kdb,kgdb: Implement switch and pass buffer from kdb -> gdb

When switching from kdb mode to kgdb mode packets were getting lost depending on the size of the fifo queue of the serial chip. When gdb initially connects if it is in kdb mode it should entirely send any character buffer over to the gdbstub when switching connections. Previously kdb was zero'ing out the character buffer and this could lead to gdb failing to connect at all, or a lengthy pause could occur on the initial connect. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

kdb,kgdb: Implement switch and pass buffer from kdb -> gdb
When switching from kdb mode to kgdb mode packets were getting lost depending on the size of the fifo queue of the serial chip. When gdb initially connects if it is in kdb mode it should entirely send any character buffer over to the gdbstub when switching connections. Previously kdb was zero'ing out the character buffer and this could lead to gdb failing to connect at all, or a lengthy pause could occur on the initial connect. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Jason Wessel
1 parent 3bdb65ec95
Showing 4 changed files with 29 additions and 21 deletions Side-by-side Diff
kernel/debug/gdbstub.c
kernel/debug/kdb/kdb_debugger.c
kernel/debug/kdb/kdb_io.c
kernel/debug/kdb/kdb_private.h
@@ -42,6 +42,8 @@
 /* Our I/O buffers. */
 static char			remcom_in_buffer[BUFMAX];
 static char			remcom_out_buffer[BUFMAX];
+static int			gdbstub_use_prev_in_buf;
+static int			gdbstub_prev_in_buf_pos;
  
 /* Storage for the registers, in GDB format. */
 static unsigned long		gdb_regs[(NUMREGBYTES +
@@ -58,6 +60,13 @@
 	int ret = -1;
 	int i;
  
+	if (unlikely(gdbstub_use_prev_in_buf)) {
+		if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
+			return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
+		else
+			gdbstub_use_prev_in_buf = 0;
+	}
+
 	/* poll any additional I/O interfaces that are defined */
 	while (ret < 0)
 		for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
@@ -109,7 +118,6 @@
 			buffer[count] = ch;
 			count = count + 1;
 		}
-		buffer[count] = 0;
  
 		if (ch == '#') {
 			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
@@ -124,6 +132,7 @@
 			if (dbg_io_ops->flush)
 				dbg_io_ops->flush();
 		}
+		buffer[count] = 0;
 	} while (checksum != xmitcsum);
 }
  
@@ -1082,12 +1091,11 @@
 	case 'c':
 		strcpy(remcom_in_buffer, cmd);
 		return 0;
-	case '?':
-		gdb_cmd_status(ks);
-		break;
-	case '\0':
-		strcpy(remcom_out_buffer, "");
-		break;
+	case '$':
+		strcpy(remcom_in_buffer, cmd);
+		gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
+		gdbstub_prev_in_buf_pos = 0;
+		return 0;
 	}
 	dbg_io_ops->write_char('+');
 	put_packet(remcom_out_buffer);
@@ -30,6 +30,8 @@
 int kdb_poll_idx = 1;
 EXPORT_SYMBOL_GPL(kdb_poll_idx);
  
+static struct kgdb_state *kdb_ks;
+
 int kdb_stub(struct kgdb_state *ks)
 {
 	int error = 0;
@@ -39,6 +41,7 @@
 	kdb_dbtrap_t db_result = KDB_DB_NOBPT;
 	int i;
  
+	kdb_ks = ks;
 	if (KDB_STATE(REENTRY)) {
 		reason = KDB_REASON_SWITCH;
 		KDB_STATE_CLEAR(REENTRY);
@@ -124,16 +127,6 @@
 	kdbnearsym_cleanup();
 	if (error == KDB_CMD_KGDB) {
 		if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) {
-	/*
-	 * This inteface glue which allows kdb to transition in into
-	 * the gdb stub.  In order to do this the '?' or '' gdb serial
-	 * packet response is processed here.  And then control is
-	 * passed to the gdbstub.
-	 */
-			if (KDB_STATE(DOING_KGDB))
-				gdbstub_state(ks, "?");
-			else
-				gdbstub_state(ks, "");
 			KDB_STATE_CLEAR(DOING_KGDB);
 			KDB_STATE_CLEAR(DOING_KGDB2);
 		}
@@ -164,5 +157,10 @@
 		return DBG_SWITCH_CPU_EVENT;
 	}
 	return kgdb_info[ks->cpu].ret_state;
+}
+
+void kdb_gdb_state_pass(char *buf)
+{
+	gdbstub_state(kdb_ks, buf);
 }
@@ -35,8 +35,8 @@
 {
 	int slen = strlen(buffer);
 	if (strncmp(buffer, "$?#3f", slen) != 0 &&
-	    strncmp(buffer, "$qSupported#37", slen) != 0 &&
-	    strncmp(buffer, "+$qSupported#37", slen) != 0) {
+	    strncmp(buffer, "$qSupported", slen) != 0 &&
+	    strncmp(buffer, "+$qSupported", slen) != 0) {
 		KDB_STATE_SET(KGDB_TRANS);
 		kdb_printf("%s", buffer);
 	}
  
@@ -390,12 +390,14 @@
 			/* Special escape to kgdb */
 			if (lastchar - buffer >= 5 &&
 			    strcmp(lastchar - 5, "$?#3f") == 0) {
+				kdb_gdb_state_pass(lastchar - 5);
 				strcpy(buffer, "kgdb");
 				KDB_STATE_SET(DOING_KGDB);
 				return buffer;
 			}
-			if (lastchar - buffer >= 14 &&
-			    strcmp(lastchar - 14, "$qSupported#37") == 0) {
+			if (lastchar - buffer >= 11 &&
+			    strcmp(lastchar - 11, "$qSupported") == 0) {
+				kdb_gdb_state_pass(lastchar - 11);
 				strcpy(buffer, "kgdb");
 				KDB_STATE_SET(DOING_KGDB2);
 				return buffer;
@@ -218,6 +218,7 @@
 extern void kdb_send_sig_info(struct task_struct *p, struct siginfo *info);
 extern void kdb_meminfo_proc_show(void);
 extern char *kdb_getstr(char *, size_t, char *);
+extern void kdb_gdb_state_pass(char *buf);
  
 /* Defines for kdb_symbol_print */
 #define KDB_SP_SPACEB	0x0001		/* Space before string */
...	...	@@ -42,6 +42,8 @@
42	42	/* Our I/O buffers. */
43	43	static char remcom_in_buffer[BUFMAX];
44	44	static char remcom_out_buffer[BUFMAX];
	45	+static int gdbstub_use_prev_in_buf;
	46	+static int gdbstub_prev_in_buf_pos;
45	47
46	48	/* Storage for the registers, in GDB format. */
47	49	static unsigned long gdb_regs[(NUMREGBYTES +
...	...	@@ -58,6 +60,13 @@
58	60	int ret = -1;
59	61	int i;
60	62
	63	+ if (unlikely(gdbstub_use_prev_in_buf)) {
	64	+ if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
	65	+ return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
	66	+ else
	67	+ gdbstub_use_prev_in_buf = 0;
	68	+ }
	69	+
61	70	/* poll any additional I/O interfaces that are defined */
62	71	while (ret < 0)
63	72	for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
...	...	@@ -109,7 +118,6 @@
109	118	buffer[count] = ch;
110	119	count = count + 1;
111	120	}
112		- buffer[count] = 0;
113	121
114	122	if (ch == '#') {
115	123	xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
...	...	@@ -124,6 +132,7 @@
124	132	if (dbg_io_ops->flush)
125	133	dbg_io_ops->flush();
126	134	}
	135	+ buffer[count] = 0;
127	136	} while (checksum != xmitcsum);
128	137	}
129	138
...	...	@@ -1082,12 +1091,11 @@
1082	1091	case 'c':
1083	1092	strcpy(remcom_in_buffer, cmd);
1084	1093	return 0;
1085		- case '?':
1086		- gdb_cmd_status(ks);
1087		- break;
1088		- case '\0':
1089		- strcpy(remcom_out_buffer, "");
1090		- break;
	1094	+ case '$':
	1095	+ strcpy(remcom_in_buffer, cmd);
	1096	+ gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
	1097	+ gdbstub_prev_in_buf_pos = 0;
	1098	+ return 0;
1091	1099	}
1092	1100	dbg_io_ops->write_char('+');
1093	1101	put_packet(remcom_out_buffer);
...	...	@@ -30,6 +30,8 @@
30	30	int kdb_poll_idx = 1;
31	31	EXPORT_SYMBOL_GPL(kdb_poll_idx);
32	32
	33	+static struct kgdb_state *kdb_ks;
	34	+
33	35	int kdb_stub(struct kgdb_state *ks)
34	36	{
35	37	int error = 0;
...	...	@@ -39,6 +41,7 @@
39	41	kdb_dbtrap_t db_result = KDB_DB_NOBPT;
40	42	int i;
41	43
	44	+ kdb_ks = ks;
42	45	if (KDB_STATE(REENTRY)) {
43	46	reason = KDB_REASON_SWITCH;
44	47	KDB_STATE_CLEAR(REENTRY);
...	...	@@ -124,16 +127,6 @@
124	127	kdbnearsym_cleanup();
125	128	if (error == KDB_CMD_KGDB) {
126	129	if (KDB_STATE(DOING_KGDB) \|\| KDB_STATE(DOING_KGDB2)) {
127		- /*
128		- * This inteface glue which allows kdb to transition in into
129		- * the gdb stub. In order to do this the '?' or '' gdb serial
130		- * packet response is processed here. And then control is
131		- * passed to the gdbstub.
132		- */
133		- if (KDB_STATE(DOING_KGDB))
134		- gdbstub_state(ks, "?");
135		- else
136		- gdbstub_state(ks, "");
137	130	KDB_STATE_CLEAR(DOING_KGDB);
138	131	KDB_STATE_CLEAR(DOING_KGDB2);
139	132	}
...	...	@@ -164,5 +157,10 @@
164	157	return DBG_SWITCH_CPU_EVENT;
165	158	}
166	159	return kgdb_info[ks->cpu].ret_state;
	160	+}
	161	+
	162	+void kdb_gdb_state_pass(char *buf)
	163	+{
	164	+ gdbstub_state(kdb_ks, buf);
167	165	}
...	...	@@ -35,8 +35,8 @@
35	35	{
36	36	int slen = strlen(buffer);
37	37	if (strncmp(buffer, "$?#3f", slen) != 0 &&
38		- strncmp(buffer, "$qSupported#37", slen) != 0 &&
39		- strncmp(buffer, "+$qSupported#37", slen) != 0) {
	38	+ strncmp(buffer, "$qSupported", slen) != 0 &&
	39	+ strncmp(buffer, "+$qSupported", slen) != 0) {
40	40	KDB_STATE_SET(KGDB_TRANS);
41	41	kdb_printf("%s", buffer);
42	42	}
43	43
...	...	@@ -390,12 +390,14 @@
390	390	/* Special escape to kgdb */
391	391	if (lastchar - buffer >= 5 &&
392	392	strcmp(lastchar - 5, "$?#3f") == 0) {
	393	+ kdb_gdb_state_pass(lastchar - 5);
393	394	strcpy(buffer, "kgdb");
394	395	KDB_STATE_SET(DOING_KGDB);
395	396	return buffer;
396	397	}
397		- if (lastchar - buffer >= 14 &&
398		- strcmp(lastchar - 14, "$qSupported#37") == 0) {
	398	+ if (lastchar - buffer >= 11 &&
	399	+ strcmp(lastchar - 11, "$qSupported") == 0) {
	400	+ kdb_gdb_state_pass(lastchar - 11);
399	401	strcpy(buffer, "kgdb");
400	402	KDB_STATE_SET(DOING_KGDB2);
401	403	return buffer;
...	...	@@ -218,6 +218,7 @@
218	218	extern void kdb_send_sig_info(struct task_struct p, struct siginfo info);
219	219	extern void kdb_meminfo_proc_show(void);
220	220	extern char kdb_getstr(char , size_t, char *);
	221	+extern void kdb_gdb_state_pass(char *buf);
221	222
222	223	/* Defines for kdb_symbol_print */
223	224	#define KDB_SP_SPACEB 0x0001 /* Space before string */