| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Jason Wessel | 3156 | 76.98% | 39 | 40.62% |
| Doug Anderson | 364 | 8.88% | 15 | 15.62% |
| Daniel R Thompson | 151 | 3.68% | 6 | 6.25% |
| Mike Travis | 141 | 3.44% | 2 | 2.08% |
| Vincent Chen | 53 | 1.29% | 1 | 1.04% |
| Sumit Garg | 53 | 1.29% | 1 | 1.04% |
| Anton Vorontsov | 44 | 1.07% | 1 | 1.04% |
| Fabian Frederick | 33 | 0.80% | 1 | 1.04% |
| Paul Mundt | 25 | 0.61% | 3 | 3.12% |
| Colin Cross | 16 | 0.39% | 1 | 1.04% |
| Dongdong Deng | 13 | 0.32% | 2 | 2.08% |
| Peter Zijlstra | 10 | 0.24% | 2 | 2.08% |
| Harvey Harrison | 4 | 0.10% | 2 | 2.08% |
| Gustavo A. R. Silva | 3 | 0.07% | 1 | 1.04% |
| John Stultz | 3 | 0.07% | 1 | 1.04% |
| Linas Vepstas | 3 | 0.07% | 1 | 1.04% |
| Ingo Molnar | 3 | 0.07% | 1 | 1.04% |
| Christoph Hellwig | 3 | 0.07% | 1 | 1.04% |
| Tiejun Chen | 3 | 0.07% | 1 | 1.04% |
| Greg Kroah-Hartman | 3 | 0.07% | 1 | 1.04% |
| caihuoqing | 2 | 0.05% | 1 | 1.04% |
| Youling Tang | 2 | 0.05% | 1 | 1.04% |
| Andrew Morton | 2 | 0.05% | 1 | 1.04% |
| Lukas Bulwahn | 1 | 0.02% | 1 | 1.04% |
| Nadav Amit | 1 | 0.02% | 1 | 1.04% |
| Emil Velikov | 1 | 0.02% | 1 | 1.04% |
| Zhen Lei | 1 | 0.02% | 1 | 1.04% |
| Jovi Zhangwei | 1 | 0.02% | 1 | 1.04% |
| Vijaya Kumar K | 1 | 0.02% | 1 | 1.04% |
| Lucas De Marchi | 1 | 0.02% | 1 | 1.04% |
| Andy Shevchenko | 1 | 0.02% | 1 | 1.04% |
| Arun Sharma | 1 | 0.02% | 1 | 1.04% |
| Jiri Slaby (SUSE) | 1 | 0.02% | 1 | 1.04% |
| Total | 4100 | 96 |
// SPDX-License-Identifier: GPL-2.0-only /* * Kernel Debug Core * * 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@ucw.cz> * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. * Copyright (C) 2005-2009 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> */ #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_KDB void 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 kgdb_wait() */ 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) */ 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; int ret = 0; if (arch_kgdb_ops.enable_nmi) arch_kgdb_ops.enable_nmi(0); /* * 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)) goto out; /* Ouch, double exception ! */ if (kgdb_info[ks->cpu].enter_kgdb != 0) goto out; ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); out: if (arch_kgdb_ops.enable_nmi) arch_kgdb_ops.enable_nmi(1); return ret; } 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_SYSRQ static 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 int dbg_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);
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