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

[Marc-André Lureau]

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.

>  } 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.