From: Andrew Burgess <aburgess@redhat.com>
To: Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>,
gdb-patches@sourceware.org
Cc: Simon Marchi <simon.marchi@efficios.com>
Subject: Re: [PATCH 5/8] gdbserver/linux-x86: make is_64bit_tdesc accept thread as a parameter
Date: Fri, 18 Nov 2022 11:32:53 +0000 [thread overview]
Message-ID: <87edu08plm.fsf@redhat.com> (raw)
In-Reply-To: <20221117194241.1776125-6-simon.marchi@efficios.com>
Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> ps_get_thread_area receives as a parameter the lwpid it must work on.
> It then calls is_64bit_tdesc, which uses the current_thread as the
> thread to work on. However, it is not said that both are the same.
>
> This became a problem when working in a following patch that pmakes
s/pmakes/makes/
> find_one_thread switch to a process but to no thread (current_thread ==
> nullptr). When libthread_db needed to get the thread area,
> is_64bit_tdesc would try to get the regcache of a nullptr thread.
>
> Fix that by making is_64bit_tdesc accept the thread to work on as a
> parameter. Find the right thread from the context, when possible (when
> we know the lwpid to work on). Otherwise, pass "current_thread", to
> retain the existing behavior.
>
> Change-Id: I44394d6be92392fa28de71982fd04517ce8a3007
> ---
> gdbserver/linux-x86-low.cc | 27 +++++++++++++++------------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
> index d2b55f6f0d2..c98a7a461fe 100644
> --- a/gdbserver/linux-x86-low.cc
> +++ b/gdbserver/linux-x86-low.cc
> @@ -275,9 +275,9 @@ static /*const*/ int i386_regmap[] =
> per the tdesc. */
>
> static int
> -is_64bit_tdesc (void)
> +is_64bit_tdesc (thread_info *thread)
I think the comment for this function needs updating, the reference to
"current inferior" probably needs to be replaced with THREAD.
With those changes, LGTM.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Thanks,
Andrew
> {
> - struct regcache *regcache = get_thread_regcache (current_thread, 0);
> + struct regcache *regcache = get_thread_regcache (thread, 0);
>
> return register_size (regcache->tdesc, 0) == 8;
> }
> @@ -292,7 +292,9 @@ ps_get_thread_area (struct ps_prochandle *ph,
> lwpid_t lwpid, int idx, void **base)
> {
> #ifdef __x86_64__
> - int use_64bit = is_64bit_tdesc ();
> + lwp_info *lwp = find_lwp_pid (ptid_t (lwpid));
> + gdb_assert (lwp != nullptr);
> + int use_64bit = is_64bit_tdesc (get_lwp_thread (lwp));
>
> if (use_64bit)
> {
> @@ -335,7 +337,9 @@ int
> x86_target::low_get_thread_area (int lwpid, CORE_ADDR *addr)
> {
> #ifdef __x86_64__
> - int use_64bit = is_64bit_tdesc ();
> + lwp_info *lwp = find_lwp_pid (ptid_t (lwpid));
> + gdb_assert (lwp != nullptr);
> + int use_64bit = is_64bit_tdesc (get_lwp_thread (lwp));
>
> if (use_64bit)
> {
> @@ -351,7 +355,6 @@ x86_target::low_get_thread_area (int lwpid, CORE_ADDR *addr)
> #endif
>
> {
> - struct lwp_info *lwp = find_lwp_pid (ptid_t (lwpid));
> struct thread_info *thr = get_lwp_thread (lwp);
> struct regcache *regcache = get_thread_regcache (thr, 1);
> unsigned int desc[4];
> @@ -379,7 +382,7 @@ bool
> x86_target::low_cannot_store_register (int regno)
> {
> #ifdef __x86_64__
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return false;
> #endif
>
> @@ -390,7 +393,7 @@ bool
> x86_target::low_cannot_fetch_register (int regno)
> {
> #ifdef __x86_64__
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return false;
> #endif
>
> @@ -815,7 +818,7 @@ x86_target::low_siginfo_fixup (siginfo_t *ptrace, gdb_byte *inf, int direction)
> int is_elf64 = linux_pid_exe_is_elf_64_file (tid, &machine);
>
> /* Is the inferior 32-bit? If so, then fixup the siginfo object. */
> - if (!is_64bit_tdesc ())
> + if (!is_64bit_tdesc (current_thread))
> return amd64_linux_siginfo_fixup_common (ptrace, inf, direction,
> FIXUP_32);
> /* No fixup for native x32 GDB. */
> @@ -1078,7 +1081,7 @@ const regs_info *
> x86_target::get_regs_info ()
> {
> #ifdef __x86_64__
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return &amd64_linux_regs_info;
> else
> #endif
> @@ -1553,7 +1556,7 @@ x86_target::install_fast_tracepoint_jump_pad (CORE_ADDR tpoint,
> char *err)
> {
> #ifdef __x86_64__
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return amd64_install_fast_tracepoint_jump_pad (tpoint, tpaddr,
> collector, lockaddr,
> orig_size, jump_entry,
> @@ -1587,7 +1590,7 @@ x86_target::get_min_fast_tracepoint_insn_len ()
> #ifdef __x86_64__
> /* On x86-64, 5-byte jump instructions with a 4-byte offset are always
> used for fast tracepoints. */
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return 5;
> #endif
>
> @@ -2931,7 +2934,7 @@ emit_ops *
> x86_target::emit_ops ()
> {
> #ifdef __x86_64__
> - if (is_64bit_tdesc ())
> + if (is_64bit_tdesc (current_thread))
> return &amd64_emit_ops;
> else
> #endif
> --
> 2.37.3
next prev parent reply other threads:[~2022-11-18 11:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 19:42 [PATCH 0/8] Fix some commit_resumed_state assertion failures (PR 28275) Simon Marchi
2022-11-17 19:42 ` [PATCH 1/8] gdb/testsuite: remove global declarations in gdb.threads/detach-step-over.exp Simon Marchi
2022-11-18 8:30 ` Aktemur, Tankut Baris
2022-11-18 15:07 ` Simon Marchi
2022-11-17 19:42 ` [PATCH 2/8] gdb/testsuite: refactor gdb.threads/detach-step-over.exp Simon Marchi
2022-11-17 19:42 ` [PATCH 3/8] gdb: fix assert when quitting GDB while a thread is stepping Simon Marchi
2022-11-17 19:42 ` [PATCH 4/8] gdbserver/linux: take condition out of callback in find_lwp_pid Simon Marchi
2022-11-18 11:28 ` Andrew Burgess
2022-11-18 16:09 ` Simon Marchi
2022-11-17 19:42 ` [PATCH 5/8] gdbserver/linux-x86: make is_64bit_tdesc accept thread as a parameter Simon Marchi
2022-11-18 11:32 ` Andrew Burgess [this message]
2022-11-18 16:12 ` Simon Marchi
2022-11-17 19:42 ` [PATCH 6/8] gdbserver: use current_process in ps_getpid Simon Marchi
2022-11-18 11:33 ` Andrew Burgess
2022-11-18 16:21 ` Simon Marchi
2022-11-17 19:42 ` [PATCH 7/8] gdbserver: switch to right process in find_one_thread Simon Marchi
2022-11-18 13:19 ` Andrew Burgess
2022-11-18 17:34 ` Simon Marchi
2022-11-17 19:42 ` [PATCH 8/8] gdb: disable commit resumed in target_kill Simon Marchi
2022-11-18 13:33 ` Andrew Burgess
2022-11-19 1:16 ` Simon Marchi
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