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Re: [PATCH v3 3/3] hw/core/loader: clear uninitialized ROM space
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH v3 3/3] hw/core/loader: clear uninitialized ROM space |
Date: |
Thu, 29 Apr 2021 16:52:19 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 |
On 4/29/21 4:13 PM, Laurent Vivier wrote:
> As for "hw/elf_ops: clear uninitialized segment space" we need to
> clear the uninitialized space when the ELF is set in ROM.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
> hw/core/loader.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index d3e5f3b423f6..8146fdcbb7a0 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -1146,9 +1146,13 @@ static void rom_reset(void *unused)
> if (rom->mr) {
> void *host = memory_region_get_ram_ptr(rom->mr);
> memcpy(host, rom->data, rom->datasize);
> + memset(host + rom->datasize, 0, rom->romsize - rom->datasize);
> } else {
> address_space_write_rom(rom->as, rom->addr,
> MEMTXATTRS_UNSPECIFIED,
> rom->data, rom->datasize);
> + address_space_set(rom->as, rom->addr + rom->datasize, 0,
> + rom->romsize - rom->datasize,
> + MEMTXATTRS_UNSPECIFIED);
> }
> if (rom->isrom) {
> /* rom needs to be written only once */
>
This is consistent with the comment from commit d60fa42e8ba
("Save memory allocation in the elf loader"):
/* datasize is the amount of memory allocated in "data". If datasize
is less
* than romsize, it means that the area from datasize to romsize is
filled
* with zeros.
*/
Therefore:
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
However depending on the underlying media, there might be cases
where we want to fill with -1 instead. Just to keep in mind, if
one day it bites us.
Regards,
Phil.