Commit de79f54f authored by Markus Metzger's avatar Markus Metzger Committed by Ingo Molnar

x86, bts, hw-branch-tracer: add _noirq variants to the debug store interface

The hw-branch-tracer uses debug store functions from an on_each_cpu()
context, which is simply wrong since the functions may sleep.

Add _noirq variants for most functions, which  may be called with
interrupts disabled.

Separate per-cpu and per-task tracing and allow per-cpu tracing to be
controlled from any cpu.

Make the hw-branch-tracer use the new debug store interface, synchronize
with hotplug cpu event using get/put_online_cpus(), and remove the
unnecessary spinlock.

Make the ptrace bts and the ds selftest code use the new interface.

Defer the ds selftest.
Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144555.658136000@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 35bb7600
......@@ -15,8 +15,8 @@
* - buffer allocation (memory accounting)
*
*
* Copyright (C) 2007-2008 Intel Corporation.
* Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
* Copyright (C) 2007-2009 Intel Corporation.
* Markus Metzger <markus.t.metzger@intel.com>, 2007-2009
*/
#ifndef _ASM_X86_DS_H
......@@ -83,8 +83,10 @@ enum ds_feature {
* The interrupt threshold is independent from the overflow callback
* to allow users to use their own overflow interrupt handling mechanism.
*
* task: the task to request recording for;
* NULL for per-cpu recording on the current cpu
* The function might sleep.
*
* task: the task to request recording for
* cpu: the cpu to request recording for
* base: the base pointer for the (non-pageable) buffer;
* size: the size of the provided buffer in bytes
* ovfl: pointer to a function to be called on buffer overflow;
......@@ -93,19 +95,28 @@ enum ds_feature {
* -1 if no interrupt threshold is requested.
* flags: a bit-mask of the above flags
*/
extern struct bts_tracer *ds_request_bts(struct task_struct *task,
void *base, size_t size,
bts_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
void *base, size_t size,
pebs_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct bts_tracer *ds_request_bts_task(struct task_struct *task,
void *base, size_t size,
bts_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
bts_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
void *base, size_t size,
pebs_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct pebs_tracer *ds_request_pebs_cpu(int cpu,
void *base, size_t size,
pebs_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
/*
* Release BTS or PEBS resources
* Suspend and resume BTS or PEBS tracing
*
* Must be called with irq's enabled.
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern void ds_release_bts(struct bts_tracer *tracer);
......@@ -115,6 +126,28 @@ extern void ds_release_pebs(struct pebs_tracer *tracer);
extern void ds_suspend_pebs(struct pebs_tracer *tracer);
extern void ds_resume_pebs(struct pebs_tracer *tracer);
/*
* Release BTS or PEBS resources
* Suspend and resume BTS or PEBS tracing
*
* Cpu tracers must call this on the traced cpu.
* Task tracers must call ds_release_~_noirq() for themselves.
*
* May be called with irq's disabled.
*
* Returns 0 if successful;
* -EPERM if the cpu tracer does not trace the current cpu.
* -EPERM if the task tracer does not trace itself.
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern int ds_release_bts_noirq(struct bts_tracer *tracer);
extern int ds_suspend_bts_noirq(struct bts_tracer *tracer);
extern int ds_resume_bts_noirq(struct bts_tracer *tracer);
extern int ds_release_pebs_noirq(struct pebs_tracer *tracer);
extern int ds_suspend_pebs_noirq(struct pebs_tracer *tracer);
extern int ds_resume_pebs_noirq(struct pebs_tracer *tracer);
/*
* The raw DS buffer state as it is used for BTS and PEBS recording.
......
This diff is collapsed.
......@@ -10,11 +10,12 @@
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/smp.h>
#include <asm/ds.h>
#define DS_SELFTEST_BUFFER_SIZE 1021 /* Intentionally chose an odd size. */
#define BUFFER_SIZE 1021 /* Intentionally chose an odd size. */
static int ds_selftest_bts_consistency(const struct bts_trace *trace)
......@@ -125,12 +126,12 @@ int ds_selftest_bts(void)
struct bts_tracer *tracer;
int error = 0;
void *top;
unsigned char buffer[DS_SELFTEST_BUFFER_SIZE];
unsigned char buffer[BUFFER_SIZE];
printk(KERN_INFO "[ds] bts selftest...");
tracer = ds_request_bts(NULL, buffer, DS_SELFTEST_BUFFER_SIZE,
NULL, (size_t)-1, BTS_KERNEL);
tracer = ds_request_bts_cpu(smp_processor_id(), buffer, BUFFER_SIZE,
NULL, (size_t)-1, BTS_KERNEL);
if (IS_ERR(tracer)) {
error = PTR_ERR(tracer);
tracer = NULL;
......
......@@ -800,8 +800,9 @@ static int ptrace_bts_config(struct task_struct *child,
if (cfg.flags & PTRACE_BTS_O_SCHED)
flags |= BTS_TIMESTAMPS;
context->tracer = ds_request_bts(child, context->buffer, context->size,
NULL, (size_t)-1, flags);
context->tracer =
ds_request_bts_task(child, context->buffer, context->size,
NULL, (size_t)-1, flags);
if (unlikely(IS_ERR(context->tracer))) {
int error = PTR_ERR(context->tracer);
......
......@@ -4,7 +4,6 @@
* Copyright (C) 2008-2009 Intel Corporation.
* Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
*/
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
......@@ -21,168 +20,113 @@
#define BTS_BUFFER_SIZE (1 << 13)
/*
* The tracer lock protects the below per-cpu tracer array.
* It needs to be held to:
* - start tracing on all cpus
* - stop tracing on all cpus
* - start tracing on a single hotplug cpu
* - stop tracing on a single hotplug cpu
* - read the trace from all cpus
* - read the trace from a single cpu
*/
static DEFINE_SPINLOCK(bts_tracer_lock);
static DEFINE_PER_CPU(struct bts_tracer *, tracer);
static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer);
#define this_tracer per_cpu(tracer, smp_processor_id())
#define this_buffer per_cpu(buffer, smp_processor_id())
static int trace_hw_branches_enabled __read_mostly;
static int trace_hw_branches_suspended __read_mostly;
static struct trace_array *hw_branch_trace __read_mostly;
/*
* Initialize the tracer for the current cpu.
* The argument is ignored.
*
* pre: bts_tracer_lock must be locked.
*/
static void bts_trace_init_cpu(void *arg)
static void bts_trace_init_cpu(int cpu)
{
if (this_tracer)
ds_release_bts(this_tracer);
per_cpu(tracer, cpu) =
ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE,
NULL, (size_t)-1, BTS_KERNEL);
this_tracer = ds_request_bts(NULL, this_buffer, BTS_BUFFER_SIZE,
NULL, (size_t)-1, BTS_KERNEL);
if (IS_ERR(this_tracer)) {
this_tracer = NULL;
return;
}
if (IS_ERR(per_cpu(tracer, cpu)))
per_cpu(tracer, cpu) = NULL;
}
static int bts_trace_init(struct trace_array *tr)
{
int cpu, avail;
spin_lock(&bts_tracer_lock);
int cpu;
hw_branch_trace = tr;
trace_hw_branches_enabled = 0;
on_each_cpu(bts_trace_init_cpu, NULL, 1);
/* Check on how many cpus we could enable tracing */
avail = 0;
for_each_online_cpu(cpu)
if (per_cpu(tracer, cpu))
avail++;
get_online_cpus();
for_each_online_cpu(cpu) {
bts_trace_init_cpu(cpu);
trace_hw_branches_enabled = (avail ? 1 : 0);
if (likely(per_cpu(tracer, cpu)))
trace_hw_branches_enabled = 1;
}
trace_hw_branches_suspended = 0;
spin_unlock(&bts_tracer_lock);
put_online_cpus();
/* If we could not enable tracing on a single cpu, we fail. */
return avail ? 0 : -EOPNOTSUPP;
}
/*
* Release the tracer for the current cpu.
* The argument is ignored.
*
* pre: bts_tracer_lock must be locked.
*/
static void bts_trace_release_cpu(void *arg)
{
if (this_tracer) {
ds_release_bts(this_tracer);
this_tracer = NULL;
}
return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
}
static void bts_trace_reset(struct trace_array *tr)
{
spin_lock(&bts_tracer_lock);
int cpu;
on_each_cpu(bts_trace_release_cpu, NULL, 1);
get_online_cpus();
for_each_online_cpu(cpu) {
if (likely(per_cpu(tracer, cpu))) {
ds_release_bts(per_cpu(tracer, cpu));
per_cpu(tracer, cpu) = NULL;
}
}
trace_hw_branches_enabled = 0;
trace_hw_branches_suspended = 0;
spin_unlock(&bts_tracer_lock);
}
/*
* Resume tracing on the current cpu.
* The argument is ignored.
*
* pre: bts_tracer_lock must be locked.
*/
static void bts_trace_resume_cpu(void *arg)
{
if (this_tracer)
ds_resume_bts(this_tracer);
put_online_cpus();
}
static void bts_trace_start(struct trace_array *tr)
{
spin_lock(&bts_tracer_lock);
int cpu;
on_each_cpu(bts_trace_resume_cpu, NULL, 1);
get_online_cpus();
for_each_online_cpu(cpu)
if (likely(per_cpu(tracer, cpu)))
ds_resume_bts(per_cpu(tracer, cpu));
trace_hw_branches_suspended = 0;
spin_unlock(&bts_tracer_lock);
}
/*
* Suspend tracing on the current cpu.
* The argument is ignored.
*
* pre: bts_tracer_lock must be locked.
*/
static void bts_trace_suspend_cpu(void *arg)
{
if (this_tracer)
ds_suspend_bts(this_tracer);
put_online_cpus();
}
static void bts_trace_stop(struct trace_array *tr)
{
spin_lock(&bts_tracer_lock);
int cpu;
on_each_cpu(bts_trace_suspend_cpu, NULL, 1);
get_online_cpus();
for_each_online_cpu(cpu)
if (likely(per_cpu(tracer, cpu)))
ds_suspend_bts(per_cpu(tracer, cpu));
trace_hw_branches_suspended = 1;
spin_unlock(&bts_tracer_lock);
put_online_cpus();
}
static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
spin_lock(&bts_tracer_lock);
if (!trace_hw_branches_enabled)
goto out;
int cpu = (long)hcpu;
switch (action) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
smp_call_function_single(cpu, bts_trace_init_cpu, NULL, 1);
if (trace_hw_branches_suspended)
smp_call_function_single(cpu, bts_trace_suspend_cpu,
NULL, 1);
/* The notification is sent with interrupts enabled. */
if (trace_hw_branches_enabled) {
bts_trace_init_cpu(cpu);
if (trace_hw_branches_suspended &&
likely(per_cpu(tracer, cpu)))
ds_suspend_bts(per_cpu(tracer, cpu));
}
break;
case CPU_DOWN_PREPARE:
smp_call_function_single(cpu, bts_trace_release_cpu, NULL, 1);
break;
/* The notification is sent with interrupts enabled. */
if (likely(per_cpu(tracer, cpu))) {
ds_release_bts(per_cpu(tracer, cpu));
per_cpu(tracer, cpu) = NULL;
}
}
out:
spin_unlock(&bts_tracer_lock);
return NOTIFY_DONE;
}
......@@ -274,7 +218,7 @@ static void trace_bts_at(const struct bts_trace *trace, void *at)
/*
* Collect the trace on the current cpu and write it into the ftrace buffer.
*
* pre: bts_tracer_lock must be locked
* pre: tracing must be suspended on the current cpu
*/
static void trace_bts_cpu(void *arg)
{
......@@ -291,10 +235,9 @@ static void trace_bts_cpu(void *arg)
if (unlikely(!this_tracer))
return;
ds_suspend_bts(this_tracer);
trace = ds_read_bts(this_tracer);
if (!trace)
goto out;
return;
for (at = trace->ds.top; (void *)at < trace->ds.end;
at += trace->ds.size)
......@@ -303,18 +246,27 @@ static void trace_bts_cpu(void *arg)
for (at = trace->ds.begin; (void *)at < trace->ds.top;
at += trace->ds.size)
trace_bts_at(trace, at);
out:
ds_resume_bts(this_tracer);
}
static void trace_bts_prepare(struct trace_iterator *iter)
{
spin_lock(&bts_tracer_lock);
int cpu;
get_online_cpus();
for_each_online_cpu(cpu)
if (likely(per_cpu(tracer, cpu)))
ds_suspend_bts(per_cpu(tracer, cpu));
/*
* We need to collect the trace on the respective cpu since ftrace
* implicitly adds the record for the current cpu.
* Once that is more flexible, we could collect the data from any cpu.
*/
on_each_cpu(trace_bts_cpu, iter->tr, 1);
spin_unlock(&bts_tracer_lock);
for_each_online_cpu(cpu)
if (likely(per_cpu(tracer, cpu)))
ds_resume_bts(per_cpu(tracer, cpu));
put_online_cpus();
}
static void trace_bts_close(struct trace_iterator *iter)
......@@ -324,12 +276,11 @@ static void trace_bts_close(struct trace_iterator *iter)
void trace_hw_branch_oops(void)
{
spin_lock(&bts_tracer_lock);
if (trace_hw_branches_enabled)
if (this_tracer) {
ds_suspend_bts_noirq(this_tracer);
trace_bts_cpu(hw_branch_trace);
spin_unlock(&bts_tracer_lock);
ds_resume_bts_noirq(this_tracer);
}
}
struct tracer bts_tracer __read_mostly =
......
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