156 lines
5.3 KiB
Diff
156 lines
5.3 KiB
Diff
http://sourceware.org/ml/gdb-patches/2016-03/msg00013.html
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Subject: [PATCH 1/2] Fix PR gdb/19676: Disable displaced stepping if /proc not mounted
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On GNU/Linux archs that support displaced stepping, if /proc is not
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mounted, GDB gets stuck not able to step past breakpoints:
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(gdb) c
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Continuing.
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dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at rtld.c:2163
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2163 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
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Cannot find AT_ENTRY auxiliary vector entry.
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(gdb) c
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Continuing.
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dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at rtld.c:2163
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2163 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
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Cannot find AT_ENTRY auxiliary vector entry.
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(gdb)
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That's because GDB can't figure out where the scratch pad is.
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This is a regression introduced by the earlier changes to make the
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Linux native target always work in non-stop mode.
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This commit makes GDB detect the case and fallback to stepping over
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breakpoints in-line.
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gdb/ChangeLog:
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2016-03-01 Pedro Alves <pedro@cascais.lan>
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PR gdb/19676
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* infrun.c (displaced_step_prepare): Also disable displaced
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stepping on NOT_SUPPORTED_ERROR.
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* linux-tdep.c (linux_displaced_step_location): If reading auxv
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fails, throw NOT_SUPPORTED_ERROR instead of generic error.
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---
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gdb/infrun.c | 3 ++-
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gdb/linux-tdep.c | 3 ++-
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2 files changed, 4 insertions(+), 2 deletions(-)
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diff --git a/gdb/infrun.c b/gdb/infrun.c
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index 3e8c9e0..696105d 100644
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--- a/gdb/infrun.c
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+++ b/gdb/infrun.c
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@@ -1894,7 +1894,8 @@ displaced_step_prepare (ptid_t ptid)
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{
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struct displaced_step_inferior_state *displaced_state;
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- if (ex.error != MEMORY_ERROR)
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+ if (ex.error != MEMORY_ERROR
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+ && ex.error != NOT_SUPPORTED_ERROR)
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throw_exception (ex);
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if (debug_infrun)
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diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
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index 555c302..f197aa7 100644
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--- a/gdb/linux-tdep.c
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+++ b/gdb/linux-tdep.c
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@@ -2426,7 +2426,8 @@ linux_displaced_step_location (struct gdbarch *gdbarch)
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location. The auxiliary vector gets us the PowerPC-side entry
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point address instead. */
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if (target_auxv_search (¤t_target, AT_ENTRY, &addr) <= 0)
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- error (_("Cannot find AT_ENTRY auxiliary vector entry."));
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+ throw_error (NOT_SUPPORTED_ERROR,
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+ _("Cannot find AT_ENTRY auxiliary vector entry."));
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/* Make certain that the address points at real code, and not a
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function descriptor. */
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--
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2.5.0
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http://sourceware.org/ml/gdb-patches/2016-03/msg00014.html
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Subject: [PATCH 2/2] Fix PR gdb/19676: Internal error in linux-thread.db.c if /proc not mounted
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If /proc is not mounted, GDB fails an assertion in find_new_threads_once:
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Continuing.
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/home/pedro/gdb/mygit/src/gdb/linux-thread-db.c:1249: internal-error: find_new_threads_once: Assertion `!target_has_execution' failed.
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A problem internal to GDB has been detected,
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further debugging may prove unreliable.
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Quit this debugging session? (y or n)
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That was supposed to catch misuses of td_ta_thr_iter, which is unsafe
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for live debugging. However, if /proc is not mounted, we still
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fallback to using it.
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I didn't bother with a warning, because GDB already prints several
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others related to failing to open /proc files.
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gdb/ChangeLog:
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2016-03-01 Pedro Alves <pedro@cascais.lan>
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PR gdb/19676
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* linux-thread-db.c (try_thread_db_load_1): Leave
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info->td_ta_thr_iter_p NULL iff debugging a live process and we
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have /proc access.
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(find_new_threads_once): Assert that we have a non-NULL
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info->td_ta_thr_iter_p instead of checking whether the target has
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execution.
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---
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gdb/linux-thread-db.c | 16 ++++++++++------
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1 file changed, 10 insertions(+), 6 deletions(-)
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diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
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index 1eb457d..ce60beb 100644
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--- a/gdb/linux-thread-db.c
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+++ b/gdb/linux-thread-db.c
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@@ -564,7 +564,6 @@ try_thread_db_load_1 (struct thread_db_info *info)
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/* These are essential. */
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CHK (TDB_VERBOSE_DLSYM (info, td_ta_map_lwp2thr));
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- CHK (TDB_VERBOSE_DLSYM (info, td_ta_thr_iter));
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CHK (TDB_VERBOSE_DLSYM (info, td_thr_validate));
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CHK (TDB_VERBOSE_DLSYM (info, td_thr_get_info));
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@@ -572,10 +571,6 @@ try_thread_db_load_1 (struct thread_db_info *info)
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TDB_DLSYM (info, td_thr_tls_get_addr);
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TDB_DLSYM (info, td_thr_tlsbase);
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-#undef TDB_VERBOSE_DLSYM
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-#undef TDB_DLSYM
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-#undef CHK
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-
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/* It's best to avoid td_ta_thr_iter if possible. That walks data
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structures in the inferior's address space that may be corrupted,
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or, if the target is running, may change while we walk them. If
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@@ -587,6 +582,15 @@ try_thread_db_load_1 (struct thread_db_info *info)
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currently on core targets, as it uses ptrace directly. */
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if (target_has_execution
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&& linux_proc_task_list_dir_exists (ptid_get_pid (inferior_ptid)))
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+ info->td_ta_thr_iter_p = NULL;
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+ else
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+ CHK (TDB_VERBOSE_DLSYM (info, td_ta_thr_iter));
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+
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+#undef TDB_VERBOSE_DLSYM
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+#undef TDB_DLSYM
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+#undef CHK
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+
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+ if (info->td_ta_thr_iter_p == NULL)
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{
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struct lwp_info *lp;
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int pid = ptid_get_pid (inferior_ptid);
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@@ -1246,7 +1250,7 @@ find_new_threads_once (struct thread_db_info *info, int iteration,
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data.new_threads = 0;
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/* See comment in thread_db_update_thread_list. */
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- gdb_assert (!target_has_execution);
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+ gdb_assert (info->td_ta_thr_iter_p != NULL);
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TRY
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{
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--
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2.5.0
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