1 files changed, 195 insertions, 0 deletions

diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c
new file mode 100644
index 000000000000..b6a3e20a49a9
--- /dev/null
+++ b/kernel/trace/trace_hw_branches.c
@@ -0,0 +1,195 @@
+/*
+ * h/w branch tracer for x86 based on bts
+ *
+ * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/ftrace.h>
+#include <linux/kallsyms.h>
+
+#include <asm/ds.h>
+
+#include "trace.h"
+
+
+#define SIZEOF_BTS (1 << 13)
+
+static DEFINE_PER_CPU(struct bts_tracer *, tracer);
+static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
+
+#define this_tracer per_cpu(tracer, smp_processor_id())
+#define this_buffer per_cpu(buffer, smp_processor_id())
+
+
+static void bts_trace_start_cpu(void *arg)
+{
+        if (this_tracer)
+                ds_release_bts(this_tracer);
+
+        this_tracer =
+                ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
+                               /* ovfl = */ NULL, /* th = */ (size_t)-1,
+                               BTS_KERNEL);
+        if (IS_ERR(this_tracer)) {
+                this_tracer = NULL;
+                return;
+        }
+}
+
+static void bts_trace_start(struct trace_array *tr)
+{
+        int cpu;
+
+        tracing_reset_online_cpus(tr);
+
+        for_each_cpu_mask(cpu, cpu_possible_map)
+                smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
+}
+
+static void bts_trace_stop_cpu(void *arg)
+{
+        if (this_tracer) {
+                ds_release_bts(this_tracer);
+                this_tracer = NULL;
+        }
+}
+
+static void bts_trace_stop(struct trace_array *tr)
+{
+        int cpu;
+
+        for_each_cpu_mask(cpu, cpu_possible_map)
+                smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
+}
+
+static int bts_trace_init(struct trace_array *tr)
+{
+        tracing_reset_online_cpus(tr);
+        bts_trace_start(tr);
+
+        return 0;
+}
+
+static void bts_trace_print_header(struct seq_file *m)
+{
+        seq_puts(m,
+                 "# CPU#        FROM                   TO         FUNCTION\n");
+        seq_puts(m,
+                 "#  |           |                     |             |\n");
+}
+
+static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
+{
+        struct trace_entry *entry = iter->ent;
+        struct trace_seq *seq = &iter->seq;
+        struct hw_branch_entry *it;
+
+        trace_assign_type(it, entry);
+
+        if (entry->type == TRACE_HW_BRANCHES) {
+                if (trace_seq_printf(seq, "%4d  ", entry->cpu) &&
+                    trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
+                                     it->from, it->to) &&
+                    (!it->from ||
+                     seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
+                    trace_seq_printf(seq, "\n"))
+                        return TRACE_TYPE_HANDLED;
+                return TRACE_TYPE_PARTIAL_LINE;;
+        }
+        return TRACE_TYPE_UNHANDLED;
+}
+
+void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
+{
+        struct ring_buffer_event *event;
+        struct hw_branch_entry *entry;
+        unsigned long irq;
+
+        event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
+        if (!event)
+                return;
+        entry   = ring_buffer_event_data(event);
+        tracing_generic_entry_update(&entry->ent, 0, from);
+        entry->ent.type = TRACE_HW_BRANCHES;
+        entry->ent.cpu = smp_processor_id();
+        entry->from = from;
+        entry->to   = to;
+        ring_buffer_unlock_commit(tr->buffer, event, irq);
+}
+
+static void trace_bts_at(struct trace_array *tr,
+                         const struct bts_trace *trace, void *at)
+{
+        struct bts_struct bts;
+        int err = 0;
+
+        WARN_ON_ONCE(!trace->read);
+        if (!trace->read)
+                return;
+
+        err = trace->read(this_tracer, at, &bts);
+        if (err < 0)
+                return;
+
+        switch (bts.qualifier) {
+        case BTS_BRANCH:
+                trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
+                break;
+        }
+}
+
+static void trace_bts_cpu(void *arg)
+{
+        struct trace_array *tr = (struct trace_array *) arg;
+        const struct bts_trace *trace;
+        unsigned char *at;
+
+        if (!this_tracer)
+                return;
+
+        ds_suspend_bts(this_tracer);
+        trace = ds_read_bts(this_tracer);
+        if (!trace)
+                goto out;
+
+        for (at = trace->ds.top; (void *)at < trace->ds.end;
+             at += trace->ds.size)
+                trace_bts_at(tr, trace, at);
+
+        for (at = trace->ds.begin; (void *)at < trace->ds.top;
+             at += trace->ds.size)
+                trace_bts_at(tr, trace, at);
+
+out:
+        ds_resume_bts(this_tracer);
+}
+
+static void trace_bts_prepare(struct trace_iterator *iter)
+{
+        int cpu;
+
+        for_each_cpu_mask(cpu, cpu_possible_map)
+                smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
+}
+
+struct tracer bts_tracer __read_mostly =
+{
+        .name           = "hw-branch-tracer",
+        .init           = bts_trace_init,
+        .reset          = bts_trace_stop,
+        .print_header   = bts_trace_print_header,
+        .print_line     = bts_trace_print_line,
+        .start          = bts_trace_start,
+        .stop           = bts_trace_stop,
+        .open           = trace_bts_prepare
+};
+
+__init static int init_bts_trace(void)
+{
+        return register_tracer(&bts_tracer);
+}
+device_initcall(init_bts_trace);