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|
/*
* Debug Store support
*
* This provides a low-level interface to the hardware's Debug Store
* feature that is used for branch trace store (BTS) and
* precise-event based sampling (PEBS).
*
* It manages:
* - DS and BTS hardware configuration
* - buffer overflow handling (to be done)
* - buffer access
*
* It does not do:
* - security checking (is the caller allowed to trace the task)
* - buffer allocation (memory accounting)
*
*
* Copyright (C) 2007-2009 Intel Corporation.
* Markus Metzger <markus.t.metzger@intel.com>, 2007-2009
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/trace_clock.h>
#include <asm/ds.h>
#include "ds_selftest.h"
/*
* The configuration for a particular DS hardware implementation:
*/
struct ds_configuration {
/* The name of the configuration: */
const char *name;
/* The size of pointer-typed fields in DS, BTS, and PEBS: */
unsigned char sizeof_ptr_field;
/* The size of a BTS/PEBS record in bytes: */
unsigned char sizeof_rec[2];
/* Control bit-masks indexed by enum ds_feature: */
unsigned long ctl[dsf_ctl_max];
};
static struct ds_configuration ds_cfg __read_mostly;
/* Maximal size of a DS configuration: */
#define MAX_SIZEOF_DS (12 * 8)
/* Maximal size of a BTS record: */
#define MAX_SIZEOF_BTS (3 * 8)
/* BTS and PEBS buffer alignment: */
#define DS_ALIGNMENT (1 << 3)
/* Mask of control bits in the DS MSR register: */
#define BTS_CONTROL \
( ds_cfg.ctl[dsf_bts] | \
ds_cfg.ctl[dsf_bts_kernel] | \
ds_cfg.ctl[dsf_bts_user] | \
ds_cfg.ctl[dsf_bts_overflow] )
/*
* A BTS or PEBS tracer.
*
* This holds the configuration of the tracer and serves as a handle
* to identify tracers.
*/
struct ds_tracer {
/* The DS context (partially) owned by this tracer. */
struct ds_context *context;
/* The buffer provided on ds_request() and its size in bytes. */
void *buffer;
size_t size;
};
struct bts_tracer {
/* The common DS part: */
struct ds_tracer ds;
/* The trace including the DS configuration: */
struct bts_trace trace;
/* Buffer overflow notification function: */
bts_ovfl_callback_t ovfl;
/* Active flags affecting trace collection. */
unsigned int flags;
};
struct pebs_tracer {
/* The common DS part: */
struct ds_tracer ds;
/* The trace including the DS configuration: */
struct pebs_trace trace;
/* Buffer overflow notification function: */
pebs_ovfl_callback_t ovfl;
};
/*
* Debug Store (DS) save area configuration (see Intel64 and IA32
* Architectures Software Developer's Manual, section 18.5)
*
* The DS configuration consists of the following fields; different
* architetures vary in the size of those fields.
*
* - double-word aligned base linear address of the BTS buffer
* - write pointer into the BTS buffer
* - end linear address of the BTS buffer (one byte beyond the end of
* the buffer)
* - interrupt pointer into BTS buffer
* (interrupt occurs when write pointer passes interrupt pointer)
* - double-word aligned base linear address of the PEBS buffer
* - write pointer into the PEBS buffer
* - end linear address of the PEBS buffer (one byte beyond the end of
* the buffer)
* - interrupt pointer into PEBS buffer
* (interrupt occurs when write pointer passes interrupt pointer)
* - value to which counter is reset following counter overflow
*
* Later architectures use 64bit pointers throughout, whereas earlier
* architectures use 32bit pointers in 32bit mode.
*
*
* We compute the base address for the first 8 fields based on:
* - the field size stored in the DS configuration
* - the relative field position
* - an offset giving the start of the respective region
*
* This offset is further used to index various arrays holding
* information for BTS and PEBS at the respective index.
*
* On later 32bit processors, we only access the lower 32bit of the
* 64bit pointer fields. The upper halves will be zeroed out.
*/
enum ds_field {
ds_buffer_base = 0,
ds_index,
ds_absolute_maximum,
ds_interrupt_threshold,
};
enum ds_qualifier {
ds_bts = 0,
ds_pebs
};
static inline unsigned long
ds_get(const unsigned char *base, enum ds_qualifier qual, enum ds_field field)
{
base += (ds_cfg.sizeof_ptr_field * (field + (4 * qual)));
return *(unsigned long *)base;
}
static inline void
ds_set(unsigned char *base, enum ds_qualifier qual, enum ds_field field,
unsigned long value)
{
base += (ds_cfg.sizeof_ptr_field * (field + (4 * qual)));
(*(unsigned long *)base) = value;
}
/*
* Locking is done only for allocating BTS or PEBS resources.
*/
static DEFINE_SPINLOCK(ds_lock);
/*
* We either support (system-wide) per-cpu or per-thread allocation.
* We distinguish the two based on the task_struct pointer, where a
* NULL pointer indicates per-cpu allocation for the current cpu.
*
* Allocations are use-counted. As soon as resources are allocated,
* further allocations must be of the same type (per-cpu or
* per-thread). We model this by counting allocations (i.e. the number
* of tracers of a certain type) for one type negatively:
* =0 no tracers
* >0 number of per-thread tracers
* <0 number of per-cpu tracers
*
* Tracers essentially gives the number of ds contexts for a certain
* type of allocation.
*/
static atomic_t tracers = ATOMIC_INIT(0);
static inline int get_tracer(struct task_struct *task)
{
int error;
spin_lock_irq(&ds_lock);
if (task) {
error = -EPERM;
if (atomic_read(&tracers) < 0)
goto out;
atomic_inc(&tracers);
} else {
error = -EPERM;
if (atomic_read(&tracers) > 0)
goto out;
atomic_dec(&tracers);
}
error = 0;
out:
spin_unlock_irq(&ds_lock);
return error;
}
static inline void put_tracer(struct task_struct *task)
{
if (task)
atomic_dec(&tracers);
else
atomic_inc(&tracers);
}
/*
* The DS context is either attached to a thread or to a cpu:
* - in the former case, the thread_struct contains a pointer to the
* attached context.
* - in the latter case, we use a static array of per-cpu context
* pointers.
*
* Contexts are use-counted. They are allocated on first access and
* deallocated when the last user puts the context.
*/
struct ds_context {
/* The DS configuration; goes into MSR_IA32_DS_AREA: */
unsigned char ds[MAX_SIZEOF_DS];
/* The owner of the BTS and PEBS configuration, respectively: */
struct bts_tracer *bts_master;
struct pebs_tracer *pebs_master;
/* Use count: */
unsigned long count;
/* Pointer to the context pointer field: */
struct ds_context **this;
/* The traced task; NULL for cpu tracing: */
struct task_struct *task;
/* The traced cpu; only valid if task is NULL: */
int cpu;
};
static DEFINE_PER_CPU(struct ds_context *, cpu_context);
static struct ds_context *ds_get_context(struct task_struct *task, int cpu)
{
struct ds_context **p_context =
(task ? &task->thread.ds_ctx : &per_cpu(cpu_context, cpu));
struct ds_context *context = NULL;
struct ds_context *new_context = NULL;
/* Chances are small that we already have a context. */
new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
if (!new_context)
return NULL;
spin_lock_irq(&ds_lock);
context = *p_context;
if (likely(!context)) {
context = new_context;
context->this = p_context;
context->task = task;
context->cpu = cpu;
context->count = 0;
*p_context = context;
}
context->count++;
spin_unlock_irq(&ds_lock);
if (context != new_context)
kfree(new_context);
return context;
}
static void ds_put_context(struct ds_context *context)
{
struct task_struct *task;
unsigned long irq;
if (!context)
return;
spin_lock_irqsave(&ds_lock, irq);
if (--context->count) {
spin_unlock_irqrestore(&ds_lock, irq);
return;
}
*(context->this) = NULL;
task = context->task;
if (task)
clear_tsk_thread_flag(task, TIF_DS_AREA_MSR);
/*
* We leave the (now dangling) pointer to the DS configuration in
* the DS_AREA msr. This is as good or as bad as replacing it with
* NULL - the hardware would crash if we enabled tracing.
*
* This saves us some problems with having to write an msr on a
* different cpu while preventing others from doing the same for the
* next context for that same cpu.
*/
spin_unlock_irqrestore(&ds_lock, irq);
/* The context might still be in use for context switching. */
if (task && (task != current))
wait_task_context_switch(task);
kfree(context);
}
static void ds_install_ds_area(struct ds_context *context)
{
unsigned long ds;
ds = (unsigned long)context->ds;
/*
* There is a race between the bts master and the pebs master.
*
* The thread/cpu access is synchronized via get/put_cpu() for
* task tracing and via wrmsr_on_cpu for cpu tracing.
*
* If bts and pebs are collected for the same task or same cpu,
* the same confiuration is written twice.
*/
if (context->task) {
get_cpu();
if (context->task == current)
wrmsrl(MSR_IA32_DS_AREA, ds);
set_tsk_thread_flag(context->task, TIF_DS_AREA_MSR);
put_cpu();
} else
wrmsr_on_cpu(context->cpu, MSR_IA32_DS_AREA,
(u32)((u64)ds), (u32)((u64)ds >> 32));
}
/*
* Call the tracer's callback on a buffer overflow.
*
* context: the ds context
* qual: the buffer type
*/
static void ds_overflow(struct ds_context *context, enum ds_qualifier qual)
{
switch (qual) {
case ds_bts:
if (context->bts_master &&
context->bts_master->ovfl)
context->bts_master->ovfl(context->bts_master);
break;
case ds_pebs:
if (context->pebs_master &&
context->pebs_master->ovfl)
context->pebs_master->ovfl(context->pebs_master);
break;
}
}
/*
* Write raw data into the BTS or PEBS buffer.
*
* The remainder of any partially written record is zeroed out.
*
* context: the DS context
* qual: the buffer type
* record: the data to write
* size: the size of the data
*/
static int ds_write(struct ds_context *context, enum ds_qualifier qual,
const void *record, size_t size)
{
int bytes_written = 0;
if (!record)
return -EINVAL;
while (size) {
unsigned long base, index, end, write_end, int_th;
unsigned long write_size, adj_write_size;
/*
* Write as much as possible without producing an
* overflow interrupt.
*
* Interrupt_threshold must either be
* - bigger than absolute_maximum or
* - point to a record between buffer_base and absolute_maximum
*
* Index points to a valid record.
*/
base = ds_get(context->ds, qual, ds_buffer_base);
index = ds_get(context->ds, qual, ds_index);
end = ds_get(context->ds, qual, ds_absolute_maximum);
int_th = ds_get(context->ds, qual, ds_interrupt_threshold);
write_end = min(end, int_th);
/*
* If we are already beyond the interrupt threshold,
* we fill the entire buffer.
*/
if (write_end <= index)
write_end = end;
if (write_end <= index)
break;
write_size = min((unsigned long) size, write_end - index);
memcpy((void *)index, record, write_size);
record = (const char *)record + write_size;
size -= write_size;
bytes_written += write_size;
adj_write_size = write_size / ds_cfg.sizeof_rec[qual];
adj_write_size *= ds_cfg.sizeof_rec[qual];
/* Zero out trailing bytes. */
memset((char *)index + write_size, 0,
adj_write_size - write_size);
index += adj_write_size;
if (index >= end)
index = base;
ds_set(context->ds, qual, ds_index, index);
if (index >= int_th)
ds_overflow(context, qual);
}
return bytes_written;
}
/*
* Branch Trace Store (BTS) uses the following format. Different
* architectures vary in the size of those fields.
* - source linear address
* - destination linear address
* - flags
*
* Later architectures use 64bit pointers throughout, whereas earlier
* architectures use 32bit pointers in 32bit mode.
*
* We compute the base address for the fields based on:
* - the field size stored in the DS configuration
* - the relative field position
*
* In order to store additional information in the BTS buffer, we use
* a special source address to indicate that the record requires
* special interpretation.
*
* Netburst indicated via a bit in the flags field whether the branch
* was predicted; this is ignored.
*
* We use two levels of abstraction:
* - the raw data level defined here
* - an arch-independent level defined in ds.h
*/
enum bts_field {
bts_from,
bts_to,
bts_flags,
bts_qual = bts_from,
bts_clock = bts_to,
bts_pid = bts_flags,
bts_qual_mask = (bts_qual_max - 1),
bts_escape = ((unsigned long)-1 & ~bts_qual_mask)
};
static inline unsigned long bts_get(const char *base, enum bts_field field)
{
base += (ds_cfg.sizeof_ptr_field * field);
return *(unsigned long *)base;
}
static inline void bts_set(char *base, enum bts_field field, unsigned long val)
{
base += (ds_cfg.sizeof_ptr_field * field);;
(*(unsigned long *)base) = val;
}
/*
* The raw BTS data is architecture dependent.
*
* For higher-level users, we give an arch-independent view.
* - ds.h defines struct bts_struct
* - bts_read translates one raw bts record into a bts_struct
* - bts_write translates one bts_struct into the raw format and
* writes it into the top of the parameter tracer's buffer.
*
* return: bytes read/written on success; -Eerrno, otherwise
*/
static int
bts_read(struct bts_tracer *tracer, const void *at, struct bts_struct *out)
{
if (!tracer)
return -EINVAL;
if (at < tracer->trace.ds.begin)
return -EINVAL;
if (tracer->trace.ds.end < (at + tracer->trace.ds.size))
return -EINVAL;
memset(out, 0, sizeof(*out));
if ((bts_get(at, bts_qual) & ~bts_qual_mask) == bts_escape) {
out->qualifier = (bts_get(at, bts_qual) & bts_qual_mask);
out->variant.event.clock = bts_get(at, bts_clock);
out->variant.event.pid = bts_get(at, bts_pid);
} else {
out->qualifier = bts_branch;
out->variant.lbr.from = bts_get(at, bts_from);
out->variant.lbr.to = bts_get(at, bts_to);
if (!out->variant.lbr.from && !out->variant.lbr.to)
out->qualifier = bts_invalid;
}
return ds_cfg.sizeof_rec[ds_bts];
}
static int bts_write(struct bts_tracer *tracer, const struct bts_struct *in)
{
unsigned char raw[MAX_SIZEOF_BTS];
if (!tracer)
return -EINVAL;
if (MAX_SIZEOF_BTS < ds_cfg.sizeof_rec[ds_bts])
return -EOVERFLOW;
switch (in->qualifier) {
case bts_invalid:
bts_set(raw, bts_from, 0);
bts_set(raw, bts_to, 0);
bts_set(raw, bts_flags, 0);
break;
case bts_branch:
bts_set(raw, bts_from, in->variant.lbr.from);
bts_set(raw, bts_to, in->variant.lbr.to);
bts_set(raw, bts_flags, 0);
break;
case bts_task_arrives:
case bts_task_departs:
bts_set(raw, bts_qual, (bts_escape | in->qualifier));
bts_set(raw, bts_clock, in->variant.event.clock);
bts_set(raw, bts_pid, in->variant.event.pid);
break;
default:
return -EINVAL;
}
return ds_write(tracer->ds.context, ds_bts, raw,
ds_cfg.sizeof_rec[ds_bts]);
}
static void ds_write_config(struct ds_context *context,
struct ds_trace *cfg, enum ds_qualifier qual)
{
unsigned char *ds = context->ds;
ds_set(ds, qual, ds_buffer_base, (unsigned long)cfg->begin);
ds_set(ds, qual, ds_index, (unsigned long)cfg->top);
ds_set(ds, qual, ds_absolute_maximum, (unsigned long)cfg->end);
ds_set(ds, qual, ds_interrupt_threshold, (unsigned long)cfg->ith);
}
static void ds_read_config(struct ds_context *context,
struct ds_trace *cfg, enum ds_qualifier qual)
{
unsigned char *ds = context->ds;
cfg->begin = (void *)ds_get(ds, qual, ds_buffer_base);
cfg->top = (void *)ds_get(ds, qual, ds_index);
cfg->end = (void *)ds_get(ds, qual, ds_absolute_maximum);
cfg->ith = (void *)ds_get(ds, qual, ds_interrupt_threshold);
}
static void ds_init_ds_trace(struct ds_trace *trace, enum ds_qualifier qual,
void *base, size_t size, size_t ith,
unsigned int flags) {
unsigned long buffer, adj;
/*
* Adjust the buffer address and size to meet alignment
* constraints:
* - buffer is double-word aligned
* - size is multiple of record size
*
* We checked the size at the very beginning; we have enough
* space to do the adjustment.
*/
buffer = (unsigned long)base;
adj = ALIGN(buffer, DS_ALIGNMENT) - buffer;
buffer += adj;
size -= adj;
trace->n = size / ds_cfg.sizeof_rec[qual];
trace->size = ds_cfg.sizeof_rec[qual];
size = (trace->n * trace->size);
trace->begin = (void *)buffer;
trace->top = trace->begin;
trace->end = (void *)(buffer + size);
/*
* The value for 'no threshold' is -1, which will set the
* threshold outside of the buffer, just like we want it.
*/
ith *= ds_cfg.sizeof_rec[qual];
trace->ith = (void *)(buffer + size - ith);
trace->flags = flags;
}
static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
enum ds_qualifier qual, struct task_struct *task,
int cpu, void *base, size_t size, size_t th)
{
struct ds_context *context;
int error;
error = -EOPNOTSUPP;
if (!ds_cfg.sizeof_rec[qual])
goto out;
error = -EINVAL;
if (!base)
goto out;
/* We need space for alignment adjustments in ds_init_ds_trace(). */
error = -EINVAL;
if (size < (DS_ALIGNMENT + ds_cfg.sizeof_rec[qual]))
goto out;
if (th != (size_t)-1) {
th *= ds_cfg.sizeof_rec[qual];
error = -EINVAL;
if (size <= th)
goto out;
}
tracer->buffer = base;
tracer->size = size;
error = -ENOMEM;
context = ds_get_context(task, cpu);
if (!context)
goto out;
tracer->context = context;
/*
* Defer any tracer-specific initialization work for the context until
* context ownership has been clarified.
*/
error = 0;
out:
return error;
}
static struct bts_tracer *ds_request_bts(struct task_struct *task, int cpu,
void *base, size_t size,
bts_ovfl_callback_t ovfl, size_t th,
unsigned int flags)
{
struct bts_tracer *tracer;
int error;
/* Buffer overflow notification is not yet implemented. */
error = -EOPNOTSUPP;
if (ovfl)
goto out;
error = get_tracer(task);
if (error < 0)
goto out;
error = -ENOMEM;
tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
if (!tracer)
goto out_put_tracer;
tracer->ovfl = ovfl;
/* Do some more error checking and acquire a tracing context. */
error = ds_request(&tracer->ds, &tracer->trace.ds,
ds_bts, task, cpu, base, size, th);
if (error < 0)
goto out_tracer;
/* Claim the bts part of the tracing context we acquired above. */
spin_lock_irq(&ds_lock);
error = -EPERM;
if (tracer->ds.context->bts_master)
goto out_unlock;
tracer->ds.context->bts_master = tracer;
spin_unlock_irq(&ds_lock);
/*
* Now that we own the bts part of the context, let's complete the
* initialization for that part.
*/
ds_init_ds_trace(&tracer->trace.ds, ds_bts, base, size, th, flags);
ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
ds_install_ds_area(tracer->ds.context);
tracer->trace.read = bts_read;
tracer->trace.write = bts_write;
/* Start tracing. */
ds_resume_bts(tracer);
return tracer;
out_unlock:
spin_unlock_irq(&ds_lock);
ds_put_context(tracer->ds.context);
out_tracer:
kfree(tracer);
out_put_tracer:
put_tracer(task);
out:
return ERR_PTR(error);
}
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)
{
return ds_request_bts(task, 0, base, size, ovfl, th, flags);
}
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)
{
return ds_request_bts(NULL, cpu, base, size, ovfl, th, flags);
}
static struct pebs_tracer *ds_request_pebs(struct task_struct *task, int cpu,
void *base, size_t size,
pebs_ovfl_callback_t ovfl, size_t th,
unsigned int flags)
{
struct pebs_tracer *tracer;
int error;
/* Buffer overflow notification is not yet implemented. */
error = -EOPNOTSUPP;
if (ovfl)
goto out;
error = get_tracer(task);
if (error < 0)
goto out;
error = -ENOMEM;
tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
if (!tracer)
goto out_put_tracer;
tracer->ovfl = ovfl;
/* Do some more error checking and acquire a tracing context. */
error = ds_request(&tracer->ds, &tracer->trace.ds,
ds_pebs, task, cpu, base, size, th);
if (error < 0)
goto out_tracer;
/* Claim the pebs part of the tracing context we acquired above. */
spin_lock_irq(&ds_lock);
error = -EPERM;
if (tracer->ds.context->pebs_master)
goto out_unlock;
tracer->ds.context->pebs_master = tracer;
spin_unlock_irq(&ds_lock);
/*
* Now that we own the pebs part of the context, let's complete the
* initialization for that part.
*/
ds_init_ds_trace(&tracer->trace.ds, ds_pebs, base, size, th, flags);
ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_pebs);
ds_install_ds_area(tracer->ds.context);
/* Start tracing. */
ds_resume_pebs(tracer);
return tracer;
out_unlock:
spin_unlock_irq(&ds_lock);
ds_put_context(tracer->ds.context);
out_tracer:
kfree(tracer);
out_put_tracer:
put_tracer(task);
out:
return ERR_PTR(error);
}
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)
{
return ds_request_pebs(task, 0, base, size, ovfl, th, flags);
}
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)
{
return ds_request_pebs(NULL, cpu, base, size, ovfl, th, flags);
}
static void ds_free_bts(struct bts_tracer *tracer)
{
struct task_struct *task;
task = tracer->ds.context->task;
WARN_ON_ONCE(tracer->ds.context->bts_master != tracer);
tracer->ds.context->bts_master = NULL;
/* Make sure tracing stopped and the tracer is not in use. */
if (task && (task != current))
wait_task_context_switch(task);
ds_put_context(tracer->ds.context);
put_tracer(task);
kfree(tracer);
}
void ds_release_bts(struct bts_tracer *tracer)
{
might_sleep();
if (!tracer)
return;
ds_suspend_bts(tracer);
ds_free_bts(tracer);
}
int ds_release_bts_noirq(struct bts_tracer *tracer)
{
struct task_struct *task;
unsigned long irq;
int error;
if (!tracer)
return 0;
task = tracer->ds.context->task;
local_irq_save(irq);
error = -EPERM;
if (!task &&
(tracer->ds.context->cpu != smp_processor_id()))
goto out;
error = -EPERM;
if (task && (task != current))
goto out;
ds_suspend_bts_noirq(tracer);
ds_free_bts(tracer);
error = 0;
out:
local_irq_restore(irq);
return error;
}
static void update_task_debugctlmsr(struct task_struct *task,
unsigned long debugctlmsr)
{
task->thread.debugctlmsr = debugctlmsr;
get_cpu();
if (task == current)
update_debugctlmsr(debugctlmsr);
put_cpu();
}
void ds_suspend_bts(struct bts_tracer *tracer)
{
struct task_struct *task;
unsigned long debugctlmsr;
int cpu;
if (!tracer)
return;
tracer->flags = 0;
task = tracer->ds.context->task;
cpu = tracer->ds.context->cpu;
WARN_ON(!task && irqs_disabled());
debugctlmsr = (task ?
task->thread.debugctlmsr :
get_debugctlmsr_on_cpu(cpu));
debugctlmsr &= ~BTS_CONTROL;
if (task)
update_task_debugctlmsr(task, debugctlmsr);
else
update_debugctlmsr_on_cpu(cpu, debugctlmsr);
}
int ds_suspend_bts_noirq(struct bts_tracer *tracer)
{
struct task_struct *task;
unsigned long debugctlmsr, irq;
int cpu, error = 0;
if (!tracer)
return 0;
tracer->flags = 0;
task = tracer->ds.context->task;
cpu = tracer->ds.context->cpu;
local_irq_save(irq);
error = -EPERM;
if (!task && (cpu != smp_processor_id()))
goto out;
debugctlmsr = (task ?
task->thread.debugctlmsr :
get_debugctlmsr());
debugctlmsr &= ~BTS_CONTROL;
if (task)
update_task_debugctlmsr(task, debugctlmsr);
else
update_debugctlmsr(debugctlmsr);
error = 0;
out:
local_irq_restore(irq);
return error;
}
static unsigned long ds_bts_control(struct bts_tracer *tracer)
{
unsigned long control;
control = ds_cfg.ctl[dsf_bts];
if (!(tracer->trace.ds.flags & BTS_KERNEL))
control |= ds_cfg.ctl[dsf_bts_kernel];
if (!(tracer->trace.ds.flags & BTS_USER))
control |= ds_cfg.ctl[dsf_bts_user];
return control;
}
void ds_resume_bts(struct bts_tracer *tracer)
{
struct task_struct *task;
unsigned long debugctlmsr;
int cpu;
if (!tracer)
return;
tracer->flags = tracer->trace.ds.flags;
task = tracer->ds.context->task;
cpu = tracer->ds.context->cpu;
WARN_ON(!task && irqs_disabled());
debugctlmsr = (task ?
task->thread.debugctlmsr :
get_debugctlmsr_on_cpu(cpu));
debugctlmsr |= ds_bts_control(tracer);
if (task)
update_task_debugctlmsr(task, debugctlmsr);
else
update_debugctlmsr_on_cpu(cpu, debugctlmsr);
}
int ds_resume_bts_noirq(struct bts_tracer *tracer)
{
struct task_struct *task;
unsigned long debugctlmsr, irq;
int cpu, error = 0;
if (!tracer)
return 0;
tracer->flags = tracer->trace.ds.flags;
task = tracer->ds.context->task;
cpu = tracer->ds.context->cpu;
local_irq_save(irq);
error = -EPERM;
if (!task && (cpu != smp_processor_id()))
goto out;
debugctlmsr = (task ?
task->thread.debugctlmsr :
get_debugctlmsr());
debugctlmsr |= ds_bts_control(tracer);
if (task)
update_task_debugctlmsr(task, debugctlmsr);
else
update_debugctlmsr(debugctlmsr);
error = 0;
out:
local_irq_restore(irq);
return error;
}
static void ds_free_pebs(struct pebs_tracer *tracer)
{
struct task_struct *task;
task = tracer->ds.context->task;
WARN_ON_ONCE(tracer->ds.context->pebs_master != tracer);
tracer->ds.context->pebs_master = NULL;
ds_put_context(tracer->ds.context);
put_tracer(task);
kfree(tracer);
}
void ds_release_pebs(struct pebs_tracer *tracer)
{
might_sleep();
if (!tracer)
return;
ds_suspend_pebs(tracer);
ds_free_pebs(tracer);
}
int ds_release_pebs_noirq(struct pebs_tracer *tracer)
{
struct task_struct *task;
unsigned long irq;
int error;
if (!tracer)
return 0;
task = tracer->ds.context->task;
local_irq_save(irq);
error = -EPERM;
if (!task &&
(tracer->ds.context->cpu != smp_processor_id()))
goto out;
error = -EPERM;
if (task && (task != current))
goto out;
ds_suspend_pebs_noirq(tracer);
ds_free_pebs(tracer);
error = 0;
out:
local_irq_restore(irq);
return error;
}
void ds_suspend_pebs(struct pebs_tracer *tracer)
{
}
int ds_suspend_pebs_noirq(struct pebs_tracer *tracer)
{
return 0;
}
void ds_resume_pebs(struct pebs_tracer *tracer)
{
}
int ds_resume_pebs_noirq(struct pebs_tracer *tracer)
{
return 0;
}
const struct bts_trace *ds_read_bts(struct bts_tracer *tracer)
{
if (!tracer)
return NULL;
ds_read_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
return &tracer->trace;
}
const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer)
{
if (!tracer)
return NULL;
ds_read_config(tracer->ds.context, &tracer->trace.ds, ds_pebs);
tracer->trace.reset_value =
*(u64 *)(tracer->ds.context->ds +
(ds_cfg.sizeof_ptr_field * 8));
return &tracer->trace;
}
int ds_reset_bts(struct bts_tracer *tracer)
{
if (!tracer)
return -EINVAL;
tracer->trace.ds.top = tracer->trace.ds.begin;
ds_set(tracer->ds.context->ds, ds_bts, ds_index,
(unsigned long)tracer->trace.ds.top);
return 0;
}
int ds_reset_pebs(struct pebs_tracer *tracer)
{
if (!tracer)
return -EINVAL;
tracer->trace.ds.top = tracer->trace.ds.begin;
ds_set(tracer->ds.context->ds, ds_bts, ds_index,
(unsigned long)tracer->trace.ds.top);
return 0;
}
int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value)
{
if (!tracer)
return -EINVAL;
*(u64 *)(tracer->ds.context->ds +
(ds_cfg.sizeof_ptr_field * 8)) = value;
return 0;
}
static const struct ds_configuration ds_cfg_netburst = {
.name = "Netburst",
.ctl[dsf_bts] = (1 << 2) | (1 << 3),
.ctl[dsf_bts_kernel] = (1 << 5),
.ctl[dsf_bts_user] = (1 << 6),
};
static const struct ds_configuration ds_cfg_pentium_m = {
.name = "Pentium M",
.ctl[dsf_bts] = (1 << 6) | (1 << 7),
};
static const struct ds_configuration ds_cfg_core2_atom = {
.name = "Core 2/Atom",
.ctl[dsf_bts] = (1 << 6) | (1 << 7),
.ctl[dsf_bts_kernel] = (1 << 9),
.ctl[dsf_bts_user] = (1 << 10),
};
static void
ds_configure(const struct ds_configuration *cfg,
struct cpuinfo_x86 *cpu)
{
unsigned long nr_pebs_fields = 0;
printk(KERN_INFO "[ds] using %s configuration\n", cfg->name);
#ifdef __i386__
nr_pebs_fields = 10;
#else
nr_pebs_fields = 18;
#endif
memset(&ds_cfg, 0, sizeof(ds_cfg));
ds_cfg = *cfg;
ds_cfg.sizeof_ptr_field =
(cpu_has(cpu, X86_FEATURE_DTES64) ? 8 : 4);
ds_cfg.sizeof_rec[ds_bts] = ds_cfg.sizeof_ptr_field * 3;
ds_cfg.sizeof_rec[ds_pebs] = ds_cfg.sizeof_ptr_field * nr_pebs_fields;
if (!cpu_has(cpu, X86_FEATURE_BTS)) {
ds_cfg.sizeof_rec[ds_bts] = 0;
printk(KERN_INFO "[ds] bts not available\n");
}
if (!cpu_has(cpu, X86_FEATURE_PEBS)) {
ds_cfg.sizeof_rec[ds_pebs] = 0;
printk(KERN_INFO "[ds] pebs not available\n");
}
printk(KERN_INFO "[ds] sizes: address: %u bit, ",
8 * ds_cfg.sizeof_ptr_field);
printk("bts/pebs record: %u/%u bytes\n",
ds_cfg.sizeof_rec[ds_bts], ds_cfg.sizeof_rec[ds_pebs]);
WARN_ON_ONCE(MAX_SIZEOF_DS < (12 * ds_cfg.sizeof_ptr_field));
}
void __cpuinit ds_init_intel(struct cpuinfo_x86 *c)
{
/* Only configure the first cpu. Others are identical. */
if (ds_cfg.name)
return;
switch (c->x86) {
case 0x6:
switch (c->x86_model) {
case 0x9:
case 0xd: /* Pentium M */
ds_configure(&ds_cfg_pentium_m, c);
break;
case 0xf:
case 0x17: /* Core2 */
case 0x1c: /* Atom */
ds_configure(&ds_cfg_core2_atom, c);
break;
case 0x1a: /* Core i7 */
default:
/* Sorry, don't know about them. */
break;
}
break;
case 0xf:
switch (c->x86_model) {
case 0x0:
case 0x1:
case 0x2: /* Netburst */
ds_configure(&ds_cfg_netburst, c);
break;
default:
/* Sorry, don't know about them. */
break;
}
break;
default:
/* Sorry, don't know about them. */
break;
}
}
static inline void ds_take_timestamp(struct ds_context *context,
enum bts_qualifier qualifier,
struct task_struct *task)
{
struct bts_tracer *tracer = context->bts_master;
struct bts_struct ts;
/* Prevent compilers from reading the tracer pointer twice. */
barrier();
if (!tracer || !(tracer->flags & BTS_TIMESTAMPS))
return;
memset(&ts, 0, sizeof(ts));
ts.qualifier = qualifier;
ts.variant.event.clock = trace_clock_global();
ts.variant.event.pid = task->pid;
bts_write(tracer, &ts);
}
/*
* Change the DS configuration from tracing prev to tracing next.
*/
void ds_switch_to(struct task_struct *prev, struct task_struct *next)
{
struct ds_context *prev_ctx = prev->thread.ds_ctx;
struct ds_context *next_ctx = next->thread.ds_ctx;
unsigned long debugctlmsr = next->thread.debugctlmsr;
/* Make sure all data is read before we start. */
barrier();
if (prev_ctx) {
update_debugctlmsr(0);
ds_take_timestamp(prev_ctx, bts_task_departs, prev);
}
if (next_ctx) {
ds_take_timestamp(next_ctx, bts_task_arrives, next);
wrmsrl(MSR_IA32_DS_AREA, (unsigned long)next_ctx->ds);
}
update_debugctlmsr(debugctlmsr);
}
static __init int ds_selftest(void)
{
if (ds_cfg.sizeof_rec[ds_bts]) {
int error;
error = ds_selftest_bts();
if (error) {
WARN(1, "[ds] selftest failed. disabling bts.\n");
ds_cfg.sizeof_rec[ds_bts] = 0;
}
}
if (ds_cfg.sizeof_rec[ds_pebs]) {
int error;
error = ds_selftest_pebs();
if (error) {
WARN(1, "[ds] selftest failed. disabling pebs.\n");
ds_cfg.sizeof_rec[ds_pebs] = 0;
}
}
return 0;
}
device_initcall(ds_selftest);
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