Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
debug-stub.c
Go to the documentation of this file.
1 /* debug-stub.c: debug-mode stub
2  *
3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells ([email protected])
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/string.h>
13 #include <linux/kernel.h>
14 #include <linux/signal.h>
15 #include <linux/sched.h>
16 #include <linux/init.h>
17 #include <linux/serial_reg.h>
18 #include <linux/start_kernel.h>
19 
20 #include <asm/serial-regs.h>
21 #include <asm/timer-regs.h>
22 #include <asm/irc-regs.h>
23 #include <asm/gdb-stub.h>
24 #include "gdb-io.h"
25 
26 /* CPU board CON5 */
27 #define __UART0(X) (*(volatile uint8_t *)(UART0_BASE + (UART_##X)))
28 
29 #define LSR_WAIT_FOR0(STATE) \
30 do { \
31 } while (!(__UART0(LSR) & UART_LSR_##STATE))
32 
33 #define FLOWCTL_QUERY0(LINE) ({ __UART0(MSR) & UART_MSR_##LINE; })
34 #define FLOWCTL_CLEAR0(LINE) do { __UART0(MCR) &= ~UART_MCR_##LINE; } while (0)
35 #define FLOWCTL_SET0(LINE) do { __UART0(MCR) |= UART_MCR_##LINE; } while (0)
36 
37 #define FLOWCTL_WAIT_FOR0(LINE) \
38 do { \
39  gdbstub_do_rx(); \
40 } while(!FLOWCTL_QUERY(LINE))
41 
43 
44 static void __init debug_stub_init(void);
45 
46 /*****************************************************************************/
47 /*
48  * debug mode handler stub
49  * - we come here with the CPU in debug mode and with exceptions disabled
50  * - handle debugging services for userspace
51  */
53 {
54  unsigned long hsr0;
55  int type = 0;
56 
57  static u8 inited = 0;
58  if (!inited) {
59  debug_stub_init();
60  type = -1;
61  inited = 1;
62  }
63 
64  hsr0 = __get_HSR(0);
65  if (hsr0 & HSR0_ETMD)
66  __set_HSR(0, hsr0 & ~HSR0_ETMD);
67 
68  /* disable single stepping */
69  __debug_status.dcr &= ~DCR_SE;
70 
71  /* kernel mode can propose an exception be handled in debug mode by jumping to a special
72  * location */
73  if (__debug_frame->pc == (unsigned long) __break_hijack_kernel_event_breaks_here) {
74  /* replace the debug frame with the kernel frame and discard
75  * the top kernel context */
76  *__debug_frame = *__frame;
77  __frame = __debug_frame->next_frame;
78  __debug_status.brr = (__debug_frame->tbr & TBR_TT) << 12;
79  __debug_status.brr |= BRR_EB;
80  }
81 
82  if (__debug_frame->pc == (unsigned long) __debug_bug_trap + 4) {
83  __debug_frame->pc = __debug_frame->lr;
84  type = __debug_frame->gr8;
85  }
86 
87 #ifdef CONFIG_GDBSTUB
88  gdbstub(type);
89 #endif
90 
91  if (hsr0 & HSR0_ETMD)
92  __set_HSR(0, __get_HSR(0) | HSR0_ETMD);
93 
94 } /* end debug_stub() */
95 
96 /*****************************************************************************/
97 /*
98  * debug stub initialisation
99  */
100 static void __init debug_stub_init(void)
101 {
102  __set_IRR(6, 0xff000000); /* map ERRs to NMI */
103  __set_IITMR(1, 0x20000000); /* ERR0/1, UART0/1 IRQ detect levels */
104 
105  asm volatile(" movgs gr0,ibar0 \n"
106  " movgs gr0,ibar1 \n"
107  " movgs gr0,ibar2 \n"
108  " movgs gr0,ibar3 \n"
109  " movgs gr0,dbar0 \n"
110  " movgs gr0,dbmr00 \n"
111  " movgs gr0,dbmr01 \n"
112  " movgs gr0,dbdr00 \n"
113  " movgs gr0,dbdr01 \n"
114  " movgs gr0,dbar1 \n"
115  " movgs gr0,dbmr10 \n"
116  " movgs gr0,dbmr11 \n"
117  " movgs gr0,dbdr10 \n"
118  " movgs gr0,dbdr11 \n"
119  );
120 
121  /* deal with debugging stub initialisation and initial pause */
122  if (__debug_frame->pc == (unsigned long) __debug_stub_init_break)
123  __debug_frame->pc = (unsigned long) start_kernel;
124 
125  /* enable the debug events we want to trap */
126  __debug_status.dcr = DCR_EBE;
127 
128 #ifdef CONFIG_GDBSTUB
129  gdbstub_init();
130 #endif
131 
132  __clr_MASK_all();
133  __clr_MASK(15);
134  __clr_RC(15);
135 
136 } /* end debug_stub_init() */
137 
138 /*****************************************************************************/
139 /*
140  * kernel "exit" trap for gdb stub
141  */
143 {
144 
145 #ifdef CONFIG_GDBSTUB
146  gdbstub_exit(status);
147 #endif
148 
149 } /* end debug_stub_exit() */
150 
151 /*****************************************************************************/
152 /*
153  * send string to serial port
154  */
155 void debug_to_serial(const char *p, int n)
156 {
157  char ch;
158 
159  for (; n > 0; n--) {
160  ch = *p++;
161  FLOWCTL_SET0(DTR);
163  // FLOWCTL_WAIT_FOR(CTS);
164 
165  if (ch == 0x0a) {
166  __UART0(TX) = 0x0d;
167  mb();
169  // FLOWCTL_WAIT_FOR(CTS);
170  }
171  __UART0(TX) = ch;
172  mb();
173 
175  }
176 
177 } /* end debug_to_serial() */
178 
179 /*****************************************************************************/
180 /*
181  * send string to serial port
182  */
183 void debug_to_serial2(const char *fmt, ...)
184 {
185  va_list va;
186  char buf[64];
187  int n;
188 
189  va_start(va, fmt);
190  n = vsprintf(buf, fmt, va);
191  va_end(va);
192 
193  debug_to_serial(buf, n);
194 
195 } /* end debug_to_serial2() */
196 
197 /*****************************************************************************/
198 /*
199  * set up the ttyS0 serial port baud rate timers
200  */
202 {
203  unsigned value, high, low;
204  u8 lcr;
205 
206  /* work out the divisor to give us the nearest higher baud rate */
207  value = __serial_clock_speed_HZ / 16 / baud;
208 
209  /* determine the baud rate range */
210  high = __serial_clock_speed_HZ / 16 / value;
211  low = __serial_clock_speed_HZ / 16 / (value + 1);
212 
213  /* pick the nearest bound */
214  if (low + (high - low) / 2 > baud)
215  value++;
216 
217  lcr = __UART0(LCR);
219  mb();
220  __UART0(DLL) = value & 0xff;
221  __UART0(DLM) = (value >> 8) & 0xff;
222  mb();
223  __UART0(LCR) = lcr;
224  mb();
225 
226 } /* end console_set_baud() */
227 
228 /*****************************************************************************/
229 /*
230  *
231  */
233 {
234  unsigned value;
235  u8 lcr;
236 
237  lcr = __UART0(LCR);
239  mb();
240  value = __UART0(DLM) << 8;
241  value |= __UART0(DLL);
242  __UART0(LCR) = lcr;
243  mb();
244 
245  return value;
246 } /* end console_get_baud() */
247 
248 /*****************************************************************************/
249 /*
250  * display BUG() info
251  */
252 #ifndef CONFIG_NO_KERNEL_MSG
253 void __debug_bug_printk(const char *file, unsigned line)
254 {
255  printk("kernel BUG at %s:%d!\n", file, line);
256 
257 } /* end __debug_bug_printk() */
258 #endif