @@ Each bootloader image can be divided in 2 parts:
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All PROGBITS sections are grouped together at the beginning of the image,
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followed by all NOBITS sections. This is true for all Trusted Firmware images
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and it is governed by the linker scripts. This ensures that the raw binary
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images are as small as possible. If a NOBITS section would sneak in between
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PROGBITS sections then the resulting binary file would contain a bunch of zero
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bytes at the location of this NOBITS section, making the image unnecessarily
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bigger. Smaller images allow faster loading from the FIP to the main memory.
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images are as small as possible. If a NOBITS section was inserted in between
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PROGBITS sections then the resulting binary file would contain zero bytes in
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place of this NOBITS section, making the image unnecessarily bigger. Smaller
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images allow faster loading from the FIP to the main memory.
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### Linker scripts and symbols
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@ -1110,47 +1110,42 @@ layout as they are easy to spot in the link map files.
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#### Common linker symbols
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Early setup code needs to know the extents of the BSS section to zero-initialise
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it before executing any C code. The following linker symbols are defined for
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this purpose:
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All BL images share the following requirements:
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* `__BSS_START__` This address must be aligned on a 16-byte boundary.
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* `__BSS_SIZE__`
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* The BSS section must be zero-initialised before executing any C code.
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* The coherent memory section (if enabled) must be zero-initialised as well.
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* The MMU setup code needs to know the extents of the coherent and read-only
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memory regions to set the right memory attributes.
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Similarly, the coherent memory section (if enabled) must be zero-initialised.
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Also, the MMU setup code needs to know the extents of this section to set the
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right memory attributes for it. The following linker symbols are defined for
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this purpose:
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The following linker symbols are defined for this purpose:
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* `__COHERENT_RAM_START__` This address must be aligned on a page-size boundary.
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* `__COHERENT_RAM_END__` This address must be aligned on a page-size boundary.
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* `__COHERENT_RAM_UNALIGNED_SIZE__`
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* `__BSS_START__` Must be aligned on a 16-byte boundary.
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* `__BSS_SIZE__`
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* `__COHERENT_RAM_START__` Must be aligned on a page-size boundary.
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* `__COHERENT_RAM_END__` Must be aligned on a page-size boundary.
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* `__COHERENT_RAM_UNALIGNED_SIZE__`
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* `__RO_START__`
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* `__RO_END__`
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#### BL1's linker symbols
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BL1's early setup code needs to know the extents of the .data section to
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relocate it from ROM to RAM before executing any C code. The following linker
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symbols are defined for this purpose:
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BL1 being the ROM image, it has additional requirements. BL1 resides in ROM and
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it is entirely executed in place but it needs some read-write memory for its
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mutable data. Its `.data` section (i.e. its allocated read-write data) must be
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relocated from ROM to RAM before executing any C code.
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* `__DATA_ROM_START__` This address must be aligned on a 16-byte boundary.
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* `__DATA_RAM_START__` This address must be aligned on a 16-byte boundary.
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* `__DATA_SIZE__`
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The following additional linker symbols are defined for BL1:
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BL1's platform setup code needs to know the extents of its read-write data
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region to figure out its memory layout. The following linker symbols are defined
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for this purpose:
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* `__BL1_ROM_END__` End address of BL1's ROM contents, covering its code
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and `.data` section in ROM.
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* `__DATA_ROM_START__` Start address of the `.data` section in ROM. Must be
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aligned on a 16-byte boundary.
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* `__DATA_RAM_START__` Address in RAM where the `.data` section should be
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copied over. Must be aligned on a 16-byte boundary.
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* `__DATA_SIZE__` Size of the `.data` section (in ROM or RAM).
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* `__BL1_RAM_START__` Start address of BL1 read-write data.
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* `__BL1_RAM_END__` End address of BL1 read-write data.
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* `__BL1_RAM_START__` This is the start address of BL1 RW data.
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* `__BL1_RAM_END__` This is the end address of BL1 RW data.
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#### BL2's, BL31's and TSP's linker symbols
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BL2, BL31 and TSP need to know the extents of their read-only section to set
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the right memory attributes for this memory region in their MMU setup code. The
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following linker symbols are defined for this purpose:
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* `__RO_START__`
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* `__RO_END__`
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### How to choose the right base addresses for each bootloader stage image
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