diff options
Diffstat (limited to 'kernel/debug/debug_core.c')
| -rw-r--r-- | kernel/debug/debug_core.c | 455 |
1 files changed, 328 insertions, 127 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0506d447aed2..0b9495187fba 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Kernel Debug Core * @@ -22,11 +23,10 @@ * * 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. */ + +#define pr_fmt(fmt) "KGDB: " fmt + #include <linux/pid_namespace.h> #include <linux/clocksource.h> #include <linux/serial_core.h> @@ -46,10 +46,13 @@ #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> @@ -61,9 +64,7 @@ static int kgdb_break_asap; struct debuggerinfo_struct kgdb_info[NR_CPUS]; -/** - * kgdb_connected - Is a host GDB connected to us? - */ +/* kgdb_connected - Is a host GDB connected to us? */ int kgdb_connected; EXPORT_SYMBOL_GPL(kgdb_connected); @@ -76,7 +77,7 @@ static int exception_level; struct kgdb_io *dbg_io_ops; static DEFINE_SPINLOCK(kgdb_registration_lock); -/* Action for the reboot notifiter, a global allow kdb to change it */ +/* 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; @@ -90,14 +91,6 @@ int dbg_switch_cpu; /* Use kdb or gdbserver mode */ int dbg_kdb_mode = 1; -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); module_param(kgdbreboot, int, 0644); @@ -123,7 +116,6 @@ static DEFINE_RAW_SPINLOCK(dbg_slave_lock); */ static atomic_t masters_in_kgdb; static atomic_t slaves_in_kgdb; -static atomic_t kgdb_break_tasklet_var; atomic_t kgdb_setting_breakpoint; struct task_struct *kgdb_usethread; @@ -159,31 +151,37 @@ early_param("nokgdbroundup", opt_nokgdbroundup); /* * Weak aliases for breakpoint management, - * can be overriden by architectures when needed: + * can be overridden by architectures when needed: */ int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) { int err; - err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, + err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); if (err) return err; - err = probe_kernel_write((char *)bpt->bpt_addr, + 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 probe_kernel_write((char *)bpt->bpt_addr, + 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 @@ -195,8 +193,8 @@ int __weak kgdb_validate_break_address(unsigned long addr) return err; err = kgdb_arch_remove_breakpoint(&tmp); if (err) - printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " - "memory destroyed at: %lx", addr); + pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n", + addr); return err; } @@ -204,6 +202,7 @@ 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) { @@ -214,6 +213,65 @@ 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 @@ -224,13 +282,10 @@ 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); } +NOKPROBE_SYMBOL(kgdb_flush_swbreak_addr); /* * SW breakpoint management: @@ -248,8 +303,8 @@ int dbg_activate_sw_breakpoints(void) error = kgdb_arch_set_breakpoint(&kgdb_break[i]); if (error) { ret = error; - printk(KERN_INFO "KGDB: BP install failed: %lx", - kgdb_break[i].bpt_addr); + pr_info("BP install failed: %lx\n", + kgdb_break[i].bpt_addr); continue; } @@ -258,6 +313,7 @@ int dbg_activate_sw_breakpoints(void) } return ret; } +NOKPROBE_SYMBOL(dbg_activate_sw_breakpoints); int dbg_set_sw_break(unsigned long addr) { @@ -311,8 +367,8 @@ int dbg_deactivate_sw_breakpoints(void) continue; error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); if (error) { - printk(KERN_INFO "KGDB: BP remove failed: %lx\n", - kgdb_break[i].bpt_addr); + pr_info("BP remove failed: %lx\n", + kgdb_break[i].bpt_addr); ret = error; } @@ -321,6 +377,7 @@ int dbg_deactivate_sw_breakpoints(void) } return ret; } +NOKPROBE_SYMBOL(dbg_deactivate_sw_breakpoints); int dbg_remove_sw_break(unsigned long addr) { @@ -348,6 +405,18 @@ int kgdb_isremovedbreak(unsigned long addr) 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; @@ -359,7 +428,7 @@ int dbg_remove_all_break(void) goto setundefined; error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); if (error) - printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", + pr_err("breakpoint remove failed: %lx\n", kgdb_break[i].bpt_addr); setundefined: kgdb_break[i].state = BP_UNDEFINED; @@ -372,6 +441,48 @@ setundefined: 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 @@ -392,13 +503,14 @@ static int kgdb_io_ready(int print_wait) if (print_wait) { #ifdef CONFIG_KGDB_KDB if (!dbg_kdb_mode) - printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); + pr_crit("waiting... or $3#33 for KDB\n"); #else - printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); + pr_crit("Waiting for remote debugger\n"); #endif } return 1; } +NOKPROBE_SYMBOL(kgdb_io_ready); static int kgdb_reenter_check(struct kgdb_state *ks) { @@ -422,8 +534,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks) exception_level = 0; kgdb_skipexception(ks->ex_vector, ks->linux_regs); dbg_activate_sw_breakpoints(); - printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", - addr); + pr_crit("re-enter error: breakpoint removed %lx\n", addr); WARN_ON_ONCE(1); return 1; @@ -433,10 +544,11 @@ static int kgdb_reenter_check(struct kgdb_state *ks) if (exception_level > 1) { dump_stack(); + kgdb_io_module_registered = false; panic("Recursive entry to debugger"); } - printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); + pr_crit("re-enter exception: ALL breakpoints killed\n"); #ifdef CONFIG_KGDB_KDB /* Allow kdb to debug itself one level */ return 0; @@ -446,6 +558,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks) return 1; } +NOKPROBE_SYMBOL(kgdb_reenter_check); static void dbg_touch_watchdogs(void) { @@ -453,6 +566,7 @@ static void dbg_touch_watchdogs(void) 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) @@ -463,6 +577,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, 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; @@ -476,6 +591,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, arch_kgdb_ops.disable_hw_break(regs); acquirelock: + rcu_read_lock(); /* * Interrupts will be restored by the 'trap return' code, except when * single stepping. @@ -511,6 +627,9 @@ cpu_loop: 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; @@ -523,13 +642,16 @@ return_normal: 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_dec(); + smp_mb__before_atomic(); atomic_dec(&slaves_in_kgdb); dbg_touch_watchdogs(); local_irq_restore(flags); + rcu_read_unlock(); return 0; } cpu_relax(); @@ -548,6 +670,7 @@ return_normal: raw_spin_unlock(&dbg_master_lock); dbg_touch_watchdogs(); local_irq_restore(flags); + rcu_read_unlock(); goto acquirelock; } @@ -563,6 +686,8 @@ return_normal: 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(); @@ -575,17 +700,25 @@ return_normal: 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() */ - if ((!kgdb_single_step) && kgdb_do_roundup) - kgdb_roundup_cpus(flags); + 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: */ - while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + - atomic_read(&slaves_in_kgdb)) != online_cpus) - cpu_relax(); + 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 @@ -608,6 +741,29 @@ cpu_master_loop: 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); } @@ -623,10 +779,14 @@ cpu_master_loop: } } + 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. */ @@ -647,19 +807,23 @@ kgdb_restore: 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_dec(); + 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 @@ -673,36 +837,34 @@ 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->kgdb_usethreadid = 0; ks->linux_regs = regs; if (kgdb_reenter_check(ks)) - goto out; /* Ouch, double exception ! */ + return 0; /* Ouch, double exception ! */ if (kgdb_info[ks->cpu].enter_kgdb != 0) - goto out; + return 0; - ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); -out: - if (arch_kgdb_ops.enable_nmi) - arch_kgdb_ops.enable_nmi(1); - return ret; + 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. It's not defined static so that only one instance with this - * name exists in the kernel. + * 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) { @@ -719,6 +881,8 @@ int kgdb_nmicallback(int cpu, void *regs) 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; @@ -731,6 +895,33 @@ int kgdb_nmicallback(int cpu, void *regs) #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) @@ -754,46 +945,75 @@ static struct console kgdbcons = { .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(int key) +static void sysrq_handle_dbg(u8 key) { if (!dbg_io_ops) { - printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); + pr_crit("ERROR: No KGDB I/O module available\n"); return; } if (!kgdb_connected) { #ifdef CONFIG_KGDB_KDB if (!dbg_kdb_mode) - printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); + pr_crit("KGDB or $3#33 for KDB\n"); #else - printk(KERN_CRIT "Entering KGDB\n"); + pr_crit("Entering KGDB\n"); #endif } kgdb_breakpoint(); } -static struct sysrq_key_op sysrq_dbg_op = { +static const struct sysrq_key_op sysrq_dbg_op = { .handler = sysrq_handle_dbg, .help_msg = "debug(g)", .action_msg = "DEBUG", }; #endif -static int kgdb_panic_event(struct notifier_block *self, - unsigned long val, - void *data) +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", (char *)data); + kdb_printf("PANIC: %s\n", msg); + kgdb_breakpoint(); - return NOTIFY_DONE; } -static struct notifier_block kgdb_panic_event_nb = { - .notifier_call = kgdb_panic_event, - .priority = INT_MAX, -}; +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) { @@ -805,6 +1025,9 @@ void __init dbg_late_init(void) 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 @@ -813,12 +1036,13 @@ 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] detatch debug client + * 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; } @@ -843,8 +1067,6 @@ static void kgdb_register_callbacks(void) kgdb_arch_late(); register_module_notifier(&dbg_module_load_nb); register_reboot_notifier(&dbg_reboot_notifier); - atomic_notifier_chain_register(&panic_notifier_list, - &kgdb_panic_event_nb); #ifdef CONFIG_MAGIC_SYSRQ register_sysrq_key('g', &sysrq_dbg_op); #endif @@ -858,16 +1080,14 @@ static void kgdb_register_callbacks(void) 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 + * 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); - atomic_notifier_chain_unregister(&panic_notifier_list, - &kgdb_panic_event_nb); kgdb_arch_exit(); #ifdef CONFIG_MAGIC_SYSRQ unregister_sysrq_key('g', &sysrq_dbg_op); @@ -879,39 +1099,6 @@ static void kgdb_unregister_callbacks(void) } } -/* - * There are times a tasklet needs to be used vs a compiled in - * break point so as to cause an exception outside a kgdb I/O module, - * such as is the case with kgdboe, where calling a breakpoint in the - * I/O driver itself would be fatal. - */ -static void kgdb_tasklet_bpt(unsigned long ing) -{ - kgdb_breakpoint(); - atomic_set(&kgdb_break_tasklet_var, 0); -} - -static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); - -void kgdb_schedule_breakpoint(void) -{ - if (atomic_read(&kgdb_break_tasklet_var) || - atomic_read(&kgdb_active) != -1 || - atomic_read(&kgdb_setting_breakpoint)) - return; - atomic_inc(&kgdb_break_tasklet_var); - tasklet_schedule(&kgdb_tasklet_breakpoint); -} -EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); - -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_dbg_io_ops: the io ops vector @@ -920,16 +1107,22 @@ static void kgdb_initial_breakpoint(void) */ 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); - if (dbg_io_ops) { - spin_unlock(&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); - printk(KERN_ERR "kgdb: Another I/O driver is already " - "registered with KGDB.\n"); - return -EBUSY; + 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) { @@ -944,13 +1137,18 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) spin_unlock(&kgdb_registration_lock); - printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", - new_dbg_io_ops->name); + 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) + if (kgdb_break_asap && + (!dbg_is_early || IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG))) kgdb_initial_breakpoint(); return 0; @@ -958,7 +1156,7 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) EXPORT_SYMBOL_GPL(kgdb_register_io_module); /** - * kkgdb_unregister_io_module - unregister KGDB IO module + * kgdb_unregister_io_module - unregister KGDB IO module * @old_dbg_io_ops: the io ops vector * * Unregister it with the KGDB core. @@ -980,8 +1178,10 @@ void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) spin_unlock(&kgdb_registration_lock); - printk(KERN_INFO - "kgdb: Unregistered I/O driver %s, debugger disabled.\n", + 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); @@ -1006,7 +1206,7 @@ int dbg_io_get_char(void) * otherwise as a quick means to stop program execution and "break" into * the debugger. */ -void kgdb_breakpoint(void) +noinline void kgdb_breakpoint(void) { atomic_inc(&kgdb_setting_breakpoint); wmb(); /* Sync point before breakpoint */ @@ -1021,7 +1221,8 @@ static int __init opt_kgdb_wait(char *str) kgdb_break_asap = 1; kdb_init(KDB_INIT_EARLY); - if (kgdb_io_module_registered) + if (kgdb_io_module_registered && + IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG)) kgdb_initial_breakpoint(); return 0; |