4 files changed, 120 insertions, 3 deletions

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 9c4dc30cdc13..a9281cca4114 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -416,6 +416,7 @@ LIB_H += util/thread.h
 LIB_H += util/trace-event.h
 LIB_H += util/probe-finder.h
 LIB_H += util/probe-event.h
+LIB_H += util/pstack.h
 LIB_H += util/cpumap.h
 
 LIB_OBJS += $(OUTPUT)util/abspath.o
@@ -451,6 +452,7 @@ LIB_OBJS += $(OUTPUT)util/callchain.o
 LIB_OBJS += $(OUTPUT)util/values.o
 LIB_OBJS += $(OUTPUT)util/debug.o
 LIB_OBJS += $(OUTPUT)util/map.o
+LIB_OBJS += $(OUTPUT)util/pstack.o
 LIB_OBJS += $(OUTPUT)util/session.o
 LIB_OBJS += $(OUTPUT)util/thread.o
 LIB_OBJS += $(OUTPUT)util/trace-event-parse.o
diff --git a/tools/perf/util/newt.c b/tools/perf/util/newt.c
index 3402453812b3..e74df1240ef6 100644
--- a/tools/perf/util/newt.c
+++ b/tools/perf/util/newt.c
@@ -9,6 +9,7 @@
 
 #include "cache.h"
 #include "hist.h"
+#include "pstack.h"
 #include "session.h"
 #include "sort.h"
 #include "symbol.h"
@@ -750,6 +751,7 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
         newtFormAddHotKey(self->form, 'A');
         newtFormAddHotKey(self->form, 'a');
         newtFormAddHotKey(self->form, NEWT_KEY_RIGHT);
+        newtFormAddHotKey(self->form, NEWT_KEY_LEFT);
         newtFormAddComponents(self->form, self->tree, NULL);
         self->selection = newt__symbol_tree_get_current(self->tree);
 
@@ -801,6 +803,7 @@ static int hist_browser__title(char *bf, size_t size, const char *input_name,
 int hists__browse(struct hists *self, const char *helpline, const char *input_name)
 {
         struct hist_browser *browser = hist_browser__new();
+        struct pstack *fstack = pstack__new(2);
         const struct thread *thread_filter = NULL;
         const struct dso *dso_filter = NULL;
         struct newtExitStruct es;
@@ -810,12 +813,16 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
         if (browser == NULL)
                 return -1;
 
+        fstack = pstack__new(2);
+        if (fstack == NULL)
+                goto out;
+
         ui_helpline__push(helpline);
 
         hist_browser__title(msg, sizeof(msg), input_name,
                             dso_filter, thread_filter);
         if (hist_browser__populate(browser, self, msg) < 0)
-                goto out;
+                goto out_free_stack;
 
         while (1) {
                 const struct thread *thread;
@@ -836,6 +843,19 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
                                 else
                                         continue;
                         }
+
+                        if (es.u.key == NEWT_KEY_LEFT) {
+                                const void *top;
+
+                                if (pstack__empty(fstack))
+                                        continue;
+                                top = pstack__pop(fstack);
+                                if (top == &dso_filter)
+                                        goto zoom_out_dso;
+                                if (top == &thread_filter)
+                                        goto zoom_out_thread;
+                                continue;
+                        }
                 }
 
                 if (browser->selection->sym != NULL &&
@@ -888,12 +908,15 @@ do_annotate:
                         hist_entry__annotate_browser(he);
                 } else if (choice == zoom_dso) {
                         if (dso_filter) {
+                                pstack__remove(fstack, &dso_filter);
+zoom_out_dso:
                                 ui_helpline__pop();
                                 dso_filter = NULL;
                         } else {
-                                ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s DSO\"",
+                                ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s DSO\"",
                                                    dso->kernel ? "the Kernel" : dso->short_name);
                                 dso_filter = dso;
+                                pstack__push(fstack, &dso_filter);
                         }
                         hists__filter_by_dso(self, dso_filter);
                         hist_browser__title(msg, sizeof(msg), input_name,
@@ -902,13 +925,16 @@ do_annotate:
                                 goto out;
                 } else if (choice == zoom_thread) {
                         if (thread_filter) {
+                                pstack__remove(fstack, &thread_filter);
+zoom_out_thread:
                                 ui_helpline__pop();
                                 thread_filter = NULL;
                         } else {
-                                ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s(%d) thread\"",
+                                ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s(%d) thread\"",
                                                    thread->comm_set ? thread->comm : "",
                                                    thread->pid);
                                 thread_filter = thread;
+                                pstack__push(fstack, &thread_filter);
                         }
                         hists__filter_by_thread(self, thread_filter);
                         hist_browser__title(msg, sizeof(msg), input_name,
@@ -918,6 +944,8 @@ do_annotate:
                 }
         }
         err = 0;
+out_free_stack:
+        pstack__delete(fstack);
 out:
         hist_browser__delete(browser);
         return err;
diff --git a/tools/perf/util/pstack.c b/tools/perf/util/pstack.c
new file mode 100644
index 000000000000..13d36faf64eb
--- /dev/null
+++ b/tools/perf/util/pstack.c
@@ -0,0 +1,75 @@
+/*
+ * Simple pointer stack
+ *
+ * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
+ */
+
+#include "util.h"
+#include "pstack.h"
+#include <linux/kernel.h>
+#include <stdlib.h>
+
+struct pstack {
+        unsigned short  top;
+        unsigned short  max_nr_entries;
+        void            *entries[0];
+};
+
+struct pstack *pstack__new(unsigned short max_nr_entries)
+{
+        struct pstack *self = zalloc((sizeof(*self) +
+                                     max_nr_entries * sizeof(void *)));
+        if (self != NULL)
+                self->max_nr_entries = max_nr_entries;
+        return self;
+}
+
+void pstack__delete(struct pstack *self)
+{
+        free(self);
+}
+
+bool pstack__empty(const struct pstack *self)
+{
+        return self->top == 0;
+}
+
+void pstack__remove(struct pstack *self, void *key)
+{
+        unsigned short i = self->top, last_index = self->top - 1;
+
+        while (i-- != 0) {
+                if (self->entries[i] == key) {
+                        if (i < last_index)
+                                memmove(self->entries + i,
+                                        self->entries + i + 1,
+                                        (last_index - i) * sizeof(void *));
+                        --self->top;
+                        return;
+                }
+        }
+        pr_err("%s: %p not on the pstack!\n", __func__, key);
+}
+
+void pstack__push(struct pstack *self, void *key)
+{
+        if (self->top == self->max_nr_entries) {
+                pr_err("%s: top=%d, overflow!\n", __func__, self->top);
+                return;
+        }
+        self->entries[self->top++] = key;
+}
+
+void *pstack__pop(struct pstack *self)
+{
+        void *ret;
+
+        if (self->top == 0) {
+                pr_err("%s: underflow!\n", __func__);
+                return NULL;
+        }
+
+        ret = self->entries[--self->top];
+        self->entries[self->top] = NULL;
+        return ret;
+}
diff --git a/tools/perf/util/pstack.h b/tools/perf/util/pstack.h
new file mode 100644
index 000000000000..5ad07023504b
--- /dev/null
+++ b/tools/perf/util/pstack.h
@@ -0,0 +1,12 @@
+#ifndef _PERF_PSTACK_
+#define _PERF_PSTACK_
+
+struct pstack;
+struct pstack *pstack__new(unsigned short max_nr_entries);
+void pstack__delete(struct pstack *self);
+bool pstack__empty(const struct pstack *self);
+void pstack__remove(struct pstack *self, void *key);
+void pstack__push(struct pstack *self, void *key);
+void *pstack__pop(struct pstack *self);
+
+#endif /* _PERF_PSTACK_ */