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Diffstat (limited to 'kernel/debug/debug_core.c')
-rw-r--r--kernel/debug/debug_core.c322
1 files changed, 202 insertions, 120 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index de407c78178..1adf62b39b9 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -29,6 +29,7 @@
*/
#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>
@@ -41,17 +42,19 @@
#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/pid.h>
#include <linux/smp.h>
#include <linux/mm.h>
+#include <linux/vmacache.h>
+#include <linux/rcupdate.h>
#include <asm/cacheflush.h>
#include <asm/byteorder.h>
-#include <asm/atomic.h>
-#include <asm/system.h>
+#include <linux/atomic.h>
#include "debug_core.h"
@@ -74,6 +77,8 @@ 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 */
+static int kgdbreboot;
/* kgdb console driver is loaded */
static int kgdb_con_registered;
/* determine if kgdb console output should be used */
@@ -95,6 +100,7 @@ static int __init opt_kgdb_con(char *str)
early_param("kgdbcon", opt_kgdb_con);
module_param(kgdb_use_con, int, 0644);
+module_param(kgdbreboot, int, 0644);
/*
* Holds information about breakpoints in a kernel. These breakpoints are
@@ -109,13 +115,15 @@ static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
*/
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 passive_cpu_wait[NR_CPUS];
-static atomic_t cpu_in_kgdb[NR_CPUS];
+static atomic_t masters_in_kgdb;
+static atomic_t slaves_in_kgdb;
static atomic_t kgdb_break_tasklet_var;
atomic_t kgdb_setting_breakpoint;
@@ -154,37 +162,39 @@ early_param("nokgdbroundup", opt_nokgdbroundup);
* Weak aliases for breakpoint management,
* can be overriden by architectures when needed:
*/
-int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
+int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
{
int err;
- err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
+ err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+ BREAK_INSTR_SIZE);
if (err)
return err;
-
- return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
- BREAK_INSTR_SIZE);
+ err = probe_kernel_write((char *)bpt->bpt_addr,
+ arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
+ return err;
}
-int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
+int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
{
- return probe_kernel_write((char *)addr,
- (char *)bundle, BREAK_INSTR_SIZE);
+ return probe_kernel_write((char *)bpt->bpt_addr,
+ (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
}
int __weak kgdb_validate_break_address(unsigned long addr)
{
- char tmp_variable[BREAK_INSTR_SIZE];
+ struct kgdb_bkpt tmp;
int err;
- /* Validate setting the breakpoint and then removing it. In the
+ /* 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.
*/
- err = kgdb_arch_set_breakpoint(addr, tmp_variable);
+ tmp.bpt_addr = addr;
+ err = kgdb_arch_set_breakpoint(&tmp);
if (err)
return err;
- err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
+ err = kgdb_arch_remove_breakpoint(&tmp);
if (err)
printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
"memory destroyed at: %lx", addr);
@@ -206,18 +216,6 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
return 0;
}
-/**
- * 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)
-{
-}
-
/*
* Some architectures need cache flushes when we set/clear a
* breakpoint:
@@ -227,10 +225,17 @@ 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);
+ if (current->mm) {
+ int i;
+
+ for (i = 0; i < VMACACHE_SIZE; i++) {
+ if (!current->vmacache[i])
+ continue;
+ flush_cache_range(current->vmacache[i],
+ addr, addr + BREAK_INSTR_SIZE);
+ }
}
+
/* Force flush instruction cache if it was outside the mm */
flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
}
@@ -240,7 +245,6 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
*/
int dbg_activate_sw_breakpoints(void)
{
- unsigned long addr;
int error;
int ret = 0;
int i;
@@ -249,16 +253,15 @@ int dbg_activate_sw_breakpoints(void)
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);
+ error = kgdb_arch_set_breakpoint(&kgdb_break[i]);
if (error) {
ret = error;
- printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
+ printk(KERN_INFO "KGDB: BP install failed: %lx",
+ kgdb_break[i].bpt_addr);
continue;
}
- kgdb_flush_swbreak_addr(addr);
+ kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
kgdb_break[i].state = BP_ACTIVE;
}
return ret;
@@ -307,7 +310,6 @@ int dbg_set_sw_break(unsigned long addr)
int dbg_deactivate_sw_breakpoints(void)
{
- unsigned long addr;
int error;
int ret = 0;
int i;
@@ -315,15 +317,14 @@ int dbg_deactivate_sw_breakpoints(void)
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);
+ error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
if (error) {
- printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
+ printk(KERN_INFO "KGDB: BP remove failed: %lx\n",
+ kgdb_break[i].bpt_addr);
ret = error;
}
- kgdb_flush_swbreak_addr(addr);
+ kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
kgdb_break[i].state = BP_SET;
}
return ret;
@@ -357,7 +358,6 @@ int kgdb_isremovedbreak(unsigned long addr)
int dbg_remove_all_break(void)
{
- unsigned long addr;
int error;
int i;
@@ -365,12 +365,10 @@ int dbg_remove_all_break(void)
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);
+ error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
if (error)
printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
- addr);
+ kgdb_break[i].bpt_addr);
setundefined:
kgdb_break[i].state = BP_UNDEFINED;
}
@@ -457,26 +455,34 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
return 1;
}
-static void dbg_cpu_switch(int cpu, int next_cpu)
+static void dbg_touch_watchdogs(void)
{
- /* Mark the cpu we are switching away from as a slave when it
- * holds the kgdb_active token. This must be done so that the
- * that all the cpus wait in for the debug core will not enter
- * again as the master. */
- if (cpu == atomic_read(&kgdb_active)) {
- kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
- kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER;
- }
- kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER;
+ touch_softlockup_watchdog_sync();
+ clocksource_touch_watchdog();
+ rcu_cpu_stall_reset();
}
-static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
+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 i, cpu;
+ int cpu;
int trace_on = 0;
+ int online_cpus = num_online_cpus();
+
+ 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:
/*
* Interrupts will be restored by the 'trap return' code, except when
@@ -489,14 +495,15 @@ acquirelock:
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 before
- * our cpu_in_kgdb[] flag setting does:
- */
- atomic_inc(&cpu_in_kgdb[cpu]);
- if (exception_level == 1)
+ /* 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
@@ -508,10 +515,12 @@ cpu_loop:
kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
goto cpu_master_loop;
} else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
- if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu)
+ if (raw_spin_trylock(&dbg_master_lock)) {
+ atomic_xchg(&kgdb_active, cpu);
break;
+ }
} else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
- if (!atomic_read(&passive_cpu_wait[cpu]))
+ if (!raw_spin_is_locked(&dbg_slave_lock))
goto return_normal;
} else {
return_normal:
@@ -522,9 +531,12 @@ return_normal:
arch_kgdb_ops.correct_hw_break();
if (trace_on)
tracing_on();
- atomic_dec(&cpu_in_kgdb[cpu]);
- touch_softlockup_watchdog_sync();
- clocksource_touch_watchdog();
+ 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);
return 0;
}
@@ -533,7 +545,7 @@ return_normal:
/*
* For single stepping, try to only enter on the processor
- * that was single stepping. To gaurd against a deadlock, the
+ * 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.
*/
@@ -541,8 +553,8 @@ return_normal:
(kgdb_info[cpu].task &&
kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
atomic_set(&kgdb_active, -1);
- touch_softlockup_watchdog_sync();
- clocksource_touch_watchdog();
+ raw_spin_unlock(&dbg_master_lock);
+ dbg_touch_watchdogs();
local_irq_restore(flags);
goto acquirelock;
@@ -563,30 +575,29 @@ return_normal:
if (dbg_io_ops->pre_exception)
dbg_io_ops->pre_exception();
- 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) {
- for (i = 0; i < NR_CPUS; i++)
- atomic_inc(&passive_cpu_wait[i]);
- }
+ 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() */
- if ((!kgdb_single_step) && kgdb_do_roundup)
+ else if ((!kgdb_single_step) && 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 (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i]))
- cpu_relax();
- }
+ while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
+ atomic_read(&slaves_in_kgdb)) != online_cpus)
+ cpu_relax();
/*
* At this point the primary processor is completely
@@ -615,7 +626,8 @@ cpu_master_loop:
if (error == DBG_PASS_EVENT) {
dbg_kdb_mode = !dbg_kdb_mode;
} else if (error == DBG_SWITCH_CPU_EVENT) {
- dbg_cpu_switch(cpu, dbg_switch_cpu);
+ kgdb_info[dbg_switch_cpu].exception_state |=
+ DCPU_NEXT_MASTER;
goto cpu_loop;
} else {
kgdb_info[cpu].ret_state = error;
@@ -627,24 +639,11 @@ cpu_master_loop:
if (dbg_io_ops->post_exception)
dbg_io_ops->post_exception();
- atomic_dec(&cpu_in_kgdb[ks->cpu]);
-
if (!kgdb_single_step) {
- for (i = NR_CPUS-1; i >= 0; i--)
- atomic_dec(&passive_cpu_wait[i]);
- /*
- * Wait till all the CPUs have quit from the debugger,
- * but allow a CPU that hit an exception and is
- * waiting to become the master to remain in the debug
- * core.
- */
- for_each_online_cpu(i) {
- while (kgdb_do_roundup &&
- atomic_read(&cpu_in_kgdb[i]) &&
- !(kgdb_info[i].exception_state &
- DCPU_WANT_MASTER))
- cpu_relax();
- }
+ 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:
@@ -655,12 +654,20 @@ kgdb_restore:
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].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);
- touch_softlockup_watchdog_sync();
- clocksource_touch_watchdog();
+ raw_spin_unlock(&dbg_master_lock);
+ dbg_touch_watchdogs();
local_irq_restore(flags);
return kgdb_info[cpu].ret_state;
@@ -678,24 +685,46 @@ 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;
+ int ret = 0;
+ if (arch_kgdb_ops.enable_nmi)
+ arch_kgdb_ops.enable_nmi(0);
+
+ 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))
- return 0; /* Ouch, double exception ! */
- kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER;
- ret = kgdb_cpu_enter(ks, regs);
- kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER |
- DCPU_IS_SLAVE);
+ 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;
}
+/*
+ * 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.
+ */
+
+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
@@ -706,12 +735,34 @@ int kgdb_nmicallback(int cpu, void *regs)
ks->cpu = cpu;
ks->linux_regs = regs;
- if (!atomic_read(&cpu_in_kgdb[cpu]) &&
- atomic_read(&kgdb_active) != -1 &&
- atomic_read(&kgdb_active) != cpu) {
- kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
- kgdb_cpu_enter(ks, regs);
- kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE;
+ 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;
+}
+
+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
@@ -761,7 +812,7 @@ static void sysrq_handle_dbg(int key)
static struct sysrq_key_op sysrq_dbg_op = {
.handler = sysrq_handle_dbg,
- .help_msg = "debug(G)",
+ .help_msg = "debug(g)",
.action_msg = "DEBUG",
};
#endif
@@ -793,6 +844,33 @@ void __init dbg_late_init(void)
kdb_init(KDB_INIT_FULL);
}
+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] detatch debug client
+ * -1 == Do nothing... and use this until the board resets
+ */
+ switch (kgdbreboot) {
+ case 1:
+ kgdb_breakpoint();
+ 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) {
@@ -800,6 +878,8 @@ static void kgdb_register_callbacks(void)
kgdb_arch_init();
if (!dbg_is_early)
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
@@ -821,6 +901,8 @@ static void kgdb_unregister_callbacks(void)
*/
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();
@@ -961,7 +1043,7 @@ 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 */
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-12-05 23:32:32 +0000