fit_payload.c

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/* SPDX-License-Identifier: GPL-2.0-or-later */
 
#include <bootmem.h>
#include <program_loading.h>
#include <fit.h>
#include <symbols.h>
 
/**
 * Place the region in free memory range.
 */
static bool fit_place_mem(const struct range_entry *r, void *arg)
{
        struct region *region = arg;
        resource_t start;
 
        if (range_entry_tag(r) != BM_MEM_RAM)
                return true;
 
        /* Linux 4.15 doesn't like 4KiB alignment. Align to 1 MiB for now. */
        start = ALIGN_UP(MAX(region->offset, range_entry_base(r)), 1 * MiB);
 
        if (start + region->size < range_entry_end(r)) {
                region->offset = (size_t)start;
                return false;
        }
 
        return true;
}
 
bool fit_payload_arch(struct prog *payload, struct fit_config_node *config,
                      struct region *kernel,
                      struct region *fdt,
                      struct region *initrd)
{
        void *arg = NULL;
 
        /**
         * The kernel ARM documentation recommends loading the kernel above 32MiB
         * in order to avoid the need to need to relocate prior to decompression.
         */
        kernel->offset = (uintptr_t)_dram + 32 * MiB;
 
        /**
         * The code assumes that bootmem_walk provides a sorted list of memory
         * regions, starting from the lowest address.
         * The order of the calls here doesn't matter, as the placement is
         * enforced in the called functions.
         * For details check code on top.
         */
        if (!bootmem_walk(fit_place_mem, kernel))
                return false;
 
        /* Mark as reserved for future allocations. */
        bootmem_add_range(kernel->offset, kernel->size, BM_MEM_PAYLOAD);
 
        /**
         * To ensure the fdt is not overwritten by the kernel decompressor, place
         * the fdt above the 128 MB from the start of RAM, as recommended by the
         * kernel documentation.
         */
        fdt->offset = (uintptr_t)_dram + 128 * MiB;
 
        if (!bootmem_walk(fit_place_mem, fdt))
                return false;
 
        /* Mark as reserved for future allocations. */
        bootmem_add_range(fdt->offset, fdt->size, BM_MEM_PAYLOAD);
 
        /* Place INITRD */
        if (config->ramdisk) {
                initrd->offset = fdt->offset + fdt->size;
 
                if (!bootmem_walk(fit_place_mem, initrd))
                        return false;
 
                /* Mark as reserved for future allocations. */
                bootmem_add_range(initrd->offset, initrd->size, BM_MEM_PAYLOAD);
        }
 
        /* Kernel expects FDT as argument */
        arg = (void *)fdt->offset;
 
        prog_set_entry(payload, (void *)kernel->offset, arg);
 
        bootmem_dump_ranges();
 
        return true;
}