1 files changed, 276 insertions, 0 deletions

diff --git a/kernel/trace/trace_bts.c b/kernel/trace/trace_bts.c
new file mode 100644
index 000000000000..23b76e4690ef
--- /dev/null
+++ b/kernel/trace/trace_bts.c
@@ -0,0 +1,276 @@
+/*
+ * BTS tracer
+ *
+ * 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())
+
+
+/*
+ * Information to interpret a BTS record.
+ * This will go into an in-kernel BTS interface.
+ */
+static unsigned char sizeof_field;
+static unsigned long debugctl_mask;
+
+#define sizeof_bts (3 * sizeof_field)
+
+static void bts_trace_cpuinit(struct cpuinfo_x86 *c)
+{
+        switch (c->x86) {
+        case 0x6:
+                switch (c->x86_model) {
+                case 0x0 ... 0xC:
+                        break;
+                case 0xD:
+                case 0xE: /* Pentium M */
+                        sizeof_field = sizeof(long);
+                        debugctl_mask = (1<<6)|(1<<7);
+                        break;
+                default:
+                        sizeof_field = 8;
+                        debugctl_mask = (1<<6)|(1<<7);
+                        break;
+                }
+                break;
+        case 0xF:
+                switch (c->x86_model) {
+                case 0x0:
+                case 0x1:
+                case 0x2: /* Netburst */
+                        sizeof_field = sizeof(long);
+                        debugctl_mask = (1<<2)|(1<<3);
+                        break;
+                default:
+                        /* sorry, don't know about them */
+                        break;
+                }
+                break;
+        default:
+                /* sorry, don't know about them */
+                break;
+        }
+}
+
+static inline void bts_enable(void)
+{
+        unsigned long debugctl;
+
+        rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
+        wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl | debugctl_mask);
+}
+
+static inline void bts_disable(void)
+{
+        unsigned long debugctl;
+
+        rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
+        wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl & ~debugctl_mask);
+}
+
+static void bts_trace_reset(struct trace_array *tr)
+{
+        int cpu;
+
+        tr->time_start = ftrace_now(tr->cpu);
+
+        for_each_online_cpu(cpu)
+                tracing_reset(tr, cpu);
+}
+
+static void bts_trace_start_cpu(void *arg)
+{
+        this_tracer =
+                ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
+                               /* ovfl = */ NULL, /* th = */ (size_t)-1);
+        if (IS_ERR(this_tracer)) {
+                this_tracer = NULL;
+                return;
+        }
+
+        bts_enable();
+}
+
+static void bts_trace_start(struct trace_array *tr)
+{
+        int cpu;
+
+        bts_trace_reset(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) {
+                bts_disable();
+
+                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)
+{
+        bts_trace_cpuinit(&boot_cpu_data);
+        bts_trace_reset(tr);
+        bts_trace_start(tr);
+
+        return 0;
+}
+
+static void bts_trace_print_header(struct seq_file *m)
+{
+#ifdef __i386__
+        seq_puts(m, "# CPU#    FROM           TO     FUNCTION\n");
+        seq_puts(m, "#  |       |             |         |\n");
+#else
+        seq_puts(m,
+                 "# CPU#        FROM                   TO         FUNCTION\n");
+        seq_puts(m,
+                 "#  |           |                     |             |\n");
+#endif
+}
+
+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 bts_entry *it;
+
+        trace_assign_type(it, entry);
+
+        if (entry->type == TRACE_BTS) {
+                int ret;
+#ifdef CONFIG_KALLSYMS
+                char function[KSYM_SYMBOL_LEN];
+                sprint_symbol(function, it->from);
+#else
+                char *function = "<unknown>";
+#endif
+
+                ret = trace_seq_printf(seq, "%4d  0x%lx -> 0x%lx [%s]\n",
+                                       entry->cpu, it->from, it->to, function);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;;
+                return TRACE_TYPE_HANDLED;
+        }
+        return TRACE_TYPE_UNHANDLED;
+}
+
+void trace_bts(struct trace_array *tr, unsigned long from, unsigned long to)
+{
+        struct ring_buffer_event *event;
+        struct bts_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_BTS;
+        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, size_t index)
+{
+        const void *raw = NULL;
+        unsigned long from, to;
+        int err;
+
+        err = ds_access_bts(this_tracer, index, &raw);
+        if (err < 0)
+                return;
+
+        from = *(const unsigned long *)raw;
+        to = *(const unsigned long *)((const char *)raw + sizeof_field);
+
+        trace_bts(tr, from, to);
+}
+
+static void trace_bts_cpu(void *arg)
+{
+        struct trace_array *tr = (struct trace_array *) arg;
+        size_t index = 0, end = 0, i;
+        int err;
+
+        if (!this_tracer)
+                return;
+
+        bts_disable();
+
+        err = ds_get_bts_index(this_tracer, &index);
+        if (err < 0)
+                goto out;
+
+        err = ds_get_bts_end(this_tracer, &end);
+        if (err < 0)
+                goto out;
+
+        for (i = index; i < end; i++)
+                trace_bts_at(tr, i);
+
+        for (i = 0; i < index; i++)
+                trace_bts_at(tr, i);
+
+out:
+        bts_enable();
+}
+
+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           = "bts",
+        .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);