switch-l4t-atf/bl2u/bl2u.ld.S
Douglas Raillard 308d359b26 Introduce unified API to zero memory
Introduce zeromem_dczva function on AArch64 that can handle unaligned
addresses and make use of DC ZVA instruction to zero a whole block at a
time. This zeroing takes place directly in the cache to speed it up
without doing external memory access.

Remove the zeromem16 function on AArch64 and replace it with an alias to
zeromem. This zeromem16 function is now deprecated.

Remove the 16-bytes alignment constraint on __BSS_START__ in
firmware-design.md as it is now not mandatory anymore (it used to comply
with zeromem16 requirements).

Change the 16-bytes alignment constraints in SP min's linker script to a
8-bytes alignment constraint as the AArch32 zeromem implementation is now
more efficient on 8-bytes aligned addresses.

Introduce zero_normalmem and zeromem helpers in platform agnostic header
that are implemented this way:
* AArch32:
	* zero_normalmem: zero using usual data access
	* zeromem: alias for zero_normalmem
* AArch64:
	* zero_normalmem: zero normal memory  using DC ZVA instruction
	                  (needs MMU enabled)
	* zeromem: zero using usual data access

Usage guidelines: in most cases, zero_normalmem should be preferred.

There are 2 scenarios where zeromem (or memset) must be used instead:
* Code that must run with MMU disabled (which means all memory is
  considered device memory for data accesses).
* Code that fills device memory with null bytes.

Optionally, the following rule can be applied if performance is
important:
* Code zeroing small areas (few bytes) that are not secrets should use
  memset to take advantage of compiler optimizations.

  Note: Code zeroing security-related critical information should use
  zero_normalmem/zeromem instead of memset to avoid removal by
  compilers' optimizations in some cases or misbehaving versions of GCC.

Fixes ARM-software/tf-issues#408

Change-Id: Iafd9663fc1070413c3e1904e54091cf60effaa82
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
2017-02-06 17:01:39 +00:00

154 lines
4.6 KiB
ArmAsm

/*
* Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
*
* 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>
OUTPUT_FORMAT(PLATFORM_LINKER_FORMAT)
OUTPUT_ARCH(PLATFORM_LINKER_ARCH)
ENTRY(bl2u_entrypoint)
MEMORY {
RAM (rwx): ORIGIN = BL2U_BASE, LENGTH = BL2U_LIMIT - BL2U_BASE
}
SECTIONS
{
. = BL2U_BASE;
ASSERT(. == ALIGN(4096),
"BL2U_BASE address is not aligned on a page boundary.")
#if SEPARATE_CODE_AND_RODATA
.text . : {
__TEXT_START__ = .;
*bl2u_entrypoint.o(.text*)
*(.text*)
*(.vectors)
. = NEXT(4096);
__TEXT_END__ = .;
} >RAM
.rodata . : {
__RODATA_START__ = .;
*(.rodata*)
. = NEXT(4096);
__RODATA_END__ = .;
} >RAM
#else
ro . : {
__RO_START__ = .;
*bl2u_entrypoint.o(.text*)
*(.text*)
*(.rodata*)
*(.vectors)
__RO_END_UNALIGNED__ = .;
/*
* Memory page(s) mapped to this section will be marked as
* read-only, executable. No RW data from the next section must
* creep in. Ensure the rest of the current memory page is unused.
*/
. = NEXT(4096);
__RO_END__ = .;
} >RAM
#endif
/*
* Define a linker symbol to mark start of the RW memory area for this
* image.
*/
__RW_START__ = . ;
.data . : {
__DATA_START__ = .;
*(.data*)
__DATA_END__ = .;
} >RAM
stacks (NOLOAD) : {
__STACKS_START__ = .;
*(tzfw_normal_stacks)
__STACKS_END__ = .;
} >RAM
/*
* The .bss section gets initialised to 0 at runtime.
* Its base address should be 16-byte aligned for better performance of the
* zero-initialization code.
*/
.bss : ALIGN(16) {
__BSS_START__ = .;
*(SORT_BY_ALIGNMENT(.bss*))
*(COMMON)
__BSS_END__ = .;
} >RAM
/*
* 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__ = .;
*(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__ = .;
} >RAM
#endif
/*
* Define a linker symbol to mark end of the RW memory area for this
* image.
*/
__RW_END__ = .;
__BL2U_END__ = .;
__BSS_SIZE__ = SIZEOF(.bss);
ASSERT(. <= BL2U_LIMIT, "BL2U image has exceeded its limit.")
}