diff options
Diffstat (limited to 'kernel/debug/debug_core.c')
| -rw-r--r-- | kernel/debug/debug_core.c | 142 |
1 files changed, 84 insertions, 58 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 9e5934780f41..ce1bb2301c06 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 * @@ -22,10 +23,6 @@ * * 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 @@ -53,9 +50,9 @@ #include <linux/pid.h> #include <linux/smp.h> #include <linux/mm.h> -#include <linux/vmacache.h> #include <linux/rcupdate.h> #include <linux/irq.h> +#include <linux/security.h> #include <asm/cacheflush.h> #include <asm/byteorder.h> @@ -80,7 +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; @@ -94,14 +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); @@ -127,7 +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; @@ -163,7 +151,7 @@ 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) { @@ -177,17 +165,23 @@ int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 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 @@ -208,6 +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) { @@ -218,6 +213,7 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs) { return 0; } +NOKPROBE_SYMBOL(kgdb_skipexception); #ifdef CONFIG_SMP @@ -225,8 +221,6 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs) * Default (weak) implementation for kgdb_roundup_cpus */ -static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd); - void __weak kgdb_call_nmi_hook(void *ignored) { /* @@ -239,6 +233,10 @@ void __weak kgdb_call_nmi_hook(void *ignored) */ 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) { @@ -266,12 +264,12 @@ void __weak kgdb_roundup_cpus(void) continue; kgdb_info[cpu].rounding_up = true; - csd->func = kgdb_call_nmi_hook; ret = smp_call_function_single_async(cpu, csd); if (ret) kgdb_info[cpu].rounding_up = false; } } +NOKPROBE_SYMBOL(kgdb_roundup_cpus); #endif @@ -284,20 +282,10 @@ static void kgdb_flush_swbreak_addr(unsigned long addr) if (!CACHE_FLUSH_IS_SAFE) return; - if (current->mm) { - int i; - - for (i = 0; i < VMACACHE_SIZE; i++) { - if (!current->vmacache.vmas[i]) - continue; - flush_cache_range(current->vmacache.vmas[i], - 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: @@ -325,6 +313,7 @@ int dbg_activate_sw_breakpoints(void) } return ret; } +NOKPROBE_SYMBOL(dbg_activate_sw_breakpoints); int dbg_set_sw_break(unsigned long addr) { @@ -388,6 +377,7 @@ int dbg_deactivate_sw_breakpoints(void) } return ret; } +NOKPROBE_SYMBOL(dbg_deactivate_sw_breakpoints); int dbg_remove_sw_break(unsigned long addr) { @@ -451,6 +441,17 @@ 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) { @@ -509,6 +510,7 @@ static int kgdb_io_ready(int print_wait) } return 1; } +NOKPROBE_SYMBOL(kgdb_io_ready); static int kgdb_reenter_check(struct kgdb_state *ks) { @@ -556,6 +558,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks) return 1; } +NOKPROBE_SYMBOL(kgdb_reenter_check); static void dbg_touch_watchdogs(void) { @@ -563,6 +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) @@ -737,6 +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); } @@ -752,6 +779,8 @@ 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(); @@ -794,6 +823,7 @@ kgdb_restore: return kgdb_info[cpu].ret_state; } +NOKPROBE_SYMBOL(kgdb_cpu_enter); /* * kgdb_handle_exception() - main entry point from a kernel exception @@ -838,6 +868,7 @@ out: 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. @@ -872,6 +903,7 @@ 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) @@ -897,6 +929,7 @@ int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code, #endif return 1; } +NOKPROBE_SYMBOL(kgdb_nmicallin); static void kgdb_console_write(struct console *co, const char *s, unsigned count) @@ -920,8 +953,22 @@ 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) { pr_crit("ERROR: No KGDB I/O module available\n"); @@ -959,6 +1006,9 @@ void kgdb_panic(const char *msg) if (panic_timeout) return; + debug_locks_off(); + console_flush_on_panic(CONSOLE_FLUSH_PENDING); + if (dbg_kdb_mode) kdb_printf("PANIC: %s\n", msg); @@ -994,12 +1044,13 @@ 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; } @@ -1056,31 +1107,6 @@ 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); - /** * kgdb_register_io_module - register KGDB IO module * @new_dbg_io_ops: the io ops vector @@ -1138,7 +1164,7 @@ 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. |