On Tue, 14 Jul 2020 at 01:44, Alistair Francis <alistair.fran...@wdc.com> wrote:
>
> From: Atish Patra <atish.pa...@wdc.com>
>
> Currently, the fdt is copied to the ROM after the reset vector. The firmware
> has to copy it to DRAM. Instead of this, directly copy the device tree to a
> pre-computed dram address. The device tree load address should be as far as
> possible from kernel and initrd images. That's why it is kept at the end of
> the DRAM or 4GB whichever is lesser.
Hi; Coverity reports an issue in this code (CID 1458136):
> +uint32_t riscv_load_fdt(hwaddr dram_base, uint64_t mem_size, void *fdt)
> +{
> + uint32_t temp, fdt_addr;
> + hwaddr dram_end = dram_base + mem_size;
> + int fdtsize = fdt_totalsize(fdt);
> +
> + if (fdtsize <= 0) {
> + error_report("invalid device-tree");
> + exit(1);
> + }
> +
> + /*
> + * We should put fdt as far as possible to avoid kernel/initrd
> overwriting
> + * its content. But it should be addressable by 32 bit system as well.
> + * Thus, put it at an aligned address that less than fdt size from end of
> + * dram or 4GB whichever is lesser.
> + */
> + temp = MIN(dram_end, 4096 * MiB);
> + fdt_addr = QEMU_ALIGN_DOWN(temp - fdtsize, 2 * MiB);
> +
> + fdt_pack(fdt);
fdt_pack() can return an error code, but we are not checking its
return value here.
(This is one of Coverity's heuristics where it only reports failure
to check errors if it sees enough other callsites in the codebase
which do check errors to make it decide this is an "always need a
check" API, which is why the error has only popped up now a year on...)
> + /* copy in the device tree */
> + qemu_fdt_dumpdtb(fdt, fdtsize);
> +
> + rom_add_blob_fixed_as("fdt", fdt, fdtsize, fdt_addr,
> + &address_space_memory);
> +
> + return fdt_addr;
> +}
thanks
-- PMM
