tracing/kprobes: Cleanup kprobe tracer code.

Simplify trace_probe to remove a union, and remove some redundant
wrappers.
And also, cleanup create_trace_probe() function.

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: <20090910235322.22412.52525.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 34 insertions, 47 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c24b7e9d97c4..4ce728ca1b18 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -180,10 +180,7 @@ static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
 
 struct trace_probe {
         struct list_head        list;
-        union {
-                struct kprobe           kp;
-                struct kretprobe        rp;
-        };
+        struct kretprobe        rp;     /* Use rp.kp for kprobe use */
         unsigned long           nhit;
         const char              *symbol;        /* symbol name */
         struct ftrace_event_call        call;
@@ -202,7 +199,7 @@ static int kretprobe_trace_func(struct kretprobe_instance *ri,
 
 static __kprobes int probe_is_return(struct trace_probe *tp)
 {
-        return (tp->rp.handler == kretprobe_trace_func);
+        return tp->rp.handler != NULL;
 }
 
 static __kprobes const char *probe_symbol(struct trace_probe *tp)
@@ -210,16 +207,6 @@ static __kprobes const char *probe_symbol(struct trace_probe *tp)
         return tp->symbol ? tp->symbol : "unknown";
 }
 
-static __kprobes unsigned int probe_offset(struct trace_probe *tp)
-{
-        return (probe_is_return(tp)) ? tp->rp.kp.offset : tp->kp.offset;
-}
-
-static __kprobes void *probe_address(struct trace_probe *tp)
-{
-        return (probe_is_return(tp)) ? tp->rp.kp.addr : tp->kp.addr;
-}
-
 static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
 {
         int ret = -EINVAL;
@@ -269,8 +256,14 @@ static void unregister_probe_event(struct trace_probe *tp);
 static DEFINE_MUTEX(probe_lock);
 static LIST_HEAD(probe_list);
 
-static struct trace_probe *alloc_trace_probe(const char *symbol,
-                                             const char *event, int nargs)
+/*
+ * Allocate new trace_probe and initialize it (including kprobes).
+ */
+static struct trace_probe *alloc_trace_probe(const char *event,
+                                             void *addr,
+                                             const char *symbol,
+                                             unsigned long offs,
+                                             int nargs, int is_return)
 {
         struct trace_probe *tp;
 
@@ -282,7 +275,16 @@ static struct trace_probe *alloc_trace_probe(const char *symbol,
                 tp->symbol = kstrdup(symbol, GFP_KERNEL);
                 if (!tp->symbol)
                         goto error;
-        }
+                tp->rp.kp.symbol_name = tp->symbol;
+                tp->rp.kp.offset = offs;
+        } else
+                tp->rp.kp.addr = addr;
+
+        if (is_return)
+                tp->rp.handler = kretprobe_trace_func;
+        else
+                tp->rp.kp.pre_handler = kprobe_trace_func;
+
         if (!event)
                 goto error;
         tp->call.name = kstrdup(event, GFP_KERNEL);
@@ -327,7 +329,7 @@ static void __unregister_trace_probe(struct trace_probe *tp)
         if (probe_is_return(tp))
                 unregister_kretprobe(&tp->rp);
         else
-                unregister_kprobe(&tp->kp);
+                unregister_kprobe(&tp->rp.kp);
 }
 
 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
@@ -349,14 +351,14 @@ static int register_trace_probe(struct trace_probe *tp)
         if (probe_is_return(tp))
                 ret = register_kretprobe(&tp->rp);
         else
-                ret = register_kprobe(&tp->kp);
+                ret = register_kprobe(&tp->rp.kp);
 
         if (ret) {
                 pr_warning("Could not insert probe(%d)\n", ret);
                 if (ret == -EILSEQ) {
                         pr_warning("Probing address(0x%p) is not an "
                                    "instruction boundary.\n",
-                                   probe_address(tp));
+                                   tp->rp.kp.addr);
                         ret = -EINVAL;
                 }
                 goto end;
@@ -530,12 +532,12 @@ static int create_trace_probe(int argc, char **argv)
          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
          */
         struct trace_probe *tp;
-        struct kprobe *kp;
         int i, ret = 0;
         int is_return = 0;
         char *symbol = NULL, *event = NULL;
         unsigned long offset = 0;
         void *addr = NULL;
+        char buf[MAX_EVENT_NAME_LEN];
 
         if (argc < 2)
                 return -EINVAL;
@@ -577,33 +579,18 @@ static int create_trace_probe(int argc, char **argv)
         /* setup a probe */
         if (!event) {
                 /* Make a new event name */
-                char buf[MAX_EVENT_NAME_LEN];
                 if (symbol)
                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c@%s%+ld",
                                  is_return ? 'r' : 'p', symbol, offset);
                 else
                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c@0x%p",
                                  is_return ? 'r' : 'p', addr);
-                tp = alloc_trace_probe(symbol, buf, argc);
-        } else
-                tp = alloc_trace_probe(symbol, event, argc);
+                event = buf;
+        }
+        tp = alloc_trace_probe(event, addr, symbol, offset, argc, is_return);
         if (IS_ERR(tp))
                 return PTR_ERR(tp);
 
-        if (is_return) {
-                kp = &tp->rp.kp;
-                tp->rp.handler = kretprobe_trace_func;
-        } else {
-                kp = &tp->kp;
-                tp->kp.pre_handler = kprobe_trace_func;
-        }
-
-        if (tp->symbol) {
-                kp->symbol_name = tp->symbol;
-                kp->offset = (unsigned int)offset;
-        } else
-                kp->addr = addr;
-
         /* parse arguments */
         ret = 0;
         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
@@ -670,9 +657,9 @@ 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+%u", probe_symbol(tp), probe_offset(tp));
+                seq_printf(m, " %s+%u", probe_symbol(tp), tp->rp.kp.offset);
         else
-                seq_printf(m, " 0x%p", probe_address(tp));
+                seq_printf(m, " 0x%p", tp->rp.kp.addr);
 
         for (i = 0; i < tp->nr_args; i++) {
                 ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
@@ -783,7 +770,7 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
         struct trace_probe *tp = v;
 
         seq_printf(m, "  %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
-                   probe_is_return(tp) ? tp->rp.kp.nmissed : tp->kp.nmissed);
+                   tp->rp.kp.nmissed);
 
         return 0;
 }
@@ -811,7 +798,7 @@ static const struct file_operations kprobe_profile_ops = {
 /* Kprobe handler */
 static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 {
-        struct trace_probe *tp = container_of(kp, struct trace_probe, kp);
+        struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
         struct kprobe_trace_entry *entry;
         struct ring_buffer_event *event;
         struct ring_buffer *buffer;
@@ -866,7 +853,7 @@ static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
 
         entry = ring_buffer_event_data(event);
         entry->nargs = tp->nr_args;
-        entry->func = (unsigned long)probe_address(tp);
+        entry->func = (unsigned long)tp->rp.kp.addr;
         entry->ret_ip = (unsigned long)ri->ret_addr;
         for (i = 0; i < tp->nr_args; i++)
                 entry->args[i] = call_fetch(&tp->args[i], regs);
@@ -945,7 +932,7 @@ static int probe_event_enable(struct ftrace_event_call *call)
         if (probe_is_return(tp))
                 return enable_kretprobe(&tp->rp);
         else
-                return enable_kprobe(&tp->kp);
+                return enable_kprobe(&tp->rp.kp);
 }
 
 static void probe_event_disable(struct ftrace_event_call *call)
@@ -955,7 +942,7 @@ static void probe_event_disable(struct ftrace_event_call *call)
         if (probe_is_return(tp))
                 disable_kretprobe(&tp->rp);
         else
-                disable_kprobe(&tp->kp);
+                disable_kprobe(&tp->rp.kp);
 }
 
 static int probe_event_raw_init(struct ftrace_event_call *event_call)