[PATCH v10 04/10] btrace: Handle stepping and goto for auxiliary instructions.

Felix Willgerodt via Gdb-patches
2023-07-18T11:58:23Z

Print the auxiliary data when stepping. Don't allow to goto an auxiliary
instruction.

This patch is in preparation for the new ptwrite feature, which is based on
auxiliary instructions.
---
gdb/record-btrace.c | 65 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 54 insertions(+), 11 deletions(-)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 02e71889eaf..c93b3d7c8de 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -2380,9 +2380,13 @@ record_btrace_single_step_forward (struct thread_info *tp)
return btrace_step_stopped ();

/* Skip gaps during replay. If we end up at a gap (at the end of the trace),
- jump back to the instruction at which we started. */
+ jump back to the instruction at which we started. If we're stepping a
+ BTRACE_INSN_AUX instruction, print the auxiliary data and skip the
+ instruction. */
+
start = *replay;
- do
+
+ for (;;)
{
unsigned int steps;

@@ -2394,8 +2398,23 @@ record_btrace_single_step_forward (struct thread_info *tp)
*replay = start;
return btrace_step_no_history ();
}
+
+ const struct btrace_insn *insn = btrace_insn_get (replay);
+ if (insn == nullptr)
+ continue;
+
+ /* If we're stepping a BTRACE_INSN_AUX instruction, print the auxiliary
+ data and skip the instruction. */
+ if (insn->iclass == BTRACE_INSN_AUX)
+ {
+ gdb_printf ("[%s]\n",
+ btinfo->aux_data.at (insn->aux_data_index).c_str ());
+ continue;
+ }
+
+ /* We have an instruction, we are done. */
+ break;
}
- while (btrace_insn_get (replay) == NULL);

/* Determine the end of the instruction trace. */
btrace_insn_end (&end, btinfo);
@@ -2426,9 +2445,12 @@ record_btrace_single_step_backward (struct thread_info *tp)

/* If we can't step any further, we reached the end of the history.
Skip gaps during replay. If we end up at a gap (at the beginning of
- the trace), jump back to the instruction at which we started. */
+ the trace), jump back to the instruction at which we started.
+ If we're stepping a BTRACE_INSN_AUX instruction, print the auxiliary
+ data and skip the instruction. */
start = *replay;
- do
+
+ for (;;)
{
unsigned int steps;

@@ -2438,8 +2460,22 @@ record_btrace_single_step_backward (struct thread_info *tp)
*replay = start;
return btrace_step_no_history ();
}
+
+ const struct btrace_insn *insn = btrace_insn_get (replay);
+ if (insn == nullptr)
+ continue;
+
+ /* Check if we're stepping a BTRACE_INSN_AUX instruction and skip it. */
+ if (insn->iclass == BTRACE_INSN_AUX)
+ {
+ gdb_printf ("[%s]\n",
+ btinfo->aux_data.at (insn->aux_data_index).c_str ());
+ continue;
+ }
+
+ /* We have an instruction, we are done. */
+ break;
}
- while (btrace_insn_get (replay) == NULL);

/* Check if we're stepping a breakpoint.

@@ -2861,26 +2897,33 @@ record_btrace_target::goto_record_end ()
/* The goto_record method of target record-btrace. */

void
-record_btrace_target::goto_record (ULONGEST insn)
+record_btrace_target::goto_record (ULONGEST insn_number)
{
struct thread_info *tp;
struct btrace_insn_iterator it;
unsigned int number;
int found;

- number = insn;
+ number = insn_number;

/* Check for wrap-arounds. */
- if (number != insn)
+ if (number != insn_number)
error (_("Instruction number out of range."));

tp = require_btrace_thread ();

found = btrace_find_insn_by_number (&it, &tp->btrace, number);

- /* Check if the instruction could not be found or is a gap. */
- if (found == 0 || btrace_insn_get (&it) == NULL)
+ /* Check if the instruction could not be found or is a gap or an
+ auxiliary instruction. */
+ if (found == 0)
+ error (_("No such instruction."));
+
+ const struct btrace_insn *insn = btrace_insn_get (&it);
+ if (insn == NULL)
error (_("No such instruction."));
+ if (insn->iclass == BTRACE_INSN_AUX)
+ error (_("Can't go to an auxiliary instruction."));

record_btrace_set_replay (tp, &it);
}
--
2.34.1