uprobes/tracing: Generalize struct uprobe_trace_entry_head

struct uprobe_trace_entry_head has a single member for reporting,
"unsigned long ip". If we want to support uretprobes we need to
create another struct which has "func" and "ret_ip" and duplicate
a lot of functions, like trace_kprobe.c does.

To avoid this copy-and-paste horror we turn ->ip into ->vaddr[]
and add couple of trivial helpers to calculate sizeof/data. This
uglifies the code a bit, but this allows us to avoid a lot more
complications later, when we add the support for ret-probes.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Anton Arapov <anton@redhat.com>

2 files changed, 36 insertions, 31 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2081971367ea..8bed1dfcb938 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -103,11 +103,6 @@ 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_uprobe.c b/kernel/trace/trace_uprobe.c
index 43d258db998e..49b400368bfd 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -28,6 +28,18 @@
 
 #define UPROBE_EVENT_SYSTEM     "uprobes"
 
+struct uprobe_trace_entry_head {
+        struct trace_entry      ent;
+        unsigned long           vaddr[];
+};
+
+#define SIZEOF_TRACE_ENTRY(is_return)                   \
+        (sizeof(struct uprobe_trace_entry_head) +       \
+         sizeof(unsigned long) * (is_return ? 2 : 1))
+
+#define DATAOF_TRACE_ENTRY(entry, is_return)            \
+        ((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
+
 struct trace_uprobe_filter {
         rwlock_t                rwlock;
         int                     nr_systemwide;
@@ -491,20 +503,19 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
         struct uprobe_trace_entry_head *entry;
         struct ring_buffer_event *event;
         struct ring_buffer *buffer;
-        u8 *data;
+        void *data;
         int size, i;
         struct ftrace_event_call *call = &tu->call;
 
-        size = sizeof(*entry) + tu->size;
-
+        size = SIZEOF_TRACE_ENTRY(false) + tu->size;
         event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
                                                   size, 0, 0);
         if (!event)
                 return 0;
 
         entry = ring_buffer_event_data(event);
-        entry->ip = instruction_pointer(regs);
-        data = (u8 *)&entry[1];
+        entry->vaddr[0] = instruction_pointer(regs);
+        data = DATAOF_TRACE_ENTRY(entry, false);
         for (i = 0; i < tu->nr_args; i++)
                 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
 
@@ -518,22 +529,22 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
 static enum print_line_t
 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
 {
-        struct uprobe_trace_entry_head *field;
+        struct uprobe_trace_entry_head *entry;
         struct trace_seq *s = &iter->seq;
         struct trace_uprobe *tu;
         u8 *data;
         int i;
 
-        field = (struct uprobe_trace_entry_head *)iter->ent;
+        entry = (struct uprobe_trace_entry_head *)iter->ent;
         tu = container_of(event, struct trace_uprobe, call.event);
 
-        if (!trace_seq_printf(s, "%s: (0x%lx)", tu->call.name, field->ip))
+        if (!trace_seq_printf(s, "%s: (0x%lx)", tu->call.name, entry->vaddr[0]))
                 goto partial;
 
-        data = (u8 *)&field[1];
+        data = DATAOF_TRACE_ENTRY(entry, false);
         for (i = 0; i < tu->nr_args; i++) {
                 if (!tu->args[i].type->print(s, tu->args[i].name,
-                                             data + tu->args[i].offset, field))
+                                             data + tu->args[i].offset, entry))
                         goto partial;
         }
 
@@ -585,16 +596,17 @@ static void probe_event_disable(struct trace_uprobe *tu, int flag)
 
 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
 {
-        int ret, i;
+        int ret, i, size;
         struct uprobe_trace_entry_head field;
-        struct trace_uprobe *tu = (struct trace_uprobe *)event_call->data;
+        struct trace_uprobe *tu = event_call->data;
 
-        DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+        DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
+        size = SIZEOF_TRACE_ENTRY(false);
         /* Set argument names as fields */
         for (i = 0; i < tu->nr_args; i++) {
                 ret = trace_define_field(event_call, tu->args[i].type->fmttype,
                                          tu->args[i].name,
-                                         sizeof(field) + tu->args[i].offset,
+                                         size + tu->args[i].offset,
                                          tu->args[i].type->size,
                                          tu->args[i].type->is_signed,
                                          FILTER_OTHER);
@@ -748,33 +760,31 @@ static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
         struct ftrace_event_call *call = &tu->call;
         struct uprobe_trace_entry_head *entry;
         struct hlist_head *head;
-        u8 *data;
-        int size, __size, i;
-        int rctx;
+        unsigned long ip;
+        void *data;
+        int size, rctx, i;
 
         if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
                 return UPROBE_HANDLER_REMOVE;
 
-        __size = sizeof(*entry) + tu->size;
-        size = ALIGN(__size + sizeof(u32), sizeof(u64));
-        size -= sizeof(u32);
+        size = SIZEOF_TRACE_ENTRY(false);
+        size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
                 return 0;
 
         preempt_disable();
-
         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
         if (!entry)
                 goto out;
 
-        entry->ip = instruction_pointer(regs);
-        data = (u8 *)&entry[1];
+        ip = instruction_pointer(regs);
+        entry->vaddr[0] = ip;
+        data = DATAOF_TRACE_ENTRY(entry, false);
         for (i = 0; i < tu->nr_args; i++)
                 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
 
         head = this_cpu_ptr(call->perf_events);
-        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head, NULL);
-
+        perf_trace_buf_submit(entry, size, rctx, ip, 1, regs, head, NULL);
  out:
         preempt_enable();
         return 0;
@@ -784,7 +794,7 @@ static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
 static
 int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
 {
-        struct trace_uprobe *tu = (struct trace_uprobe *)event->data;
+        struct trace_uprobe *tu = event->data;
 
         switch (type) {
         case TRACE_REG_REGISTER: