linux/arch/x86/kernel/ds.c
Tejun Heo 0fe1e00954 percpu: make percpu symbols in x86 unique
This patch updates percpu related symbols in x86 such that percpu
symbols are unique and don't clash with local symbols.  This serves
two purposes of decreasing the possibility of global percpu symbol
collision and allowing dropping per_cpu__ prefix from percpu symbols.

* arch/x86/kernel/cpu/common.c: rename local variable to avoid collision

* arch/x86/kvm/svm.c: s/svm_data/sd/ for local variables to avoid collision

* arch/x86/kernel/cpu/cpu_debug.c: s/cpu_arr/cpud_arr/
  				   s/priv_arr/cpud_priv_arr/
				   s/cpu_priv_count/cpud_priv_count/

* arch/x86/kernel/cpu/intel_cacheinfo.c: s/cpuid4_info/ici_cpuid4_info/
  					 s/cache_kobject/ici_cache_kobject/
					 s/index_kobject/ici_index_kobject/

* arch/x86/kernel/ds.c: s/cpu_context/cpu_ds_context/

Partly based on Rusty Russell's "alloc_percpu: rename percpu vars
which cause name clashes" patch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: (kvm) Avi Kivity <avi@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: x86@kernel.org
2009-10-29 22:34:14 +09:00

1437 lines
32 KiB
C

/*
* 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];
/* The number of pebs counter reset values in the DS structure. */
unsigned char nr_counter_reset;
/* 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 0x80
/* Maximal size of a BTS record: */
#define MAX_SIZEOF_BTS (3 * 8)
/* BTS and PEBS buffer alignment: */
#define DS_ALIGNMENT (1 << 3)
/* Number of buffer pointers in DS: */
#define NUM_DS_PTR_FIELDS 8
/* Size of a pebs reset value in DS: */
#define PEBS_RESET_FIELD_SIZE 8
/* 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_ds_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_ds_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, unsigned long field)
{
base += (ds_cfg.sizeof_ptr_field * field);
return *(unsigned long *)base;
}
static inline void bts_set(char *base, unsigned long 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;
size_t req_size;
error = -EOPNOTSUPP;
if (!ds_cfg.sizeof_rec[qual])
goto out;
error = -EINVAL;
if (!base)
goto out;
req_size = ds_cfg.sizeof_rec[qual];
/* We might need space for alignment adjustments. */
if (!IS_ALIGNED((unsigned long)base, DS_ALIGNMENT))
req_size += DS_ALIGNMENT;
error = -EINVAL;
if (size < req_size)
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.counters = ds_cfg.nr_counter_reset;
memcpy(tracer->trace.counter_reset,
tracer->ds.context->ds +
(NUM_DS_PTR_FIELDS * ds_cfg.sizeof_ptr_field),
ds_cfg.nr_counter_reset * PEBS_RESET_FIELD_SIZE);
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_pebs, ds_index,
(unsigned long)tracer->trace.ds.top);
return 0;
}
int ds_set_pebs_reset(struct pebs_tracer *tracer,
unsigned int counter, u64 value)
{
if (!tracer)
return -EINVAL;
if (ds_cfg.nr_counter_reset < counter)
return -EINVAL;
*(u64 *)(tracer->ds.context->ds +
(NUM_DS_PTR_FIELDS * ds_cfg.sizeof_ptr_field) +
(counter * PEBS_RESET_FIELD_SIZE)) = 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),
.nr_counter_reset = 1,
};
static const struct ds_configuration ds_cfg_pentium_m = {
.name = "Pentium M",
.ctl[dsf_bts] = (1 << 6) | (1 << 7),
.nr_counter_reset = 1,
};
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),
.nr_counter_reset = 1,
};
static const struct ds_configuration ds_cfg_core_i7 = {
.name = "Core i7",
.ctl[dsf_bts] = (1 << 6) | (1 << 7),
.ctl[dsf_bts_kernel] = (1 << 9),
.ctl[dsf_bts_user] = (1 << 10),
.nr_counter_reset = 4,
};
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
/*
* Starting with version 2, architectural performance
* monitoring supports a format specifier.
*/
if ((cpuid_eax(0xa) & 0xff) > 1) {
unsigned long perf_capabilities, format;
rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_capabilities);
format = (perf_capabilities >> 8) & 0xf;
switch (format) {
case 0:
nr_pebs_fields = 18;
break;
case 1:
nr_pebs_fields = 22;
break;
default:
printk(KERN_INFO
"[ds] unknown PEBS format: %lu\n", format);
nr_pebs_fields = 0;
break;
}
}
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_PEBS_COUNTERS < ds_cfg.nr_counter_reset);
}
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 */
ds_configure(&ds_cfg_core_i7, c);
break;
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);