[IRIX] eliminate deprecated_insert_raw_breakpoint uses

The IRIX support wants to set a breakpoint to be hit when the startup
phase is complete, which is where shared libraries have been mapped
in.  AFAIU, for most IRIX ports, that location is the entry point.

For MIPS IRIX however, GDB needs to set a breakpoint earlier, in
__dbx_link, as explained by:

 #ifdef SYS_syssgi
   /* On mips-irix, we need to stop the inferior early enough during
      the startup phase in order to be able to load the shared library
      symbols and insert the breakpoints that are located in these shared
      libraries.  Stopping at the program entry point is not good enough
      because the -init code is executed before the execution reaches
      that point.

      So what we need to do is to insert a breakpoint in the runtime
      loader (rld), more precisely in __dbx_link().  This procedure is
      called by rld once all shared libraries have been mapped, but before
      the -init code is executed.  Unfortuantely, this is not straightforward,
      as rld is not part of the executable we are running, and thus we need
      the inferior to run until rld itself has been mapped in memory.

      For this, we trace all syssgi() syscall exit events.  Each time
      we detect such an event, we iterate over each text memory maps,
      get its associated fd, and scan the symbol table for __dbx_link().
      When found, we know that rld has been mapped, and that we can insert
      the breakpoint at the symbol address.  Once the dbx_link() breakpoint
      has been inserted, the syssgi() notifications are no longer necessary,
      so they should be canceled.  */
   proc_trace_syscalls_1 (pi, SYS_syssgi, PR_SYSEXIT, FLAG_SET, 0);
 #endif

The loop in irix_solib_create_inferior_hook then runs until whichever
breakpoint is hit first, the one set by solib-irix.c or the one set by
procfs.c.

Note the comment in disable_break talks about __dbx_init, but I think
that's a typo for __dbx_link:

 -  /* Note that it is possible that we have stopped at a location that
 -     is different from the location where we inserted our breakpoint.
 -     On mips-irix, we can actually land in __dbx_init(), so we should
 -     not check the PC against our breakpoint address here.  See procfs.c
 -     for more details.  */

This looks very much like referring to the loop in
irix_solib_create_inferior_hook stopping at __dbx_link instead of at
the entry point.

What this patch does is convert these deprecated raw breakpoints to
standard solib_event breakpoints.  When the first solib-event
breakpoint is hit, we delete all solib-event breakpoints.  We do that
in the so_ops->handle_event hook.

This allows getting rid of the loop in irix_solib_create_inferior_hook
completely, which should allow properly handling signals and other
events in the early startup phase, like in SVR4.

Built on x86_64 Fedora 20 with --enable-targets=all (builds
solib-irix.c).

Joel tested that with an earlier version of this patch "info shared"
after starting a program gave the same list of shared libraries as
before.

gdb/ChangeLog:
2014-09-12  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (remove_solib_event_breakpoints_at_next_stop)
	(create_and_insert_solib_event_breakpoint): New functions.
	* breakpoint.h (create_and_insert_solib_event_breakpoint)
	(remove_solib_event_breakpoints_at_next_stop): New declarations.
	* procfs.c (dbx_link_bpt_addr, dbx_link_bpt): Delete globals.
	(remove_dbx_link_breakpoint): Delete function.
	(insert_dbx_link_bpt_in_file): Use
	create_and_insert_solib_event_breakpoint instead of
	deprecated_insert_raw_breakpoint.
	(procfs_wait): Don't check whether we hit __dbx_link here.
	(procfs_mourn_inferior): Don't delete the __dbx_link breakpoint
	here.
	* solib-irix.c (base_breakpoint): Delete global.
	(disable_break): Delete function.
	(enable_break): Use create_solib_event_breakpoint
	instead of deprecated_insert_raw_breakpoint.
	(irix_solib_handle_event): New function.
	(irix_solib_create_inferior_hook): Don't run the target or disable
	the mapping-complete breakpoint here.
	(_initialize_irix_solib): Install irix_solib_handle_event as
	so_ops->handle_event hook.

1 files changed, 5 insertions, 42 deletions

diff --git a/gdb/procfs.c b/gdb/procfs.c
index 3465bc5..699fcd9 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -2902,13 +2902,6 @@ static void do_detach (int signo);
 static void proc_trace_syscalls_1 (procinfo *pi, int syscallnum,
 				   int entry_or_exit, int mode, int from_tty);
 
-/* On mips-irix, we need to insert a breakpoint at __dbx_link during
-   the startup phase.  The following two variables are used to record
-   the address of the breakpoint, and the code that was replaced by
-   a breakpoint.  */
-static int dbx_link_bpt_addr = 0;
-static void *dbx_link_bpt;
-
 /* Sets up the inferior to be debugged.  Registers to trace signals,
    hardware faults, and syscalls.  Note: does not set RLC flag: caller
    may want to customize that.  Returns zero for success (note!
@@ -3380,23 +3373,6 @@ syscall_is_lwp_create (procinfo *pi, int scall)
   return 0;
 }
 
-/* Remove the breakpoint that we inserted in __dbx_link().
-   Does nothing if the breakpoint hasn't been inserted or has already
-   been removed.  */
-
-static void
-remove_dbx_link_breakpoint (void)
-{
-  if (dbx_link_bpt_addr == 0)
-    return;
-
-  if (deprecated_remove_raw_breakpoint (target_gdbarch (), dbx_link_bpt) != 0)
-    warning (_("Unable to remove __dbx_link breakpoint."));
-
-  dbx_link_bpt_addr = 0;
-  dbx_link_bpt = NULL;
-}
-
 #ifdef SYS_syssgi
 /* Return the address of the __dbx_link() function in the file
    refernced by ABFD by scanning its symbol table.  Return 0 if
@@ -3461,10 +3437,12 @@ insert_dbx_link_bpt_in_file (int fd, CORE_ADDR ignored)
   sym_addr = dbx_link_addr (abfd);
   if (sym_addr != 0)
     {
+      struct breakpoint *dbx_link_bpt;
+
       /* Insert the breakpoint.  */
-      dbx_link_bpt_addr = sym_addr;
-      dbx_link_bpt = deprecated_insert_raw_breakpoint (target_gdbarch (), NULL,
-						       sym_addr);
+      dbx_link_bpt
+	= create_and_insert_solib_event_breakpoint (target_gdbarch (),
+						    sym_addr);
       if (dbx_link_bpt == NULL)
 	{
 	  warning (_("Failed to insert dbx_link breakpoint."));
@@ -3894,14 +3872,6 @@ wait_again:
 #if (FLTTRACE != FLTBPT)	/* Avoid "duplicate case" error.  */
 		case FLTTRACE:
 #endif
-		  /* If we hit our __dbx_link() internal breakpoint,
-		     then remove it.  See comments in procfs_init_inferior()
-		     for more details.	*/
-		  if (dbx_link_bpt_addr != 0
-		      && dbx_link_bpt_addr
-			 == regcache_read_pc (get_current_regcache ()))
-		    remove_dbx_link_breakpoint ();
-
 		  wstat = (SIGTRAP << 8) | 0177;
 		  break;
 		case FLTSTACK:
@@ -4340,13 +4310,6 @@ procfs_mourn_inferior (struct target_ops *ops)
 
   generic_mourn_inferior ();
 
-  if (dbx_link_bpt != NULL)
-    {
-      deprecated_remove_raw_breakpoint (target_gdbarch (), dbx_link_bpt);
-      dbx_link_bpt_addr = 0;
-      dbx_link_bpt = NULL;
-    }
-
   inf_child_maybe_unpush_target (ops);
 }