Re: [PATCH v4 12/17] dump/dump: Add arch section support

[Janosch Frank]

On 7/26/22 13:30, Marc-André Lureau wrote:
> Hi
>
> On Tue, Jul 26, 2022 at 1:23 PM Janosch Frank <frankja@linux.ibm.com> wrote:
> > Add hooks which architectures can use to add arbitrary data to custom
> > sections.
> >
> > Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> > ---
> >   dump/dump.c                |  5 +++++
> >   include/sysemu/dump-arch.h | 27 +++++++++++++++++++++++++++
> >   2 files changed, 32 insertions(+)
> >
> > diff --git a/dump/dump.c b/dump/dump.c
> > index 298a1e923f..1ec4c3b6c3 100644
> > --- a/dump/dump.c
> > +++ b/dump/dump.c
> > @@ -398,6 +398,7 @@ static void prepare_elf_section_hdrs(DumpState *s)
> >       /*
> >        * Section ordering:
> >        * - HDR zero (if needed)
> > +     * - Arch section hdrs
> >        * - String table hdr
> >        */
> >       sizeof_shdr = dump_is_64bit(s) ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr);
> > @@ -415,6 +416,8 @@ static void prepare_elf_section_hdrs(DumpState *s)
> >           return;
> >       }
> >
> > +    buff_hdr += dump_arch_sections_write_hdr(&s->dump_info, s, buff_hdr);
> > +
> >       /*
> >        * String table needs to be last section since strings are added
> >        * via arch_sections_write_hdr().
> > @@ -758,6 +761,7 @@ static void dump_end(DumpState *s, Error **errp)
> >           return;
> >       }
> >       s->elf_section_data = g_malloc0(s->elf_section_data_size);
> > +    dump_arch_sections_write(&s->dump_info, s, s->elf_section_data);
> >
> >       /* write sections to vmcore */
> >       write_elf_sections(s, errp);
> > @@ -1929,6 +1933,7 @@ static void dump_init(DumpState *s, int fd, bool 
> > has_format,
> >        * If phdr_num overflowed we have at least one section header
> >        * More sections/hdrs can be added by the architectures
> >        */
> > +    dump_arch_sections_add(&s->dump_info, (void *)s);
> >       if (s->shdr_num > 1) {
> >           /* Reserve the string table */
> >           s->shdr_num += 1;
> > diff --git a/include/sysemu/dump-arch.h b/include/sysemu/dump-arch.h
> > index e25b02e990..de77908424 100644
> > --- a/include/sysemu/dump-arch.h
> > +++ b/include/sysemu/dump-arch.h
> > @@ -21,6 +21,9 @@ typedef struct ArchDumpInfo {
> >       uint32_t page_size;      /* The target's page size. If it's variable and
> >                                 * unknown, then this should be the maximum. */
> >       uint64_t phys_base;      /* The target's physmem base. */
> > +    void (*arch_sections_add_fn)(void *opaque);
> > +    uint64_t (*arch_sections_write_hdr_fn)(void *opaque, uint8_t *buff);
> > +    void (*arch_sections_write_fn)(void *opaque, uint8_t *buff);
>
> Why not pass DumpState? If there is an issue with header declaration
> order, you can always move the declaration in include/qemu/typedefs.h,
> I guess.

The CPU note function passes the opaque pointer so I did as the same.
If you want I can have a look if it makes sense to move over to DumpState.

> >   } ArchDumpInfo;
> >
> >   struct GuestPhysBlockList; /* memory_mapping.h */
> > @@ -28,4 +31,28 @@ int cpu_get_dump_info(ArchDumpInfo *info,
> >                         const struct GuestPhysBlockList *guest_phys_blocks);
> >   ssize_t cpu_get_note_size(int class, int machine, int nr_cpus);
> >
> > +static inline void dump_arch_sections_add(ArchDumpInfo *info, void *opaque)
> > +{
> > +    if (info->arch_sections_add_fn) {
> > +        info->arch_sections_add_fn(opaque);
> > +    }
> > +}
> > +
> > +static inline uint64_t dump_arch_sections_write_hdr(ArchDumpInfo *info,
> > +                                                void *opaque, uint8_t *buff)
> > +{
> > +    if (info->arch_sections_write_hdr_fn) {
> > +        return info->arch_sections_write_hdr_fn(opaque, buff);
> > +    }
> > +    return 0;
> > +}
> > +
> > +static inline void dump_arch_sections_write(ArchDumpInfo *info, void *opaque,
> > +                                            uint8_t *buff)
> > +{
> > +    if (info->arch_sections_write_fn) {
> > +        info->arch_sections_write_fn(opaque, buff);
> > +    }
> > +}
>
> We probably don't need those static inline helpers in the header.