Re: [PATCH v5 15/15] gdb, solib-svr4: support namespaces in DSO iteration

[Kevin Buettner <kevinb@redhat.com>]

On Thu,  2 Jun 2022 15:25:14 +0200
Markus Metzger via Gdb-patches <gdb-patches@sourceware.org> wrote:

> When looking up names, GDB needs to stay within one linker namespace to
> find the correct instance in case the same name is provided in more than
> one namespace.
> 
> Modify svr4_iterate_over_objfiles_in_search_order() to stay within the
> namespace of the current_objfile argument.  If no current_objfile is
> provided (i.e. it is nullptr), iterate over objfiles in the initial
> namespace.
> 
> For objfiles that do not have a corresponding so_list to provide the
> namespace, assume that the objfile was loaded into the initial namespace.
> This would cover the main executable objfile (which is indeed loaded into
> the initial namespace) as well as manually added symbol files.
> 
> Expected fails:
> 
>   - gdb.base/non-lazy-array-index.exp: the expression parser may lookup
>     global symbols, which may result in xfers to read auxv for determining
>     the debug base as part of svr4_iterate_over_objfiles_in_search_order().
> 
>   - gdb.server/non-lazy-array-index.exp: symbol lookup may access the
>     target to read AUXV in order to determine the debug base for SVR4
>     linker namespaces.
> 
> Known issues:
> 
>   - get_symbol_address() and get_msymbol_address() search objfiles for a
>     'better' match.  This was introduced by
> 
>         4b610737f02 Handle copy relocations
> 
>     to handle copy relocations but it now causes a wrong address to be
>     read after symbol lookup actually cound the correct symbol.  This can
>     be seen, for example, with gdb.base/dlmopen.exp when compiled with
>     clang.
> 
>   - gnu ifuncs are only looked up in the initial namespace.
> 
>   - lookup_minimal_symbol() and lookup_minimal_symbol_text() directly
>     iterate over objfiles and are not aware of linker namespaces.
> ---
>  gdb/solib-svr4.c                              | 78 ++++++++++++++++++-
>  gdb/testsuite/gdb.base/dlmopen-lib-dep.c      | 21 +++++
>  gdb/testsuite/gdb.base/dlmopen-lib.c          |  5 +-
>  gdb/testsuite/gdb.base/dlmopen.exp            | 40 ++++++++--
>  .../gdb.base/non-lazy-array-index.exp         | 18 ++++-
>  .../gdb.server/bkpt-other-inferior.exp        | 13 +++-
>  6 files changed, 159 insertions(+), 16 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.base/dlmopen-lib-dep.c

Okay.

Kevin