Re: 64bit startup

[Samuel Thibault]

Luca, le sam. 06 janv. 2024 00:42:35 +0100, a ecrit:
> Il 05/01/24 19:12, Sergey Bugaev ha scritto:
> > /servers/crash-dump-core crashes on the memset () call in
> > hurd:exec/elfcore.c:fetch_thread_fpregset (); the (*fpregs) pointer is
> > NULL. The caller passes fpregs = &note.data.pr_fpreg, where note.data
> > is of type struct elf_lwpstatus, defined in hurd:include/sys/procfs.h,
> > whose pr_fpreg field is of type prfpregset_t, which is a typedef to
> > fpregset_t, which was an actual struct on i386, but is a pointer on
> > x86_64. This would've been easier to debug if I had debuginfo :)
> 
> I had this small patch applied that apparently is enough for me to have some
> kind of core dump, I'm not sure if it's a good solution:

You probably rather want to fix fetch_thread_fpregset, so as to properly
put the floating state into pr_fpreg.

This probably needs to actually copy over explicit fields, but that's
what we need anyway.

> diff --git a/exec/elfcore.c b/exec/elfcore.c
> index c6aa2bc8b..405fa8e0c 100644
> --- a/exec/elfcore.c
> +++ b/exec/elfcore.c
> @@ -544,6 +544,11 @@ dump_core (task_t task, file_t file, off_t corelimit,
>        note.data.pr_info.si_code = sigcode;
>        note.data.pr_info.si_errno = sigerror;
> 
> +#ifdef __x86_64__
> +      struct _libc_fpstate fpstate;
> +      memset(&fpstate, 0, sizeof(fpstate));
> +      note.data.pr_fpreg = &fpstate;
> +#endif
>        fetch_thread_regset (threads[i], &note.data.pr_reg);
>        fetch_thread_fpregset (threads[i], &note.data.pr_fpreg);
> 
> 
> HTH
> Luca