[7/8] Initialise target descrption after skipping extra traps for --wrapper

Message ID 86380dhfes.fsf@gmail.com
State New, archived
Headers

Commit Message

Yao Qi July 24, 2015, 1:08 p.m. UTC
  Pedro Alves <palves@redhat.com> writes:

> Yes, I think they should.  It's what the GDB side used to do already
> when that code was x86 gdb only (and hence that shell comment, which
> gdbserver doesn't use yet), and then other archs followed suit.
> "Going through the shell" is the exact same as going through
> the exec wrapper -- we're not interested in debugging the shell,
> and it may well have a different bitness/architecture of the target
> program we want to debug.
>
> In practice that hook's implementation should want to avoid work if some
> flag is not set, to avoid unnecessary ptrace syscalls and thus ends up
> not doing anything when going through the shell/exec-wrapper.

OK.

>
>> I'll test this patch on targets other than x86 (such as arm and
>> aarch64) and see if it causes fails.

I tested the patch on aarch64-linux, and no regressions are found.  I'll
push the following patch in.
  

Comments

Pedro Alves July 24, 2015, 1:44 p.m. UTC | #1
On 07/24/2015 02:08 PM, Yao Qi wrote:

>>> I'll test this patch on targets other than x86 (such as arm and
>>> aarch64) and see if it causes fails.
> 
> I tested the patch on aarch64-linux, and no regressions are found.  I'll
> push the following patch in.
> 

Great, looks good to me.

Thanks,
Pedro Alves
  

Patch

diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index fa9dc29..ac1ad6f 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -822,6 +822,14 @@  linux_create_inferior (char *program, char **allargs)
   return pid;
 }
 
+/* Implement the arch_setup target_ops method.  */
+
+static void
+linux_arch_setup (void)
+{
+  the_low_target.arch_setup ();
+}
+
 /* Attach to an inferior process.  Returns 0 on success, ERRNO on
    error.  */
 
@@ -2105,23 +2113,35 @@  linux_low_filter_event (int lwpid, int wstat)
     {
       struct process_info *proc;
 
-      /* Architecture-specific setup after inferior is running.  This
-	 needs to happen after we have attached to the inferior and it
-	 is stopped for the first time, but before we access any
-	 inferior registers.  */
+      /* Architecture-specific setup after inferior is running.  */
       proc = find_process_pid (pid_of (thread));
-      if (proc->priv->new_inferior)
+      if (proc->tdesc == NULL)
 	{
-	  struct thread_info *saved_thread;
+	  if (proc->attached)
+	    {
+	      struct thread_info *saved_thread;
 
-	  saved_thread = current_thread;
-	  current_thread = thread;
+	      /* This needs to happen after we have attached to the
+		 inferior and it is stopped for the first time, but
+		 before we access any inferior registers.  */
+	      saved_thread = current_thread;
+	      current_thread = thread;
 
-	  the_low_target.arch_setup ();
+	      the_low_target.arch_setup ();
 
-	  current_thread = saved_thread;
+	      current_thread = saved_thread;
 
-	  proc->priv->new_inferior = 0;
+	      proc->priv->new_inferior = 0;
+	    }
+	  else
+	    {
+	      /* The process is started, but GDBserver will do
+		 architecture-specific setup after the program stops at
+		 the first instruction.  */
+	      child->status_pending_p = 1;
+	      child->status_pending = wstat;
+	      return child;
+	    }
 	}
     }
 
@@ -3651,6 +3671,14 @@  linux_resume_one_lwp_throw (struct lwp_info *lwp,
   struct thread_info *thread = get_lwp_thread (lwp);
   struct thread_info *saved_thread;
   int fast_tp_collecting;
+  struct process_info *proc = get_thread_process (thread);
+
+  /* Note that target description may not be initialised
+     (proc->tdesc == NULL) at this point because the program hasn't
+     stopped at the first instruction yet.  It means GDBserver skips
+     the extra traps from the wrapper program (see option --wrapper).
+     Code in this function that requires register access should be
+     guarded by proc->tdesc == NULL or something else.  */
 
   if (lwp->stopped == 0)
     return;
@@ -3661,7 +3689,7 @@  linux_resume_one_lwp_throw (struct lwp_info *lwp,
 
   /* Cancel actions that rely on GDB not changing the PC (e.g., the
      user used the "jump" command, or "set $pc = foo").  */
-  if (lwp->stop_pc != get_pc (lwp))
+  if (thread->while_stepping != NULL && lwp->stop_pc != get_pc (lwp))
     {
       /* Collecting 'while-stepping' actions doesn't make sense
 	 anymore.  */
@@ -3787,7 +3815,7 @@  linux_resume_one_lwp_throw (struct lwp_info *lwp,
       step = 1;
     }
 
-  if (the_low_target.get_pc != NULL)
+  if (proc->tdesc != NULL && the_low_target.get_pc != NULL)
     {
       struct regcache *regcache = get_thread_regcache (current_thread, 1);
 
@@ -4014,6 +4042,12 @@  need_step_over_p (struct inferior_list_entry *entry, void *dummy)
   struct lwp_info *lwp = get_thread_lwp (thread);
   struct thread_info *saved_thread;
   CORE_ADDR pc;
+  struct process_info *proc = get_thread_process (thread);
+
+  /* GDBserver is skipping the extra traps from the wrapper program,
+     don't have to do step over.  */
+  if (proc->tdesc == NULL)
+    return 0;
 
   /* LWPs which will not be resumed are not interesting, because we
      might not wait for them next time through linux_wait.  */
@@ -6635,6 +6669,7 @@  current_lwp_ptid (void)
 
 static struct target_ops linux_target_ops = {
   linux_create_inferior,
+  linux_arch_setup,
   linux_attach,
   linux_kill,
   linux_detach,
diff --git a/gdb/gdbserver/lynx-low.c b/gdb/gdbserver/lynx-low.c
index ee7b28a..5cf03be 100644
--- a/gdb/gdbserver/lynx-low.c
+++ b/gdb/gdbserver/lynx-low.c
@@ -722,6 +722,7 @@  lynx_request_interrupt (void)
 
 static struct target_ops lynx_target_ops = {
   lynx_create_inferior,
+  NULL,  /* arch_setup */
   lynx_attach,
   lynx_kill,
   lynx_detach,
diff --git a/gdb/gdbserver/nto-low.c b/gdb/gdbserver/nto-low.c
index 9276736..19f492f 100644
--- a/gdb/gdbserver/nto-low.c
+++ b/gdb/gdbserver/nto-low.c
@@ -925,6 +925,7 @@  nto_supports_non_stop (void)
 
 static struct target_ops nto_target_ops = {
   nto_create_inferior,
+  NULL,  /* arch_setup */
   nto_attach,
   nto_kill,
   nto_detach,
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index df514f6..6b8617c 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -272,6 +272,7 @@  start_inferior (char **argv)
 	    }
 	  while (last_status.value.sig != GDB_SIGNAL_TRAP);
 	}
+      target_arch_setup ();
       return signal_pid;
     }
 
@@ -279,6 +280,8 @@  start_inferior (char **argv)
      (assuming success).  */
   last_ptid = mywait (pid_to_ptid (signal_pid), &last_status, 0, 0);
 
+  target_arch_setup ();
+
   if (last_status.kind != TARGET_WAITKIND_EXITED
       && last_status.kind != TARGET_WAITKIND_SIGNALLED)
     {
diff --git a/gdb/gdbserver/spu-low.c b/gdb/gdbserver/spu-low.c
index a56a889..cbee960 100644
--- a/gdb/gdbserver/spu-low.c
+++ b/gdb/gdbserver/spu-low.c
@@ -638,6 +638,7 @@  spu_request_interrupt (void)
 
 static struct target_ops spu_target_ops = {
   spu_create_inferior,
+  NULL,  /* arch_setup */
   spu_attach,
   spu_kill,
   spu_detach,
diff --git a/gdb/gdbserver/target.h b/gdb/gdbserver/target.h
index 9a40867..fefd8d1 100644
--- a/gdb/gdbserver/target.h
+++ b/gdb/gdbserver/target.h
@@ -74,6 +74,9 @@  struct target_ops
 
   int (*create_inferior) (char *program, char **args);
 
+  /* Architecture-specific setup.  */
+  void (*arch_setup) (void);
+
   /* Attach to a running process.
 
      PID is the process ID to attach to, specified by the user
@@ -445,6 +448,13 @@  void set_target_ops (struct target_ops *);
 #define create_inferior(program, args) \
   (*the_target->create_inferior) (program, args)
 
+#define target_arch_setup()			 \
+  do						 \
+    {						 \
+      if (the_target->arch_setup != NULL)	 \
+	(*the_target->arch_setup) ();		 \
+    } while (0)
+
 #define myattach(pid) \
   (*the_target->attach) (pid)
 
diff --git a/gdb/gdbserver/win32-low.c b/gdb/gdbserver/win32-low.c
index 64caf24..7ccb3dd 100644
--- a/gdb/gdbserver/win32-low.c
+++ b/gdb/gdbserver/win32-low.c
@@ -1785,6 +1785,7 @@  win32_get_tib_address (ptid_t ptid, CORE_ADDR *addr)
 
 static struct target_ops win32_target_ops = {
   win32_create_inferior,
+  NULL,  /* arch_setup */
   win32_attach,
   win32_kill,
   win32_detach,