kgdb: Always process the whole breakpoint list on activate or deactivate

[linux-3.10.git] / kernel / kgdb.c

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 7d70146340224b501c2c77dec5fdc0a40bb1820a..2eb517e2351462bd263d8976cf3d2108ecfeebc2 100644 (file)
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -129,6 +129,7 @@ struct task_struct          *kgdb_usethread;
 struct task_struct             *kgdb_contthread;
 
 int                            kgdb_single_step;
+pid_t                          kgdb_sstep_pid;
 
 /* Our I/O buffers. */
 static char                    remcom_in_buffer[BUFMAX];
@@ -541,12 +542,17 @@ static struct task_struct *getthread(struct pt_regs *regs, int tid)
         */
        if (tid == 0 || tid == -1)
                tid = -atomic_read(&kgdb_active) - 2;
-       if (tid < 0) {
+       if (tid < -1 && tid > -NR_CPUS - 2) {
                if (kgdb_info[-tid - 2].task)
                        return kgdb_info[-tid - 2].task;
                else
                        return idle_task(-tid - 2);
        }
+       if (tid <= 0) {
+               printk(KERN_ERR "KGDB: Internal thread select error\n");
+               dump_stack();
+               return NULL;
+       }
 
        /*
         * find_task_by_pid_ns() does not take the tasklist lock anymore
@@ -619,7 +625,8 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
 static int kgdb_activate_sw_breakpoints(void)
 {
        unsigned long addr;
-       int error = 0;
+       int error;
+       int ret = 0;
        int i;
 
        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
@@ -629,13 +636,16 @@ static int kgdb_activate_sw_breakpoints(void)
                addr = kgdb_break[i].bpt_addr;
                error = kgdb_arch_set_breakpoint(addr,
                                kgdb_break[i].saved_instr);
-               if (error)
-                       return error;
+               if (error) {
+                       ret = error;
+                       printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
+                       continue;
+               }
 
                kgdb_flush_swbreak_addr(addr);
                kgdb_break[i].state = BP_ACTIVE;
        }
-       return 0;
+       return ret;
 }
 
 static int kgdb_set_sw_break(unsigned long addr)
@@ -682,7 +692,8 @@ static int kgdb_set_sw_break(unsigned long addr)
 static int kgdb_deactivate_sw_breakpoints(void)
 {
        unsigned long addr;
-       int error = 0;
+       int error;
+       int ret = 0;
        int i;
 
        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
@@ -691,13 +702,15 @@ static int kgdb_deactivate_sw_breakpoints(void)
                addr = kgdb_break[i].bpt_addr;
                error = kgdb_arch_remove_breakpoint(addr,
                                        kgdb_break[i].saved_instr);
-               if (error)
-                       return error;
+               if (error) {
+                       printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
+                       ret = error;
+               }
 
                kgdb_flush_swbreak_addr(addr);
                kgdb_break[i].state = BP_SET;
        }
-       return 0;
+       return ret;
 }
 
 static int kgdb_remove_sw_break(unsigned long addr)
@@ -1204,8 +1217,10 @@ static int gdb_cmd_exception_pass(struct kgdb_state *ks)
                return 1;
 
        } else {
-               error_packet(remcom_out_buffer, -EINVAL);
-               return 0;
+               kgdb_msg_write("KGDB only knows signal 9 (pass)"
+                       " and 15 (pass and disconnect)\n"
+                       "Executing a continue without signal passing\n", 0);
+               remcom_in_buffer[0] = 'c';
        }
 
        /* Indicate fall through */
@@ -1395,6 +1410,7 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
        struct kgdb_state kgdb_var;
        struct kgdb_state *ks = &kgdb_var;
        unsigned long flags;
+       int sstep_tries = 100;
        int error = 0;
        int i, cpu;
 
@@ -1425,13 +1441,14 @@ acquirelock:
                cpu_relax();
 
        /*
-        * Do not start the debugger connection on this CPU if the last
-        * instance of the exception handler wanted to come into the
-        * debugger on a different CPU via a single step
+        * For single stepping, try to only enter on the processor
+        * that was single stepping.  To gaurd 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 &&
-           atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
-
+           (kgdb_info[cpu].task &&
+            kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
                atomic_set(&kgdb_active, -1);
                touch_softlockup_watchdog();
                clocksource_touch_watchdog();
@@ -1524,6 +1541,13 @@ acquirelock:
        }
 
 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;
+       }
        /* Free kgdb_active */
        atomic_set(&kgdb_active, -1);
        touch_softlockup_watchdog();