add new system file

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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/kernel/debug/kdb/kdb_io.c
..
..
@@ -49,14 +49,88 @@
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 	return 0;
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 }
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51
 
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-static int kdb_read_get_key(char *buffer, size_t bufsize)
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+/**
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+ * kdb_handle_escape() - validity check on an accumulated escape sequence.
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+ * @buf:	Accumulated escape characters to be examined. Note that buf
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+ *		is not a string, it is an array of characters and need not be
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+ *		nil terminated.
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+ * @sz:		Number of accumulated escape characters.
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+ *
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+ * Return: -1 if the escape sequence is unwanted, 0 if it is incomplete,
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+ * otherwise it returns a mapped key value to pass to the upper layers.
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+ */
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+static int kdb_handle_escape(char *buf, size_t sz)
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+{
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+	char *lastkey = buf + sz - 1;
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+
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+	switch (sz) {
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+	case 1:
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+		if (*lastkey == '\e')
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+			return 0;
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+		break;
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+
72
+	case 2: /* \e<something> */
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+		if (*lastkey == '[')
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+			return 0;
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+		break;
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+
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+	case 3:
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+		switch (*lastkey) {
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+		case 'A': /* \e[A, up arrow */
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+			return 16;
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+		case 'B': /* \e[B, down arrow */
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+			return 14;
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+		case 'C': /* \e[C, right arrow */
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+			return 6;
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+		case 'D': /* \e[D, left arrow */
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+			return 2;
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+		case '1': /* \e[<1,3,4>], may be home, del, end */
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+		case '3':
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+		case '4':
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+			return 0;
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+		}
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+		break;
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+
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+	case 4:
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+		if (*lastkey == '~') {
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+			switch (buf[2]) {
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+			case '1': /* \e[1~, home */
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+				return 1;
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+			case '3': /* \e[3~, del */
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+				return 4;
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+			case '4': /* \e[4~, end */
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+				return 5;
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+			}
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+		}
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+		break;
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+	}
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+
108
+	return -1;
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+}
110
+
111
+/**
112
+ * kdb_getchar() - Read a single character from a kdb console (or consoles).
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+ *
114
+ * Other than polling the various consoles that are currently enabled,
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+ * most of the work done in this function is dealing with escape sequences.
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+ *
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+ * An escape key could be the start of a vt100 control sequence such as \e[D
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+ * (left arrow) or it could be a character in its own right.  The standard
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+ * method for detecting the difference is to wait for 2 seconds to see if there
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+ * are any other characters.  kdb is complicated by the lack of a timer service
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+ * (interrupts are off), by multiple input sources. Escape sequence processing
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+ * has to be done as states in the polling loop.
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+ *
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+ * Return: The key pressed or a control code derived from an escape sequence.
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+ */
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+char kdb_getchar(void)
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127
 {
54
128
 #define ESCAPE_UDELAY 1000
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129
 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
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-	char escape_data[5];	/* longest vt100 escape sequence is 4 bytes */
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-	char *ped = escape_data;
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+	char buf[4];	/* longest vt100 escape sequence is 4 bytes */
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+	char *pbuf = buf;
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132
 	int escape_delay = 0;
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-	get_char_func *f, *f_escape = NULL;
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+	get_char_func *f, *f_prev = NULL;
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134
 	int key;
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135
 
62
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 	for (f = &kdb_poll_funcs[0]; ; ++f) {
..
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@@ -65,109 +139,37 @@
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 			touch_nmi_watchdog();
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140
 			f = &kdb_poll_funcs[0];
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141
 		}
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-		if (escape_delay == 2) {
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-			*ped = '\0';
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-			ped = escape_data;
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-			--escape_delay;
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-		}
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-		if (escape_delay == 1) {
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-			key = *ped++;
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-			if (!*ped)
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-				--escape_delay;
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-			break;
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-		}
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+
79
143
 		key = (*f)();
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144
 		if (key == -1) {
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145
 			if (escape_delay) {
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146
 				udelay(ESCAPE_UDELAY);
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-				--escape_delay;
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+				if (--escape_delay == 0)
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+					return '\e';
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 			}
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150
 			continue;
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151
 		}
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-		if (bufsize <= 2) {
88
-			if (key == '\r')
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-				key = '\n';
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-			*buffer++ = key;
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-			*buffer = '\0';
92
-			return -1;
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-		}
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-		if (escape_delay == 0 && key == '\e') {
152
+
153
+		/*
154
+		 * When the first character is received (or we get a change
155
+		 * input source) we set ourselves up to handle an escape
156
+		 * sequences (just in case).
157
+		 */
158
+		if (f_prev != f) {
159
+			f_prev = f;
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+			pbuf = buf;
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161
 			escape_delay = ESCAPE_DELAY;
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-			ped = escape_data;
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-			f_escape = f;
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162
 		}
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-		if (escape_delay) {
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-			*ped++ = key;
101
-			if (f_escape != f) {
102
-				escape_delay = 2;
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-				continue;
104
-			}
105
-			if (ped - escape_data == 1) {
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-				/* \e */
107
-				continue;
108
-			} else if (ped - escape_data == 2) {
109
-				/* \e<something> */
110
-				if (key != '[')
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-					escape_delay = 2;
112
-				continue;
113
-			} else if (ped - escape_data == 3) {
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-				/* \e[<something> */
115
-				int mapkey = 0;
116
-				switch (key) {
117
-				case 'A': /* \e[A, up arrow */
118
-					mapkey = 16;
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-					break;
120
-				case 'B': /* \e[B, down arrow */
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-					mapkey = 14;
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-					break;
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-				case 'C': /* \e[C, right arrow */
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-					mapkey = 6;
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-					break;
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-				case 'D': /* \e[D, left arrow */
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-					mapkey = 2;
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-					break;
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-				case '1': /* dropthrough */
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-				case '3': /* dropthrough */
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-				/* \e[<1,3,4>], may be home, del, end */
132
-				case '4':
133
-					mapkey = -1;
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-					break;
135
-				}
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-				if (mapkey != -1) {
137
-					if (mapkey > 0) {
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-						escape_data[0] = mapkey;
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-						escape_data[1] = '\0';
140
-					}
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-					escape_delay = 2;
142
-				}
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-				continue;
144
-			} else if (ped - escape_data == 4) {
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-				/* \e[<1,3,4><something> */
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-				int mapkey = 0;
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-				if (key == '~') {
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-					switch (escape_data[2]) {
149
-					case '1': /* \e[1~, home */
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-						mapkey = 1;
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-						break;
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-					case '3': /* \e[3~, del */
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-						mapkey = 4;
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-						break;
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-					case '4': /* \e[4~, end */
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-						mapkey = 5;
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-						break;
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-					}
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-				}
160
-				if (mapkey > 0) {
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-					escape_data[0] = mapkey;
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-					escape_data[1] = '\0';
163
-				}
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-				escape_delay = 2;
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-				continue;
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-			}
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-		}
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-		break;	/* A key to process */
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+
164
+		*pbuf++ = key;
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+		key = kdb_handle_escape(buf, pbuf - buf);
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+		if (key < 0) /* no escape sequence; return best character */
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+			return buf[pbuf - buf == 2 ? 1 : 0];
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+		if (key > 0)
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+			return key;
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170
 	}
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-	return key;
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+
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+	unreachable();
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173
 }
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174
 
173
175
 /*
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@@ -188,17 +190,7 @@
188
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  *	function.  It is not reentrant - it relies on the fact
189
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  *	that while kdb is running on only one "master debug" cpu.
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192
  * Remarks:
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- *
192
- * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
193
- * wants a single key.
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- *
195
- * An escape key could be the start of a vt100 control sequence such as \e[D
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- * (left arrow) or it could be a character in its own right.  The standard
197
- * method for detecting the difference is to wait for 2 seconds to see if there
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- * are any other characters.  kdb is complicated by the lack of a timer service
199
- * (interrupts are off), by multiple input sources and by the need to sometimes
200
- * return after just one key.  Escape sequence processing has to be done as
201
- * states in the polling loop.
193
+ *	The buffer size must be >= 2.
202
194
  */
203
195
 
204
196
 static char *kdb_read(char *buffer, size_t bufsize)
..
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@@ -233,9 +225,7 @@
233
225
 	*cp = '\0';
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226
 	kdb_printf("%s", buffer);
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227
 poll_again:
236
-	key = kdb_read_get_key(buffer, bufsize);
237
-	if (key == -1)
238
-		return buffer;
228
+	key = kdb_getchar();
239
229
 	if (key != 9)
240
230
 		tab = 0;
241
231
 	switch (key) {
..
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@@ -446,7 +436,7 @@
446
436
 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
447
437
 {
448
438
 	if (prompt && kdb_prompt_str != prompt)
449
-		strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
439
+		strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
450
440
 	kdb_printf(kdb_prompt_str);
451
441
 	kdb_nextline = 1;	/* Prompt and input resets line number */
452
442
 	return kdb_read(buffer, bufsize);
..
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@@ -552,6 +542,44 @@
552
542
 	return 0;
553
543
 }
554
544
 
545
+static void kdb_msg_write(const char *msg, int msg_len)
546
+{
547
+	struct console *c;
548
+	const char *cp;
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+	int len;
550
+
551
+	if (msg_len == 0)
552
+		return;
553
+
554
+	cp = msg;
555
+	len = msg_len;
556
+
557
+	while (len--) {
558
+		dbg_io_ops->write_char(*cp);
559
+		cp++;
560
+	}
561
+
562
+	for_each_console(c) {
563
+		if (!(c->flags & CON_ENABLED))
564
+			continue;
565
+		if (c == dbg_io_ops->cons)
566
+			continue;
567
+		/*
568
+		 * Set oops_in_progress to encourage the console drivers to
569
+		 * disregard their internal spin locks: in the current calling
570
+		 * context the risk of deadlock is a bigger problem than risks
571
+		 * due to re-entering the console driver. We operate directly on
572
+		 * oops_in_progress rather than using bust_spinlocks() because
573
+		 * the calls bust_spinlocks() makes on exit are not appropriate
574
+		 * for this calling context.
575
+		 */
576
+		++oops_in_progress;
577
+		c->write(c, msg, msg_len);
578
+		--oops_in_progress;
579
+		touch_nmi_watchdog();
580
+	}
581
+}
582
+
555
583
 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
556
584
 {
557
585
 	int diag;
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@@ -563,8 +591,7 @@
563
591
 	int this_cpu, old_cpu;
564
592
 	char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
565
593
 	char *moreprompt = "more> ";
566
-	struct console *c = console_drivers;
567
-	unsigned long uninitialized_var(flags);
594
+	unsigned long flags;
568
595
 
569
596
 	/* Serialize kdb_printf if multiple cpus try to write at once.
570
597
 	 * But if any cpu goes recursive in kdb, just print the output,
..
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@@ -701,23 +728,11 @@
701
728
 	 */
702
729
 	retlen = strlen(kdb_buffer);
703
730
 	cp = (char *) printk_skip_headers(kdb_buffer);
704
-	if (!dbg_kdb_mode && kgdb_connected) {
731
+	if (!dbg_kdb_mode && kgdb_connected)
705
732
 		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
706
-	} else {
707
-		if (dbg_io_ops && !dbg_io_ops->is_console) {
708
-			len = retlen - (cp - kdb_buffer);
709
-			cp2 = cp;
710
-			while (len--) {
711
-				dbg_io_ops->write_char(*cp2);
712
-				cp2++;
713
-			}
714
-		}
715
-		while (c) {
716
-			c->write(c, cp, retlen - (cp - kdb_buffer));
717
-			touch_nmi_watchdog();
718
-			c = c->next;
719
-		}
720
-	}
733
+	else
734
+		kdb_msg_write(cp, retlen - (cp - kdb_buffer));
735
+
721
736
 	if (logging) {
722
737
 		saved_loglevel = console_loglevel;
723
738
 		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
..
..
@@ -750,7 +765,7 @@
750
765
 
751
766
 	/* check for having reached the LINES number of printed lines */
752
767
 	if (kdb_nextline >= linecount) {
753
-		char buf1[16] = "";
768
+		char ch;
754
769
 
755
770
 		/* Watch out for recursion here.  Any routine that calls
756
771
 		 * kdb_printf will come back through here.  And kdb_read
..
..
@@ -766,58 +781,43 @@
766
781
 			moreprompt = "more> ";
767
782
 
768
783
 		kdb_input_flush();
769
-		c = console_drivers;
770
-
771
-		if (dbg_io_ops && !dbg_io_ops->is_console) {
772
-			len = strlen(moreprompt);
773
-			cp = moreprompt;
774
-			while (len--) {
775
-				dbg_io_ops->write_char(*cp);
776
-				cp++;
777
-			}
778
-		}
779
-		while (c) {
780
-			c->write(c, moreprompt, strlen(moreprompt));
781
-			touch_nmi_watchdog();
782
-			c = c->next;
783
-		}
784
+		kdb_msg_write(moreprompt, strlen(moreprompt));
784
785
 
785
786
 		if (logging)
786
787
 			printk("%s", moreprompt);
787
788
 
788
-		kdb_read(buf1, 2); /* '2' indicates to return
789
-				    * immediately after getting one key. */
789
+		ch = kdb_getchar();
790
790
 		kdb_nextline = 1;	/* Really set output line 1 */
791
791
 
792
792
 		/* empty and reset the buffer: */
793
793
 		kdb_buffer[0] = '\0';
794
794
 		next_avail = kdb_buffer;
795
795
 		size_avail = sizeof(kdb_buffer);
796
-		if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
796
+		if ((ch == 'q') || (ch == 'Q')) {
797
797
 			/* user hit q or Q */
798
798
 			KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
799
799
 			KDB_STATE_CLEAR(PAGER);
800
800
 			/* end of command output; back to normal mode */
801
801
 			kdb_grepping_flag = 0;
802
802
 			kdb_printf("\n");
803
-		} else if (buf1[0] == ' ') {
803
+		} else if (ch == ' ') {
804
804
 			kdb_printf("\r");
805
805
 			suspend_grep = 1; /* for this recursion */
806
-		} else if (buf1[0] == '\n') {
806
+		} else if (ch == '\n' || ch == '\r') {
807
807
 			kdb_nextline = linecount - 1;
808
808
 			kdb_printf("\r");
809
809
 			suspend_grep = 1; /* for this recursion */
810
-		} else if (buf1[0] == '/' && !kdb_grepping_flag) {
810
+		} else if (ch == '/' && !kdb_grepping_flag) {
811
811
 			kdb_printf("\r");
812
812
 			kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
813
813
 				   kdbgetenv("SEARCHPROMPT") ?: "search> ");
814
814
 			*strchrnul(kdb_grep_string, '\n') = '\0';
815
815
 			kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
816
816
 			suspend_grep = 1; /* for this recursion */
817
-		} else if (buf1[0] && buf1[0] != '\n') {
818
-			/* user hit something other than enter */
817
+		} else if (ch) {
818
+			/* user hit something unexpected */
819
819
 			suspend_grep = 1; /* for this recursion */
820
-			if (buf1[0] != '/')
820
+			if (ch != '/')
821
821
 				kdb_printf(
822
822
 				    "\nOnly 'q', 'Q' or '/' are processed at "
823
823
 				    "more prompt, input ignored\n");