diff options
Diffstat (limited to 'kernel/trace/trace_hw_branches.c')
| -rw-r--r-- | kernel/trace/trace_hw_branches.c | 195 |
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 00000000000..649df22d435 --- /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(cpu, cpu_possible_mask) + 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(cpu, cpu_possible_mask) + 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(cpu, cpu_possible_mask) + 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); |