/* * 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; struct kgdb_state { int ex_vector; int signo; int err_code; int cpu; int pass_exception; 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; /* 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_validate_break_address(unsigned long addr) { char tmp_variable[BREAK_INSTR_SIZE]; return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE); } 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); } 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; *long_val = 0; while (**ptr) { hex_val = hex(**ptr); if (hex_val < 0) break; *long_val = (*long_val << 4) | hex_val; num++; (*ptr)++; } 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 + 1); 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 idle tasks: */ if (tid <= 0) return idle_task(-tid); /* * 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); /* 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); 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 = 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) return error; kgdb_flush_swbreak_addr(addr); kgdb_break[i].state = BP_ACTIVE; } return 0; } 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 = 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) return error; kgdb_flush_swbreak_addr(addr); kgdb_break[i].state = BP_SET; } return 0; } 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, idle tasks to -1 ... -NR_CPUs: */ static inline int shadow_pid(int realpid) { if (realpid) return realpid; return -1-raw_smp_processor_id(); } 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 (i = 0; i < NR_CPUS; 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 *thread; unsigned char thref[8]; char *ptr; int i; switch (remcom_in_buffer[1]) { case 's': case 'f': if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) { error_packet(remcom_out_buffer, -EINVAL); break; } if (remcom_in_buffer[1] == 'f') ks->threadid = 1; remcom_out_buffer[0] = 'm'; ptr = remcom_out_buffer + 1; for (i = 0; i < 17; ks->threadid++) { thread = getthread(ks->linux_regs, ks->threadid); if (thread) { int_to_threadref(thref, ks->threadid); pack_threadid(ptr, thref); ptr += BUF_THREAD_ID_SIZE; *(ptr++) = ','; i++; } } *(--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 (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, "Shadow task %d for pid 0", (int)(-ks->threadid-1)); 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 { error_packet(remcom_out_buffer, -EINVAL); return 0; } /* 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 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(); /* * Do not start the debugger connection on this CPU if the last * instance of the exception handler wanted to come into the * debugger on a different CPU via a single step */ if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && atomic_read(&kgdb_cpu_doing_single_step) != cpu) { atomic_set(&kgdb_active, -1); 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 || !kgdb_contthread) { 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_contthread) && 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 = NULL; 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 || !kgdb_contthread) { 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: /* Free kgdb_active */ atomic_set(&kgdb_active, -1); 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 = "Gdb", .action_msg = "GDB", }; #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);