4 files changed, 62 insertions, 1 deletions

diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index c190c2414197..12c95368124a 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -32,6 +32,7 @@
 #include "os.h"
 #include "umid.h"
 #include "irq_kern.h"
+#include "choose-mode.h"
 
 static int do_unlink_socket(struct notifier_block *notifier, 
                             unsigned long what, void *data)
@@ -276,6 +277,7 @@ void mconsole_proc(struct mc_request *req)
     go - continue the UML after a 'stop' \n\
     log <string> - make UML enter <string> into the kernel log\n\
     proc <file> - returns the contents of the UML's /proc/<file>\n\
+    stack <pid> - returns the stack of the specified pid\n\
 "
 
 void mconsole_help(struct mc_request *req)
@@ -479,6 +481,56 @@ void mconsole_sysrq(struct mc_request *req)
 }
 #endif
 
+/* Mconsole stack trace
+ *  Added by Allan Graves, Jeff Dike
+ *  Dumps a stacks registers to the linux console.
+ *  Usage stack <pid>.
+ */
+void do_stack(struct mc_request *req)
+{
+        char *ptr = req->request.data;
+        int pid_requested= -1;
+        struct task_struct *from = NULL;
+        struct task_struct *to = NULL;
+
+        /* Would be nice:
+         * 1) Send showregs output to mconsole.
+         * 2) Add a way to stack dump all pids.
+         */
+
+        ptr += strlen("stack");
+        while(isspace(*ptr)) ptr++;
+
+        /* Should really check for multiple pids or reject bad args here */
+        /* What do the arguments in mconsole_reply mean? */
+        if(sscanf(ptr, "%d", &pid_requested) == 0){
+                mconsole_reply(req, "Please specify a pid", 1, 0);
+                return;
+        }
+
+        from = current;
+        to = find_task_by_pid(pid_requested);
+
+        if((to == NULL) || (pid_requested == 0)) {
+                mconsole_reply(req, "Couldn't find that pid", 1, 0);
+                return;
+        }
+        to->thread.saved_task = current;
+
+        switch_to(from, to, from);
+        mconsole_reply(req, "Stack Dumped to console and message log", 0, 0);
+}
+
+void mconsole_stack(struct mc_request *req)
+{
+        /* This command doesn't work in TT mode, so let's check and then
+         * get out of here
+         */
+        CHOOSE_MODE(mconsole_reply(req, "Sorry, this doesn't work in TT mode",
+                                   1, 0),
+                    do_stack(req));
+}
+
 /* Changed by mconsole_setup, which is __setup, and called before SMP is
  * active.
  */
diff --git a/arch/um/drivers/mconsole_user.c b/arch/um/drivers/mconsole_user.c
index fe5afb13252c..a5b8aeade1c5 100644
--- a/arch/um/drivers/mconsole_user.c
+++ b/arch/um/drivers/mconsole_user.c
@@ -30,6 +30,7 @@ static struct mconsole_command commands[] = {
         { "go", mconsole_go, MCONSOLE_INTR },
         { "log", mconsole_log, MCONSOLE_INTR },
         { "proc", mconsole_proc, MCONSOLE_PROC },
+        { "stack", mconsole_stack, MCONSOLE_INTR },
 };
 
 /* Initialized in mconsole_init, which is an initcall */
diff --git a/arch/um/include/mconsole.h b/arch/um/include/mconsole.h
index cfa368e045a5..b1b512f47035 100644
--- a/arch/um/include/mconsole.h
+++ b/arch/um/include/mconsole.h
@@ -81,6 +81,7 @@ extern void mconsole_stop(struct mc_request *req);
 extern void mconsole_go(struct mc_request *req);
 extern void mconsole_log(struct mc_request *req);
 extern void mconsole_proc(struct mc_request *req);
+extern void mconsole_stack(struct mc_request *req);
 
 extern int mconsole_get_request(int fd, struct mc_request *req);
 extern int mconsole_notify(char *sock_name, int type, const void *data, 
diff --git a/arch/um/kernel/process_kern.c b/arch/um/kernel/process_kern.c
index 1143f5e522b2..39cf568ccfaf 100644
--- a/arch/um/kernel/process_kern.c
+++ b/arch/um/kernel/process_kern.c
@@ -119,7 +119,14 @@ void *_switch_to(void *prev, void *next, void *last)
         to->thread.prev_sched = from;
         set_current(to);
 
-        CHOOSE_MODE_PROC(switch_to_tt, switch_to_skas, prev, next);
+        do {
+                current->thread.saved_task = NULL ;
+                CHOOSE_MODE_PROC(switch_to_tt, switch_to_skas, prev, next);
+                if(current->thread.saved_task)
+                        show_regs(&(current->thread.regs));
+                next= current->thread.saved_task;
+                prev= current;
+        } while(current->thread.saved_task);
 
         return(current->thread.prev_sched);