4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9 * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12 * Copyright (C) 2005-2008 Wind River Systems, Inc.
13 * Copyright (C) 2007 MontaVista Software, Inc.
14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( jason.wessel@windriver.com )
18 * George Anzinger <george@mvista.com>
19 * Anurekh Saxena (anurekh.saxena@timesys.com)
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
26 * This file is licensed under the terms of the GNU General Public License
27 * version 2. This program is licensed "as is" without any warranty of any
28 * kind, whether express or implied.
30 #include <linux/pid_namespace.h>
31 #include <linux/interrupt.h>
32 #include <linux/spinlock.h>
33 #include <linux/console.h>
34 #include <linux/threads.h>
35 #include <linux/uaccess.h>
36 #include <linux/kernel.h>
37 #include <linux/module.h>
38 #include <linux/ptrace.h>
39 #include <linux/reboot.h>
40 #include <linux/string.h>
41 #include <linux/delay.h>
42 #include <linux/sched.h>
43 #include <linux/sysrq.h>
44 #include <linux/init.h>
45 #include <linux/kgdb.h>
46 #include <linux/pid.h>
47 #include <linux/smp.h>
50 #include <asm/cacheflush.h>
51 #include <asm/byteorder.h>
52 #include <asm/atomic.h>
53 #include <asm/system.h>
55 static int kgdb_break_asap;
64 long kgdb_usethreadid;
65 struct pt_regs *linux_regs;
68 static struct debuggerinfo_struct {
70 struct task_struct *task;
74 * kgdb_connected - Is a host GDB connected to us?
77 EXPORT_SYMBOL_GPL(kgdb_connected);
79 /* All the KGDB handlers are installed */
80 static int kgdb_io_module_registered;
82 /* Guard for recursive entry */
83 static int exception_level;
85 static struct kgdb_io *kgdb_io_ops;
86 static DEFINE_SPINLOCK(kgdb_registration_lock);
88 /* kgdb console driver is loaded */
89 static int kgdb_con_registered;
90 /* determine if kgdb console output should be used */
91 static int kgdb_use_con;
93 static int __init opt_kgdb_con(char *str)
99 early_param("kgdbcon", opt_kgdb_con);
101 module_param(kgdb_use_con, int, 0644);
104 * Holds information about breakpoints in a kernel. These breakpoints are
105 * added and removed by gdb.
107 static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
108 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
112 * The CPU# of the active CPU, or -1 if none:
114 atomic_t kgdb_active = ATOMIC_INIT(-1);
117 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
118 * bootup code (which might not have percpu set up yet):
120 static atomic_t passive_cpu_wait[NR_CPUS];
121 static atomic_t cpu_in_kgdb[NR_CPUS];
122 atomic_t kgdb_setting_breakpoint;
124 struct task_struct *kgdb_usethread;
125 struct task_struct *kgdb_contthread;
127 int kgdb_single_step;
129 /* Our I/O buffers. */
130 static char remcom_in_buffer[BUFMAX];
131 static char remcom_out_buffer[BUFMAX];
133 /* Storage for the registers, in GDB format. */
134 static unsigned long gdb_regs[(NUMREGBYTES +
135 sizeof(unsigned long) - 1) /
136 sizeof(unsigned long)];
138 /* to keep track of the CPU which is doing the single stepping*/
139 atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
142 * If you are debugging a problem where roundup (the collection of
143 * all other CPUs) is a problem [this should be extremely rare],
144 * then use the nokgdbroundup option to avoid roundup. In that case
145 * the other CPUs might interfere with your debugging context, so
146 * use this with care:
148 int kgdb_do_roundup = 1;
150 static int __init opt_nokgdbroundup(char *str)
157 early_param("nokgdbroundup", opt_nokgdbroundup);
160 * Finally, some KGDB code :-)
164 * Weak aliases for breakpoint management,
165 * can be overriden by architectures when needed:
167 int __weak kgdb_validate_break_address(unsigned long addr)
169 char tmp_variable[BREAK_INSTR_SIZE];
171 return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE);
174 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
178 err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
182 return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
186 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
188 return probe_kernel_write((char *)addr,
189 (char *)bundle, BREAK_INSTR_SIZE);
192 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
194 return instruction_pointer(regs);
197 int __weak kgdb_arch_init(void)
203 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
204 * @regs: Current &struct pt_regs.
206 * This function will be called if the particular architecture must
207 * disable hardware debugging while it is processing gdb packets or
208 * handling exception.
210 void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
215 * GDB remote protocol parser:
218 static const char hexchars[] = "0123456789abcdef";
220 static int hex(char ch)
222 if ((ch >= 'a') && (ch <= 'f'))
223 return ch - 'a' + 10;
224 if ((ch >= '0') && (ch <= '9'))
226 if ((ch >= 'A') && (ch <= 'F'))
227 return ch - 'A' + 10;
231 /* scan for the sequence $<data>#<checksum> */
232 static void get_packet(char *buffer)
234 unsigned char checksum;
235 unsigned char xmitcsum;
241 * Spin and wait around for the start character, ignore all
244 while ((ch = (kgdb_io_ops->read_char())) != '$')
254 * now, read until a # or end of buffer is found:
256 while (count < (BUFMAX - 1)) {
257 ch = kgdb_io_ops->read_char();
260 checksum = checksum + ch;
267 xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
268 xmitcsum += hex(kgdb_io_ops->read_char());
270 if (checksum != xmitcsum)
271 /* failed checksum */
272 kgdb_io_ops->write_char('-');
274 /* successful transfer */
275 kgdb_io_ops->write_char('+');
276 if (kgdb_io_ops->flush)
277 kgdb_io_ops->flush();
279 } while (checksum != xmitcsum);
283 * Send the packet in buffer.
284 * Check for gdb connection if asked for.
286 static void put_packet(char *buffer)
288 unsigned char checksum;
293 * $<packet info>#<checksum>.
296 kgdb_io_ops->write_char('$');
300 while ((ch = buffer[count])) {
301 kgdb_io_ops->write_char(ch);
306 kgdb_io_ops->write_char('#');
307 kgdb_io_ops->write_char(hexchars[checksum >> 4]);
308 kgdb_io_ops->write_char(hexchars[checksum & 0xf]);
309 if (kgdb_io_ops->flush)
310 kgdb_io_ops->flush();
312 /* Now see what we get in reply. */
313 ch = kgdb_io_ops->read_char();
316 ch = kgdb_io_ops->read_char();
318 /* If we get an ACK, we are done. */
323 * If we get the start of another packet, this means
324 * that GDB is attempting to reconnect. We will NAK
325 * the packet being sent, and stop trying to send this
329 kgdb_io_ops->write_char('-');
330 if (kgdb_io_ops->flush)
331 kgdb_io_ops->flush();
337 static char *pack_hex_byte(char *pkt, u8 byte)
339 *pkt++ = hexchars[byte >> 4];
340 *pkt++ = hexchars[byte & 0xf];
346 * Convert the memory pointed to by mem into hex, placing result in buf.
347 * Return a pointer to the last char put in buf (null). May return an error.
349 int kgdb_mem2hex(char *mem, char *buf, int count)
355 * We use the upper half of buf as an intermediate buffer for the
356 * raw memory copy. Hex conversion will work against this one.
360 err = probe_kernel_read(tmp, mem, count);
363 buf = pack_hex_byte(buf, *tmp);
375 * Copy the binary array pointed to by buf into mem. Fix $, #, and
376 * 0x7d escaped with 0x7d. Return a pointer to the character after
377 * the last byte written.
379 static int kgdb_ebin2mem(char *buf, char *mem, int count)
384 while (count-- > 0) {
389 err = probe_kernel_write(mem, &c, 1);
400 * Convert the hex array pointed to by buf into binary to be placed in mem.
401 * Return a pointer to the character AFTER the last byte written.
402 * May return an error.
404 int kgdb_hex2mem(char *buf, char *mem, int count)
410 * We use the upper half of buf as an intermediate buffer for the
411 * raw memory that is converted from hex.
413 tmp_raw = buf + count * 2;
415 tmp_hex = tmp_raw - 1;
416 while (tmp_hex >= buf) {
418 *tmp_raw = hex(*tmp_hex--);
419 *tmp_raw |= hex(*tmp_hex--) << 4;
422 return probe_kernel_write(mem, tmp_raw, count);
426 * While we find nice hex chars, build a long_val.
427 * Return number of chars processed.
429 int kgdb_hex2long(char **ptr, long *long_val)
437 hex_val = hex(**ptr);
441 *long_val = (*long_val << 4) | hex_val;
449 /* Write memory due to an 'M' or 'X' packet. */
450 static int write_mem_msg(int binary)
452 char *ptr = &remcom_in_buffer[1];
454 unsigned long length;
457 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
458 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
460 err = kgdb_ebin2mem(ptr, (char *)addr, length);
462 err = kgdb_hex2mem(ptr, (char *)addr, length);
465 if (CACHE_FLUSH_IS_SAFE)
466 flush_icache_range(addr, addr + length + 1);
473 static void error_packet(char *pkt, int error)
477 pkt[1] = hexchars[(error / 10)];
478 pkt[2] = hexchars[(error % 10)];
483 * Thread ID accessors. We represent a flat TID space to GDB, where
484 * the per CPU idle threads (which under Linux all have PID 0) are
485 * remapped to negative TIDs.
488 #define BUF_THREAD_ID_SIZE 16
490 static char *pack_threadid(char *pkt, unsigned char *id)
494 limit = pkt + BUF_THREAD_ID_SIZE;
496 pkt = pack_hex_byte(pkt, *id++);
501 static void int_to_threadref(unsigned char *id, int value)
506 scan = (unsigned char *)id;
509 *scan++ = (value >> 24) & 0xff;
510 *scan++ = (value >> 16) & 0xff;
511 *scan++ = (value >> 8) & 0xff;
512 *scan++ = (value & 0xff);
515 static struct task_struct *getthread(struct pt_regs *regs, int tid)
518 * Non-positive TIDs are remapped idle tasks:
521 return idle_task(-tid);
524 * find_task_by_pid_ns() does not take the tasklist lock anymore
525 * but is nicely RCU locked - hence is a pretty resilient
528 return find_task_by_pid_ns(tid, &init_pid_ns);
532 * CPU debug state control:
536 static void kgdb_wait(struct pt_regs *regs)
541 local_irq_save(flags);
542 cpu = raw_smp_processor_id();
543 kgdb_info[cpu].debuggerinfo = regs;
544 kgdb_info[cpu].task = current;
546 * Make sure the above info reaches the primary CPU before
547 * our cpu_in_kgdb[] flag setting does:
550 atomic_set(&cpu_in_kgdb[cpu], 1);
553 * The primary CPU must be active to enter here, but this is
554 * guard in case the primary CPU had not been selected if
555 * this was an entry via nmi.
557 while (atomic_read(&kgdb_active) == -1)
560 /* Wait till primary CPU goes completely into the debugger. */
561 while (!atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)]))
564 /* Wait till primary CPU is done with debugging */
565 while (atomic_read(&passive_cpu_wait[cpu]))
568 kgdb_info[cpu].debuggerinfo = NULL;
569 kgdb_info[cpu].task = NULL;
571 /* fix up hardware debug registers on local cpu */
572 if (arch_kgdb_ops.correct_hw_break)
573 arch_kgdb_ops.correct_hw_break();
575 /* Signal the primary CPU that we are done: */
576 atomic_set(&cpu_in_kgdb[cpu], 0);
577 local_irq_restore(flags);
582 * Some architectures need cache flushes when we set/clear a
585 static void kgdb_flush_swbreak_addr(unsigned long addr)
587 if (!CACHE_FLUSH_IS_SAFE)
591 flush_cache_range(current->mm->mmap_cache,
592 addr, addr + BREAK_INSTR_SIZE);
594 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
599 * SW breakpoint management:
601 static int kgdb_activate_sw_breakpoints(void)
607 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
608 if (kgdb_break[i].state != BP_SET)
611 addr = kgdb_break[i].bpt_addr;
612 error = kgdb_arch_set_breakpoint(addr,
613 kgdb_break[i].saved_instr);
617 kgdb_flush_swbreak_addr(addr);
618 kgdb_break[i].state = BP_ACTIVE;
623 static int kgdb_set_sw_break(unsigned long addr)
625 int err = kgdb_validate_break_address(addr);
632 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
633 if ((kgdb_break[i].state == BP_SET) &&
634 (kgdb_break[i].bpt_addr == addr))
637 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
638 if (kgdb_break[i].state == BP_REMOVED &&
639 kgdb_break[i].bpt_addr == addr) {
646 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
647 if (kgdb_break[i].state == BP_UNDEFINED) {
657 kgdb_break[breakno].state = BP_SET;
658 kgdb_break[breakno].type = BP_BREAKPOINT;
659 kgdb_break[breakno].bpt_addr = addr;
664 static int kgdb_deactivate_sw_breakpoints(void)
670 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
671 if (kgdb_break[i].state != BP_ACTIVE)
673 addr = kgdb_break[i].bpt_addr;
674 error = kgdb_arch_remove_breakpoint(addr,
675 kgdb_break[i].saved_instr);
679 kgdb_flush_swbreak_addr(addr);
680 kgdb_break[i].state = BP_SET;
685 static int kgdb_remove_sw_break(unsigned long addr)
689 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
690 if ((kgdb_break[i].state == BP_SET) &&
691 (kgdb_break[i].bpt_addr == addr)) {
692 kgdb_break[i].state = BP_REMOVED;
699 int kgdb_isremovedbreak(unsigned long addr)
703 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
704 if ((kgdb_break[i].state == BP_REMOVED) &&
705 (kgdb_break[i].bpt_addr == addr))
711 int remove_all_break(void)
717 /* Clear memory breakpoints. */
718 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
719 if (kgdb_break[i].state != BP_SET)
721 addr = kgdb_break[i].bpt_addr;
722 error = kgdb_arch_remove_breakpoint(addr,
723 kgdb_break[i].saved_instr);
726 kgdb_break[i].state = BP_REMOVED;
729 /* Clear hardware breakpoints. */
730 if (arch_kgdb_ops.remove_all_hw_break)
731 arch_kgdb_ops.remove_all_hw_break();
737 * Remap normal tasks to their real PID, idle tasks to -1 ... -NR_CPUs:
739 static inline int shadow_pid(int realpid)
744 return -1-raw_smp_processor_id();
747 static char gdbmsgbuf[BUFMAX + 1];
749 static void kgdb_msg_write(const char *s, int len)
758 /* Fill and send buffers... */
760 bufptr = gdbmsgbuf + 1;
762 /* Calculate how many this time */
763 if ((len << 1) > (BUFMAX - 2))
764 wcount = (BUFMAX - 2) >> 1;
768 /* Pack in hex chars */
769 for (i = 0; i < wcount; i++)
770 bufptr = pack_hex_byte(bufptr, s[i]);
778 put_packet(gdbmsgbuf);
783 * Return true if there is a valid kgdb I/O module. Also if no
784 * debugger is attached a message can be printed to the console about
785 * waiting for the debugger to attach.
787 * The print_wait argument is only to be true when called from inside
788 * the core kgdb_handle_exception, because it will wait for the
789 * debugger to attach.
791 static int kgdb_io_ready(int print_wait)
797 if (atomic_read(&kgdb_setting_breakpoint))
800 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
805 * All the functions that start with gdb_cmd are the various
806 * operations to implement the handlers for the gdbserial protocol
807 * where KGDB is communicating with an external debugger
810 /* Handle the '?' status packets */
811 static void gdb_cmd_status(struct kgdb_state *ks)
814 * We know that this packet is only sent
815 * during initial connect. So to be safe,
816 * we clear out our breakpoints now in case
817 * GDB is reconnecting.
821 remcom_out_buffer[0] = 'S';
822 pack_hex_byte(&remcom_out_buffer[1], ks->signo);
825 /* Handle the 'g' get registers request */
826 static void gdb_cmd_getregs(struct kgdb_state *ks)
828 struct task_struct *thread;
829 void *local_debuggerinfo;
832 thread = kgdb_usethread;
834 thread = kgdb_info[ks->cpu].task;
835 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
837 local_debuggerinfo = NULL;
838 for (i = 0; i < NR_CPUS; i++) {
840 * Try to find the task on some other
841 * or possibly this node if we do not
842 * find the matching task then we try
843 * to approximate the results.
845 if (thread == kgdb_info[i].task)
846 local_debuggerinfo = kgdb_info[i].debuggerinfo;
851 * All threads that don't have debuggerinfo should be
852 * in __schedule() sleeping, since all other CPUs
853 * are in kgdb_wait, and thus have debuggerinfo.
855 if (local_debuggerinfo) {
856 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
859 * Pull stuff saved during switch_to; nothing
860 * else is accessible (or even particularly
863 * This should be enough for a stack trace.
865 sleeping_thread_to_gdb_regs(gdb_regs, thread);
867 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
870 /* Handle the 'G' set registers request */
871 static void gdb_cmd_setregs(struct kgdb_state *ks)
873 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
875 if (kgdb_usethread && kgdb_usethread != current) {
876 error_packet(remcom_out_buffer, -EINVAL);
878 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
879 strcpy(remcom_out_buffer, "OK");
883 /* Handle the 'm' memory read bytes */
884 static void gdb_cmd_memread(struct kgdb_state *ks)
886 char *ptr = &remcom_in_buffer[1];
887 unsigned long length;
891 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
892 kgdb_hex2long(&ptr, &length) > 0) {
893 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
895 error_packet(remcom_out_buffer, err);
897 error_packet(remcom_out_buffer, -EINVAL);
901 /* Handle the 'M' memory write bytes */
902 static void gdb_cmd_memwrite(struct kgdb_state *ks)
904 int err = write_mem_msg(0);
907 error_packet(remcom_out_buffer, err);
909 strcpy(remcom_out_buffer, "OK");
912 /* Handle the 'X' memory binary write bytes */
913 static void gdb_cmd_binwrite(struct kgdb_state *ks)
915 int err = write_mem_msg(1);
918 error_packet(remcom_out_buffer, err);
920 strcpy(remcom_out_buffer, "OK");
923 /* Handle the 'D' or 'k', detach or kill packets */
924 static void gdb_cmd_detachkill(struct kgdb_state *ks)
928 /* The detach case */
929 if (remcom_in_buffer[0] == 'D') {
930 error = remove_all_break();
932 error_packet(remcom_out_buffer, error);
934 strcpy(remcom_out_buffer, "OK");
937 put_packet(remcom_out_buffer);
940 * Assume the kill case, with no exit code checking,
941 * trying to force detach the debugger:
948 /* Handle the 'R' reboot packets */
949 static int gdb_cmd_reboot(struct kgdb_state *ks)
951 /* For now, only honor R0 */
952 if (strcmp(remcom_in_buffer, "R0") == 0) {
953 printk(KERN_CRIT "Executing emergency reboot\n");
954 strcpy(remcom_out_buffer, "OK");
955 put_packet(remcom_out_buffer);
958 * Execution should not return from
959 * machine_emergency_restart()
961 machine_emergency_restart();
969 /* Handle the 'q' query packets */
970 static void gdb_cmd_query(struct kgdb_state *ks)
972 struct task_struct *thread;
973 unsigned char thref[8];
977 switch (remcom_in_buffer[1]) {
980 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
981 error_packet(remcom_out_buffer, -EINVAL);
985 if (remcom_in_buffer[1] == 'f')
988 remcom_out_buffer[0] = 'm';
989 ptr = remcom_out_buffer + 1;
991 for (i = 0; i < 17; ks->threadid++) {
992 thread = getthread(ks->linux_regs, ks->threadid);
994 int_to_threadref(thref, ks->threadid);
995 pack_threadid(ptr, thref);
996 ptr += BUF_THREAD_ID_SIZE;
1005 /* Current thread id */
1006 strcpy(remcom_out_buffer, "QC");
1007 ks->threadid = shadow_pid(current->pid);
1008 int_to_threadref(thref, ks->threadid);
1009 pack_threadid(remcom_out_buffer + 2, thref);
1012 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1013 error_packet(remcom_out_buffer, -EINVAL);
1017 ptr = remcom_in_buffer + 17;
1018 kgdb_hex2long(&ptr, &ks->threadid);
1019 if (!getthread(ks->linux_regs, ks->threadid)) {
1020 error_packet(remcom_out_buffer, -EINVAL);
1023 if (ks->threadid > 0) {
1024 kgdb_mem2hex(getthread(ks->linux_regs,
1025 ks->threadid)->comm,
1026 remcom_out_buffer, 16);
1028 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1030 sprintf(tmpstr, "Shadow task %d for pid 0",
1031 (int)(-ks->threadid-1));
1032 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1038 /* Handle the 'H' task query packets */
1039 static void gdb_cmd_task(struct kgdb_state *ks)
1041 struct task_struct *thread;
1044 switch (remcom_in_buffer[1]) {
1046 ptr = &remcom_in_buffer[2];
1047 kgdb_hex2long(&ptr, &ks->threadid);
1048 thread = getthread(ks->linux_regs, ks->threadid);
1049 if (!thread && ks->threadid > 0) {
1050 error_packet(remcom_out_buffer, -EINVAL);
1053 kgdb_usethread = thread;
1054 ks->kgdb_usethreadid = ks->threadid;
1055 strcpy(remcom_out_buffer, "OK");
1058 ptr = &remcom_in_buffer[2];
1059 kgdb_hex2long(&ptr, &ks->threadid);
1060 if (!ks->threadid) {
1061 kgdb_contthread = NULL;
1063 thread = getthread(ks->linux_regs, ks->threadid);
1064 if (!thread && ks->threadid > 0) {
1065 error_packet(remcom_out_buffer, -EINVAL);
1068 kgdb_contthread = thread;
1070 strcpy(remcom_out_buffer, "OK");
1075 /* Handle the 'T' thread query packets */
1076 static void gdb_cmd_thread(struct kgdb_state *ks)
1078 char *ptr = &remcom_in_buffer[1];
1079 struct task_struct *thread;
1081 kgdb_hex2long(&ptr, &ks->threadid);
1082 thread = getthread(ks->linux_regs, ks->threadid);
1084 strcpy(remcom_out_buffer, "OK");
1086 error_packet(remcom_out_buffer, -EINVAL);
1089 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1090 static void gdb_cmd_break(struct kgdb_state *ks)
1093 * Since GDB-5.3, it's been drafted that '0' is a software
1094 * breakpoint, '1' is a hardware breakpoint, so let's do that.
1096 char *bpt_type = &remcom_in_buffer[1];
1097 char *ptr = &remcom_in_buffer[2];
1099 unsigned long length;
1102 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1104 if (*bpt_type > '4')
1107 if (*bpt_type != '0' && *bpt_type != '1')
1113 * Test if this is a hardware breakpoint, and
1116 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1120 if (*(ptr++) != ',') {
1121 error_packet(remcom_out_buffer, -EINVAL);
1124 if (!kgdb_hex2long(&ptr, &addr)) {
1125 error_packet(remcom_out_buffer, -EINVAL);
1128 if (*(ptr++) != ',' ||
1129 !kgdb_hex2long(&ptr, &length)) {
1130 error_packet(remcom_out_buffer, -EINVAL);
1134 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1135 error = kgdb_set_sw_break(addr);
1136 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1137 error = kgdb_remove_sw_break(addr);
1138 else if (remcom_in_buffer[0] == 'Z')
1139 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1140 (int)length, *bpt_type);
1141 else if (remcom_in_buffer[0] == 'z')
1142 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1143 (int) length, *bpt_type);
1146 strcpy(remcom_out_buffer, "OK");
1148 error_packet(remcom_out_buffer, error);
1151 /* Handle the 'C' signal / exception passing packets */
1152 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1154 /* C09 == pass exception
1155 * C15 == detach kgdb, pass exception
1157 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1159 ks->pass_exception = 1;
1160 remcom_in_buffer[0] = 'c';
1162 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1164 ks->pass_exception = 1;
1165 remcom_in_buffer[0] = 'D';
1171 error_packet(remcom_out_buffer, -EINVAL);
1175 /* Indicate fall through */
1180 * This function performs all gdbserial command procesing
1182 static int gdb_serial_stub(struct kgdb_state *ks)
1187 /* Clear the out buffer. */
1188 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1190 if (kgdb_connected) {
1191 unsigned char thref[8];
1194 /* Reply to host that an exception has occurred */
1195 ptr = remcom_out_buffer;
1197 ptr = pack_hex_byte(ptr, ks->signo);
1198 ptr += strlen(strcpy(ptr, "thread:"));
1199 int_to_threadref(thref, shadow_pid(current->pid));
1200 ptr = pack_threadid(ptr, thref);
1202 put_packet(remcom_out_buffer);
1205 kgdb_usethread = kgdb_info[ks->cpu].task;
1206 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1207 ks->pass_exception = 0;
1212 /* Clear the out buffer. */
1213 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1215 get_packet(remcom_in_buffer);
1217 switch (remcom_in_buffer[0]) {
1218 case '?': /* gdbserial status */
1221 case 'g': /* return the value of the CPU registers */
1222 gdb_cmd_getregs(ks);
1224 case 'G': /* set the value of the CPU registers - return OK */
1225 gdb_cmd_setregs(ks);
1227 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
1228 gdb_cmd_memread(ks);
1230 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1231 gdb_cmd_memwrite(ks);
1233 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1234 gdb_cmd_binwrite(ks);
1236 /* kill or detach. KGDB should treat this like a
1239 case 'D': /* Debugger detach */
1240 case 'k': /* Debugger detach via kill */
1241 gdb_cmd_detachkill(ks);
1242 goto default_handle;
1243 case 'R': /* Reboot */
1244 if (gdb_cmd_reboot(ks))
1245 goto default_handle;
1247 case 'q': /* query command */
1250 case 'H': /* task related */
1253 case 'T': /* Query thread status */
1256 case 'z': /* Break point remove */
1257 case 'Z': /* Break point set */
1260 case 'C': /* Exception passing */
1261 tmp = gdb_cmd_exception_pass(ks);
1263 goto default_handle;
1266 /* Fall through on tmp < 0 */
1267 case 'c': /* Continue packet */
1268 case 's': /* Single step packet */
1269 if (kgdb_contthread && kgdb_contthread != current) {
1270 /* Can't switch threads in kgdb */
1271 error_packet(remcom_out_buffer, -EINVAL);
1274 kgdb_activate_sw_breakpoints();
1275 /* Fall through to default processing */
1278 error = kgdb_arch_handle_exception(ks->ex_vector,
1285 * Leave cmd processing on error, detach,
1286 * kill, continue, or single step.
1288 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1289 remcom_in_buffer[0] == 'k') {
1296 /* reply to the request */
1297 put_packet(remcom_out_buffer);
1301 if (ks->pass_exception)
1306 static int kgdb_reenter_check(struct kgdb_state *ks)
1310 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1313 /* Panic on recursive debugger calls: */
1315 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1316 kgdb_deactivate_sw_breakpoints();
1319 * If the break point removed ok at the place exception
1320 * occurred, try to recover and print a warning to the end
1321 * user because the user planted a breakpoint in a place that
1322 * KGDB needs in order to function.
1324 if (kgdb_remove_sw_break(addr) == 0) {
1325 exception_level = 0;
1326 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1327 kgdb_activate_sw_breakpoints();
1328 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed\n");
1334 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1336 if (exception_level > 1) {
1338 panic("Recursive entry to debugger");
1341 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1343 panic("Recursive entry to debugger");
1349 * kgdb_handle_exception() - main entry point from a kernel exception
1351 * Locking hierarchy:
1352 * interface locks, if any (begin_session)
1353 * kgdb lock (kgdb_active)
1356 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1358 struct kgdb_state kgdb_var;
1359 struct kgdb_state *ks = &kgdb_var;
1360 unsigned long flags;
1364 ks->cpu = raw_smp_processor_id();
1365 ks->ex_vector = evector;
1367 ks->ex_vector = evector;
1368 ks->err_code = ecode;
1369 ks->kgdb_usethreadid = 0;
1370 ks->linux_regs = regs;
1372 if (kgdb_reenter_check(ks))
1373 return 0; /* Ouch, double exception ! */
1377 * Interrupts will be restored by the 'trap return' code, except when
1380 local_irq_save(flags);
1382 cpu = raw_smp_processor_id();
1385 * Acquire the kgdb_active lock:
1387 while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1391 * Do not start the debugger connection on this CPU if the last
1392 * instance of the exception handler wanted to come into the
1393 * debugger on a different CPU via a single step
1395 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1396 atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
1398 atomic_set(&kgdb_active, -1);
1399 local_irq_restore(flags);
1404 if (!kgdb_io_ready(1)) {
1406 goto kgdb_restore; /* No I/O connection, so resume the system */
1410 * Don't enter if we have hit a removed breakpoint.
1412 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1415 /* Call the I/O driver's pre_exception routine */
1416 if (kgdb_io_ops->pre_exception)
1417 kgdb_io_ops->pre_exception();
1419 kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1420 kgdb_info[ks->cpu].task = current;
1422 kgdb_disable_hw_debug(ks->linux_regs);
1425 * Get the passive CPU lock which will hold all the non-primary
1426 * CPU in a spin state while the debugger is active
1428 if (!kgdb_single_step || !kgdb_contthread) {
1429 for (i = 0; i < NR_CPUS; i++)
1430 atomic_set(&passive_cpu_wait[i], 1);
1434 /* Signal the other CPUs to enter kgdb_wait() */
1435 if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup)
1436 kgdb_roundup_cpus(flags);
1440 * spin_lock code is good enough as a barrier so we don't
1443 atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1446 * Wait for the other CPUs to be notified and be waiting for us:
1448 for_each_online_cpu(i) {
1449 while (!atomic_read(&cpu_in_kgdb[i]))
1454 * At this point the primary processor is completely
1455 * in the debugger and all secondary CPUs are quiescent
1457 kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1458 kgdb_deactivate_sw_breakpoints();
1459 kgdb_single_step = 0;
1460 kgdb_contthread = NULL;
1461 exception_level = 0;
1463 /* Talk to debugger with gdbserial protocol */
1464 error = gdb_serial_stub(ks);
1466 /* Call the I/O driver's post_exception routine */
1467 if (kgdb_io_ops->post_exception)
1468 kgdb_io_ops->post_exception();
1470 kgdb_info[ks->cpu].debuggerinfo = NULL;
1471 kgdb_info[ks->cpu].task = NULL;
1472 atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1474 if (!kgdb_single_step || !kgdb_contthread) {
1475 for (i = NR_CPUS-1; i >= 0; i--)
1476 atomic_set(&passive_cpu_wait[i], 0);
1478 * Wait till all the CPUs have quit
1479 * from the debugger.
1481 for_each_online_cpu(i) {
1482 while (atomic_read(&cpu_in_kgdb[i]))
1488 /* Free kgdb_active */
1489 atomic_set(&kgdb_active, -1);
1490 local_irq_restore(flags);
1495 int kgdb_nmicallback(int cpu, void *regs)
1498 if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1499 atomic_read(&kgdb_active) != cpu) {
1500 kgdb_wait((struct pt_regs *)regs);
1507 void kgdb_console_write(struct console *co, const char *s, unsigned count)
1509 unsigned long flags;
1511 /* If we're debugging, or KGDB has not connected, don't try
1513 if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1516 local_irq_save(flags);
1517 kgdb_msg_write(s, count);
1518 local_irq_restore(flags);
1521 static struct console kgdbcons = {
1523 .write = kgdb_console_write,
1524 .flags = CON_PRINTBUFFER | CON_ENABLED,
1528 #ifdef CONFIG_MAGIC_SYSRQ
1529 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1532 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1535 if (!kgdb_connected)
1536 printk(KERN_CRIT "Entering KGDB\n");
1541 static struct sysrq_key_op sysrq_gdb_op = {
1542 .handler = sysrq_handle_gdb,
1544 .action_msg = "GDB",
1548 static void kgdb_register_callbacks(void)
1550 if (!kgdb_io_module_registered) {
1551 kgdb_io_module_registered = 1;
1553 #ifdef CONFIG_MAGIC_SYSRQ
1554 register_sysrq_key('g', &sysrq_gdb_op);
1556 if (kgdb_use_con && !kgdb_con_registered) {
1557 register_console(&kgdbcons);
1558 kgdb_con_registered = 1;
1563 static void kgdb_unregister_callbacks(void)
1566 * When this routine is called KGDB should unregister from the
1567 * panic handler and clean up, making sure it is not handling any
1568 * break exceptions at the time.
1570 if (kgdb_io_module_registered) {
1571 kgdb_io_module_registered = 0;
1573 #ifdef CONFIG_MAGIC_SYSRQ
1574 unregister_sysrq_key('g', &sysrq_gdb_op);
1576 if (kgdb_con_registered) {
1577 unregister_console(&kgdbcons);
1578 kgdb_con_registered = 0;
1583 static void kgdb_initial_breakpoint(void)
1585 kgdb_break_asap = 0;
1587 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1592 * kkgdb_register_io_module - register KGDB IO module
1593 * @new_kgdb_io_ops: the io ops vector
1595 * Register it with the KGDB core.
1597 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1601 spin_lock(&kgdb_registration_lock);
1604 spin_unlock(&kgdb_registration_lock);
1606 printk(KERN_ERR "kgdb: Another I/O driver is already "
1607 "registered with KGDB.\n");
1611 if (new_kgdb_io_ops->init) {
1612 err = new_kgdb_io_ops->init();
1614 spin_unlock(&kgdb_registration_lock);
1619 kgdb_io_ops = new_kgdb_io_ops;
1621 spin_unlock(&kgdb_registration_lock);
1623 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1624 new_kgdb_io_ops->name);
1627 kgdb_register_callbacks();
1629 if (kgdb_break_asap)
1630 kgdb_initial_breakpoint();
1634 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1637 * kkgdb_unregister_io_module - unregister KGDB IO module
1638 * @old_kgdb_io_ops: the io ops vector
1640 * Unregister it with the KGDB core.
1642 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1644 BUG_ON(kgdb_connected);
1647 * KGDB is no longer able to communicate out, so
1648 * unregister our callbacks and reset state.
1650 kgdb_unregister_callbacks();
1652 spin_lock(&kgdb_registration_lock);
1654 WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1657 spin_unlock(&kgdb_registration_lock);
1660 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1661 old_kgdb_io_ops->name);
1663 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1666 * kgdb_breakpoint - generate breakpoint exception
1668 * This function will generate a breakpoint exception. It is used at the
1669 * beginning of a program to sync up with a debugger and can be used
1670 * otherwise as a quick means to stop program execution and "break" into
1673 void kgdb_breakpoint(void)
1675 atomic_set(&kgdb_setting_breakpoint, 1);
1676 wmb(); /* Sync point before breakpoint */
1677 arch_kgdb_breakpoint();
1678 wmb(); /* Sync point after breakpoint */
1679 atomic_set(&kgdb_setting_breakpoint, 0);
1681 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1683 static int __init opt_kgdb_wait(char *str)
1685 kgdb_break_asap = 1;
1687 if (kgdb_io_module_registered)
1688 kgdb_initial_breakpoint();
1693 early_param("kgdbwait", opt_kgdb_wait);