[binutils-gdb/gdb-8.1-branch] gdb.base/breakpoint-in-ro-region.exp regression on sss targets (PR gdb/22583)

[Pedro Alves <palves at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f740fa5094817e948853bbcba46410a05175260d

commit f740fa5094817e948853bbcba46410a05175260d
Author: Pedro Alves <palves@redhat.com>
Date:   Thu Jan 11 17:50:59 2018 +0000

    gdb.base/breakpoint-in-ro-region.exp regression on sss targets (PR gdb/22583)
    
    As Maciej reported at
    <https://sourceware.org/ml/gdb-patches/2017-12/msg00212.html>, this
    commit:
    
     commit d930703d68ae160ddfe8ebe5fdcf416fb6090e1e
     Date: Thu Nov 16 18:44:43 2017 +0000
     Subject: Don't ever Quit out of resume
    
    caused regressions on software single-set targets, specifically:
    
     FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind
     FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw on: single-step breakpoint is not left behind
     FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw off: step in ro region (cannot insert hw break)
     FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw off: single-step breakpoint is not left behind
     FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw on: single-step breakpoint is not left behind
    
    and indeed detailed logs indicate a breakpoint is left lingering, e.g.:
    
     (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: step in ro region (cannot insert sw break)
     maint info breakpoints 0
     Num     Type           Disp Enb Address    What
     0       sw single-step keep y   0x00400774 in main at [...]/gdb/testsuite/gdb.base/breakpoint-in-ro-region.c:24 inf 1 thread 1
    	 stop only in thread 1
     (gdb) FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind
    
    vs:
    
     (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: step in ro region (cannot insert sw break)
     maint info breakpoints 0
     No breakpoint or watchpoint matching '0'.
     (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind
    
    as at commit d930703d68ae^.
    
    Before commit d930703d68ae, we had a cleanup installed in 'resume'
    that would delete single-step breakpoints on error:
    
      /* Resuming.  */
    
      /* Things to clean up if we QUIT out of resume ().  */
      static void
      resume_cleanups (void *ignore)
      {
        if (!ptid_equal (inferior_ptid, null_ptid))
         delete_single_step_breakpoints (inferior_thread ());
    
        normal_stop ();
      }
    
    That whole function was removed by d930703d68ae mainly to eliminate
    the normal_stop call:
    
    ~~~~
        Note that the exception called from within resume ends up calling
        normal_stop via resume_cleanups.  That's very borked though, because
        normal_stop is going to re-handle whatever was the last reported
        event, possibly even re-running a hook stop...
    ~~~~
    
    But as the regression shows, removing resume_cleanups completely went
    a bit too far, as the delete_single_step_breakpoints call is still
    necessary.
    
    So fix the regression by reinstating the
    delete_single_step_breakpoints call on error.  However, since we're
    trying to eliminate cleanups, restore it in a different form (using
    TRY/CATCH).
    
    Tested on x86-64 GNU/Linux both top of master and on top of a series
    that implements software single-step on x86.
    
    gdb/ChangeLog:
    2018-01-11  Pedro Alves  <palves@redhat.com>
    
    	PR gdb/22583
    	* infrun.c (resume): Rename to ...
    	(resume_1): ... this.
    	(resume): Reimplement as wrapper around resume_1.

Diff:
---
 gdb/ChangeLog |  7 +++++++
 gdb/infrun.c  | 33 ++++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8edb782..d40b914 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2018-01-11  Pedro Alves  <palves@redhat.com>
 
+	PR gdb/22583
+	* infrun.c (resume): Rename to ...
+	(resume_1): ... this.
+	(resume): Reimplement as wrapper around resume_1.
+
+2018-01-11  Pedro Alves  <palves@redhat.com>
+
 	PR remote/22597
 	* remote.c (remote_parse_stop_reply): Default to the last-set
 	general thread instead of to 'magic_null_ptid'.
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 7e8d8da..7d6aa7d 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2355,10 +2355,11 @@ do_target_resume (ptid_t resume_ptid, int step, enum gdb_signal sig)
 }
 
 /* Resume the inferior.  SIG is the signal to give the inferior
-   (GDB_SIGNAL_0 for none).  */
+   (GDB_SIGNAL_0 for none).  Note: don't call this directly; instead
+   call 'resume', which handles exceptions.  */
 
-void
-resume (enum gdb_signal sig)
+static void
+resume_1 (enum gdb_signal sig)
 {
   struct regcache *regcache = get_current_regcache ();
   struct gdbarch *gdbarch = regcache->arch ();
@@ -2730,6 +2731,32 @@ resume (enum gdb_signal sig)
   do_target_resume (resume_ptid, step, sig);
   tp->resumed = 1;
 }
+
+/* Resume the inferior.  SIG is the signal to give the inferior
+   (GDB_SIGNAL_0 for none).  This is a wrapper around 'resume_1' that
+   rolls back state on error.  */
+
+void
+resume (gdb_signal sig)
+{
+  TRY
+    {
+      resume_1 (sig);
+    }
+  CATCH (ex, RETURN_MASK_ALL)
+    {
+      /* If resuming is being aborted for any reason, delete any
+	 single-step breakpoint resume_1 may have created, to avoid
+	 confusing the following resumption, and to avoid leaving
+	 single-step breakpoints perturbing other threads, in case
+	 we're running in non-stop mode.  */
+      if (inferior_ptid != null_ptid)
+	delete_single_step_breakpoints (inferior_thread ());
+      throw_exception (ex);
+    }
+  END_CATCH
+}
+
 
 /* Proceeding.  */