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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#define pr_fmt(fmt) "KGDB: " fmt
#include <linux/pid_namespace.h>#include <linux/clocksource.h>#include <linux/serial_core.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/string.h>#include <linux/delay.h>#include <linux/sched.h>#include <linux/sysrq.h>#include <linux/reboot.h>#include <linux/init.h>#include <linux/kgdb.h>#include <linux/kdb.h>#include <linux/nmi.h>#include <linux/pid.h>#include <linux/smp.h>#include <linux/mm.h>#include <linux/rcupdate.h>#include <linux/irq.h>#include <linux/security.h>
#include <asm/cacheflush.h>#include <asm/byteorder.h>#include <linux/atomic.h>
#include "debug_core.h"
static int kgdb_break_asap;
struct debuggerinfo_struct 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 */int kgdb_io_module_registered;
/* Guard for recursive entry */static int exception_level;
struct kgdb_io *dbg_io_ops;static DEFINE_SPINLOCK(kgdb_registration_lock);
/* Action for the reboot notifier, a global allow kdb to change it */static int kgdbreboot;/* kgdb console driver is loaded */static int kgdb_con_registered;/* determine if kgdb console output should be used */static int kgdb_use_con;/* Flag for alternate operations for early debugging */bool dbg_is_early = true;/* Next cpu to become the master debug core */int dbg_switch_cpu;
/* Use kdb or gdbserver mode */int dbg_kdb_mode = 1;
module_param(kgdb_use_con, int, 0644);module_param(kgdbreboot, 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);EXPORT_SYMBOL_GPL(kgdb_active);static DEFINE_RAW_SPINLOCK(dbg_master_lock);static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
/* * 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 masters_in_kgdb;static atomic_t slaves_in_kgdb;atomic_t kgdb_setting_breakpoint;
struct task_struct *kgdb_usethread;struct task_struct *kgdb_contthread;
int kgdb_single_step;static pid_t kgdb_sstep_pid;
/* 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 overridden by architectures when needed: */int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt){ int err;
err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); if (err) return err; err = copy_to_kernel_nofault((char *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); return err;}NOKPROBE_SYMBOL(kgdb_arch_set_breakpoint);
int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt){ return copy_to_kernel_nofault((char *)bpt->bpt_addr, (char *)bpt->saved_instr, BREAK_INSTR_SIZE);}NOKPROBE_SYMBOL(kgdb_arch_remove_breakpoint);
int __weak kgdb_validate_break_address(unsigned long addr){ struct kgdb_bkpt tmp; int err;
if (kgdb_within_blocklist(addr)) return -EINVAL;
/* Validate setting the breakpoint and then removing it. If 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. */ tmp.bpt_addr = addr; err = kgdb_arch_set_breakpoint(&tmp); if (err) return err; err = kgdb_arch_remove_breakpoint(&tmp); if (err) pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n", addr); return err;}
unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs){ return instruction_pointer(regs);}NOKPROBE_SYMBOL(kgdb_arch_pc);
int __weak kgdb_arch_init(void){ return 0;}
int __weak kgdb_skipexception(int exception, struct pt_regs *regs){ return 0;}NOKPROBE_SYMBOL(kgdb_skipexception);
#ifdef CONFIG_SMP
/* * Default (weak) implementation for kgdb_roundup_cpus */
void __weak kgdb_call_nmi_hook(void *ignored){ /* * NOTE: get_irq_regs() is supposed to get the registers from * before the IPI interrupt happened and so is supposed to * show where the processor was. In some situations it's * possible we might be called without an IPI, so it might be * safer to figure out how to make kgdb_breakpoint() work * properly here. */ kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());}NOKPROBE_SYMBOL(kgdb_call_nmi_hook);
static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd) = CSD_INIT(kgdb_call_nmi_hook, NULL);
void __weak kgdb_roundup_cpus(void){ call_single_data_t *csd; int this_cpu = raw_smp_processor_id(); int cpu; int ret;
for_each_online_cpu(cpu) { /* No need to roundup ourselves */ if (cpu == this_cpu) continue;
csd = &per_cpu(kgdb_roundup_csd, cpu);
/* * If it didn't round up last time, don't try again * since smp_call_function_single_async() will block. * * If rounding_up is false then we know that the * previous call must have at least started and that * means smp_call_function_single_async() won't block. */ if (kgdb_info[cpu].rounding_up) continue; kgdb_info[cpu].rounding_up = true;
ret = smp_call_function_single_async(cpu, csd); if (ret) kgdb_info[cpu].rounding_up = false; }}NOKPROBE_SYMBOL(kgdb_roundup_cpus);
#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;
/* Force flush instruction cache if it was outside the mm */ flush_icache_range(addr, addr + BREAK_INSTR_SIZE);}NOKPROBE_SYMBOL(kgdb_flush_swbreak_addr);
/* * SW breakpoint management: */int dbg_activate_sw_breakpoints(void){ int error; int ret = 0; int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { if (kgdb_break[i].state != BP_SET) continue;
error = kgdb_arch_set_breakpoint(&kgdb_break[i]); if (error) { ret = error; pr_info("BP install failed: %lx\n", kgdb_break[i].bpt_addr); continue; }
kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); kgdb_break[i].state = BP_ACTIVE; } return ret;}NOKPROBE_SYMBOL(dbg_activate_sw_breakpoints);
int dbg_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;}
int dbg_deactivate_sw_breakpoints(void){ int error; int ret = 0; int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { if (kgdb_break[i].state != BP_ACTIVE) continue; error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); if (error) { pr_info("BP remove failed: %lx\n", kgdb_break[i].bpt_addr); ret = error; }
kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); kgdb_break[i].state = BP_SET; } return ret;}NOKPROBE_SYMBOL(dbg_deactivate_sw_breakpoints);
int dbg_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;}
int kgdb_has_hit_break(unsigned long addr){ int i;
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { if (kgdb_break[i].state == BP_ACTIVE && kgdb_break[i].bpt_addr == addr) return 1; } return 0;}
int dbg_remove_all_break(void){ int error; int i;
/* Clear memory breakpoints. */ for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { if (kgdb_break[i].state != BP_ACTIVE) goto setundefined; error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); if (error) pr_err("breakpoint remove failed: %lx\n", kgdb_break[i].bpt_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;}
void kgdb_free_init_mem(void){ int i;
/* Clear init memory breakpoints. */ for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { if (init_section_contains((void *)kgdb_break[i].bpt_addr, 0)) kgdb_break[i].state = BP_UNDEFINED; }}
#ifdef CONFIG_KGDB_KDBvoid kdb_dump_stack_on_cpu(int cpu){ if (cpu == raw_smp_processor_id() || !IS_ENABLED(CONFIG_SMP)) { dump_stack(); return; }
if (!(kgdb_info[cpu].exception_state & DCPU_IS_SLAVE)) { kdb_printf("ERROR: Task on cpu %d didn't stop in the debugger\n", cpu); return; }
/* * In general, architectures don't support dumping the stack of a * "running" process that's not the current one. From the point of * view of the Linux, kernel processes that are looping in the kgdb * slave loop are still "running". There's also no API (that actually * works across all architectures) that can do a stack crawl based * on registers passed as a parameter. * * Solve this conundrum by asking slave CPUs to do the backtrace * themselves. */ kgdb_info[cpu].exception_state |= DCPU_WANT_BT; while (kgdb_info[cpu].exception_state & DCPU_WANT_BT) cpu_relax();}#endif
/* * 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 (!dbg_io_ops) return 0; if (kgdb_connected) return 1; if (atomic_read(&kgdb_setting_breakpoint)) return 1; if (print_wait) {#ifdef CONFIG_KGDB_KDB if (!dbg_kdb_mode) pr_crit("waiting... or $3#33 for KDB\n");#else pr_crit("Waiting for remote debugger\n");#endif } return 1;}NOKPROBE_SYMBOL(kgdb_io_ready);
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); dbg_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 (dbg_remove_sw_break(addr) == 0) { exception_level = 0; kgdb_skipexception(ks->ex_vector, ks->linux_regs); dbg_activate_sw_breakpoints(); pr_crit("re-enter error: breakpoint removed %lx\n", addr); WARN_ON_ONCE(1);
return 1; } dbg_remove_all_break(); kgdb_skipexception(ks->ex_vector, ks->linux_regs);
if (exception_level > 1) { dump_stack(); kgdb_io_module_registered = false; panic("Recursive entry to debugger"); }
pr_crit("re-enter exception: ALL breakpoints killed\n");#ifdef CONFIG_KGDB_KDB /* Allow kdb to debug itself one level */ return 0;#endif dump_stack(); panic("Recursive entry to debugger");
return 1;}NOKPROBE_SYMBOL(kgdb_reenter_check);
static void dbg_touch_watchdogs(void){ touch_softlockup_watchdog_sync(); clocksource_touch_watchdog(); rcu_cpu_stall_reset();}NOKPROBE_SYMBOL(dbg_touch_watchdogs);
static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, int exception_state){ unsigned long flags; int sstep_tries = 100; int error; int cpu; int trace_on = 0; int online_cpus = num_online_cpus(); u64 time_left;
kgdb_info[ks->cpu].enter_kgdb++; kgdb_info[ks->cpu].exception_state |= exception_state;
if (exception_state == DCPU_WANT_MASTER) atomic_inc(&masters_in_kgdb); else atomic_inc(&slaves_in_kgdb);
if (arch_kgdb_ops.disable_hw_break) arch_kgdb_ops.disable_hw_break(regs);
acquirelock: rcu_read_lock(); /* * Interrupts will be restored by the 'trap return' code, except when * single stepping. */ local_irq_save(flags);
cpu = ks->cpu; kgdb_info[cpu].debuggerinfo = regs; kgdb_info[cpu].task = current; kgdb_info[cpu].ret_state = 0; kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
/* Make sure the above info reaches the primary CPU */ smp_mb();
if (exception_level == 1) { if (raw_spin_trylock(&dbg_master_lock)) atomic_xchg(&kgdb_active, cpu); goto cpu_master_loop; }
/* * CPU will loop if it is a slave or request to become a kgdb * master cpu and acquire the kgdb_active lock: */ while (1) {cpu_loop: if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; goto cpu_master_loop; } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { if (raw_spin_trylock(&dbg_master_lock)) { atomic_xchg(&kgdb_active, cpu); break; } } else if (kgdb_info[cpu].exception_state & DCPU_WANT_BT) { dump_stack(); kgdb_info[cpu].exception_state &= ~DCPU_WANT_BT; } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { if (!raw_spin_is_locked(&dbg_slave_lock)) goto return_normal; } else {return_normal: /* Return to normal operation by executing any * hw breakpoint fixup. */ if (arch_kgdb_ops.correct_hw_break) arch_kgdb_ops.correct_hw_break(); if (trace_on) tracing_on(); kgdb_info[cpu].debuggerinfo = NULL; kgdb_info[cpu].task = NULL; kgdb_info[cpu].exception_state &= ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); kgdb_info[cpu].enter_kgdb--; smp_mb__before_atomic(); atomic_dec(&slaves_in_kgdb); dbg_touch_watchdogs(); local_irq_restore(flags); rcu_read_unlock(); return 0; } cpu_relax(); }
/* * For single stepping, try to only enter on the processor * that was single stepping. To guard 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); raw_spin_unlock(&dbg_master_lock); dbg_touch_watchdogs(); local_irq_restore(flags); rcu_read_unlock();
goto acquirelock; }
if (!kgdb_io_ready(1)) { kgdb_info[cpu].ret_state = 1; goto kgdb_restore; /* No I/O connection, 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;
atomic_inc(&ignore_console_lock_warning);
/* Call the I/O driver's pre_exception routine */ if (dbg_io_ops->pre_exception) dbg_io_ops->pre_exception();
/* * 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) raw_spin_lock(&dbg_slave_lock);
#ifdef CONFIG_SMP /* If send_ready set, slaves are already waiting */ if (ks->send_ready) atomic_set(ks->send_ready, 1);
/* Signal the other CPUs to enter the debug trap handler */ else if ((!kgdb_single_step) && kgdb_do_roundup) kgdb_roundup_cpus();#endif
/* * Wait for the other CPUs to be notified and be waiting for us: */ time_left = MSEC_PER_SEC; while (kgdb_do_roundup && --time_left && (atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) != online_cpus) udelay(1000); if (!time_left) pr_crit("Timed out waiting for secondary CPUs.\n");
/* * At this point the primary processor is completely * in the debugger and all secondary CPUs are quiescent */ dbg_deactivate_sw_breakpoints(); kgdb_single_step = 0; kgdb_contthread = current; exception_level = 0; trace_on = tracing_is_on(); if (trace_on) tracing_off();
while (1) {cpu_master_loop: if (dbg_kdb_mode) { kgdb_connected = 1; error = kdb_stub(ks); if (error == -1) continue; kgdb_connected = 0; } else { /* * This is a brutal way to interfere with the debugger * and prevent gdb being used to poke at kernel memory. * This could cause trouble if lockdown is applied when * there is already an active gdb session. For now the * answer is simply "don't do that". Typically lockdown * *will* be applied before the debug core gets started * so only developers using kgdb for fairly advanced * early kernel debug can be biten by this. Hopefully * they are sophisticated enough to take care of * themselves, especially with help from the lockdown * message printed on the console! */ if (security_locked_down(LOCKDOWN_DBG_WRITE_KERNEL)) { if (IS_ENABLED(CONFIG_KGDB_KDB)) { /* Switch back to kdb if possible... */ dbg_kdb_mode = 1; continue; } else { /* ... otherwise just bail */ break; } } error = gdb_serial_stub(ks); }
if (error == DBG_PASS_EVENT) { dbg_kdb_mode = !dbg_kdb_mode; } else if (error == DBG_SWITCH_CPU_EVENT) { kgdb_info[dbg_switch_cpu].exception_state |= DCPU_NEXT_MASTER; goto cpu_loop; } else { kgdb_info[cpu].ret_state = error; break; } }
dbg_activate_sw_breakpoints();
/* Call the I/O driver's post_exception routine */ if (dbg_io_ops->post_exception) dbg_io_ops->post_exception();
atomic_dec(&ignore_console_lock_warning);
if (!kgdb_single_step) { raw_spin_unlock(&dbg_slave_lock); /* Wait till all the CPUs have quit from the debugger. */ while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) 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; } if (arch_kgdb_ops.correct_hw_break) arch_kgdb_ops.correct_hw_break(); if (trace_on) tracing_on();
kgdb_info[cpu].debuggerinfo = NULL; kgdb_info[cpu].task = NULL; kgdb_info[cpu].exception_state &= ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); kgdb_info[cpu].enter_kgdb--; smp_mb__before_atomic(); atomic_dec(&masters_in_kgdb); /* Free kgdb_active */ atomic_set(&kgdb_active, -1); raw_spin_unlock(&dbg_master_lock); dbg_touch_watchdogs(); local_irq_restore(flags); rcu_read_unlock();
return kgdb_info[cpu].ret_state;}NOKPROBE_SYMBOL(kgdb_cpu_enter);
/* * kgdb_handle_exception() - main entry point from a kernel exception * * Locking hierarchy: * interface locks, if any (begin_session) * kgdb lock (kgdb_active) */intkgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs){ struct kgdb_state kgdb_var; struct kgdb_state *ks = &kgdb_var; /* * Avoid entering the debugger if we were triggered due to an oops * but panic_timeout indicates the system should automatically * reboot on panic. We don't want to get stuck waiting for input * on such systems, especially if its "just" an oops. */ if (signo != SIGTRAP && panic_timeout) return 1;
memset(ks, 0, sizeof(struct kgdb_state)); ks->cpu = raw_smp_processor_id(); ks->ex_vector = evector; ks->signo = signo; ks->err_code = ecode; ks->linux_regs = regs;
if (kgdb_reenter_check(ks)) return 0; /* Ouch, double exception ! */ if (kgdb_info[ks->cpu].enter_kgdb != 0) return 0;
return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);}NOKPROBE_SYMBOL(kgdb_handle_exception);
/* * GDB places a breakpoint at this function to know dynamically loaded objects. */static int module_event(struct notifier_block *self, unsigned long val, void *data){ return 0;}
static struct notifier_block dbg_module_load_nb = { .notifier_call = module_event,};
int kgdb_nmicallback(int cpu, void *regs){#ifdef CONFIG_SMP struct kgdb_state kgdb_var; struct kgdb_state *ks = &kgdb_var;
kgdb_info[cpu].rounding_up = false;
memset(ks, 0, sizeof(struct kgdb_state)); ks->cpu = cpu; ks->linux_regs = regs;
if (kgdb_info[ks->cpu].enter_kgdb == 0 && raw_spin_is_locked(&dbg_master_lock)) { kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); return 0; }#endif return 1;}NOKPROBE_SYMBOL(kgdb_nmicallback);
int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code, atomic_t *send_ready){#ifdef CONFIG_SMP if (!kgdb_io_ready(0) || !send_ready) return 1;
if (kgdb_info[cpu].enter_kgdb == 0) { struct kgdb_state kgdb_var; struct kgdb_state *ks = &kgdb_var;
memset(ks, 0, sizeof(struct kgdb_state)); ks->cpu = cpu; ks->ex_vector = trapnr; ks->signo = SIGTRAP; ks->err_code = err_code; ks->linux_regs = regs; ks->send_ready = send_ready; kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); return 0; }#endif return 1;}NOKPROBE_SYMBOL(kgdb_nmicallin);
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 || dbg_kdb_mode) return;
local_irq_save(flags); gdbstub_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,};
static int __init opt_kgdb_con(char *str){ kgdb_use_con = 1;
if (kgdb_io_module_registered && !kgdb_con_registered) { register_console(&kgdbcons); kgdb_con_registered = 1; }
return 0;}
early_param("kgdbcon", opt_kgdb_con);
#ifdef CONFIG_MAGIC_SYSRQstatic void sysrq_handle_dbg(u8 key){ if (!dbg_io_ops) { pr_crit("ERROR: No KGDB I/O module available\n"); return; } if (!kgdb_connected) {#ifdef CONFIG_KGDB_KDB if (!dbg_kdb_mode) pr_crit("KGDB or $3#33 for KDB\n");#else pr_crit("Entering KGDB\n");#endif }
kgdb_breakpoint();}
static const struct sysrq_key_op sysrq_dbg_op = { .handler = sysrq_handle_dbg, .help_msg = "debug(g)", .action_msg = "DEBUG",};#endif
void kgdb_panic(const char *msg){ if (!kgdb_io_module_registered) return;
/* * We don't want to get stuck waiting for input from user if * "panic_timeout" indicates the system should automatically * reboot on panic. */ if (panic_timeout) return;
debug_locks_off(); console_flush_on_panic(CONSOLE_FLUSH_PENDING);
if (dbg_kdb_mode) kdb_printf("PANIC: %s\n", msg);
kgdb_breakpoint();}
static void kgdb_initial_breakpoint(void){ kgdb_break_asap = 0;
pr_crit("Waiting for connection from remote gdb...\n"); kgdb_breakpoint();}
void __weak kgdb_arch_late(void){}
void __init dbg_late_init(void){ dbg_is_early = false; if (kgdb_io_module_registered) kgdb_arch_late(); kdb_init(KDB_INIT_FULL);
if (kgdb_io_module_registered && kgdb_break_asap) kgdb_initial_breakpoint();}
static intdbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x){ /* * Take the following action on reboot notify depending on value: * 1 == Enter debugger * 0 == [the default] detach debug client * -1 == Do nothing... and use this until the board resets */ switch (kgdbreboot) { case 1: kgdb_breakpoint(); goto done; case -1: goto done; } if (!dbg_kdb_mode) gdbstub_exit(code);done: return NOTIFY_DONE;}
static struct notifier_block dbg_reboot_notifier = { .notifier_call = dbg_notify_reboot, .next = NULL, .priority = INT_MAX,};
static void kgdb_register_callbacks(void){ if (!kgdb_io_module_registered) { kgdb_io_module_registered = 1; kgdb_arch_init(); if (!dbg_is_early) kgdb_arch_late(); register_module_notifier(&dbg_module_load_nb); register_reboot_notifier(&dbg_reboot_notifier);#ifdef CONFIG_MAGIC_SYSRQ register_sysrq_key('g', &sysrq_dbg_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 * handlers 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; unregister_reboot_notifier(&dbg_reboot_notifier); unregister_module_notifier(&dbg_module_load_nb); kgdb_arch_exit();#ifdef CONFIG_MAGIC_SYSRQ unregister_sysrq_key('g', &sysrq_dbg_op);#endif if (kgdb_con_registered) { unregister_console(&kgdbcons); kgdb_con_registered = 0; } }}
/** * kgdb_register_io_module - register KGDB IO module * @new_dbg_io_ops: the io ops vector * * Register it with the KGDB core. */int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops){ struct kgdb_io *old_dbg_io_ops; int err;
spin_lock(&kgdb_registration_lock);
old_dbg_io_ops = dbg_io_ops; if (old_dbg_io_ops) { if (!old_dbg_io_ops->deinit) { spin_unlock(&kgdb_registration_lock);
pr_err("KGDB I/O driver %s can't replace %s.\n", new_dbg_io_ops->name, old_dbg_io_ops->name); return -EBUSY; } pr_info("Replacing I/O driver %s with %s\n", old_dbg_io_ops->name, new_dbg_io_ops->name); }
if (new_dbg_io_ops->init) { err = new_dbg_io_ops->init(); if (err) { spin_unlock(&kgdb_registration_lock); return err; } }
dbg_io_ops = new_dbg_io_ops;
spin_unlock(&kgdb_registration_lock);
if (old_dbg_io_ops) { old_dbg_io_ops->deinit(); return 0; }
pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name);
/* Arm KGDB now. */ kgdb_register_callbacks();
if (kgdb_break_asap && (!dbg_is_early || IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG))) kgdb_initial_breakpoint();
return 0;}EXPORT_SYMBOL_GPL(kgdb_register_io_module);
/** * kgdb_unregister_io_module - unregister KGDB IO module * @old_dbg_io_ops: the io ops vector * * Unregister it with the KGDB core. */void kgdb_unregister_io_module(struct kgdb_io *old_dbg_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(dbg_io_ops != old_dbg_io_ops); dbg_io_ops = NULL;
spin_unlock(&kgdb_registration_lock);
if (old_dbg_io_ops->deinit) old_dbg_io_ops->deinit();
pr_info("Unregistered I/O driver %s, debugger disabled\n", old_dbg_io_ops->name);}EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
int dbg_io_get_char(void){ int ret = dbg_io_ops->read_char(); if (ret == NO_POLL_CHAR) return -1; if (!dbg_kdb_mode) return ret; if (ret == 127) return 8; return ret;}
/** * 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. */noinline void kgdb_breakpoint(void){ atomic_inc(&kgdb_setting_breakpoint); wmb(); /* Sync point before breakpoint */ arch_kgdb_breakpoint(); wmb(); /* Sync point after breakpoint */ atomic_dec(&kgdb_setting_breakpoint);}EXPORT_SYMBOL_GPL(kgdb_breakpoint);
static int __init opt_kgdb_wait(char *str){ kgdb_break_asap = 1;
kdb_init(KDB_INIT_EARLY); if (kgdb_io_module_registered && IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG)) kgdb_initial_breakpoint();
return 0;}
early_param("kgdbwait", opt_kgdb_wait);