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>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c24b7e9..4ce728c 100644 (file)
--- 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)