[PATCH] Fix gdb.cp/gdb2495.exp on powerpc64le

[Tom de Vries <tdevries@suse.de>]

From: Tom de Vries <tdevries@loganberry-1.arch.suse.de>

On powerpc64le-linux I ran into this FAIL:
...
(gdb) p exceptions.throw_function()^M
terminate called after throwing an instance of 'int'^M
^M
Program received signal SIGABRT, Aborted.^M
0x00007ffff7979838 in raise () from /lib64/libc.so.6^M
The program being debugged was signaled while in a function called from GDB.^M
GDB remains in the frame where the signal was received.^M
To change this behavior use "set unwindonsignal on".^M
Evaluation of the expression containing the function^M
(SimpleException::throw_function()) will be abandoned.^M
When the function is done executing, GDB will silently stop.^M
(gdb) FAIL: gdb.cp/gdb2495.exp: call a function that raises an exception \
  without a handler.
...

The following happens:
- we start an inferior call
- an internal breakpoint is set on the global entry point of std::terminate
- the inferior call uses the local entry point
- the breakpoint is not triggered
- we run into std::terminate

We can fix this by simply adding the missing gdbarch_skip_entrypoint call in
create_std_terminate_master_breakpoint, but we try to do this a bit more
generic, by:
- adding a variant of function create_internal_breakpoint which takes a
  minimal symbol instead of an address as argument
- in the new function:
  - using both gdbarch_convert_from_func_ptr_addr and gdbarch_skip_entrypoint
  - documenting why we don't need to use gdbarch_addr_bits_remove
  - adding a note about possibly
    needing gdbarch_deprecated_function_start_offset.
- using the new function in:
  - create_std_terminate_master_breakpoint
  - create_exception_master_breakpoint_hook, which currently uses only
    gdbarch_convert_from_func_ptr_addr.

Note: we could use the new function in more locations in breakpoint.c, but
as we're not aware of any related failures, we declare this out of scope for
this patch.

Tested on x86_64-linux, powerpc64le-linux.

Co-Authored-By: Ulrich Weigand <uweigand@de.ibm.com>
PR tdep/29793
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29793
---
 gdb/breakpoint.c | 42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 490708938ec..578d45b15af 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -3283,6 +3283,8 @@ set_breakpoint_number (int internal, struct breakpoint *b)
     }
 }
 
+/* Create a TYPE breakpoint on ADDRESS from an object file with GDBARCH.  */
+
 static struct breakpoint *
 create_internal_breakpoint (struct gdbarch *gdbarch,
 			    CORE_ADDR address, enum bptype type)
@@ -3295,6 +3297,33 @@ create_internal_breakpoint (struct gdbarch *gdbarch,
   return add_to_breakpoint_chain (std::move (b));
 }
 
+/* Create a TYPE breakpoint on minimal symbol MSYM from an object file with
+   GDBARCH.  */
+
+static struct breakpoint *
+create_internal_breakpoint (struct gdbarch *gdbarch,
+			    struct bound_minimal_symbol &msym, enum bptype type)
+{
+  CORE_ADDR address;
+
+  address = msym.value_address ();
+
+  address = gdbarch_convert_from_func_ptr_addr
+    (gdbarch, address, current_inferior ()->top_target ());
+
+  /* Note that we're not using gdbarch_addr_bits_remove here, because that's
+     related to addresses in $pc.  We're getting the address from the
+     minimal symbol table.  */
+
+  /* Is gdbarch_deprecated_function_start_offset needed here?  Or is that dealt
+     with elsewhere?  Needs testing on vax.  */
+
+  if (gdbarch_skip_entrypoint_p (gdbarch))
+    address = gdbarch_skip_entrypoint (gdbarch, address);
+
+  return create_internal_breakpoint (gdbarch, address, type);
+}
+
 static const char *const longjmp_names[] =
   {
     "longjmp", "_longjmp", "siglongjmp", "_siglongjmp"
@@ -3544,8 +3573,6 @@ create_std_terminate_master_breakpoint (void)
 
   for (struct program_space *pspace : program_spaces)
     {
-      CORE_ADDR addr;
-
       set_current_program_space (pspace);
 
       for (objfile *objfile : current_program_space->objfiles ())
@@ -3573,8 +3600,8 @@ create_std_terminate_master_breakpoint (void)
 	      bp_objfile_data->terminate_msym = m;
 	    }
 
-	  addr = bp_objfile_data->terminate_msym.value_address ();
-	  b = create_internal_breakpoint (objfile->arch (), addr,
+	  b = create_internal_breakpoint (objfile->arch (),
+					  bp_objfile_data->terminate_msym,
 					  bp_std_terminate_master);
 	  b->locspec = new_explicit_location_spec_function (func_name);
 	  b->enable_state = bp_disabled;
@@ -3643,7 +3670,6 @@ create_exception_master_breakpoint_hook (objfile *objfile)
   struct breakpoint *b;
   struct gdbarch *gdbarch;
   struct breakpoint_objfile_data *bp_objfile_data;
-  CORE_ADDR addr;
 
   bp_objfile_data = get_breakpoint_objfile_data (objfile);
 
@@ -3666,10 +3692,8 @@ create_exception_master_breakpoint_hook (objfile *objfile)
       bp_objfile_data->exception_msym = debug_hook;
     }
 
-  addr = bp_objfile_data->exception_msym.value_address ();
-  addr = gdbarch_convert_from_func_ptr_addr
-    (gdbarch, addr, current_inferior ()->top_target ());
-  b = create_internal_breakpoint (gdbarch, addr, bp_exception_master);
+  b = create_internal_breakpoint (gdbarch, bp_objfile_data->exception_msym,
+				  bp_exception_master);
   b->locspec = new_explicit_location_spec_function (func_name);
   b->enable_state = bp_disabled;
 

base-commit: f9f88aede3bb84efd088a59a5f6bccb3a6bb6516
-- 
2.35.3