| Message ID | 20220721132256.2171-8-frankja@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dump: Add arch section and s390x PV dump | expand |
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. > > return; > > -- > 2.34.1 >
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 >> > >
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; return;
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(-)