Re: Problems with commit 'kallsyms: add support for relative offsets in kallsyms address table' (in mmotm)

[Guenter Roeck]

On 01/24/2016 09:20 AM, Ard Biesheuvel wrote:
[ ... ]
> > > OK, there's an additional issue in my latest version: the
> > > kallsyms_relative_base value itself is not relocated.
> > >
> > > If you have more time to burn on this, could you try the following on
> > > top? (If not, that is also fine, I will look into it myself on Monday)
> > >
> > > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> > > index 5ab13394dfd9..0f43f0751d47 100644
> > > --- a/scripts/kallsyms.c
> > > +++ b/scripts/kallsyms.c
> > > @@ -137,8 +137,10 @@ static int read_symbol(FILE *in, struct sym_entry *s)
> > >                  sym++;
> > >
> > >          /* Ignore most absolute/undefined (?) symbols. */
> > > -       if (strcmp(sym, "_text") == 0)
> > > +       if (strcmp(sym, "_text") == 0) {
> > >                  _text = s->addr;
> > > +               stype = 'T';
> > > +       }
> > >          else if (check_symbol_range(sym, s->addr, text_ranges,
> > >                                      ARRAY_SIZE(text_ranges)) == 0)
> > >                  /* nothing to do */;
> > > @@ -406,7 +408,7 @@ static void write_src(void)
> > >
> > >          if (base_relative) {
> > >                  output_label("kallsyms_relative_base");
> > > -               printf("\tPTR\t%#llx\n", relative_base);
> > > +               printf("\tPTR\t_text - %#llx\n", _text - relative_base);
> > >                  printf("\n");
> > >          }
> >
> > Does not help.
>
> For x86? Or none of them?

I tested sparc32 and x86_64/nosmp. Doesn't help for any of them.
sparc32 has the following absolute symbols.

f035a420 A _etext
f03d9000 A _sdata
f03de8c4 A jiffies
f03f8860 A _edata
f03fc000 A __init_begin
f041bdc8 A __init_text_end
f0423000 A __bss_start
f0423000 A __init_end
f044457d A __bss_stop
f044457d A _end

This results in:

kallsyms failure: absolute symbol value 0xf035a420 out of range in relative mode

This is with binutils 2.22. I didn't test with binutils 2.25 for sparc, or re-test mips.


Looks like I'll need to add more test cases with binutils 2.22 vs. 2.25 for various
architectures, as well as more SMP vs. !SMP builds.

Guenter