tracing: Provide trace events interface for uprobes

Implements trace_event support for uprobes. In its current form
it can be used to put probes at a specified offset in a file and
dump the required registers when the code flow reaches the
probed address.

The following example shows how to dump the instruction pointer
and %ax a register at the probed text address.  Here we are
trying to probe zfree in /bin/zsh:

 # cd /sys/kernel/debug/tracing/
 # cat /proc/`pgrep  zsh`/maps | grep /bin/zsh | grep r-xp
 00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh
 # objdump -T /bin/zsh | grep -w zfree
 0000000000446420 g    DF .text  0000000000000012  Base
 zfree # echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events
 # cat uprobe_events
 p:uprobes/p_zsh_0x46420 /bin/zsh:0x0000000000046420
 # echo 1 > events/uprobes/enable
 # sleep 20
 # echo 0 > events/uprobes/enable
 # cat trace
 # tracer: nop
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
              zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
              zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
              zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
              zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120411103043.GB29437@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

7 files changed, 823 insertions, 6 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index ce5a5c54ac8f..ea4bff6295fc 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -386,6 +386,22 @@ config KPROBE_EVENT
           This option is also required by perf-probe subcommand of perf tools.
           If you want to use perf tools, this option is strongly recommended.
 
+config UPROBE_EVENT
+        bool "Enable uprobes-based dynamic events"
+        depends on ARCH_SUPPORTS_UPROBES
+        depends on MMU
+        select UPROBES
+        select PROBE_EVENTS
+        select TRACING
+        default n
+        help
+          This allows the user to add tracing events on top of userspace
+          dynamic events (similar to tracepoints) on the fly via the trace
+          events interface. Those events can be inserted wherever uprobes
+          can probe, and record various registers.
+          This option is required if you plan to use perf-probe subcommand
+          of perf tools on user space applications.
+
 config PROBE_EVENTS
         def_bool n
 
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index fa10d5ca5ab1..1734c03e048b 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -62,5 +62,6 @@ ifeq ($(CONFIG_TRACING),y)
 obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
 endif
 obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
+obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 95059f091a24..1bcdbec95a11 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -103,6 +103,11 @@ struct kretprobe_trace_entry_head {
         unsigned long           ret_ip;
 };
 
+struct uprobe_trace_entry_head {
+        struct trace_entry      ent;
+        unsigned long           ip;
+};
+
 /*
  * trace_flag_type is an enumeration that holds different
  * states when a trace occurs. These are:
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f8b777367d8e..b31d3d5699fe 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -525,7 +525,7 @@ static int create_trace_probe(int argc, char **argv)
 
                 /* Parse fetch argument */
                 ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
-                                                                is_return);
+                                                is_return, true);
                 if (ret) {
                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
                         goto error;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 8e526b9286e9..daa9980153af 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -550,7 +550,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 
 /* Recursive argument parser */
 static int parse_probe_arg(char *arg, const struct fetch_type *t,
-                     struct fetch_param *f, bool is_return)
+                     struct fetch_param *f, bool is_return, bool is_kprobe)
 {
         unsigned long param;
         long offset;
@@ -558,6 +558,11 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
         int ret;
 
         ret = 0;
+
+        /* Until uprobe_events supports only reg arguments */
+        if (!is_kprobe && arg[0] != '%')
+                return -EINVAL;
+
         switch (arg[0]) {
         case '$':
                 ret = parse_probe_vars(arg + 1, t, f, is_return);
@@ -619,7 +624,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
                                 return -ENOMEM;
 
                         dprm->offset = offset;
-                        ret = parse_probe_arg(arg, t2, &dprm->orig, is_return);
+                        ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
+                                                        is_kprobe);
                         if (ret)
                                 kfree(dprm);
                         else {
@@ -677,7 +683,7 @@ static int __parse_bitfield_probe_arg(const char *bf,
 
 /* String length checking wrapper */
 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-                struct probe_arg *parg, bool is_return)
+                struct probe_arg *parg, bool is_return, bool is_kprobe)
 {
         const char *t;
         int ret;
@@ -703,7 +709,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
         }
         parg->offset = *size;
         *size += parg->type->size;
-        ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+        ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);
 
         if (ret >= 0 && t != NULL)
                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 2df9a18e0252..933708677814 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -66,6 +66,7 @@
 #define TP_FLAG_TRACE           1
 #define TP_FLAG_PROFILE         2
 #define TP_FLAG_REGISTERED      4
+#define TP_FLAG_UPROBE          8
 
 
 /* data_rloc: data relative location, compatible with u32 */
@@ -143,7 +144,7 @@ static inline int is_good_name(const char *name)
 }
 
 extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
-                   struct probe_arg *parg, bool is_return);
+                   struct probe_arg *parg, bool is_return, bool is_kprobe);
 
 extern int traceprobe_conflict_field_name(const char *name,
                                struct probe_arg *args, int narg);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 000000000000..2b36ac68549e
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,788 @@
+/*
+ * uprobes-based tracing events
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Copyright (C) IBM Corporation, 2010-2012
+ * Author:      Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/namei.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM     "uprobes"
+
+/*
+ * uprobe event core functions
+ */
+struct trace_uprobe;
+struct uprobe_trace_consumer {