1 files changed, 208 insertions, 0 deletions

diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
new file mode 100644
index 000000000000..483fa4e7aaac
--- /dev/null
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -0,0 +1,208 @@
+/*
+ * Kernel Debugger Architecture Independent Stack Traceback
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
+ * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/kdb.h>
+#include <linux/nmi.h>
+#include <asm/system.h>
+#include "kdb_private.h"
+
+
+static void kdb_show_stack(struct task_struct *p, void *addr)
+{
+        int old_lvl = console_loglevel;
+        console_loglevel = 15;
+        kdb_set_current_task(p);
+        if (addr) {
+                show_stack((struct task_struct *)p, addr);
+        } else if (kdb_current_regs) {
+#ifdef CONFIG_X86
+                show_stack(p, &kdb_current_regs->sp);
+#else
+                show_stack(p, NULL);
+#endif
+        } else {
+                show_stack(p, NULL);
+        }
+        console_loglevel = old_lvl;
+}
+
+/*
+ * kdb_bt
+ *
+ *      This function implements the 'bt' command.  Print a stack
+ *      traceback.
+ *
+ *      bt [<address-expression>]       (addr-exp is for alternate stacks)
+ *      btp <pid>                       Kernel stack for <pid>
+ *      btt <address-expression>        Kernel stack for task structure at
+ *                                      <address-expression>
+ *      bta [DRSTCZEUIMA]               All useful processes, optionally
+ *                                      filtered by state
+ *      btc [<cpu>]                     The current process on one cpu,
+ *                                      default is all cpus
+ *
+ *      bt <address-expression> refers to a address on the stack, that location
+ *      is assumed to contain a return address.
+ *
+ *      btt <address-expression> refers to the address of a struct task.
+ *
+ * Inputs:
+ *      argc    argument count
+ *      argv    argument vector
+ * Outputs:
+ *      None.
+ * Returns:
+ *      zero for success, a kdb diagnostic if error
+ * Locking:
+ *      none.
+ * Remarks:
+ *      Backtrack works best when the code uses frame pointers.  But even
+ *      without frame pointers we should get a reasonable trace.
+ *
+ *      mds comes in handy when examining the stack to do a manual traceback or
+ *      to get a starting point for bt <address-expression>.
+ */
+
+static int
+kdb_bt1(struct task_struct *p, unsigned long mask,
+        int argcount, int btaprompt)
+{
+        char buffer[2];
+        if (kdb_getarea(buffer[0], (unsigned long)p) ||
+            kdb_getarea(buffer[0], (unsigned long)(p+1)-1))
+                return KDB_BADADDR;
+        if (!kdb_task_state(p, mask))
+                return 0;
+        kdb_printf("Stack traceback for pid %d\n", p->pid);
+        kdb_ps1(p);
+        kdb_show_stack(p, NULL);
+        if (btaprompt) {
+                kdb_getstr(buffer, sizeof(buffer),
+                           "Enter <q> to end, <cr> to continue:");
+                if (buffer[0] == 'q') {
+                        kdb_printf("\n");
+                        return 1;
+                }
+        }
+        touch_nmi_watchdog();
+        return 0;
+}
+
+int
+kdb_bt(int argc, const char **argv)
+{
+        int diag;
+        int argcount = 5;
+        int btaprompt = 1;
+        int nextarg;
+        unsigned long addr;
+        long offset;
+
+        kdbgetintenv("BTARGS", &argcount);      /* Arguments to print */
+        kdbgetintenv("BTAPROMPT", &btaprompt);  /* Prompt after each
+                                                 * proc in bta */
+
+        if (strcmp(argv[0], "bta") == 0) {
+                struct task_struct *g, *p;
+                unsigned long cpu;
+                unsigned long mask = kdb_task_state_string(argc ? argv[1] :
+                                                           NULL);
+                if (argc == 0)
+                        kdb_ps_suppressed();
+                /* Run the active tasks first */
+                for_each_online_cpu(cpu) {
+                        p = kdb_curr_task(cpu);
+                        if (kdb_bt1(p, mask, argcount, btaprompt))
+                                return 0;
+                }
+                /* Now the inactive tasks */
+                kdb_do_each_thread(g, p) {
+                        if (task_curr(p))
+                                continue;
+                        if (kdb_bt1(p, mask, argcount, btaprompt))
+                                return 0;
+                } kdb_while_each_thread(g, p);
+        } else if (strcmp(argv[0], "btp") == 0) {
+                struct task_struct *p;
+                unsigned long pid;
+                if (argc != 1)
+                        return KDB_ARGCOUNT;
+                diag = kdbgetularg((char *)argv[1], &pid);
+                if (diag)
+                        return diag;
+                p = find_task_by_pid_ns(pid, &init_pid_ns);
+                if (p) {
+                        kdb_set_current_task(p);
+                        return kdb_bt1(p, ~0UL, argcount, 0);
+                }
+                kdb_printf("No process with pid == %ld found\n", pid);
+                return 0;
+        } else if (strcmp(argv[0], "btt") == 0) {
+                if (argc != 1)
+                        return KDB_ARGCOUNT;
+                diag = kdbgetularg((char *)argv[1], &addr);
+                if (diag)
+                        return diag;
+                kdb_set_current_task((struct task_struct *)addr);
+                return kdb_bt1((struct task_struct *)addr, ~0UL, argcount, 0);
+        } else if (strcmp(argv[0], "btc") == 0) {
+                unsigned long cpu = ~0;
+                struct task_struct *save_current_task = kdb_current_task;
+                char buf[80];
+                if (argc > 1)
+                        return KDB_ARGCOUNT;
+                if (argc == 1) {
+                        diag = kdbgetularg((char *)argv[1], &cpu);
+                        if (diag)
+                                return diag;
+                }
+                /* Recursive use of kdb_parse, do not use argv after
+                 * this point */
+                argv = NULL;
+                if (cpu != ~0) {
+                        if (cpu >= num_possible_cpus() || !cpu_online(cpu)) {
+                                kdb_printf("no process for cpu %ld\n", cpu);
+                                return 0;
+                        }
+                        sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
+                        kdb_parse(buf);
+                        return 0;
+                }
+                kdb_printf("btc: cpu status: ");
+                kdb_parse("cpu\n");
+                for_each_online_cpu(cpu) {
+                        sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
+                        kdb_parse(buf);
+                        touch_nmi_watchdog();
+                }
+                kdb_set_current_task(save_current_task);
+                return 0;
+        } else {
+                if (argc) {
+                        nextarg = 1;
+                        diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
+                                             &offset, NULL);
+                        if (diag)
+                                return diag;
+                        kdb_show_stack(kdb_current_task, (void *)addr);
+                        return 0;
+                } else {
+                        return kdb_bt1(kdb_current_task, ~0UL, argcount, 0);
+                }
+        }
+
+        /* NOTREACHED */
+        return 0;
+}