tracing/kprobes: Fix probe offset to be unsigned

Prohibit user to specify negative offset from symbols.
Since kprobe.offset is unsigned int, the offset must be always positive
value.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090910235314.22412.64631.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

2 files changed, 14 insertions, 19 deletions

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 3de751747164..db5531865648 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -25,15 +25,15 @@ probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
 
 Synopsis of kprobe_events
 -------------------------
-  p[:EVENT] SYMBOL[+offs|-offs]|MEMADDR [FETCHARGS]     : Set a probe
-  r[:EVENT] SYMBOL[+0] [FETCHARGS]                      : Set a return probe
+  p[:EVENT] SYMBOL[+offs]|MEMADDR [FETCHARGS]   : Set a probe
+  r[:EVENT] SYMBOL[+0] [FETCHARGS]              : Set a return probe
 
- EVENT                  : Event name. If omitted, the event name is generated
-                          based on SYMBOL+offs or MEMADDR.
- SYMBOL[+offs|-offs]    : Symbol+offset where the probe is inserted.
- MEMADDR                : Address where the probe is inserted.
+ EVENT          : Event name. If omitted, the event name is generated
+                  based on SYMBOL+offs or MEMADDR.
+ SYMBOL[+offs]  : Symbol+offset where the probe is inserted.
+ MEMADDR        : Address where the probe is inserted.
 
- FETCHARGS              : Arguments. Each probe can have up to 128 args.
+ FETCHARGS      : Arguments. Each probe can have up to 128 args.
   %REG  : Fetch register REG
   sN    : Fetch Nth entry of stack (N >= 0)
   sa    : Fetch stack address.
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 19a6de63b44b..c24b7e9d97c4 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -210,7 +210,7 @@ static __kprobes const char *probe_symbol(struct trace_probe *tp)
         return tp->symbol ? tp->symbol : "unknown";
 }
 
-static __kprobes long probe_offset(struct trace_probe *tp)
+static __kprobes unsigned int probe_offset(struct trace_probe *tp)
 {
         return (probe_is_return(tp)) ? tp->rp.kp.offset : tp->kp.offset;
 }
@@ -380,7 +380,7 @@ end:
 }
 
 /* Split symbol and offset. */
-static int split_symbol_offset(char *symbol, long *offset)
+static int split_symbol_offset(char *symbol, unsigned long *offset)
 {
         char *tmp;
         int ret;
@@ -389,16 +389,11 @@ static int split_symbol_offset(char *symbol, long *offset)
                 return -EINVAL;
 
         tmp = strchr(symbol, '+');
-        if (!tmp)
-                tmp = strchr(symbol, '-');
-
         if (tmp) {
                 /* skip sign because strict_strtol doesn't accept '+' */
-                ret = strict_strtol(tmp + 1, 0, offset);
+                ret = strict_strtoul(tmp + 1, 0, offset);
                 if (ret)
                         return ret;
-                if (*tmp == '-')
-                        *offset = -(*offset);
                 *tmp = '\0';
         } else
                 *offset = 0;
@@ -520,7 +515,7 @@ static int create_trace_probe(int argc, char **argv)
 {
         /*
          * Argument syntax:
-         *  - Add kprobe: p[:EVENT] SYMBOL[+OFFS|-OFFS]|ADDRESS [FETCHARGS]
+         *  - Add kprobe: p[:EVENT] SYMBOL[+OFFS]|ADDRESS [FETCHARGS]
          *  - Add kretprobe: r[:EVENT] SYMBOL[+0] [FETCHARGS]
          * Fetch args:
          *  aN  : fetch Nth of function argument. (N:0-)
@@ -539,7 +534,7 @@ static int create_trace_probe(int argc, char **argv)
         int i, ret = 0;
         int is_return = 0;
         char *symbol = NULL, *event = NULL;
-        long offset = 0;
+        unsigned long offset = 0;
         void *addr = NULL;
 
         if (argc < 2)
@@ -605,7 +600,7 @@ static int create_trace_probe(int argc, char **argv)
 
         if (tp->symbol) {
                 kp->symbol_name = tp->symbol;
-                kp->offset = offset;
+                kp->offset = (unsigned int)offset;
         } else
                 kp->addr = addr;
 
@@ -675,7 +670,7 @@ static int probes_seq_show(struct seq_file *m, void *v)
         seq_printf(m, ":%s", tp->call.name);
 
         if (tp->symbol)
-                seq_printf(m, " %s%+ld", probe_symbol(tp), probe_offset(tp));
+                seq_printf(m, " %s+%u", probe_symbol(tp), probe_offset(tp));
         else
                 seq_printf(m, " 0x%p", probe_address(tp));