On 7/21/22 17:07, Marc-André Lureau wrote:
> Hi
>
> On Thu, Jul 21, 2022 at 5:23 PM Janosch Frank <frankja@linux.ibm.com> wrote:
>>
>> For the upcoming string table and arch section support we need to
>> modify the elf layout a bit. Instead of the segments, i.e. the guest's
>> memory contents, beeing the last area the section data will live at
>> the end of the file. This will allow us to write the section data
>> after all guest memory has been dumped which is important for the s390
>> PV dump support.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>> dump/dump.c | 21 ++++++++++++---------
>> 1 file changed, 12 insertions(+), 9 deletions(-)
>>
>> diff --git a/dump/dump.c b/dump/dump.c
>> index 980702d476..6f3274c5af 100644
>> --- a/dump/dump.c
>> +++ b/dump/dump.c
>> @@ -590,6 +590,9 @@ static void dump_begin(DumpState *s, Error **errp)
>> * --------------
>> * | memory |
>> * --------------
>> + * | sectn data |
>> + * --------------
>> +
>> *
>> * we only know where the memory is saved after we write elf note into
>> * vmcore.
>> @@ -1817,18 +1820,18 @@ static void dump_init(DumpState *s, int fd, bool has_format,
>> }
>> }
>>
>> + tmp = (s->phdr_num == PN_XNUM) ? s->sh_info : s->phdr_num;
>> if (dump_is_64bit(s)) {
>> - s->phdr_offset = sizeof(Elf64_Ehdr);
>> - s->shdr_offset = s->phdr_offset + sizeof(Elf64_Phdr) * s->phdr_num;
>> - s->note_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
>> - s->memory_offset = s->note_offset + s->note_size;
>> + s->shdr_offset = sizeof(Elf64_Ehdr);
>> + s->phdr_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
>> + s->note_offset = s->phdr_offset + sizeof(Elf64_Phdr) * tmp;
>> } else {
>> -
>> - s->phdr_offset = sizeof(Elf32_Ehdr);
>> - s->shdr_offset = s->phdr_offset + sizeof(Elf32_Phdr) * s->phdr_num;
>> - s->note_offset = s->shdr_offset + sizeof(Elf32_Shdr) * s->shdr_num;
>> - s->memory_offset = s->note_offset + s->note_size;
>> + s->shdr_offset = sizeof(Elf32_Ehdr);
>> + s->phdr_offset = s->shdr_offset + sizeof(Elf32_Shdr) * s->shdr_num;
>> + s->note_offset = s->phdr_offset + sizeof(Elf32_Phdr) * tmp;
>> }
>> + s->memory_offset = s->note_offset + s->note_size;
>> + s->section_offset = s->memory_offset + s->total_size;
>
> Ah! section_offset was actually added from commit e71d353360 ("dump:
> Add more offset variables"), but unused until now. It's worth
> explaining in the commit message.
I think I'll just move it to this patch so the previous one really only
does re-ordering and doesn't introduce new struct members.
>
>>
>> return;
>>
>> --
>> 2.34.1
>>
>
>