[1/1] gdb, breakpoint: add breakpoint location debugging logs
Commit Message
From: Mihails Strasuns <mihails.strasuns@intel.com>
Add new commands:
set debug breakpoints on|off
show debug breakpoints
This patch introduces new debugging information that prints
breakpoint location insertion and removal flow.
The debug output looks like:
~~~
(gdb) set debug breakpoints 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.
[breakpoints] update_global_location_list: UGLL_MAY_INSERT
(gdb) c
Continuing.
[breakpoints] update_global_location_list: UGLL_INSERT
[breakpoints] insert_bp_location: bp_location (0x562881637fb0) at address 0x555555555137 in main at main.c:4
[breakpoints] insert_bp_location: bp_location (0x56288179a4f0) at address 0x7ffff7fd37b5 <dl_main+8661>
[breakpoints] insert_bp_location: bp_location (0x56288179ea60) at address 0x7ffff7fe509e <dl_open_worker+1150>
[breakpoints] insert_bp_location: bp_location (0x5628817184d0) at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
[breakpoints] remove_breakpoint_1: bp_location (0x562881637fb0) due to regular remove at address 0x555555555137 in main at main.c:4
[breakpoints] remove_breakpoint_1: bp_location (0x56288179a4f0) due to regular remove at address 0x7ffff7fd37b5 <dl_main+8661>
[breakpoints] remove_breakpoint_1: bp_location (0x56288179ea60) due to regular remove at address 0x7ffff7fe509e <dl_open_worker+1150>
[breakpoints] remove_breakpoint_1: bp_location (0x5628817184d0) due to regular remove at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
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 | 66 +++++++++++++++++++++++++++++++++++++++++++++
gdb/doc/gdb.texinfo | 8 ++++++
3 files changed, 78 insertions(+)
Comments
> Date: Tue, 21 Feb 2023 10:05:01 +0100
> From: Christina Schimpe via Gdb-patches <gdb-patches@sourceware.org>
>
> From: Mihails Strasuns <mihails.strasuns@intel.com>
>
> Add new commands:
>
> set debug breakpoints on|off
> show debug breakpoints
>
> This patch introduces new debugging information that prints
> breakpoint location insertion and removal flow.
>
> The debug output looks like:
> ~~~
> (gdb) set debug breakpoints 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.
> [breakpoints] update_global_location_list: UGLL_MAY_INSERT
> (gdb) c
> Continuing.
> [breakpoints] update_global_location_list: UGLL_INSERT
> [breakpoints] insert_bp_location: bp_location (0x562881637fb0) at address 0x555555555137 in main at main.c:4
> [breakpoints] insert_bp_location: bp_location (0x56288179a4f0) at address 0x7ffff7fd37b5 <dl_main+8661>
> [breakpoints] insert_bp_location: bp_location (0x56288179ea60) at address 0x7ffff7fe509e <dl_open_worker+1150>
> [breakpoints] insert_bp_location: bp_location (0x5628817184d0) at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
> [breakpoints] remove_breakpoint_1: bp_location (0x562881637fb0) due to regular remove at address 0x555555555137 in main at main.c:4
> [breakpoints] remove_breakpoint_1: bp_location (0x56288179a4f0) due to regular remove at address 0x7ffff7fd37b5 <dl_main+8661>
> [breakpoints] remove_breakpoint_1: bp_location (0x56288179ea60) due to regular remove at address 0x7ffff7fe509e <dl_open_worker+1150>
> [breakpoints] remove_breakpoint_1: bp_location (0x5628817184d0) due to regular remove at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
>
> 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 | 66 +++++++++++++++++++++++++++++++++++++++++++++
> gdb/doc/gdb.texinfo | 8 ++++++
> 3 files changed, 78 insertions(+)
Thanks, the documentation parts are okay.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
On 21/02/2023 10:05, Christina Schimpe via Gdb-patches wrote:
> From: Mihails Strasuns <mihails.strasuns@intel.com>
>
> Add new commands:
>
> set debug breakpoints on|off
> show debug breakpoints
>
> This patch introduces new debugging information that prints
> breakpoint location insertion and removal flow.
>
> The debug output looks like:
> ~~~
> (gdb) set debug breakpoints 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.
> [breakpoints] update_global_location_list: UGLL_MAY_INSERT
> (gdb) c
> Continuing.
> [breakpoints] update_global_location_list: UGLL_INSERT
> [breakpoints] insert_bp_location: bp_location (0x562881637fb0) at address 0x555555555137 in main at main.c:4
> [breakpoints] insert_bp_location: bp_location (0x56288179a4f0) at address 0x7ffff7fd37b5 <dl_main+8661>
> [breakpoints] insert_bp_location: bp_location (0x56288179ea60) at address 0x7ffff7fe509e <dl_open_worker+1150>
> [breakpoints] insert_bp_location: bp_location (0x5628817184d0) at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
> [breakpoints] remove_breakpoint_1: bp_location (0x562881637fb0) due to regular remove at address 0x555555555137 in main at main.c:4
> [breakpoints] remove_breakpoint_1: bp_location (0x56288179a4f0) due to regular remove at address 0x7ffff7fd37b5 <dl_main+8661>
> [breakpoints] remove_breakpoint_1: bp_location (0x56288179ea60) due to regular remove at address 0x7ffff7fe509e <dl_open_worker+1150>
> [breakpoints] remove_breakpoint_1: bp_location (0x5628817184d0) due to regular remove at address 0x7ffff7fe63f4 <_dl_close_worker+2356>
>
> Breakpoint 2, 0x0000555555555137 in main () at main.c:4
> 4 }
> ~~~
>
> Co-Authored-By: Christina Schimpe <christina.schimpe@intel.com>
Other than a small nit, this looks ok to me, Reviewed-By: Bruno Larsen
<blarsen@redhat.com>
(please note that the rb tag is not enough for pushing).
> ---
> gdb/NEWS | 4 +++
> gdb/breakpoint.c | 66 +++++++++++++++++++++++++++++++++++++++++++++
> gdb/doc/gdb.texinfo | 8 ++++++
> 3 files changed, 78 insertions(+)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 75cd11b204e..f64e0a68c85 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -3,6 +3,10 @@
>
> *** Changes since GDB 13
>
> +* set debug breakpoints on|off
> + show debug breakpoints
> + Print additional debug messages about breakpoint insertion and removal.
> +
> * Multi-target feature configuration
>
> GDB now supports the individual configuration of remote targets' feature
> diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
> index 0db3adaf916..1c8a05c6cbd 100644
> --- a/gdb/breakpoint.c
> +++ b/gdb/breakpoint.c
> @@ -163,6 +163,8 @@ static bool bl_address_is_meaningful (bp_location *loc);
>
> static int find_loc_num_by_location (const bp_location *loc);
>
> +static std::string breakpoint_location_to_buffer (bp_location *bl);
> +
> /* update_global_location_list's modes of operation wrt to whether to
> insert locations now. */
> enum ugll_insert_mode
> @@ -198,6 +200,22 @@ enum ugll_insert_mode
> UGLL_INSERT
> };
>
> +static const char *
> +ugll_insert_mode_text (ugll_insert_mode insert_mode)
> +{
> + 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";
> + }
> +
> + gdb_assert_not_reached ("must handle all enum values");
> +}
> +
> static void update_global_location_list (enum ugll_insert_mode);
>
> static void update_global_location_list_nothrow (enum ugll_insert_mode);
> @@ -508,6 +526,19 @@ show_always_inserted_mode (struct ui_file *file, int from_tty,
> value);
> }
>
> +static bool debug_breakpoints = 0;
s/0/false.
@@ -3,6 +3,10 @@
*** Changes since GDB 13
+* set debug breakpoints on|off
+ show debug breakpoints
+ Print additional debug messages about breakpoint insertion and removal.
+
* Multi-target feature configuration
GDB now supports the individual configuration of remote targets' feature
@@ -163,6 +163,8 @@ static bool bl_address_is_meaningful (bp_location *loc);
static int find_loc_num_by_location (const bp_location *loc);
+static std::string breakpoint_location_to_buffer (bp_location *bl);
+
/* update_global_location_list's modes of operation wrt to whether to
insert locations now. */
enum ugll_insert_mode
@@ -198,6 +200,22 @@ enum ugll_insert_mode
UGLL_INSERT
};
+static const char *
+ugll_insert_mode_text (ugll_insert_mode insert_mode)
+{
+ 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";
+ }
+
+ gdb_assert_not_reached ("must handle all enum values");
+}
+
static void update_global_location_list (enum ugll_insert_mode);
static void update_global_location_list_nothrow (enum ugll_insert_mode);
@@ -508,6 +526,19 @@ show_always_inserted_mode (struct ui_file *file, int from_tty,
value);
}
+static bool debug_breakpoints = 0;
+
+#define breakpoint_debug_printf(fmt, ...) \
+ debug_prefixed_printf_cond (debug_breakpoints, "breakpoints",fmt,\
+ ##__VA_ARGS__)
+
+static void
+show_debug_breakpoints (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
@@ -2710,6 +2741,11 @@ insert_bp_location (struct bp_location *bl,
if (!should_be_inserted (bl) || (bl->inserted && !bl->needs_update))
return 0;
+ breakpoint_debug_printf ("bp_location (%s) at address %s %s",
+ host_address_to_string (bl),
+ paddress (bl->gdbarch, bl->address),
+ breakpoint_location_to_buffer (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 +3306,8 @@ remove_breakpoints_inf (inferior *inf)
{
int val;
+ breakpoint_debug_printf ("remove_breakpoints_inf (%d)", inf->num);
+
for (bp_location *bl : all_bp_locations ())
{
if (bl->pspace != inf->pspace)
@@ -3914,6 +3952,13 @@ detach_breakpoints (ptid_t ptid)
static int
remove_breakpoint_1 (struct bp_location *bl, enum remove_bp_reason reason)
{
+ breakpoint_debug_printf ("bp_location (%s) due to %s at address %s %s",
+ host_address_to_string (bl),
+ (reason == REMOVE_BREAKPOINT
+ ? "regular remove" : "detach"),
+ paddress (bl->gdbarch, bl->address),
+ breakpoint_location_to_buffer (bl).c_str ());
+
int val;
/* BL is never in moribund_locations by our callers. */
@@ -6216,6 +6261,16 @@ print_breakpoint_location (const breakpoint *b,
}
}
+static std::string
+breakpoint_location_to_buffer (bp_location *bl)
+{
+ string_file stb;
+ current_uiout->redirect (&stb);
+ print_breakpoint_location (bl->owner, bl);
+ current_uiout->redirect (nullptr);
+ return stb.string ();
+}
+
static const char *
bptype_string (enum bptype type)
{
@@ -11146,6 +11201,8 @@ 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 ("%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
@@ -14876,6 +14933,15 @@ when execution stops."),
&breakpoint_set_cmdlist,
&breakpoint_show_cmdlist);
+ add_setshow_boolean_cmd ("breakpoints", class_maintenance,
+ &debug_breakpoints, _("\
+Set breakpoint location debugging."), _("\
+Show breakpoint location debugging."), _("\
+When non-zero, breakpoint location specific debugging is enabled."),
+ NULL,
+ show_debug_breakpoints,
+ &setdebuglist, &showdebuglist);
+
add_setshow_enum_cmd ("condition-evaluation", class_breakpoint,
condition_evaluation_enums,
&condition_evaluation_mode_1, _("\
@@ -28272,6 +28272,14 @@ 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