RE: [PING][PATCH v5 1/1] gdb, breakpoint: add breakpoint location debugging logs

["Schimpe, Christina" <christina.schimpe@intel.com>]

Kindly pinging for this patch.

Thanks,
Christina

> -----Original Message-----
> From: Gdb-patches <gdb-patches-
> bounces+christina.schimpe=intel.com@sourceware.org> On Behalf Of Christina
> Schimpe via Gdb-patches
> Sent: Monday, June 12, 2023 10:15 AM
> To: gdb-patches@sourceware.org
> Cc: aburgess@redhat.com; simark@simark.ca; eliz@gnu.org;
> blarsen@redhat.com
> Subject: [PATCH v5 1/1] gdb, breakpoint: add breakpoint location debugging logs
> 
> From: Mihails Strasuns <mihails.strasuns@intel.com>
> 
> Add new commands:
> 
>   set debug breakpoint on|off
>   show debug breakpoint
> 
> This patch introduces new debugging information that prints breakpoint location
> insertion and removal flow.
> 
> The debug output looks like:
> ~~~
> (gdb) set debug breakpoint on
> (gdb) disassemble main
> Dump of assembler code for function main:
>    0x0000555555555129 <+0>:	endbr64
>    0x000055555555512d <+4>:	push   %rbp
>    0x000055555555512e <+5>:	mov    %rsp,%rbp
> => 0x0000555555555131 <+8>:	mov    $0x0,%eax
>    0x0000555555555136 <+13>:	pop    %rbp
>    0x0000555555555137 <+14>:	ret
> End of assembler dump.
> (gdb) break *0x0000555555555137
> Breakpoint 2 at 0x555555555137: file main.c, line 4.
> [breakpoint] update_global_location_list: insert_mode = UGLL_MAY_INSERT
> (gdb) c
> Continuing.
> [breakpoint] update_global_location_list: insert_mode = UGLL_INSERT
> [breakpoint] insert_bp_location: Breakpoint 2 (0x5565daddb1e0) at address
> 0x555555555137 in main at main.c:4 [breakpoint] insert_bp_location: Breakpoint
> -2 (0x5565dab51c10) at address 0x7ffff7fd37b5 [breakpoint] insert_bp_location:
> Breakpoint -5 (0x5565dab68f30) at address 0x7ffff7fe509e [breakpoint]
> insert_bp_location: Breakpoint -7 (0x5565dab694f0) at address 0x7ffff7fe63f4
> [breakpoint] remove_breakpoint_1: Breakpoint 2 (0x5565daddb1e0) at address
> 0x555555555137 in main at main.c:4 due to regular remove [breakpoint]
> remove_breakpoint_1: Breakpoint -2 (0x5565dab51c10) at address
> 0x7ffff7fd37b5 due to regular remove [breakpoint] remove_breakpoint_1:
> Breakpoint -5 (0x5565dab68f30) at address 0x7ffff7fe509e due to regular remove
> [breakpoint] remove_breakpoint_1: Breakpoint -7 (0x5565dab694f0) at address
> 0x7ffff7fe63f4 due to regular remove
> 
> Breakpoint 2, 0x0000555555555137 in main () at main.c:4
> 4	}
> ~~~
> 
> Co-Authored-By: Christina Schimpe <christina.schimpe@intel.com>
> ---
>  gdb/NEWS            |   4 ++
>  gdb/breakpoint.c    | 109 ++++++++++++++++++++++++++++++++++++++++++++
>  gdb/breakpoint.h    |   4 ++
>  gdb/doc/gdb.texinfo |   8 ++++
>  4 files changed, 125 insertions(+)
> 
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 649a3a9824a..2aafe103dab 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -80,6 +80,10 @@
> 
>  * New commands
> 
> +set debug breakpoint on|off
> +  show debug breakpoint
> +  Print additional debug messages about breakpoint insertion and removal.
> +
>  maintenance print record-instruction [ N ]
>    Print the recorded information for a given instruction.  If N is not given
>    prints how GDB would undo the last instruction executed.  If N is negative, diff --
> git a/gdb/breakpoint.c b/gdb/breakpoint.c index da6c8de9d14..dc502df9d79
> 100644
> --- a/gdb/breakpoint.c
> +++ b/gdb/breakpoint.c
> @@ -83,6 +83,7 @@
>  #include "progspace-and-thread.h"
>  #include "gdbsupport/array-view.h"
>  #include "gdbsupport/gdb_optional.h"
> +#include "gdbsupport/common-utils.h"
> 
>  /* Prototypes for local functions.  */
> 
> @@ -200,6 +201,68 @@ enum ugll_insert_mode
>    UGLL_INSERT
>  };
> 
> +/* Return a textual version of INSERT_MODE.  */
> +
> +static const char *
> +ugll_insert_mode_text (ugll_insert_mode insert_mode) {
> +/* Make sure the compiler warns if a new ugll_insert_mode enumerator is
> added
> +   but not handled here.  */
> +DIAGNOSTIC_PUSH
> +DIAGNOSTIC_ERROR_SWITCH
> +  switch (insert_mode)
> +    {
> +    case UGLL_DONT_INSERT:
> +      return "UGLL_DONT_INSERT";
> +    case UGLL_MAY_INSERT:
> +      return "UGLL_MAY_INSERT";
> +    case UGLL_INSERT:
> +      return "UGLL_INSERT";
> +    }
> +DIAGNOSTIC_POP
> +
> +  gdb_assert_not_reached ("must handle all enum values"); }
> +
> +/* Return a textual version of REASON.  */
> +
> +static const char *
> +remove_bp_reason_str (remove_bp_reason reason) {
> +/* Make sure the compiler warns if a new remove_bp_reason enumerator is
> added
> +   but not handled here.  */
> +DIAGNOSTIC_PUSH
> +DIAGNOSTIC_ERROR_SWITCH
> +  switch (reason)
> +    {
> +    case REMOVE_BREAKPOINT:
> +      return "regular remove";
> +    case DETACH_BREAKPOINT:
> +      return "detach";
> +    }
> +DIAGNOSTIC_POP
> +
> +  gdb_assert_not_reached ("must handle all enum values"); }
> +
> +/* Return a textual version of breakpoint BL describing number, location and
> +   address.  */
> +
> +static std::string
> +breakpoint_location_address_str (const bp_location* bl) {
> +  std::string str = string_printf ("Breakpoint %d (%s) at address %s",
> +				   bl->owner->number,
> +				   host_address_to_string (bl),
> +				   paddress (bl->gdbarch, bl->address));
> +
> +  std::string loc_string = bl->to_string ();  if (!loc_string.empty ())
> +    str += string_printf (" %s", loc_string.c_str ());
> +
> +  return str;
> +}
> +
>  static void update_global_location_list (enum ugll_insert_mode);
> 
>  static void update_global_location_list_nothrow (enum ugll_insert_mode); @@ -
> 510,6 +573,22 @@ show_always_inserted_mode (struct ui_file *file, int from_tty,
>  	      value);
>  }
> 
> +/* True if breakpoint debug output is enabled.  */ static bool
> +debug_breakpoint = false;
> +
> +/* Print a "breakpoint" debug statement.  */ #define
> +breakpoint_debug_printf(fmt, ...) \
> +  debug_prefixed_printf_cond (debug_breakpoint, "breakpoint", fmt, \
> +			      ##__VA_ARGS__)
> +
> +/* "show debug breakpoint" implementation.  */ static void
> +show_debug_breakpoint (struct ui_file *file, int from_tty,
> +		       struct cmd_list_element *c, const char *value) {
> +  gdb_printf (file, _("Breakpoint location debugging is %s.\n"),
> +value); }
> +
>  /* See breakpoint.h.  */
> 
>  int
> @@ -2728,6 +2807,8 @@ insert_bp_location (struct bp_location *bl,
>    if (!should_be_inserted (bl) || (bl->inserted && !bl->needs_update))
>      return 0;
> 
> +  breakpoint_debug_printf ("%s", breakpoint_location_address_str
> + (bl).c_str ());
> +
>    /* Note we don't initialize bl->target_info, as that wipes out
>       the breakpoint location's shadow_contents if the breakpoint
>       is still inserted at that location.  This in turn breaks @@ -3270,6 +3351,8 @@
> remove_breakpoints_inf (inferior *inf)  {
>    int val;
> 
> +  breakpoint_debug_printf ("inf->num = %d", inf->num);
> +
>    for (bp_location *bl : all_bp_locations ())
>      {
>        if (bl->pspace != inf->pspace)
> @@ -3914,6 +3997,10 @@ detach_breakpoints (ptid_t ptid)  static int
>  remove_breakpoint_1 (struct bp_location *bl, enum remove_bp_reason reason)
> {
> +  breakpoint_debug_printf ("%s due to %s",
> +			   breakpoint_location_address_str (bl).c_str (),
> +			   remove_bp_reason_str (reason));
> +
>    int val;
> 
>    /* BL is never in moribund_locations by our callers.  */ @@ -7424,6 +7511,16
> @@ bp_location::bp_location (breakpoint *owner)  {  }
> 
> +/* See breakpoint.h.  */
> +
> +std::string bp_location::to_string () const {
> +  string_file stb;
> +  ui_out_redirect_pop redir (current_uiout, &stb);
> +  print_breakpoint_location (this->owner, this);
> +  return stb.string ();
> +}
> +
>  /* Decrement reference count.  If the reference count reaches 0,
>     destroy the bp_location.  Sets *BLP to NULL.  */
> 
> @@ -11157,6 +11254,9 @@ update_global_location_list (enum ugll_insert_mode
> insert_mode)
>    /* Last breakpoint location program space that was marked for update.  */
>    int last_pspace_num = -1;
> 
> +  breakpoint_debug_printf ("insert_mode = %s",
> +			   ugll_insert_mode_text (insert_mode));
> +
>    /* Used in the duplicates detection below.  When iterating over all
>       bp_locations, points to the first bp_location of a given address.
>       Breakpoints and watchpoints of different types are never @@ -14899,6
> +14999,15 @@ when execution stops."),
>  				&breakpoint_set_cmdlist,
>  				&breakpoint_show_cmdlist);
> 
> +  add_setshow_boolean_cmd ("breakpoint", class_maintenance,
> +			   &debug_breakpoint, _("\
> +Set breakpoint location debugging."), _("\ Show breakpoint location
> +debugging."), _("\ When on, breakpoint location specific debugging is
> +enabled."),
> +			   NULL,
> +			   show_debug_breakpoint,
> +			   &setdebuglist, &showdebuglist);
> +
>    add_setshow_enum_cmd ("condition-evaluation", class_breakpoint,
>  			condition_evaluation_enums,
>  			&condition_evaluation_mode_1, _("\
> diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h index
> da150585f73..f4896293bb7 100644
> --- a/gdb/breakpoint.h
> +++ b/gdb/breakpoint.h
> @@ -509,6 +509,10 @@ class bp_location : public refcounted_object, public
> intrusive_list_node<bp_loca
> 
>    /* The objfile the symbol or minimal symbol were found in.  */
>    const struct objfile *objfile = NULL;
> +
> +  /* Return a string representation of the bp_location.
> +     This is only meant to be used in debug messages.  */  std::string
> + to_string () const;
>  };
> 
>  /* A policy class for bp_location reference counting.  */ diff --git
> a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 40d1f244417..ce0444c3c02
> 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -28356,6 +28356,14 @@ debugging info.
>  Turn on or off debugging messages for built-in XML parsers.
>  @item show debug xml
>  Displays the current state of XML debugging messages.
> +
> +@item set debug breakpoints
> +@cindex breakpoint debugging info
> +Turns on or off display of @value{GDBN} debugging info for breakpoint
> +insertion and removal.  The default is off.
> +@item show debug breakpoints
> +Displays the current state of displaying @value{GDBN} debugging info
> +for breakpoint insertion and removal.
>  @end table
> 
>  @node Other Misc Settings
> --
> 2.25.1
> 
> Intel Deutschland GmbH
> Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
> Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de> Managing Directors:
> Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva Chairperson of the
> Supervisory Board: Nicole Lau Registered Office: Munich Commercial Register:
> Amtsgericht Muenchen HRB 186928

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928