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    SubjectRe: [PATCH v3 04/12] module: Add printk format to add module build ID to stacktraces
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    Quoting Andy Shevchenko (2021-04-08 07:05:54)
    > On Thu, Apr 08, 2021 at 03:44:57PM +0200, Jessica Yu wrote:
    > > +++ Stephen Boyd [30/03/21 20:05 -0700]:
    >
    > ...
    >
    > > > +static void init_build_id(struct module *mod, const struct load_info *info)
    > > > +{
    > > > + const Elf_Shdr *sechdr;
    > > > + unsigned int i;
    > > > +
    > > > + for (i = 0; i < info->hdr->e_shnum; i++) {
    > > > + sechdr = &info->sechdrs[i];
    > > > + if (!sect_empty(sechdr) && sechdr->sh_type == SHT_NOTE &&
    > > > + !build_id_parse_buf((void *)sechdr->sh_addr, mod->build_id,
    > > > + sechdr->sh_size))
    > > > + break;
    > > > + }
    > > > +}
    > >
    > > Why not just look for the .note.gnu.build-id section instead of trying
    > > to parse each note section? Doesn't it always contain the build id? At
    > > least the ld man page seems to suggest this section name should be
    > > consistent.

    That's basically what this code is doing. We're looking through all the
    section headers and finding the ones that are notes and then
    build_id_parse_buf() is checking to see if that note is a GNU type note
    (name == "GNU") and is of the type NT_GNU_BUILD_ID (type == 3). We don't
    need to check for a section name of ".note.gnu.build-id", we can use the
    existing code in build_id_parse_buf() that looks for the name and type.

    >
    > Interesting idea (in positive way!), I'm wondering what Clang does in such
    > case.
    >

    Clang also inserts a GNU build ID and it works with these patches.

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