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From: Florian Weimer <fweimer@redhat.com>
To: "H.J. Lu via Gdb-patches" <gdb-patches@sourceware.org>
Cc: GNU C Library <libc-alpha@sourceware.org>, "H.J. Lu" <hjl.tools@gmail.com>
Subject: Re: [PATCH v2] gdbserver: Check r_version < 1 for Linux debugger
 interface
References: <YRrK+nOJmShP932/@gmail.com>
 <CAMe9rOrWbRA+SGBZeue3PKk2V59o0BxTHAh7zpGiqBGsTFpBTQ@mail.gmail.com>
Date: Tue, 17 Aug 2021 15:48:53 +0200
In-Reply-To: <CAMe9rOrWbRA+SGBZeue3PKk2V59o0BxTHAh7zpGiqBGsTFpBTQ@mail.gmail.com>
 (H. J. Lu via Gdb-patches's message of "Mon, 16 Aug 2021 15:02:37
 -0700")
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* H. J. Lu via Gdb-patches:

> Set r_version == 2 breaks GDB due to
>
> static CORE_ADDR
> solib_svr4_r_ldsomap (struct svr4_info *info)
> {
>   struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
>   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
>   enum bfd_endian byte_order = type_byte_order (ptr_type);
>   ULONGEST version = 0;
>
>   try
>     {
>       /* Check version, and return zero if `struct r_debug' doesn't have
>          the r_ldsomap member.  */
>       version
>         = read_memory_unsigned_integer (info->debug_base +
> lmo->r_version_offset,
>                                         lmo->r_version_size, byte_order);
>     }
>   catch (const gdb_exception_error &ex)
>     {
>       exception_print (gdb_stderr, ex);
>     }
>
>   if (version < 2 || lmo->r_ldsomap_offset == -1)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> glibc doesn't have r_ldsomap.  But r_ldsomap_offset is set
> unconditionally.   Shouldn't it be set only if the target debugger
> interface has it?

glibc should add r_ldsomap_offset and switch its own version number to
3, I think.

Thanks,
Florian