SAFE public projects git trees. - safe/jmp/linux-2.6/blob - kernel/trace/trace_hw_branches.c

   1 /*
   2  * h/w branch tracer for x86 based on bts
   3  *
   4  * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
   5  *
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/fs.h>
  10 #include <linux/debugfs.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/kallsyms.h>
  13
  14 #include <asm/ds.h>
  15
  16 #include "trace.h"
  17
  18
  19 #define SIZEOF_BTS (1 << 13)
  20
  21 static DEFINE_PER_CPU(struct bts_tracer *, tracer);
  22 static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
  23
  24 #define this_tracer per_cpu(tracer, smp_processor_id())
  25 #define this_buffer per_cpu(buffer, smp_processor_id())
  26
  27
  28 static void bts_trace_reset(struct trace_array *tr)
  29 {
  30         int cpu;
  31
  32         tr->time_start = ftrace_now(tr->cpu);
  33
  34         for_each_online_cpu(cpu)
  35                 tracing_reset(tr, cpu);
  36 }
  37
  38 static void bts_trace_start_cpu(void *arg)
  39 {
  40         if (this_tracer)
  41                 ds_release_bts(this_tracer);
  42
  43         this_tracer =
  44                 ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
  45                                /* ovfl = */ NULL, /* th = */ (size_t)-1,
  46                                BTS_KERNEL);
  47         if (IS_ERR(this_tracer)) {
  48                 this_tracer = NULL;
  49                 return;
  50         }
  51 }
  52
  53 static void bts_trace_start(struct trace_array *tr)
  54 {
  55         int cpu;
  56
  57         bts_trace_reset(tr);
  58
  59         for_each_cpu_mask(cpu, cpu_possible_map)
  60                 smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
  61 }
  62
  63 static void bts_trace_stop_cpu(void *arg)
  64 {
  65         if (this_tracer) {
  66                 ds_release_bts(this_tracer);
  67                 this_tracer = NULL;
  68         }
  69 }
  70
  71 static void bts_trace_stop(struct trace_array *tr)
  72 {
  73         int cpu;
  74
  75         for_each_cpu_mask(cpu, cpu_possible_map)
  76                 smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
  77 }
  78
  79 static int bts_trace_init(struct trace_array *tr)
  80 {
  81         bts_trace_reset(tr);
  82         bts_trace_start(tr);
  83
  84         return 0;
  85 }
  86
  87 static void bts_trace_print_header(struct seq_file *m)
  88 {
  89         seq_puts(m,
  90                  "# CPU#        FROM                   TO         FUNCTION\n");
  91         seq_puts(m,
  92                  "#  |           |                     |             |\n");
  93 }
  94
  95 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
  96 {
  97         struct trace_entry *entry = iter->ent;
  98         struct trace_seq *seq = &iter->seq;
  99         struct hw_branch_entry *it;
 100
 101         trace_assign_type(it, entry);
 102
 103         if (entry->type == TRACE_HW_BRANCHES) {
 104                 if (trace_seq_printf(seq, "%4d  ", entry->cpu) &&
 105                     trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
 106                                      it->from, it->to) &&
 107                     (!it->from ||
 108                      seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
 109                     trace_seq_printf(seq, "\n"))
 110                         return TRACE_TYPE_HANDLED;
 111                 return TRACE_TYPE_PARTIAL_LINE;;
 112         }
 113         return TRACE_TYPE_UNHANDLED;
 114 }
 115
 116 void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
 117 {
 118         struct ring_buffer_event *event;
 119         struct hw_branch_entry *entry;
 120         unsigned long irq;
 121
 122         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
 123         if (!event)
 124                 return;
 125         entry   = ring_buffer_event_data(event);
 126         tracing_generic_entry_update(&entry->ent, 0, from);
 127         entry->ent.type = TRACE_HW_BRANCHES;
 128         entry->ent.cpu = smp_processor_id();
 129         entry->from = from;
 130         entry->to   = to;
 131         ring_buffer_unlock_commit(tr->buffer, event, irq);
 132 }
 133
 134 static void trace_bts_at(struct trace_array *tr,
 135                          const struct bts_trace *trace, void *at)
 136 {
 137         struct bts_struct bts;
 138         int err = 0;
 139
 140         WARN_ON_ONCE(!trace->read);
 141         if (!trace->read)
 142                 return;
 143
 144         err = trace->read(this_tracer, at, &bts);
 145         if (err < 0)
 146                 return;
 147
 148         switch (bts.qualifier) {
 149         case BTS_BRANCH:
 150                 trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
 151                 break;
 152         }
 153 }
 154
 155 static void trace_bts_cpu(void *arg)
 156 {
 157         struct trace_array *tr = (struct trace_array *) arg;
 158         const struct bts_trace *trace;
 159         unsigned char *at;
 160
 161         if (!this_tracer)
 162                 return;
 163
 164         ds_suspend_bts(this_tracer);
 165         trace = ds_read_bts(this_tracer);
 166         if (!trace)
 167                 goto out;
 168
 169         for (at = trace->ds.top; (void *)at < trace->ds.end;
 170              at += trace->ds.size)
 171                 trace_bts_at(tr, trace, at);
 172
 173         for (at = trace->ds.begin; (void *)at < trace->ds.top;
 174              at += trace->ds.size)
 175                 trace_bts_at(tr, trace, at);
 176
 177 out:
 178         ds_resume_bts(this_tracer);
 179 }
 180
 181 static void trace_bts_prepare(struct trace_iterator *iter)
 182 {
 183         int cpu;
 184
 185         for_each_cpu_mask(cpu, cpu_possible_map)
 186                 smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
 187 }
 188
 189 struct tracer bts_tracer __read_mostly =
 190 {
 191         .name           = "hw-branch-tracer",
 192         .init           = bts_trace_init,
 193         .reset          = bts_trace_stop,
 194         .print_header   = bts_trace_print_header,
 195         .print_line     = bts_trace_print_line,
 196         .start          = bts_trace_start,
 197         .stop           = bts_trace_stop,
 198         .open           = trace_bts_prepare
 199 };
 200
 201 __init static int init_bts_trace(void)
 202 {
 203         return register_tracer(&bts_tracer);
 204 }
 205 device_initcall(init_bts_trace);