* [PATCH v2] gdb: add 'maintenance print record-instruction' command
@ 2022-12-12 10:44 Bruno Larsen
2022-12-12 13:54 ` Eli Zaretskii
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Bruno Larsen @ 2022-12-12 10:44 UTC (permalink / raw)
To: gdb-patches; +Cc: Bruno Larsen
While chasing some reverse debugging bugs, I found myself wondering what
was recorded by GDB to undo and redo a certain instruction. This commit
implements a simple way of printing that information.
---
gdb/NEWS | 6 ++++
gdb/doc/gdb.texinfo | 8 +++++
gdb/record-full.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+)
diff --git a/gdb/NEWS b/gdb/NEWS
index c4ccfcc9e32..d6ce6bf86a0 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -103,6 +103,12 @@
* New commands
+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,
+ prints how GDB would undo the N-th previous instruction, and if N is
+ positive, it prints how GDB will redo the N-th following instruction.
+
maintenance set ignore-prologue-end-flag on|off
maintenance show ignore-prologue-end-flag
This setting, which is off by default, controls whether GDB ignores the
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 5b566669975..807af351e79 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -40531,6 +40531,14 @@ that symbol is described. The type chain produced by this command is
a recursive definition of the data type as stored in @value{GDBN}'s
data structures, including its flags and contained types.
+@kindex maint print record-instruction
+@item maint print record-instruction
+@itemx maint print record-instruction @var{N}
+@cindex print how GDB recorded a given instruction. If N is not positive
+number, it prints the values stored by the inferior before the N-th previous
+instruction was exectued. If N is positive, print the values after the N-th
+following instruction is executed. If N is not given, 0 is assumed.
+
@kindex maint selftest
@cindex self tests
@item maint selftest @r{[}-verbose@r{]} @r{[}@var{filter}@r{]}
diff --git a/gdb/record-full.c b/gdb/record-full.c
index 48b92281fe6..25e1fd22c6f 100644
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -2764,6 +2764,79 @@ set_record_full_insn_max_num (const char *args, int from_tty,
}
}
+/* Implement the 'maintenance print record-instruction' command. */
+
+static void
+maintenance_print_record_instruction (const char *args, int from_tty)
+{
+ struct record_full_entry* to_print = record_full_list;
+
+ if (args != nullptr)
+ {
+ int offset = value_as_long (parse_and_eval (args));
+ if (offset > 0)
+ {
+ /* Move forward OFFSET instructions. We know we found the
+ end of an instruction when to_print->type is 0. */
+ while (to_print->next != nullptr && offset > 0)
+ {
+ to_print = to_print->next;
+ if (to_print->type == record_full_end)
+ offset--;
+ }
+ if (offset != 0)
+ error (_("Not enough recorded history"));
+ }
+ else
+ {
+ while (to_print->prev != nullptr && offset < 0)
+ {
+ to_print = to_print->prev;
+ if (to_print->type == record_full_end)
+ offset++;
+ }
+ if (offset != 0)
+ error (_("Not enough recorded history"));
+ }
+ }
+ gdb_assert (to_print != nullptr);
+
+ /* Go back to the start of the instruction. */
+ while (to_print->prev != nullptr && to_print->prev->type != record_full_end)
+ to_print = to_print->prev;
+
+ while (to_print->type != record_full_end)
+ {
+ switch (to_print->type)
+ {
+ case record_full_reg:
+ {
+ gdb_byte* b = record_full_get_loc (to_print);
+ gdb_printf ("Register %%%s changed:",
+ gdbarch_register_name (target_gdbarch (),
+ to_print->u.reg.num));
+ for (int i = 0; i < to_print->u.reg.len; i++)
+ gdb_printf (" %02x",b[i]);
+ gdb_printf ("\n");
+ break;
+ }
+ case record_full_mem:
+ {
+ gdb_byte* b = record_full_get_loc (to_print);
+ gdb_printf ("%d bytes of memory at address %s changed from:",
+ to_print->u.mem.len,
+ print_core_address (target_gdbarch (),
+ to_print->u.mem.addr));
+ for (int i = 0; i < to_print->u.mem.len; i++)
+ gdb_printf (" %02x",b[i]);
+ gdb_printf ("\n");
+ break;
+ }
+ }
+ to_print = to_print->next;
+ }
+}
+
void _initialize_record_full ();
void
_initialize_record_full ()
@@ -2868,4 +2941,12 @@ When ON, query if PREC cannot record memory change of next instruction."),
c = add_alias_cmd ("memory-query", record_full_memory_query_cmds.show,
no_class, 1,&show_record_cmdlist);
deprecate_cmd (c, "show record full memory-query");
+
+ add_cmd ("record-instruction", class_maintenance,
+ maintenance_print_record_instruction,
+ _("\
+Print a recorded instruction.\nIf no argument is provided, print the last \
+instruction recorded.\nIf a negative argument is given, prints how the nth \
+previous instruction will be undone.\nIf a positive argument is given, prints \
+how the nth following instruction will be redone."), &maintenanceprintlist);
}
--
2.38.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-12 10:44 [PATCH v2] gdb: add 'maintenance print record-instruction' command Bruno Larsen
@ 2022-12-12 13:54 ` Eli Zaretskii
2022-12-14 0:46 ` Lancelot SIX
2022-12-16 13:25 ` Pedro Alves
2 siblings, 0 replies; 7+ messages in thread
From: Eli Zaretskii @ 2022-12-12 13:54 UTC (permalink / raw)
To: Bruno Larsen; +Cc: gdb-patches
> Cc: Bruno Larsen <blarsen@redhat.com>
> Date: Mon, 12 Dec 2022 11:44:17 +0100
> From: Bruno Larsen via Gdb-patches <gdb-patches@sourceware.org>
>
> While chasing some reverse debugging bugs, I found myself wondering what
> was recorded by GDB to undo and redo a certain instruction. This commit
> implements a simple way of printing that information.
> ---
> gdb/NEWS | 6 ++++
> gdb/doc/gdb.texinfo | 8 +++++
> gdb/record-full.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 95 insertions(+)
Thanks.
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -103,6 +103,12 @@
>
> * New commands
>
> +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,
> + prints how GDB would undo the N-th previous instruction, and if N is
> + positive, it prints how GDB will redo the N-th following instruction.
This part is OK.
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -40531,6 +40531,14 @@ that symbol is described. The type chain produced by this command is
> a recursive definition of the data type as stored in @value{GDBN}'s
> data structures, including its flags and contained types.
>
> +@kindex maint print record-instruction
> +@item maint print record-instruction
> +@itemx maint print record-instruction @var{N}
> +@cindex print how GDB recorded a given instruction. If N is not positive
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Some editing snafu happened here, it seems?
> +number, it prints the values stored by the inferior before the N-th previous
> +instruction was exectued. If N is positive, print the values after the N-th
> +following instruction is executed. If N is not given, 0 is assumed.
In all places where you use "M" (upper-case), you should use "@var{n}"
(with @var and in lower-case).
The gdb.texinfo part is OK with those nits fixed.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-12 10:44 [PATCH v2] gdb: add 'maintenance print record-instruction' command Bruno Larsen
2022-12-12 13:54 ` Eli Zaretskii
@ 2022-12-14 0:46 ` Lancelot SIX
2022-12-14 10:04 ` Lancelot SIX
2022-12-16 10:03 ` Bruno Larsen
2022-12-16 13:25 ` Pedro Alves
2 siblings, 2 replies; 7+ messages in thread
From: Lancelot SIX @ 2022-12-14 0:46 UTC (permalink / raw)
To: Bruno Larsen; +Cc: gdb-patches
Hi Bruno,
I have a couple more comments and suggestions below.
On Mon, Dec 12, 2022 at 11:44:17AM +0100, Bruno Larsen via Gdb-patches wrote:
> While chasing some reverse debugging bugs, I found myself wondering what
> was recorded by GDB to undo and redo a certain instruction. This commit
> implements a simple way of printing that information.
> ---
> gdb/NEWS | 6 ++++
> gdb/doc/gdb.texinfo | 8 +++++
> gdb/record-full.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 95 insertions(+)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index c4ccfcc9e32..d6ce6bf86a0 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -103,6 +103,12 @@
>
> * New commands
>
> +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,
> + prints how GDB would undo the N-th previous instruction, and if N is
> + positive, it prints how GDB will redo the N-th following instruction.
> +
> maintenance set ignore-prologue-end-flag on|off
> maintenance show ignore-prologue-end-flag
> This setting, which is off by default, controls whether GDB ignores the
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 5b566669975..807af351e79 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -40531,6 +40531,14 @@ that symbol is described. The type chain produced by this command is
> a recursive definition of the data type as stored in @value{GDBN}'s
> data structures, including its flags and contained types.
>
> +@kindex maint print record-instruction
> +@item maint print record-instruction
> +@itemx maint print record-instruction @var{N}
> +@cindex print how GDB recorded a given instruction. If N is not positive
> +number, it prints the values stored by the inferior before the N-th previous
> +instruction was exectued. If N is positive, print the values after the N-th
> +following instruction is executed. If N is not given, 0 is assumed.
> +
> @kindex maint selftest
> @cindex self tests
> @item maint selftest @r{[}-verbose@r{]} @r{[}@var{filter}@r{]}
> diff --git a/gdb/record-full.c b/gdb/record-full.c
> index 48b92281fe6..25e1fd22c6f 100644
> --- a/gdb/record-full.c
> +++ b/gdb/record-full.c
> @@ -2764,6 +2764,79 @@ set_record_full_insn_max_num (const char *args, int from_tty,
> }
> }
>
> +/* Implement the 'maintenance print record-instruction' command. */
> +
> +static void
> +maintenance_print_record_instruction (const char *args, int from_tty)
> +{
> + struct record_full_entry* to_print = record_full_list;
> +
> + if (args != nullptr)
> + {
> + int offset = value_as_long (parse_and_eval (args));
> + if (offset > 0)
> + {
> + /* Move forward OFFSET instructions. We know we found the
> + end of an instruction when to_print->type is 0. */
I think the literal 0 in the comment is a left-over from V1, right?
> + while (to_print->next != nullptr && offset > 0)
> + {
> + to_print = to_print->next;
> + if (to_print->type == record_full_end)
> + offset--;
> + }
> + if (offset != 0)
> + error (_("Not enough recorded history"));
> + }
> + else
> + {
> + while (to_print->prev != nullptr && offset < 0)
> + {
> + to_print = to_print->prev;
> + if (to_print->type == record_full_end)
> + offset++;
> + }
> + if (offset != 0)
> + error (_("Not enough recorded history"));
> + }
> + }
> + gdb_assert (to_print != nullptr);
> +
> + /* Go back to the start of the instruction. */
> + while (to_print->prev != nullptr && to_print->prev->type != record_full_end)
> + to_print = to_print->prev;
> +
> + while (to_print->type != record_full_end)
> + {
> + switch (to_print->type)
> + {
> + case record_full_reg:
> + {
> + gdb_byte* b = record_full_get_loc (to_print);
^^
The space comes before the * here.
> + gdb_printf ("Register %%%s changed:",
The '%' prefix for register names is specific to the att assembler
syntax. Do we want this here? I think in most places GDB uses the
plain register name without such prefix.
> + gdbarch_register_name (target_gdbarch (),
> + to_print->u.reg.num));
> + for (int i = 0; i < to_print->u.reg.len; i++)
> + gdb_printf (" %02x",b[i]);
^
Space after the ",".
> + gdb_printf ("\n");
Did you consider printing the register value instead of the bytes
composing the value? I think something like this could do:
auto mark = value_mark ();
type *regtype = gdbarch_register_type (target_gdbarch (),
to_print->u.reg.num);
value *val
= value_from_contents (regtype, record_full_get_loc (to_print));
gdb_printf ("Register %s changed: %s\n",
gdbarch_register_name (target_gdbarch (),
to_print->u.reg.num),
hex_string (value_as_long (val)));
value_free_to_mark (mark);
This would however not work for vector registers (anything which does
not fit in a long long). You might want to use something like
`value_print` to handle all cases, unless its output is too fancy:
struct value_print_options opts;
get_user_print_options (&opts);
auto mark = value_mark ();
type *regtype = gdbarch_register_type (target_gdbarch (),
to_print->u.reg.num);
value *val
= value_from_contents (regtype, record_full_get_loc (to_print));
gdb_printf ("Register %s changed: %s\n",
gdbarch_register_name (target_gdbarch (),
to_print->u.reg.num));
value_print (val, gdb_stdout, &opts);
gdb_printf ("\n");
value_free_to_mark (mark);
Not sure if there is a cleaner way to achieve this, but it should do the
trick.
> + break;
> + }
> + case record_full_mem:
> + {
> + gdb_byte* b = record_full_get_loc (to_print);
Same here, the space shoud be before the "*".
> + gdb_printf ("%d bytes of memory at address %s changed from:",
> + to_print->u.mem.len,
> + print_core_address (target_gdbarch (),
> + to_print->u.mem.addr));
> + for (int i = 0; i < to_print->u.mem.len; i++)
> + gdb_printf (" %02x",b[i]);
Space after the ",".
Best,
Lancelot.
> + gdb_printf ("\n");
> + break;
> + }
> + }
> + to_print = to_print->next;
> + }
> +}
> +
> void _initialize_record_full ();
> void
> _initialize_record_full ()
> @@ -2868,4 +2941,12 @@ When ON, query if PREC cannot record memory change of next instruction."),
> c = add_alias_cmd ("memory-query", record_full_memory_query_cmds.show,
> no_class, 1,&show_record_cmdlist);
> deprecate_cmd (c, "show record full memory-query");
> +
> + add_cmd ("record-instruction", class_maintenance,
> + maintenance_print_record_instruction,
> + _("\
> +Print a recorded instruction.\nIf no argument is provided, print the last \
> +instruction recorded.\nIf a negative argument is given, prints how the nth \
> +previous instruction will be undone.\nIf a positive argument is given, prints \
> +how the nth following instruction will be redone."), &maintenanceprintlist);
> }
> --
> 2.38.1
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-14 0:46 ` Lancelot SIX
@ 2022-12-14 10:04 ` Lancelot SIX
2022-12-14 16:30 ` Tom Tromey
2022-12-16 10:03 ` Bruno Larsen
1 sibling, 1 reply; 7+ messages in thread
From: Lancelot SIX @ 2022-12-14 10:04 UTC (permalink / raw)
To: Bruno Larsen, gdb-patches
> struct value_print_options opts;
> get_user_print_options (&opts);
> auto mark = value_mark ();
Hi,
I forgot about scoped_value_mark which is probably much better than
manually doing the value_mark () ; value_free_to_mark () dance.
Lancelot.
> type *regtype = gdbarch_register_type (target_gdbarch (),
> to_print->u.reg.num);
> value *val
> = value_from_contents (regtype, record_full_get_loc (to_print));
>
> gdb_printf ("Register %s changed: %s\n",
> gdbarch_register_name (target_gdbarch (),
> to_print->u.reg.num));
> value_print (val, gdb_stdout, &opts);
> gdb_printf ("\n");
> value_free_to_mark (mark);
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-14 10:04 ` Lancelot SIX
@ 2022-12-14 16:30 ` Tom Tromey
0 siblings, 0 replies; 7+ messages in thread
From: Tom Tromey @ 2022-12-14 16:30 UTC (permalink / raw)
To: Lancelot SIX via Gdb-patches; +Cc: Bruno Larsen, Lancelot SIX
Lancelot> I forgot about scoped_value_mark which is probably much better than
Lancelot> manually doing the value_mark () ; value_free_to_mark () dance.
You don't normally need to bother with this at all, it's automatically
managed by the command loop.
Tom
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-14 0:46 ` Lancelot SIX
2022-12-14 10:04 ` Lancelot SIX
@ 2022-12-16 10:03 ` Bruno Larsen
1 sibling, 0 replies; 7+ messages in thread
From: Bruno Larsen @ 2022-12-16 10:03 UTC (permalink / raw)
To: Lancelot SIX; +Cc: gdb-patches
On 14/12/2022 01:46, Lancelot SIX wrote:
> Hi Bruno,
>
> I have a couple more comments and suggestions below.
>
> On Mon, Dec 12, 2022 at 11:44:17AM +0100, Bruno Larsen via Gdb-patches wrote:
>> While chasing some reverse debugging bugs, I found myself wondering what
>> was recorded by GDB to undo and redo a certain instruction. This commit
>> implements a simple way of printing that information.
>> ---
>> gdb/NEWS | 6 ++++
>> gdb/doc/gdb.texinfo | 8 +++++
>> gdb/record-full.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 95 insertions(+)
>>
>> diff --git a/gdb/NEWS b/gdb/NEWS
>> index c4ccfcc9e32..d6ce6bf86a0 100644
>> --- a/gdb/NEWS
>> +++ b/gdb/NEWS
>> @@ -103,6 +103,12 @@
>>
>> * New commands
>>
>> +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,
>> + prints how GDB would undo the N-th previous instruction, and if N is
>> + positive, it prints how GDB will redo the N-th following instruction.
>> +
>> maintenance set ignore-prologue-end-flag on|off
>> maintenance show ignore-prologue-end-flag
>> This setting, which is off by default, controls whether GDB ignores the
>> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
>> index 5b566669975..807af351e79 100644
>> --- a/gdb/doc/gdb.texinfo
>> +++ b/gdb/doc/gdb.texinfo
>> @@ -40531,6 +40531,14 @@ that symbol is described. The type chain produced by this command is
>> a recursive definition of the data type as stored in @value{GDBN}'s
>> data structures, including its flags and contained types.
>>
>> +@kindex maint print record-instruction
>> +@item maint print record-instruction
>> +@itemx maint print record-instruction @var{N}
>> +@cindex print how GDB recorded a given instruction. If N is not positive
>> +number, it prints the values stored by the inferior before the N-th previous
>> +instruction was exectued. If N is positive, print the values after the N-th
>> +following instruction is executed. If N is not given, 0 is assumed.
>> +
>> @kindex maint selftest
>> @cindex self tests
>> @item maint selftest @r{[}-verbose@r{]} @r{[}@var{filter}@r{]}
>> diff --git a/gdb/record-full.c b/gdb/record-full.c
>> index 48b92281fe6..25e1fd22c6f 100644
>> --- a/gdb/record-full.c
>> +++ b/gdb/record-full.c
>> @@ -2764,6 +2764,79 @@ set_record_full_insn_max_num (const char *args, int from_tty,
>> }
>> }
>>
>> +/* Implement the 'maintenance print record-instruction' command. */
>> +
>> +static void
>> +maintenance_print_record_instruction (const char *args, int from_tty)
>> +{
>> + struct record_full_entry* to_print = record_full_list;
>> +
>> + if (args != nullptr)
>> + {
>> + int offset = value_as_long (parse_and_eval (args));
>> + if (offset > 0)
>> + {
>> + /* Move forward OFFSET instructions. We know we found the
>> + end of an instruction when to_print->type is 0. */
> I think the literal 0 in the comment is a left-over from V1, right?
>
>> + while (to_print->next != nullptr && offset > 0)
>> + {
>> + to_print = to_print->next;
>> + if (to_print->type == record_full_end)
>> + offset--;
>> + }
>> + if (offset != 0)
>> + error (_("Not enough recorded history"));
>> + }
>> + else
>> + {
>> + while (to_print->prev != nullptr && offset < 0)
>> + {
>> + to_print = to_print->prev;
>> + if (to_print->type == record_full_end)
>> + offset++;
>> + }
>> + if (offset != 0)
>> + error (_("Not enough recorded history"));
>> + }
>> + }
>> + gdb_assert (to_print != nullptr);
>> +
>> + /* Go back to the start of the instruction. */
>> + while (to_print->prev != nullptr && to_print->prev->type != record_full_end)
>> + to_print = to_print->prev;
>> +
>> + while (to_print->type != record_full_end)
>> + {
>> + switch (to_print->type)
>> + {
>> + case record_full_reg:
>> + {
>> + gdb_byte* b = record_full_get_loc (to_print);
> ^^
>
> The space comes before the * here.
>
>> + gdb_printf ("Register %%%s changed:",
> The '%' prefix for register names is specific to the att assembler
> syntax. Do we want this here? I think in most places GDB uses the
> plain register name without such prefix.
>
>> + gdbarch_register_name (target_gdbarch (),
>> + to_print->u.reg.num));
>> + for (int i = 0; i < to_print->u.reg.len; i++)
>> + gdb_printf (" %02x",b[i]);
> ^
> Space after the ",".
>
>> + gdb_printf ("\n");
> Did you consider printing the register value instead of the bytes
> composing the value? I think something like this could do:
>
> auto mark = value_mark ();
> type *regtype = gdbarch_register_type (target_gdbarch (),
> to_print->u.reg.num);
> value *val
> = value_from_contents (regtype, record_full_get_loc (to_print));
>
> gdb_printf ("Register %s changed: %s\n",
> gdbarch_register_name (target_gdbarch (),
> to_print->u.reg.num),
> hex_string (value_as_long (val)));
> value_free_to_mark (mark);
>
> This would however not work for vector registers (anything which does
> not fit in a long long). You might want to use something like
> `value_print` to handle all cases, unless its output is too fancy:
>
> struct value_print_options opts;
> get_user_print_options (&opts);
> auto mark = value_mark ();
> type *regtype = gdbarch_register_type (target_gdbarch (),
> to_print->u.reg.num);
> value *val
> = value_from_contents (regtype, record_full_get_loc (to_print));
>
> gdb_printf ("Register %s changed: %s\n",
> gdbarch_register_name (target_gdbarch (),
> to_print->u.reg.num));
> value_print (val, gdb_stdout, &opts);
> gdb_printf ("\n");
> value_free_to_mark (mark);
>
> Not sure if there is a cleaner way to achieve this, but it should do the
> trick.
Hi Lancelot,
Thanks for the review, I've fixed all the style nits.
I wasn't aware of how to do this, thanks for explaining! I was a bit
reticent of using the value_as_long option specifically because I wanted
to handle all types of registers, but if I can make value_print work it
will definitely be better. However, when I tried this I got the
following output:
(gdb) maint print record-instruction
8 bytes of memory at address 0x00007fffffffde48 changed from: e0 de ff
ff ff 7f 00 00
(gdb) Register rip changed: (void (*)()) 0x40113e <main+8>
I see a few issues here:
* The casting at the front is pretty confusing. I want the printing to
be raw so the user can see what is going on
* I'm not necessary fond of the <main+8> at the end, mostly because I am
worried that it might be misplaced in other instances
* it is being printed after the gdb prompt
I'm saying this mostly because it will probably take me a while to make
a new version, but I really appreciate your feedback!
--
Cheers,
Bruno
>
>> + break;
>> + }
>> + case record_full_mem:
>> + {
>> + gdb_byte* b = record_full_get_loc (to_print);
> Same here, the space shoud be before the "*".
>
>> + gdb_printf ("%d bytes of memory at address %s changed from:",
>> + to_print->u.mem.len,
>> + print_core_address (target_gdbarch (),
>> + to_print->u.mem.addr));
>> + for (int i = 0; i < to_print->u.mem.len; i++)
>> + gdb_printf (" %02x",b[i]);
> Space after the ",".
>
> Best,
> Lancelot.
>
>> + gdb_printf ("\n");
>> + break;
>> + }
>> + }
>> + to_print = to_print->next;
>> + }
>> +}
>> +
>> void _initialize_record_full ();
>> void
>> _initialize_record_full ()
>> @@ -2868,4 +2941,12 @@ When ON, query if PREC cannot record memory change of next instruction."),
>> c = add_alias_cmd ("memory-query", record_full_memory_query_cmds.show,
>> no_class, 1,&show_record_cmdlist);
>> deprecate_cmd (c, "show record full memory-query");
>> +
>> + add_cmd ("record-instruction", class_maintenance,
>> + maintenance_print_record_instruction,
>> + _("\
>> +Print a recorded instruction.\nIf no argument is provided, print the last \
>> +instruction recorded.\nIf a negative argument is given, prints how the nth \
>> +previous instruction will be undone.\nIf a positive argument is given, prints \
>> +how the nth following instruction will be redone."), &maintenanceprintlist);
>> }
>> --
>> 2.38.1
>>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] gdb: add 'maintenance print record-instruction' command
2022-12-12 10:44 [PATCH v2] gdb: add 'maintenance print record-instruction' command Bruno Larsen
2022-12-12 13:54 ` Eli Zaretskii
2022-12-14 0:46 ` Lancelot SIX
@ 2022-12-16 13:25 ` Pedro Alves
2 siblings, 0 replies; 7+ messages in thread
From: Pedro Alves @ 2022-12-16 13:25 UTC (permalink / raw)
To: Bruno Larsen, gdb-patches
On 2022-12-12 10:44 a.m., Bruno Larsen via Gdb-patches wrote:
> While chasing some reverse debugging bugs, I found myself wondering what
> was recorded by GDB to undo and redo a certain instruction. This commit
> implements a simple way of printing that information.
Please include an example of this working in the commit log.
> ---
> gdb/NEWS | 6 ++++
> gdb/doc/gdb.texinfo | 8 +++++
> gdb/record-full.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 95 insertions(+)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index c4ccfcc9e32..d6ce6bf86a0 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -103,6 +103,12 @@
>
> * New commands
>
> +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,
> + prints how GDB would undo the N-th previous instruction, and if N is
> + positive, it prints how GDB will redo the N-th following instruction.
I noticed missing double space after period in the sentences above.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-12-16 13:25 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-12-12 10:44 [PATCH v2] gdb: add 'maintenance print record-instruction' command Bruno Larsen
2022-12-12 13:54 ` Eli Zaretskii
2022-12-14 0:46 ` Lancelot SIX
2022-12-14 10:04 ` Lancelot SIX
2022-12-14 16:30 ` Tom Tromey
2022-12-16 10:03 ` Bruno Larsen
2022-12-16 13:25 ` Pedro Alves
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