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-rw-r--r--kernel/debug/debug_core.c107
-rw-r--r--kernel/debug/debug_core.h24
-rw-r--r--kernel/debug/gdbstub.c36
3 files changed, 150 insertions, 17 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 7e03969330bc..6e1fa829fdeb 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -43,6 +43,7 @@
#include <linux/sysrq.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>
@@ -77,6 +78,11 @@ static DEFINE_SPINLOCK(kgdb_registration_lock);
static int kgdb_con_registered;
/* determine if kgdb console output should be used */
static int kgdb_use_con;
+/* Next cpu to become the master debug core */
+int dbg_switch_cpu;
+
+/* Use kdb or gdbserver mode */
+static int dbg_kdb_mode = 1;
static int __init opt_kgdb_con(char *str)
{
@@ -100,6 +106,7 @@ static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
* The CPU# of the active CPU, or -1 if none:
*/
atomic_t kgdb_active = ATOMIC_INIT(-1);
+EXPORT_SYMBOL_GPL(kgdb_active);
/*
* We use NR_CPUs not PERCPU, in case kgdb is used to debug early
@@ -301,7 +308,7 @@ int dbg_set_sw_break(unsigned long addr)
return 0;
}
-static int kgdb_deactivate_sw_breakpoints(void)
+int dbg_deactivate_sw_breakpoints(void)
{
unsigned long addr;
int error;
@@ -395,8 +402,14 @@ static int kgdb_io_ready(int print_wait)
return 1;
if (atomic_read(&kgdb_setting_breakpoint))
return 1;
- if (print_wait)
+ if (print_wait) {
+#ifdef CONFIG_KGDB_KDB
+ if (!dbg_kdb_mode)
+ printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
+#else
printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
+#endif
+ }
return 1;
}
@@ -410,7 +423,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
/* Panic on recursive debugger calls: */
exception_level++;
addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
- kgdb_deactivate_sw_breakpoints();
+ dbg_deactivate_sw_breakpoints();
/*
* If the break point removed ok at the place exception
@@ -443,11 +456,24 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
return 1;
}
+static void dbg_cpu_switch(int cpu, int next_cpu)
+{
+ /* 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;
+}
+
static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
{
unsigned long flags;
int sstep_tries = 100;
- int error = 0;
+ int error;
int i, cpu;
int trace_on = 0;
acquirelock:
@@ -460,6 +486,8 @@ acquirelock:
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 before
* our cpu_in_kgdb[] flag setting does:
@@ -471,7 +499,11 @@ acquirelock:
* master cpu and acquire the kgdb_active lock:
*/
while (1) {
- if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
+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 (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu)
break;
} else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
@@ -513,7 +545,7 @@ return_normal:
}
if (!kgdb_io_ready(1)) {
- error = 1;
+ kgdb_info[cpu].ret_state = 1;
goto kgdb_restore; /* No I/O connection, resume the system */
}
@@ -548,7 +580,7 @@ return_normal:
* Wait for the other CPUs to be notified and be waiting for us:
*/
for_each_online_cpu(i) {
- while (!atomic_read(&cpu_in_kgdb[i]))
+ while (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i]))
cpu_relax();
}
@@ -557,7 +589,7 @@ return_normal:
* in the debugger and all secondary CPUs are quiescent
*/
kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
- kgdb_deactivate_sw_breakpoints();
+ dbg_deactivate_sw_breakpoints();
kgdb_single_step = 0;
kgdb_contthread = current;
exception_level = 0;
@@ -565,8 +597,26 @@ return_normal:
if (trace_on)
tracing_off();
- /* Talk to debugger with gdbserial protocol */
- error = gdb_serial_stub(ks);
+ while (1) {
+cpu_master_loop:
+ if (dbg_kdb_mode) {
+ kgdb_connected = 1;
+ error = kdb_stub(ks);
+ } else {
+ error = gdb_serial_stub(ks);
+ }
+
+ if (error == DBG_PASS_EVENT) {
+ dbg_kdb_mode = !dbg_kdb_mode;
+ kgdb_connected = 0;
+ } else if (error == DBG_SWITCH_CPU_EVENT) {
+ dbg_cpu_switch(cpu, dbg_switch_cpu);
+ goto cpu_loop;
+ } else {
+ kgdb_info[cpu].ret_state = error;
+ break;
+ }
+ }
/* Call the I/O driver's post_exception routine */
if (dbg_io_ops->post_exception)
@@ -578,11 +628,16 @@ return_normal:
for (i = NR_CPUS-1; i >= 0; i--)
atomic_dec(&passive_cpu_wait[i]);
/*
- * Wait till all the CPUs have quit
- * from the debugger.
+ * 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 (atomic_read(&cpu_in_kgdb[i]))
+ while (kgdb_do_roundup &&
+ atomic_read(&cpu_in_kgdb[i]) &&
+ !(kgdb_info[i].exception_state &
+ DCPU_WANT_MASTER))
cpu_relax();
}
}
@@ -603,7 +658,7 @@ kgdb_restore:
clocksource_touch_watchdog();
local_irq_restore(flags);
- return error;
+ return kgdb_info[cpu].ret_state;
}
/*
@@ -632,7 +687,8 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
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;
+ kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER |
+ DCPU_IS_SLAVE);
return ret;
}
@@ -665,7 +721,7 @@ static void kgdb_console_write(struct console *co, const char *s,
/* If we're debugging, or KGDB has not connected, don't try
* and print. */
- if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
+ if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
return;
local_irq_save(flags);
@@ -687,8 +743,14 @@ static void sysrq_handle_dbg(int key, struct tty_struct *tty)
printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
return;
}
- if (!kgdb_connected)
+ if (!kgdb_connected) {
+#ifdef CONFIG_KGDB_KDB
+ if (!dbg_kdb_mode)
+ printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
+#else
printk(KERN_CRIT "Entering KGDB\n");
+#endif
+ }
kgdb_breakpoint();
}
@@ -817,6 +879,16 @@ void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
}
EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
+int dbg_io_get_char(void)
+{
+ int ret = dbg_io_ops->read_char();
+ if (!dbg_kdb_mode)
+ return ret;
+ if (ret == 127)
+ return 8;
+ return ret;
+}
+
/**
* kgdb_breakpoint - generate breakpoint exception
*
@@ -839,6 +911,7 @@ static int __init opt_kgdb_wait(char *str)
{
kgdb_break_asap = 1;
+ kdb_init(KDB_INIT_EARLY);
if (kgdb_io_module_registered)
kgdb_initial_breakpoint();
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index db554f9be51d..44cf3de8cf9e 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -38,6 +38,8 @@ struct debuggerinfo_struct {
void *debuggerinfo;
struct task_struct *task;
int exception_state;
+ int ret_state;
+ int irq_depth;
};
extern struct debuggerinfo_struct kgdb_info[];
@@ -47,9 +49,31 @@ extern int dbg_remove_all_break(void);
extern int dbg_set_sw_break(unsigned long addr);
extern int dbg_remove_sw_break(unsigned long addr);
extern int dbg_activate_sw_breakpoints(void);
+extern int dbg_deactivate_sw_breakpoints(void);
+
+/* polled character access to i/o module */
+extern int dbg_io_get_char(void);
+
+/* stub return value for switching between the gdbstub and kdb */
+#define DBG_PASS_EVENT -12345
+/* Switch from one cpu to another */
+#define DBG_SWITCH_CPU_EVENT -123456
+extern int dbg_switch_cpu;
/* gdbstub interface functions */
extern int gdb_serial_stub(struct kgdb_state *ks);
extern void gdbstub_msg_write(const char *s, int len);
+/* gdbstub functions used for kdb <-> gdbstub transition */
+extern int gdbstub_state(struct kgdb_state *ks, char *cmd);
+
+#ifdef CONFIG_KGDB_KDB
+extern int kdb_stub(struct kgdb_state *ks);
+#else /* ! CONFIG_KGDB_KDB */
+static inline int kdb_stub(struct kgdb_state *ks)
+{
+ return DBG_PASS_EVENT;
+}
+#endif /* CONFIG_KGDB_KDB */
+
#endif /* _DEBUG_CORE_H_ */
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index ccdf0929f12d..188203a19657 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -887,6 +887,13 @@ int gdb_serial_stub(struct kgdb_state *ks)
case 'Z': /* Break point set */
gdb_cmd_break(ks);
break;
+#ifdef CONFIG_KGDB_KDB
+ case '3': /* Escape into back into kdb */
+ if (remcom_in_buffer[1] == '\0') {
+ gdb_cmd_detachkill(ks);
+ return DBG_PASS_EVENT;
+ }
+#endif
case 'C': /* Exception passing */
tmp = gdb_cmd_exception_pass(ks);
if (tmp > 0)
@@ -932,3 +939,32 @@ kgdb_exit:
error = 1;
return error;
}
+
+int gdbstub_state(struct kgdb_state *ks, char *cmd)
+{
+ int error;
+
+ switch (cmd[0]) {
+ case 'e':
+ error = kgdb_arch_handle_exception(ks->ex_vector,
+ ks->signo,
+ ks->err_code,
+ remcom_in_buffer,
+ remcom_out_buffer,
+ ks->linux_regs);
+ return error;
+ case 's':
+ case 'c':
+ strcpy(remcom_in_buffer, cmd);
+ return 0;
+ case '?':
+ gdb_cmd_status(ks);
+ break;
+ case '\0':
+ strcpy(remcom_out_buffer, "");
+ break;
+ }
+ dbg_io_ops->write_char('+');
+ put_packet(remcom_out_buffer);
+ return 0;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.