On 4/15/21 10:44 AM, Philippe Mathieu-Daudé wrote:
> On 4/14/21 2:41 PM, Laurent Vivier wrote:
>> Le 14/04/2021 à 14:16, Philippe Mathieu-Daudé a écrit :
>>> On 4/14/21 12:58 PM, Laurent Vivier wrote:
>>>> When the mem_size of the segment is bigger than the file_size,
>>>> and if this space doesn't overlap another segment, it needs
>>>> to be cleared.
>>>>
>>>> This bug is very similar to the one we had for linux-user,
>>>> 22d113b52f41 ("linux-user: Fix loading of BSS segments"),
>>>> where .bss section is encoded as an extension of the the data
>>>> one by setting the segment p_memsz > p_filesz.
>>>>
>>>> Signed-off-by: Laurent Vivier <laur...@vivier.eu>
>>>> ---
>>>> include/hw/elf_ops.h | 17 +++++++++++++++++
>>>> 1 file changed, 17 insertions(+)
>>>>
>>>> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
>>>> index 6ee458e7bc3c..e3dcee3ee349 100644
>>>> --- a/include/hw/elf_ops.h
>>>> +++ b/include/hw/elf_ops.h
>>>> @@ -562,6 +562,23 @@ static int glue(load_elf, SZ)(const char *name, int
>>>> fd,
>>>> if (res != MEMTX_OK) {
>>>> goto fail;
>>>> }
>>>> + /*
>>>> + * We need to zero'ify the space that is not copied
>>>> + * from file
>>>> + */
>>>> + if (file_size < mem_size) {
>>>> + static uint8_t zero[4096];
>>>
>>> Given it is unlikely, maybe better use:
>>>
>>> g_autofree uint8_t *zero = g_new0(uint8_t, 4096);
>>
>> I don't know what is the best solution but this seems to introduce a lot of
>> complexity only to have
>> a page of 0s.
>
> Less complex alternative is to use dma_memory_set():
>
> dma_memory_set(as, file_size, 0, mem_size - file_size);
>
> Actually we should extract address_space_set() from it, keeping
> the dma_barrier() call in dma_memory_set(), and use address_space_set()
> here.
>
> What do you think?
I'll post a patch.
