perf: Factorize trace events raw sample buffer operations

Introduce ftrace_perf_buf_prepare() and ftrace_perf_buf_submit() to
gather the common code that operates on raw events sampling buffer.
This cleans up redundant code between regular trace events, syscall
events and kprobe events.

Changelog v1->v2:
- Rename function name as per Masami and Frederic's suggestion
- Add __kprobes for ftrace_perf_buf_prepare() and make
  ftrace_perf_buf_submit() inline as per Masami's suggestion
- Export ftrace_perf_buf_prepare since modules will use it

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4B60E92D.9000808@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 10 insertions, 76 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d6266cad6953..2e28ee36646f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1243,14 +1243,10 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
         struct ftrace_event_call *call = &tp->call;
         struct kprobe_trace_entry *entry;
-        struct trace_entry *ent;
-        int size, __size, i, pc, __cpu;
+        int size, __size, i;
         unsigned long irq_flags;
-        char *trace_buf;
-        char *raw_data;
         int rctx;
 
-        pc = preempt_count();
         __size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
@@ -1258,45 +1254,16 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
                      "profile buffer not large enough"))
                 return 0;
 
-        /*
-         * Protect the non nmi buffer
-         * This also protects the rcu read side
-         */
-        local_irq_save(irq_flags);
-
-        rctx = perf_swevent_get_recursion_context();
-        if (rctx < 0)
-                goto end_recursion;
-
-        __cpu = smp_processor_id();
-
-        if (in_nmi())
-                trace_buf = rcu_dereference(perf_trace_buf_nmi);
-        else
-                trace_buf = rcu_dereference(perf_trace_buf);
-
-        if (!trace_buf)
-                goto end;
-
-        raw_data = per_cpu_ptr(trace_buf, __cpu);
-
-        /* Zero dead bytes from alignment to avoid buffer leak to userspace */
-        *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
-        entry = (struct kprobe_trace_entry *)raw_data;
-        ent = &entry->ent;
+        entry = ftrace_perf_buf_prepare(size, call->id, &rctx, &irq_flags);
+        if (!entry)
+                return 0;
 
-        tracing_generic_entry_update(ent, irq_flags, pc);
-        ent->type = call->id;
         entry->nargs = tp->nr_args;
         entry->ip = (unsigned long)kp->addr;
         for (i = 0; i < tp->nr_args; i++)
                 entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
-        perf_tp_event(call->id, entry->ip, 1, entry, size);
 
-end:
-        perf_swevent_put_recursion_context(rctx);
-end_recursion:
-        local_irq_restore(irq_flags);
+        ftrace_perf_buf_submit(entry, size, rctx, entry->ip, 1, irq_flags);
 
         return 0;
 }
@@ -1308,14 +1275,10 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
         struct ftrace_event_call *call = &tp->call;
         struct kretprobe_trace_entry *entry;
-        struct trace_entry *ent;
-        int size, __size, i, pc, __cpu;
+        int size, __size, i;
         unsigned long irq_flags;
-        char *trace_buf;
-        char *raw_data;
         int rctx;
 
-        pc = preempt_count();
         __size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
@@ -1323,46 +1286,17 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
                      "profile buffer not large enough"))
                 return 0;
 
-        /*
-         * Protect the non nmi buffer
-         * This also protects the rcu read side
-         */
-        local_irq_save(irq_flags);
-
-        rctx = perf_swevent_get_recursion_context();
-        if (rctx < 0)
-                goto end_recursion;
-
-        __cpu = smp_processor_id();
-
-        if (in_nmi())
-                trace_buf = rcu_dereference(perf_trace_buf_nmi);
-        else
-                trace_buf = rcu_dereference(perf_trace_buf);
-
-        if (!trace_buf)
-                goto end;
-
-        raw_data = per_cpu_ptr(trace_buf, __cpu);
-
-        /* Zero dead bytes from alignment to avoid buffer leak to userspace */
-        *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
-        entry = (struct kretprobe_trace_entry *)raw_data;
-        ent = &entry->ent;
+        entry = ftrace_perf_buf_prepare(size, call->id, &rctx, &irq_flags);
+        if (!entry)
+                return 0;
 
-        tracing_generic_entry_update(ent, irq_flags, pc);
-        ent->type = call->id;
         entry->nargs = tp->nr_args;
         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].fetch, regs);
-        perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
 
-end:
-        perf_swevent_put_recursion_context(rctx);
-end_recursion:
-        local_irq_restore(irq_flags);
+        ftrace_perf_buf_submit(entry, size, rctx, entry->ret_ip, 1, irq_flags);
 
         return 0;
 }