Re: [testsuite patch] for: [PATCH] [PR corefiles/17808] i386: Fix internal error when prstatus in core file is too big

[Pedro Alves <palves at redhat dot com>]

> Any other comments?

Do we need to do the same in other places?  This grep seems to suggest yes:

$ grep assert * | grep sizeof | grep regset
amd64obsd-tdep.c:  gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
amd64-tdep.c:  gdb_assert (len == tdep->sizeof_fpregset);
amd64-tdep.c:  gdb_assert (len == tdep->sizeof_fpregset);
i386obsd-tdep.c:  gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
i386-tdep.c:  gdb_assert (len == tdep->sizeof_gregset);
i386-tdep.c:  gdb_assert (len == tdep->sizeof_gregset);
i386-tdep.c:  gdb_assert (len == tdep->sizeof_fpregset);
i386-tdep.c:  gdb_assert (len == tdep->sizeof_fpregset);
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips_elf_gregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips_elf_gregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips_elf_fpregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips_elf_fpregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips64_elf_gregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips64_elf_gregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips64_elf_fpregset_t));
mips-linux-tdep.c:  gdb_assert (len == sizeof (mips64_elf_fpregset_t));
mn10300-linux-tdep.c:  gdb_assert (len == sizeof (mn10300_elf_gregset_t));
mn10300-linux-tdep.c:  gdb_assert (len == sizeof (mn10300_elf_fpregset_t));
mn10300-linux-tdep.c:  gdb_assert (len == sizeof (mn10300_elf_gregset_t));

On 01/08/2015 04:16 PM, Andreas Arnez wrote:
> Note that this behavior deviates from the default policy: In general, if
> some future kernel adds new registers to a register set, then a GDB
> unaware of this extension would read the known subset and just ignore
> the unknown bytes.

That's a good point.

get_core_register_section checks the section size already:

get_core_register_section (struct regcache *regcache,
			   const struct regset *regset,
			   const char *name,
			   int min_size,
			   int which,
			   const char *human_name,
			   int required)
{
...
  size = bfd_section_size (core_bfd, section);
  if (size < min_size)
    {
      warning (_("Section `%s' in core file too small."), section_name);
      return;
    }
...

Should we remove all those asserts, and make it the
job of get_core_register_section to warn if the section
size is bigger than expected?  We may need to pass
the "expected" section size to the callback, in addition
to the "minimum" size though.

Thanks,
Pedro Alves