Linux-2.6.33.2/kernel/kgdb.c
/*
* KGDB stub.
*
* Maintainer: Jason Wessel <jason.wessel@windriver.com>
*
* Copyright (C) 2000-2001 VERITAS Software Corporation.
* Copyright (C) 2002-2004 Timesys Corporation
* Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
* Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
* Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
* Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
* Copyright (C) 2005-2008 Wind River Systems, Inc.
* Copyright (C) 2007 MontaVista Software, Inc.
* Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*
* Contributors at various stages not listed above:
* Jason Wessel ( jason.wessel@windriver.com )
* George Anzinger <george@mvista.com>
* Anurekh Saxena (anurekh.saxena@timesys.com)
* Lake Stevens Instrument Division (Glenn Engel)
* Jim Kingdon, Cygnus Support.
*
* Original KGDB stub: David Grothe <dave@gcom.com>,
* Tigran Aivazian <tigran@sco.com>
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program is licensed "as is" without any warranty of any
* kind, whether express or implied.
*/
#include <linux/pid_namespace.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/console.h>
#include <linux/threads.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/sysrq.h>
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/pid.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <asm/cacheflush.h>
#include <asm/byteorder.h>
#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/unaligned.h>
static int kgdb_break_asap;
#define KGDB_MAX_THREAD_QUERY 17
struct kgdb_state {
int ex_vector;
int signo;
int err_code;
int cpu;
int pass_exception;
unsigned long thr_query;
unsigned long threadid;
long kgdb_usethreadid;
struct pt_regs *linux_regs;
};
static struct debuggerinfo_struct {
void *debuggerinfo;
struct task_struct *task;
} kgdb_info[NR_CPUS];
/**
* kgdb_connected - Is a host GDB connected to us?
*/
int kgdb_connected;
EXPORT_SYMBOL_GPL(kgdb_connected);
/* All the KGDB handlers are installed */
static int kgdb_io_module_registered;
/* Guard for recursive entry */
static int exception_level;
static struct kgdb_io *kgdb_io_ops;
static DEFINE_SPINLOCK(kgdb_registration_lock);
/* kgdb console driver is loaded */
static int kgdb_con_registered;
/* determine if kgdb console output should be used */
static int kgdb_use_con;
static int __init opt_kgdb_con(char *str)
{
kgdb_use_con = 1;
return 0;
}
early_param("kgdbcon", opt_kgdb_con);
module_param(kgdb_use_con, int, 0644);
/*
* Holds information about breakpoints in a kernel. These breakpoints are
* added and removed by gdb.
*/
static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
[0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
};
/*
* The CPU# of the active CPU, or -1 if none:
*/
atomic_t kgdb_active = ATOMIC_INIT(-1);
/*
* We use NR_CPUs not PERCPU, in case kgdb is used to debug early
* bootup code (which might not have percpu set up yet):
*/
static atomic_t passive_cpu_wait[NR_CPUS];
static atomic_t cpu_in_kgdb[NR_CPUS];
atomic_t kgdb_setting_breakpoint;
struct task_struct *kgdb_usethread;
struct task_struct *kgdb_contthread;
int kgdb_single_step;
pid_t kgdb_sstep_pid;
/* Our I/O buffers. */
static char remcom_in_buffer[BUFMAX];
static char remcom_out_buffer[BUFMAX];
/* Storage for the registers, in GDB format. */
static unsigned long gdb_regs[(NUMREGBYTES +
sizeof(unsigned long) - 1) /
sizeof(unsigned long)];
/* to keep track of the CPU which is doing the single stepping*/
atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
/*
* If you are debugging a problem where roundup (the collection of
* all other CPUs) is a problem [this should be extremely rare],
* then use the nokgdbroundup option to avoid roundup. In that case
* the other CPUs might interfere with your debugging context, so
* use this with care:
*/
static int kgdb_do_roundup = 1;
static int __init opt_nokgdbroundup(char *str)
{
kgdb_do_roundup = 0;
return 0;
}
early_param("nokgdbroundup", opt_nokgdbroundup);
/*
* Finally, some KGDB code :-)
*/
/*
* Weak aliases for breakpoint management,
* can be overriden by architectures when needed:
*/
int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
{
int err;
err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
if (err)
return err;
return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
BREAK_INSTR_SIZE);
}
int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
{
return probe_kernel_write((char *)addr,
(char *)bundle, BREAK_INSTR_SIZE);
}
int __weak kgdb_validate_break_address(unsigned long addr)
{
char tmp_variable[BREAK_INSTR_SIZE];
int err;
/* Validate setting the breakpoint and then removing it. In the
* remove fails, the kernel needs to emit a bad message because we
* are deep trouble not being able to put things back the way we
* found them.
*/
err = kgdb_arch_set_breakpoint(addr, tmp_variable);
if (err)
return err;
err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
if (err)
printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
"memory destroyed at: %lx", addr);
return err;
}
unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
{
return instruction_pointer(regs);
}
int __weak kgdb_arch_init(void)
{
return 0;
}
int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
{
return 0;
}
void __weak
kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
{
return;
}
/**
* kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
* @regs: Current &struct pt_regs.
*
* This function will be called if the particular architecture must
* disable hardware debugging while it is processing gdb packets or
* handling exception.
*/
void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
{
}
/*
* GDB remote protocol parser:
*/
static int hex(char ch)
{
if ((ch >= 'a') && (ch <= 'f'))
return ch - 'a' + 10;
if ((ch >= '0') && (ch <= '9'))
return ch - '0';
if ((ch >= 'A') && (ch <= 'F'))
return ch - 'A' + 10;
return -1;
}
/* scan for the sequence $<data>#<checksum> */
static void get_packet(char *buffer)
{
unsigned char checksum;
unsigned char xmitcsum;
int count;
char ch;
do {
/*
* Spin and wait around for the start character, ignore all
* other characters:
*/
while ((ch = (kgdb_io_ops->read_char())) != '$')
/* nothing */;
kgdb_connected = 1;
checksum = 0;
xmitcsum = -1;
count = 0;
/*
* now, read until a # or end of buffer is found:
*/
while (count < (BUFMAX - 1)) {
ch = kgdb_io_ops->read_char();
if (ch == '#')
break;
checksum = checksum + ch;
buffer[count] = ch;
count = count + 1;
}
buffer[count] = 0;
if (ch == '#') {
xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
xmitcsum += hex(kgdb_io_ops->read_char());
if (checksum != xmitcsum)
/* failed checksum */
kgdb_io_ops->write_char('-');
else
/* successful transfer */
kgdb_io_ops->write_char('+');
if (kgdb_io_ops->flush)
kgdb_io_ops->flush();
}
} while (checksum != xmitcsum);
}
/*
* Send the packet in buffer.
* Check for gdb connection if asked for.
*/
static void put_packet(char *buffer)
{
unsigned char checksum;
int count;
char ch;
/*
* $<packet info>#<checksum>.
*/
while (1) {
kgdb_io_ops->write_char('$');
checksum = 0;
count = 0;
while ((ch = buffer[count])) {
kgdb_io_ops->write_char(ch);
checksum += ch;
count++;
}
kgdb_io_ops->write_char('#');
kgdb_io_ops->write_char(hex_asc_hi(checksum));
kgdb_io_ops->write_char(hex_asc_lo(checksum));
if (kgdb_io_ops->flush)
kgdb_io_ops->flush();
/* Now see what we get in reply. */
ch = kgdb_io_ops->read_char();
if (ch == 3)
ch = kgdb_io_ops->read_char();
/* If we get an ACK, we are done. */
if (ch == '+')
return;
/*
* If we get the start of another packet, this means
* that GDB is attempting to reconnect. We will NAK
* the packet being sent, and stop trying to send this
* packet.
*/
if (ch == '$') {
kgdb_io_ops->write_char('-');
if (kgdb_io_ops->flush)
kgdb_io_ops->flush();
return;
}
}
}
/*
* Convert the memory pointed to by mem into hex, placing result in buf.
* Return a pointer to the last char put in buf (null). May return an error.
*/
int kgdb_mem2hex(char *mem, char *buf, int count)
{
char *tmp;
int err;
/*
* We use the upper half of buf as an intermediate buffer for the
* raw memory copy. Hex conversion will work against this one.
*/
tmp = buf + count;
err = probe_kernel_read(tmp, mem, count);
if (!err) {
while (count > 0) {
buf = pack_hex_byte(buf, *tmp);
tmp++;
count--;
}
*buf = 0;
}
return err;
}
/*
* Copy the binary array pointed to by buf into mem. Fix $, #, and
* 0x7d escaped with 0x7d. Return a pointer to the character after
* the last byte written.
*/
static int kgdb_ebin2mem(char *buf, char *mem, int count)
{
int err = 0;
char c;
while (count-- > 0) {
c = *buf++;
if (c == 0x7d)
c = *buf++ ^ 0x20;
err = probe_kernel_write(mem, &c, 1);
if (err)
break;
mem++;
}
return err;
}
/*
* Convert the hex array pointed to by buf into binary to be placed in mem.
* Return a pointer to the character AFTER the last byte written.
* May return an error.
*/
int kgdb_hex2mem(char *buf, char *mem, int count)
{
char *tmp_raw;
char *tmp_hex;
/*
* We use the upper half of buf as an intermediate buffer for the
* raw memory that is converted from hex.
*/
tmp_raw = buf + count * 2;
tmp_hex = tmp_raw - 1;
while (tmp_hex >= buf) {
tmp_raw--;
*tmp_raw = hex(*tmp_hex--);
*tmp_raw |= hex(*tmp_hex--) << 4;
}
return probe_kernel_write(mem, tmp_raw, count);
}
/*
* While we find nice hex chars, build a long_val.
* Return number of chars processed.
*/
int kgdb_hex2long(char **ptr, unsigned long *long_val)
{
int hex_val;
int num = 0;
int negate = 0;
*long_val = 0;
if (**ptr == '-') {
negate = 1;
(*ptr)++;
}
while (**ptr) {
hex_val = hex(**ptr);
if (hex_val < 0)
break;
*long_val = (*long_val << 4) | hex_val;
num++;
(*ptr)++;
}
if (negate)
*long_val = -*long_val;
return num;
}
/* Write memory due to an 'M' or 'X' packet. */
static int write_mem_msg(int binary)
{
char *ptr = &remcom_in_buffer[1];
unsigned long addr;
unsigned long length;
int err;
if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
if (binary)
err = kgdb_ebin2mem(ptr, (char *)addr, length);
else
err = kgdb_hex2mem(ptr, (char *)addr, length);
if (err)
return err;
if (CACHE_FLUSH_IS_SAFE)
flush_icache_range(addr, addr + length);
return 0;
}
return -EINVAL;
}
static void error_packet(char *pkt, int error)
{
error = -error;
pkt[0] = 'E';
pkt[1] = hex_asc[(error / 10)];
pkt[2] = hex_asc[(error % 10)];
pkt[3] = '\0';
}
/*
* Thread ID accessors. We represent a flat TID space to GDB, where
* the per CPU idle threads (which under Linux all have PID 0) are
* remapped to negative TIDs.
*/
#define BUF_THREAD_ID_SIZE 16
static char *pack_threadid(char *pkt, unsigned char *id)
{
char *limit;
limit = pkt + BUF_THREAD_ID_SIZE;
while (pkt < limit)
pkt = pack_hex_byte(pkt, *id++);
return pkt;
}
static void int_to_threadref(unsigned char *id, int value)
{
unsigned char *scan;
int i = 4;
scan = (unsigned char *)id;
while (i--)
*scan++ = 0;
put_unaligned_be32(value, scan);
}
static struct task_struct *getthread(struct pt_regs *regs, int tid)
{
/*
* Non-positive TIDs are remapped to the cpu shadow information
*/
if (tid == 0 || tid == -1)
tid = -atomic_read(&kgdb_active) - 2;
if (tid < -1 && tid > -NR_CPUS - 2) {
if (kgdb_info[-tid - 2].task)
return kgdb_info[-tid - 2].task;
else
return idle_task(-tid - 2);
}
if (tid <= 0) {
printk(KERN_ERR "KGDB: Internal thread select error\n");
dump_stack();
return NULL;
}
/*
* find_task_by_pid_ns() does not take the tasklist lock anymore
* but is nicely RCU locked - hence is a pretty resilient
* thing to use:
*/
return find_task_by_pid_ns(tid, &init_pid_ns);
}
/*
* CPU debug state control:
*/
#ifdef CONFIG_SMP
static void kgdb_wait(struct pt_regs *regs)
{
unsigned long flags;
int cpu;
local_irq_save(flags);
cpu = raw_smp_processor_id();
kgdb_info[cpu].debuggerinfo = regs;
kgdb_info[cpu].task = current;
/*
* Make sure the above info reaches the primary CPU before
* our cpu_in_kgdb[] flag setting does:
*/
smp_wmb();
atomic_set(&cpu_in_kgdb[cpu], 1);
/* Disable any cpu specific hw breakpoints */
kgdb_disable_hw_debug(regs);
/* Wait till primary CPU is done with debugging */
while (atomic_read(&passive_cpu_wait[cpu]))
cpu_relax();
kgdb_info[cpu].debuggerinfo = NULL;
kgdb_info[cpu].task = NULL;
/* fix up hardware debug registers on local cpu */
if (arch_kgdb_ops.correct_hw_break)
arch_kgdb_ops.correct_hw_break();
/* Signal the primary CPU that we are done: */
atomic_set(&cpu_in_kgdb[cpu], 0);
touch_softlockup_watchdog_sync();
clocksource_touch_watchdog();
local_irq_restore(flags);
}
#endif
/*
* Some architectures need cache flushes when we set/clear a
* breakpoint:
*/
static void kgdb_flush_swbreak_addr(unsigned long addr)
{
if (!CACHE_FLUSH_IS_SAFE)
return;
if (current->mm && current->mm->mmap_cache) {
flush_cache_range(current->mm->mmap_cache,
addr, addr + BREAK_INSTR_SIZE);
}
/* Force flush instruction cache if it was outside the mm */
flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
}
/*
* SW breakpoint management:
*/
static int kgdb_activate_sw_breakpoints(void)
{
unsigned long addr;
int error;
int ret = 0;
int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if (kgdb_break[i].state != BP_SET)
continue;
addr = kgdb_break[i].bpt_addr;
error = kgdb_arch_set_breakpoint(addr,
kgdb_break[i].saved_instr);
if (error) {
ret = error;
printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
continue;
}
kgdb_flush_swbreak_addr(addr);
kgdb_break[i].state = BP_ACTIVE;
}
return ret;
}
static int kgdb_set_sw_break(unsigned long addr)
{
int err = kgdb_validate_break_address(addr);
int breakno = -1;
int i;
if (err)
return err;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if ((kgdb_break[i].state == BP_SET) &&
(kgdb_break[i].bpt_addr == addr))
return -EEXIST;
}
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if (kgdb_break[i].state == BP_REMOVED &&
kgdb_break[i].bpt_addr == addr) {
breakno = i;
break;
}
}
if (breakno == -1) {
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if (kgdb_break[i].state == BP_UNDEFINED) {
breakno = i;
break;
}
}
}
if (breakno == -1)
return -E2BIG;
kgdb_break[breakno].state = BP_SET;
kgdb_break[breakno].type = BP_BREAKPOINT;
kgdb_break[breakno].bpt_addr = addr;
return 0;
}
static int kgdb_deactivate_sw_breakpoints(void)
{
unsigned long addr;
int error;
int ret = 0;
int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if (kgdb_break[i].state != BP_ACTIVE)
continue;
addr = kgdb_break[i].bpt_addr;
error = kgdb_arch_remove_breakpoint(addr,
kgdb_break[i].saved_instr);
if (error) {
printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
ret = error;
}
kgdb_flush_swbreak_addr(addr);
kgdb_break[i].state = BP_SET;
}
return ret;
}
static int kgdb_remove_sw_break(unsigned long addr)
{
int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if ((kgdb_break[i].state == BP_SET) &&
(kgdb_break[i].bpt_addr == addr)) {
kgdb_break[i].state = BP_REMOVED;
return 0;
}
}
return -ENOENT;
}
int kgdb_isremovedbreak(unsigned long addr)
{
int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if ((kgdb_break[i].state == BP_REMOVED) &&
(kgdb_break[i].bpt_addr == addr))
return 1;
}
return 0;
}
static int remove_all_break(void)
{
unsigned long addr;
int error;
int i;
/* Clear memory breakpoints. */
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
if (kgdb_break[i].state != BP_ACTIVE)
goto setundefined;
addr = kgdb_break[i].bpt_addr;
error = kgdb_arch_remove_breakpoint(addr,
kgdb_break[i].saved_instr);
if (error)
printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
addr);
setundefined:
kgdb_break[i].state = BP_UNDEFINED;
}
/* Clear hardware breakpoints. */
if (arch_kgdb_ops.remove_all_hw_break)
arch_kgdb_ops.remove_all_hw_break();
return 0;
}
/*
* Remap normal tasks to their real PID,
* CPU shadow threads are mapped to -CPU - 2
*/
static inline int shadow_pid(int realpid)
{
if (realpid)
return realpid;
return -raw_smp_processor_id() - 2;
}
static char gdbmsgbuf[BUFMAX + 1];
static void kgdb_msg_write(const char *s, int len)
{
char *bufptr;
int wcount;
int i;
/* 'O'utput */
gdbmsgbuf[0] = 'O';
/* Fill and send buffers... */
while (len > 0) {
bufptr = gdbmsgbuf + 1;
/* Calculate how many this time */
if ((len << 1) > (BUFMAX - 2))
wcount = (BUFMAX - 2) >> 1;
else
wcount = len;
/* Pack in hex chars */
for (i = 0; i < wcount; i++)
bufptr = pack_hex_byte(bufptr, s[i]);
*bufptr = '\0';
/* Move up */
s += wcount;
len -= wcount;
/* Write packet */
put_packet(gdbmsgbuf);
}
}
/*
* Return true if there is a valid kgdb I/O module. Also if no
* debugger is attached a message can be printed to the console about
* waiting for the debugger to attach.
*
* The print_wait argument is only to be true when called from inside
* the core kgdb_handle_exception, because it will wait for the
* debugger to attach.
*/
static int kgdb_io_ready(int print_wait)
{
if (!kgdb_io_ops)
return 0;
if (kgdb_connected)
return 1;
if (atomic_read(&kgdb_setting_breakpoint))
return 1;
if (print_wait)
printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
return 1;
}
/*
* All the functions that start with gdb_cmd are the various
* operations to implement the handlers for the gdbserial protocol
* where KGDB is communicating with an external debugger
*/
/* Handle the '?' status packets */
static void gdb_cmd_status(struct kgdb_state *ks)
{
/*
* We know that this packet is only sent
* during initial connect. So to be safe,
* we clear out our breakpoints now in case
* GDB is reconnecting.
*/
remove_all_break();
remcom_out_buffer[0] = 'S';
pack_hex_byte(&remcom_out_buffer[1], ks->signo);
}
/* Handle the 'g' get registers request */
static void gdb_cmd_getregs(struct kgdb_state *ks)
{
struct task_struct *thread;
void *local_debuggerinfo;
int i;
thread = kgdb_usethread;
if (!thread) {
thread = kgdb_info[ks->cpu].task;
local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
} else {
local_debuggerinfo = NULL;
for_each_online_cpu(i) {
/*
* Try to find the task on some other
* or possibly this node if we do not
* find the matching task then we try
* to approximate the results.
*/
if (thread == kgdb_info[i].task)
local_debuggerinfo = kgdb_info[i].debuggerinfo;
}
}
/*
* All threads that don't have debuggerinfo should be
* in schedule() sleeping, since all other CPUs
* are in kgdb_wait, and thus have debuggerinfo.
*/
if (local_debuggerinfo) {
pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
} else {
/*
* Pull stuff saved during switch_to; nothing
* else is accessible (or even particularly
* relevant).
*
* This should be enough for a stack trace.
*/
sleeping_thread_to_gdb_regs(gdb_regs, thread);
}
kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
}
/* Handle the 'G' set registers request */
static void gdb_cmd_setregs(struct kgdb_state *ks)
{
kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
if (kgdb_usethread && kgdb_usethread != current) {
error_packet(remcom_out_buffer, -EINVAL);
} else {
gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
strcpy(remcom_out_buffer, "OK");
}
}
/* Handle the 'm' memory read bytes */
static void gdb_cmd_memread(struct kgdb_state *ks)
{
char *ptr = &remcom_in_buffer[1];
unsigned long length;
unsigned long addr;
int err;
if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
kgdb_hex2long(&ptr, &length) > 0) {
err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
if (err)
error_packet(remcom_out_buffer, err);
} else {
error_packet(remcom_out_buffer, -EINVAL);
}
}
/* Handle the 'M' memory write bytes */
static void gdb_cmd_memwrite(struct kgdb_state *ks)
{
int err = write_mem_msg(0);
if (err)
error_packet(remcom_out_buffer, err);
else
strcpy(remcom_out_buffer, "OK");
}
/* Handle the 'X' memory binary write bytes */
static void gdb_cmd_binwrite(struct kgdb_state *ks)
{
int err = write_mem_msg(1);
if (err)
error_packet(remcom_out_buffer, err);
else
strcpy(remcom_out_buffer, "OK");
}
/* Handle the 'D' or 'k', detach or kill packets */
static void gdb_cmd_detachkill(struct kgdb_state *ks)
{
int error;
/* The detach case */
if (remcom_in_buffer[0] == 'D') {
error = remove_all_break();
if (error < 0) {
error_packet(remcom_out_buffer, error);
} else {
strcpy(remcom_out_buffer, "OK");
kgdb_connected = 0;
}
put_packet(remcom_out_buffer);
} else {
/*
* Assume the kill case, with no exit code checking,
* trying to force detach the debugger:
*/
remove_all_break();
kgdb_connected = 0;
}
}
/* Handle the 'R' reboot packets */
static int gdb_cmd_reboot(struct kgdb_state *ks)
{
/* For now, only honor R0 */
if (strcmp(remcom_in_buffer, "R0") == 0) {
printk(KERN_CRIT "Executing emergency reboot\n");
strcpy(remcom_out_buffer, "OK");
put_packet(remcom_out_buffer);
/*
* Execution should not return from
* machine_emergency_restart()
*/
machine_emergency_restart();
kgdb_connected = 0;
return 1;
}
return 0;
}
/* Handle the 'q' query packets */
static void gdb_cmd_query(struct kgdb_state *ks)
{
struct task_struct *g;
struct task_struct *p;
unsigned char thref[8];
char *ptr;
int i;
int cpu;
int finished = 0;
switch (remcom_in_buffer[1]) {
case 's':
case 'f':
if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
error_packet(remcom_out_buffer, -EINVAL);
break;
}
i = 0;
remcom_out_buffer[0] = 'm';
ptr = remcom_out_buffer + 1;
if (remcom_in_buffer[1] == 'f') {
/* Each cpu is a shadow thread */
for_each_online_cpu(cpu) {
ks->thr_query = 0;
int_to_threadref(thref, -cpu - 2);
pack_threadid(ptr, thref);
ptr += BUF_THREAD_ID_SIZE;
*(ptr++) = ',';
i++;
}
}
do_each_thread(g, p) {
if (i >= ks->thr_query && !finished) {
int_to_threadref(thref, p->pid);
pack_threadid(ptr, thref);
ptr += BUF_THREAD_ID_SIZE;
*(ptr++) = ',';
ks->thr_query++;
if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
finished = 1;
}
i++;
} while_each_thread(g, p);
*(--ptr) = '\0';
break;
case 'C':
/* Current thread id */
strcpy(remcom_out_buffer, "QC");
ks->threadid = shadow_pid(current->pid);
int_to_threadref(thref, ks->threadid);
pack_threadid(remcom_out_buffer + 2, thref);
break;
case 'T':
if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
error_packet(remcom_out_buffer, -EINVAL);
break;
}
ks->threadid = 0;
ptr = remcom_in_buffer + 17;
kgdb_hex2long(&ptr, &ks->threadid);
if (!getthread(ks->linux_regs, ks->threadid)) {
error_packet(remcom_out_buffer, -EINVAL);
break;
}
if ((int)ks->threadid > 0) {
kgdb_mem2hex(getthread(ks->linux_regs,
ks->threadid)->comm,
remcom_out_buffer, 16);
} else {
static char tmpstr[23 + BUF_THREAD_ID_SIZE];
sprintf(tmpstr, "shadowCPU%d",
(int)(-ks->threadid - 2));
kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
}
break;
}
}
/* Handle the 'H' task query packets */
static void gdb_cmd_task(struct kgdb_state *ks)
{
struct task_struct *thread;
char *ptr;
switch (remcom_in_buffer[1]) {
case 'g':
ptr = &remcom_in_buffer[2];
kgdb_hex2long(&ptr, &ks->threadid);
thread = getthread(ks->linux_regs, ks->threadid);
if (!thread && ks->threadid > 0) {
error_packet(remcom_out_buffer, -EINVAL);
break;
}
kgdb_usethread = thread;
ks->kgdb_usethreadid = ks->threadid;
strcpy(remcom_out_buffer, "OK");
break;
case 'c':
ptr = &remcom_in_buffer[2];
kgdb_hex2long(&ptr, &ks->threadid);
if (!ks->threadid) {
kgdb_contthread = NULL;
} else {
thread = getthread(ks->linux_regs, ks->threadid);
if (!thread && ks->threadid > 0) {
error_packet(remcom_out_buffer, -EINVAL);
break;
}
kgdb_contthread = thread;
}
strcpy(remcom_out_buffer, "OK");
break;
}
}
/* Handle the 'T' thread query packets */
static void gdb_cmd_thread(struct kgdb_state *ks)
{
char *ptr = &remcom_in_buffer[1];
struct task_struct *thread;
kgdb_hex2long(&ptr, &ks->threadid);
thread = getthread(ks->linux_regs, ks->threadid);
if (thread)
strcpy(remcom_out_buffer, "OK");
else
error_packet(remcom_out_buffer, -EINVAL);
}
/* Handle the 'z' or 'Z' breakpoint remove or set packets */
static void gdb_cmd_break(struct kgdb_state *ks)
{
/*
* Since GDB-5.3, it's been drafted that '0' is a software
* breakpoint, '1' is a hardware breakpoint, so let's do that.
*/
char *bpt_type = &remcom_in_buffer[1];
char *ptr = &remcom_in_buffer[2];
unsigned long addr;
unsigned long length;
int error = 0;
if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
/* Unsupported */
if (*bpt_type > '4')
return;
} else {
if (*bpt_type != '0' && *bpt_type != '1')
/* Unsupported. */
return;
}
/*
* Test if this is a hardware breakpoint, and
* if we support it:
*/
if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
/* Unsupported. */
return;
if (*(ptr++) != ',') {
error_packet(remcom_out_buffer, -EINVAL);
return;
}
if (!kgdb_hex2long(&ptr, &addr)) {
error_packet(remcom_out_buffer, -EINVAL);
return;
}
if (*(ptr++) != ',' ||
!kgdb_hex2long(&ptr, &length)) {
error_packet(remcom_out_buffer, -EINVAL);
return;
}
if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
error = kgdb_set_sw_break(addr);
else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
error = kgdb_remove_sw_break(addr);
else if (remcom_in_buffer[0] == 'Z')
error = arch_kgdb_ops.set_hw_breakpoint(addr,
(int)length, *bpt_type - '0');
else if (remcom_in_buffer[0] == 'z')
error = arch_kgdb_ops.remove_hw_breakpoint(addr,
(int) length, *bpt_type - '0');
if (error == 0)
strcpy(remcom_out_buffer, "OK");
else
error_packet(remcom_out_buffer, error);
}
/* Handle the 'C' signal / exception passing packets */
static int gdb_cmd_exception_pass(struct kgdb_state *ks)
{
/* C09 == pass exception
* C15 == detach kgdb, pass exception
*/
if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
ks->pass_exception = 1;
remcom_in_buffer[0] = 'c';
} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
ks->pass_exception = 1;
remcom_in_buffer[0] = 'D';
remove_all_break();
kgdb_connected = 0;
return 1;
} else {
kgdb_msg_write("KGDB only knows signal 9 (pass)"
" and 15 (pass and disconnect)\n"
"Executing a continue without signal passing\n", 0);
remcom_in_buffer[0] = 'c';
}
/* Indicate fall through */
return -1;
}
/*
* This function performs all gdbserial command procesing
*/
static int gdb_serial_stub(struct kgdb_state *ks)
{
int error = 0;
int tmp;
/* Clear the out buffer. */
memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
if (kgdb_connected) {
unsigned char thref[8];
char *ptr;
/* Reply to host that an exception has occurred */
ptr = remcom_out_buffer;
*ptr++ = 'T';
ptr = pack_hex_byte(ptr, ks->signo);
ptr += strlen(strcpy(ptr, "thread:"));
int_to_threadref(thref, shadow_pid(current->pid));
ptr = pack_threadid(ptr, thref);
*ptr++ = ';';
put_packet(remcom_out_buffer);
}
kgdb_usethread = kgdb_info[ks->cpu].task;
ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
ks->pass_exception = 0;
while (1) {
error = 0;
/* Clear the out buffer. */
memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
get_packet(remcom_in_buffer);
switch (remcom_in_buffer[0]) {
case '?': /* gdbserial status */
gdb_cmd_status(ks);
break;
case 'g': /* return the value of the CPU registers */
gdb_cmd_getregs(ks);
break;
case 'G': /* set the value of the CPU registers - return OK */
gdb_cmd_setregs(ks);
break;
case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
gdb_cmd_memread(ks);
break;
case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
gdb_cmd_memwrite(ks);
break;
case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
gdb_cmd_binwrite(ks);
break;
/* kill or detach. KGDB should treat this like a
* continue.
*/
case 'D': /* Debugger detach */
case 'k': /* Debugger detach via kill */
gdb_cmd_detachkill(ks);
goto default_handle;
case 'R': /* Reboot */
if (gdb_cmd_reboot(ks))
goto default_handle;
break;
case 'q': /* query command */
gdb_cmd_query(ks);
break;
case 'H': /* task related */
gdb_cmd_task(ks);
break;
case 'T': /* Query thread status */
gdb_cmd_thread(ks);
break;
case 'z': /* Break point remove */
case 'Z': /* Break point set */
gdb_cmd_break(ks);
break;
case 'C': /* Exception passing */
tmp = gdb_cmd_exception_pass(ks);
if (tmp > 0)
goto default_handle;
if (tmp == 0)
break;
/* Fall through on tmp < 0 */
case 'c': /* Continue packet */
case 's': /* Single step packet */
if (kgdb_contthread && kgdb_contthread != current) {
/* Can't switch threads in kgdb */
error_packet(remcom_out_buffer, -EINVAL);
break;
}
kgdb_activate_sw_breakpoints();
/* Fall through to default processing */
default:
default_handle:
error = kgdb_arch_handle_exception(ks->ex_vector,
ks->signo,
ks->err_code,
remcom_in_buffer,
remcom_out_buffer,
ks->linux_regs);
/*
* Leave cmd processing on error, detach,
* kill, continue, or single step.
*/
if (error >= 0 || remcom_in_buffer[0] == 'D' ||
remcom_in_buffer[0] == 'k') {
error = 0;
goto kgdb_exit;
}
}
/* reply to the request */
put_packet(remcom_out_buffer);
}
kgdb_exit:
if (ks->pass_exception)
error = 1;
return error;
}
static int kgdb_reenter_check(struct kgdb_state *ks)
{
unsigned long addr;
if (atomic_read(&kgdb_active) != raw_smp_processor_id())
return 0;
/* Panic on recursive debugger calls: */
exception_level++;
addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
kgdb_deactivate_sw_breakpoints();
/*
* If the break point removed ok at the place exception
* occurred, try to recover and print a warning to the end
* user because the user planted a breakpoint in a place that
* KGDB needs in order to function.
*/
if (kgdb_remove_sw_break(addr) == 0) {
exception_level = 0;
kgdb_skipexception(ks->ex_vector, ks->linux_regs);
kgdb_activate_sw_breakpoints();
printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
addr);
WARN_ON_ONCE(1);
return 1;
}
remove_all_break();
kgdb_skipexception(ks->ex_vector, ks->linux_regs);
if (exception_level > 1) {
dump_stack();
panic("Recursive entry to debugger");
}
printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
dump_stack();
panic("Recursive entry to debugger");
return 1;
}
/*
* kgdb_handle_exception() - main entry point from a kernel exception
*
* Locking hierarchy:
* interface locks, if any (begin_session)
* kgdb lock (kgdb_active)
*/
int
kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
{
struct kgdb_state kgdb_var;
struct kgdb_state *ks = &kgdb_var;
unsigned long flags;
int sstep_tries = 100;
int error = 0;
int i, cpu;
ks->cpu = raw_smp_processor_id();
ks->ex_vector = evector;
ks->signo = signo;
ks->ex_vector = evector;
ks->err_code = ecode;
ks->kgdb_usethreadid = 0;
ks->linux_regs = regs;
if (kgdb_reenter_check(ks))
return 0; /* Ouch, double exception ! */
acquirelock:
/*
* Interrupts will be restored by the 'trap return' code, except when
* single stepping.
*/
local_irq_save(flags);
cpu = raw_smp_processor_id();
/*
* Acquire the kgdb_active lock:
*/
while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
cpu_relax();
/*
* For single stepping, try to only enter on the processor
* that was single stepping. To gaurd against a deadlock, the
* kernel will only try for the value of sstep_tries before
* giving up and continuing on.
*/
if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
(kgdb_info[cpu].task &&
kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
atomic_set(&kgdb_active, -1);
touch_softlockup_watchdog_sync();
clocksource_touch_watchdog();
local_irq_restore(flags);
goto acquirelock;
}
if (!kgdb_io_ready(1)) {
error = 1;
goto kgdb_restore; /* No I/O connection, so resume the system */
}
/*
* Don't enter if we have hit a removed breakpoint.
*/
if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
goto kgdb_restore;
/* Call the I/O driver's pre_exception routine */
if (kgdb_io_ops->pre_exception)
kgdb_io_ops->pre_exception();
kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
kgdb_info[ks->cpu].task = current;
kgdb_disable_hw_debug(ks->linux_regs);
/*
* Get the passive CPU lock which will hold all the non-primary
* CPU in a spin state while the debugger is active
*/
if (!kgdb_single_step) {
for (i = 0; i < NR_CPUS; i++)
atomic_set(&passive_cpu_wait[i], 1);
}
/*
* spin_lock code is good enough as a barrier so we don't
* need one here:
*/
atomic_set(&cpu_in_kgdb[ks->cpu], 1);
#ifdef CONFIG_SMP
/* Signal the other CPUs to enter kgdb_wait() */
if ((!kgdb_single_step) && kgdb_do_roundup)
kgdb_roundup_cpus(flags);
#endif
/*
* Wait for the other CPUs to be notified and be waiting for us:
*/
for_each_online_cpu(i) {
while (!atomic_read(&cpu_in_kgdb[i]))
cpu_relax();
}
/*
* At this point the primary processor is completely
* in the debugger and all secondary CPUs are quiescent
*/
kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
kgdb_deactivate_sw_breakpoints();
kgdb_single_step = 0;
kgdb_contthread = current;
exception_level = 0;
/* Talk to debugger with gdbserial protocol */
error = gdb_serial_stub(ks);
/* Call the I/O driver's post_exception routine */
if (kgdb_io_ops->post_exception)
kgdb_io_ops->post_exception();
kgdb_info[ks->cpu].debuggerinfo = NULL;
kgdb_info[ks->cpu].task = NULL;
atomic_set(&cpu_in_kgdb[ks->cpu], 0);
if (!kgdb_single_step) {
for (i = NR_CPUS-1; i >= 0; i--)
atomic_set(&passive_cpu_wait[i], 0);
/*
* Wait till all the CPUs have quit
* from the debugger.
*/
for_each_online_cpu(i) {
while (atomic_read(&cpu_in_kgdb[i]))
cpu_relax();
}
}
kgdb_restore:
if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
if (kgdb_info[sstep_cpu].task)
kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
else
kgdb_sstep_pid = 0;
}
/* Free kgdb_active */
atomic_set(&kgdb_active, -1);
touch_softlockup_watchdog_sync();
clocksource_touch_watchdog();
local_irq_restore(flags);
return error;
}
int kgdb_nmicallback(int cpu, void *regs)
{
#ifdef CONFIG_SMP
if (!atomic_read(&cpu_in_kgdb[cpu]) &&
atomic_read(&kgdb_active) != cpu &&
atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
kgdb_wait((struct pt_regs *)regs);
return 0;
}
#endif
return 1;
}
static void kgdb_console_write(struct console *co, const char *s,
unsigned count)
{
unsigned long flags;
/* If we're debugging, or KGDB has not connected, don't try
* and print. */
if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
return;
local_irq_save(flags);
kgdb_msg_write(s, count);
local_irq_restore(flags);
}
static struct console kgdbcons = {
.name = "kgdb",
.write = kgdb_console_write,
.flags = CON_PRINTBUFFER | CON_ENABLED,
.index = -1,
};
#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_handle_gdb(int key, struct tty_struct *tty)
{
if (!kgdb_io_ops) {
printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
return;
}
if (!kgdb_connected)
printk(KERN_CRIT "Entering KGDB\n");
kgdb_breakpoint();
}
static struct sysrq_key_op sysrq_gdb_op = {
.handler = sysrq_handle_gdb,
.help_msg = "debug(G)",
.action_msg = "DEBUG",
};
#endif
static void kgdb_register_callbacks(void)
{
if (!kgdb_io_module_registered) {
kgdb_io_module_registered = 1;
kgdb_arch_init();
#ifdef CONFIG_MAGIC_SYSRQ
register_sysrq_key('g', &sysrq_gdb_op);
#endif
if (kgdb_use_con && !kgdb_con_registered) {
register_console(&kgdbcons);
kgdb_con_registered = 1;
}
}
}
static void kgdb_unregister_callbacks(void)
{
/*
* When this routine is called KGDB should unregister from the
* panic handler and clean up, making sure it is not handling any
* break exceptions at the time.
*/
if (kgdb_io_module_registered) {
kgdb_io_module_registered = 0;
kgdb_arch_exit();
#ifdef CONFIG_MAGIC_SYSRQ
unregister_sysrq_key('g', &sysrq_gdb_op);
#endif
if (kgdb_con_registered) {
unregister_console(&kgdbcons);
kgdb_con_registered = 0;
}
}
}
static void kgdb_initial_breakpoint(void)
{
kgdb_break_asap = 0;
printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
kgdb_breakpoint();
}
/**
* kgdb_register_io_module - register KGDB IO module
* @new_kgdb_io_ops: the io ops vector
*
* Register it with the KGDB core.
*/
int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
{
int err;
spin_lock(&kgdb_registration_lock);
if (kgdb_io_ops) {
spin_unlock(&kgdb_registration_lock);
printk(KERN_ERR "kgdb: Another I/O driver is already "
"registered with KGDB.\n");
return -EBUSY;
}
if (new_kgdb_io_ops->init) {
err = new_kgdb_io_ops->init();
if (err) {
spin_unlock(&kgdb_registration_lock);
return err;
}
}
kgdb_io_ops = new_kgdb_io_ops;
spin_unlock(&kgdb_registration_lock);
printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
new_kgdb_io_ops->name);
/* Arm KGDB now. */
kgdb_register_callbacks();
if (kgdb_break_asap)
kgdb_initial_breakpoint();
return 0;
}
EXPORT_SYMBOL_GPL(kgdb_register_io_module);
/**
* kkgdb_unregister_io_module - unregister KGDB IO module
* @old_kgdb_io_ops: the io ops vector
*
* Unregister it with the KGDB core.
*/
void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
{
BUG_ON(kgdb_connected);
/*
* KGDB is no longer able to communicate out, so
* unregister our callbacks and reset state.
*/
kgdb_unregister_callbacks();
spin_lock(&kgdb_registration_lock);
WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
kgdb_io_ops = NULL;
spin_unlock(&kgdb_registration_lock);
printk(KERN_INFO
"kgdb: Unregistered I/O driver %s, debugger disabled.\n",
old_kgdb_io_ops->name);
}
EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
/**
* kgdb_breakpoint - generate breakpoint exception
*
* This function will generate a breakpoint exception. It is used at the
* beginning of a program to sync up with a debugger and can be used
* otherwise as a quick means to stop program execution and "break" into
* the debugger.
*/
void kgdb_breakpoint(void)
{
atomic_set(&kgdb_setting_breakpoint, 1);
wmb(); /* Sync point before breakpoint */
arch_kgdb_breakpoint();
wmb(); /* Sync point after breakpoint */
atomic_set(&kgdb_setting_breakpoint, 0);
}
EXPORT_SYMBOL_GPL(kgdb_breakpoint);
static int __init opt_kgdb_wait(char *str)
{
kgdb_break_asap = 1;
if (kgdb_io_module_registered)
kgdb_initial_breakpoint();
return 0;
}
early_param("kgdbwait", opt_kgdb_wait);