• Antonio Nino Diaz's avatar
    Add comments about mismatched TCR_ELx and xlat tables · 883d1b5d
    Antonio Nino Diaz authored
    When the MMU is enabled and the translation tables are mapped, data
    read/writes to the translation tables are made using the attributes
    specified in the translation tables themselves. However, the MMU
    performs table walks with the attributes specified in TCR_ELx. They are
    completely independent, so special care has to be taken to make sure
    that they are the same.
    
    This has to be done manually because it is not practical to have a test
    in the code. Such a test would need to know the virtual memory region
    that contains the translation tables and check that for all of the
    tables the attributes match the ones in TCR_ELx. As the tables may not
    even be mapped at all, this isn't a test that can be made generic.
    
    The flags used by enable_mmu_xxx() have been moved to the same header
    where the functions are.
    
    Also, some comments in the linker scripts related to the translation
    tables have been fixed.
    
    Change-Id: I1754768bffdae75f53561b1c4a5baf043b45a304
    Signed-o...
    883d1b5d
bl1.ld.S 5.19 KB
/*
 * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <platform_def.h>
#include <xlat_tables_defs.h>

OUTPUT_FORMAT(PLATFORM_LINKER_FORMAT)
OUTPUT_ARCH(PLATFORM_LINKER_ARCH)
ENTRY(bl1_entrypoint)

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
}

SECTIONS
{
    . = BL1_RO_BASE;
    ASSERT(. == ALIGN(PAGE_SIZE),
           "BL1_RO_BASE address is not aligned on a page boundary.")

#if SEPARATE_CODE_AND_RODATA
    .text . : {
        __TEXT_START__ = .;
        *bl1_entrypoint.o(.text*)
        *(.text*)
        *(.vectors)
        . = NEXT(PAGE_SIZE);
        __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*)

        /* 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__ = .;
    } >ROM
#endif

    ASSERT(__CPU_OPS_END__ > __CPU_OPS_START__,
           "cpu_ops not defined for this platform.")

    . = BL1_RW_BASE;
    ASSERT(BL1_RW_BASE == ALIGN(PAGE_SIZE),
           "BL1_RW_BASE address is not aligned on a page boundary.")

    /*
     * The .data section gets copied from ROM to RAM at runtime.
     * Its LMA should be 16-byte aligned to allow efficient copying of 16-bytes
     * aligned regions in it.
     * Its VMA must be page-aligned as it marks the first read/write page.
     *
     * It must be placed at a lower address than the stacks if the stack
     * protector is enabled. Alternatively, the .data.stack_protector_canary
     * section can be placed independently of the main .data section.
     */
    .data . : ALIGN(16) {
        __DATA_RAM_START__ = .;
        *(.data*)
        __DATA_RAM_END__ = .;
    } >RAM AT>ROM

    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__ = .;
        *(.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. The tables are initialized to zero by the translation
     * tables library.
     */
    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(PAGE_SIZE) {
        __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(PAGE_SIZE);
        __COHERENT_RAM_END__ = .;
    } >RAM
#endif

    __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.")

    __BSS_SIZE__ = SIZEOF(.bss);

#if USE_COHERENT_MEM
    __COHERENT_RAM_UNALIGNED_SIZE__ =
        __COHERENT_RAM_END_UNALIGNED__ - __COHERENT_RAM_START__;
#endif

    ASSERT(. <= BL1_RW_LIMIT, "BL1's RW section has exceeded its limit.")
}