linux/arch/x86/kernel/ds.c
Cyrill Gorcunov 431ef7a2a4 x86: debug Store - call kfree if only we really need it
We should call for kfree if only we really need it.
Though it's safe to call kfree with NULL pointer passed
in this code we've already tested the pointer and can
eliminate the call

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17 17:41:34 +02:00

465 lines
11 KiB
C

/*
* Debug Store support
*
* This provides a low-level interface to the hardware's Debug Store
* feature that is used for last branch recording (LBR) and
* precise-event based sampling (PEBS).
*
* Different architectures use a different DS layout/pointer size.
* The below functions therefore work on a void*.
*
*
* Since there is no user for PEBS, yet, only LBR (or branch
* trace store, BTS) is supported.
*
*
* Copyright (C) 2007 Intel Corporation.
* Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
*/
#include <asm/ds.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/slab.h>
/*
* 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
*
* On later architectures, the last branch recording hardware uses
* 64bit pointers even in 32bit mode.
*
*
* Branch Trace Store (BTS) records store information about control
* flow changes. They at least provide the following information:
* - source linear address
* - destination linear address
*
* Netburst supported a predicated bit that had been dropped in later
* architectures. We do not suppor it.
*
*
* In order to abstract from the actual DS and BTS layout, we describe
* the access to the relevant fields.
* Thanks to Andi Kleen for proposing this design.
*
* The implementation, however, is not as general as it might seem. In
* order to stay somewhat simple and efficient, we assume an
* underlying unsigned type (mostly a pointer type) and we expect the
* field to be at least as big as that type.
*/
/*
* A special from_ip address to indicate that the BTS record is an
* info record that needs to be interpreted or skipped.
*/
#define BTS_ESCAPE_ADDRESS (-1)
/*
* A field access descriptor
*/
struct access_desc {
unsigned char offset;
unsigned char size;
};
/*
* The configuration for a particular DS/BTS hardware implementation.
*/
struct ds_configuration {
/* the DS configuration */
unsigned char sizeof_ds;
struct access_desc bts_buffer_base;
struct access_desc bts_index;
struct access_desc bts_absolute_maximum;
struct access_desc bts_interrupt_threshold;
/* the BTS configuration */
unsigned char sizeof_bts;
struct access_desc from_ip;
struct access_desc to_ip;
/* BTS variants used to store additional information like
timestamps */
struct access_desc info_type;
struct access_desc info_data;
unsigned long debugctl_mask;
};
/*
* The global configuration used by the below accessor functions
*/
static struct ds_configuration ds_cfg;
/*
* Accessor functions for some DS and BTS fields using the above
* global ptrace_bts_cfg.
*/
static inline unsigned long get_bts_buffer_base(char *base)
{
return *(unsigned long *)(base + ds_cfg.bts_buffer_base.offset);
}
static inline void set_bts_buffer_base(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.bts_buffer_base.offset)) = value;
}
static inline unsigned long get_bts_index(char *base)
{
return *(unsigned long *)(base + ds_cfg.bts_index.offset);
}
static inline void set_bts_index(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.bts_index.offset)) = value;
}
static inline unsigned long get_bts_absolute_maximum(char *base)
{
return *(unsigned long *)(base + ds_cfg.bts_absolute_maximum.offset);
}
static inline void set_bts_absolute_maximum(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.bts_absolute_maximum.offset)) = value;
}
static inline unsigned long get_bts_interrupt_threshold(char *base)
{
return *(unsigned long *)(base + ds_cfg.bts_interrupt_threshold.offset);
}
static inline void set_bts_interrupt_threshold(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.bts_interrupt_threshold.offset)) = value;
}
static inline unsigned long get_from_ip(char *base)
{
return *(unsigned long *)(base + ds_cfg.from_ip.offset);
}
static inline void set_from_ip(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.from_ip.offset)) = value;
}
static inline unsigned long get_to_ip(char *base)
{
return *(unsigned long *)(base + ds_cfg.to_ip.offset);
}
static inline void set_to_ip(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.to_ip.offset)) = value;
}
static inline unsigned char get_info_type(char *base)
{
return *(unsigned char *)(base + ds_cfg.info_type.offset);
}
static inline void set_info_type(char *base, unsigned char value)
{
(*(unsigned char *)(base + ds_cfg.info_type.offset)) = value;
}
static inline unsigned long get_info_data(char *base)
{
return *(unsigned long *)(base + ds_cfg.info_data.offset);
}
static inline void set_info_data(char *base, unsigned long value)
{
(*(unsigned long *)(base + ds_cfg.info_data.offset)) = value;
}
int ds_allocate(void **dsp, size_t bts_size_in_bytes)
{
size_t bts_size_in_records;
unsigned long bts;
void *ds;
if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
return -EOPNOTSUPP;
if (bts_size_in_bytes < 0)
return -EINVAL;
bts_size_in_records =
bts_size_in_bytes / ds_cfg.sizeof_bts;
bts_size_in_bytes =
bts_size_in_records * ds_cfg.sizeof_bts;
if (bts_size_in_bytes <= 0)
return -EINVAL;
bts = (unsigned long)kzalloc(bts_size_in_bytes, GFP_KERNEL);
if (!bts)
return -ENOMEM;
ds = kzalloc(ds_cfg.sizeof_ds, GFP_KERNEL);
if (!ds) {
kfree((void *)bts);
return -ENOMEM;
}
set_bts_buffer_base(ds, bts);
set_bts_index(ds, bts);
set_bts_absolute_maximum(ds, bts + bts_size_in_bytes);
set_bts_interrupt_threshold(ds, bts + bts_size_in_bytes + 1);
*dsp = ds;
return 0;
}
int ds_free(void **dsp)
{
if (*dsp) {
kfree((void *)get_bts_buffer_base(*dsp));
kfree(*dsp);
*dsp = NULL;
}
return 0;
}
int ds_get_bts_size(void *ds)
{
int size_in_bytes;
if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
return -EOPNOTSUPP;
if (!ds)
return 0;
size_in_bytes =
get_bts_absolute_maximum(ds) -
get_bts_buffer_base(ds);
return size_in_bytes;
}
int ds_get_bts_end(void *ds)
{
int size_in_bytes = ds_get_bts_size(ds);
if (size_in_bytes <= 0)
return size_in_bytes;
return size_in_bytes / ds_cfg.sizeof_bts;
}
int ds_get_bts_index(void *ds)
{
int index_offset_in_bytes;
if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
return -EOPNOTSUPP;
index_offset_in_bytes =
get_bts_index(ds) -
get_bts_buffer_base(ds);
return index_offset_in_bytes / ds_cfg.sizeof_bts;
}
int ds_set_overflow(void *ds, int method)
{
switch (method) {
case DS_O_SIGNAL:
return -EOPNOTSUPP;
case DS_O_WRAP:
return 0;
default:
return -EINVAL;
}
}
int ds_get_overflow(void *ds)
{
return DS_O_WRAP;
}
int ds_clear(void *ds)
{
int bts_size = ds_get_bts_size(ds);
unsigned long bts_base;
if (bts_size <= 0)
return bts_size;
bts_base = get_bts_buffer_base(ds);
memset((void *)bts_base, 0, bts_size);
set_bts_index(ds, bts_base);
return 0;
}
int ds_read_bts(void *ds, int index, struct bts_struct *out)
{
void *bts;
if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
return -EOPNOTSUPP;
if (index < 0)
return -EINVAL;
if (index >= ds_get_bts_size(ds))
return -EINVAL;
bts = (void *)(get_bts_buffer_base(ds) + (index * ds_cfg.sizeof_bts));
memset(out, 0, sizeof(*out));
if (get_from_ip(bts) == BTS_ESCAPE_ADDRESS) {
out->qualifier = get_info_type(bts);
out->variant.jiffies = get_info_data(bts);
} else {
out->qualifier = BTS_BRANCH;
out->variant.lbr.from_ip = get_from_ip(bts);
out->variant.lbr.to_ip = get_to_ip(bts);
}
return sizeof(*out);;
}
int ds_write_bts(void *ds, const struct bts_struct *in)
{
unsigned long bts;
if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
return -EOPNOTSUPP;
if (ds_get_bts_size(ds) <= 0)
return -ENXIO;
bts = get_bts_index(ds);
memset((void *)bts, 0, ds_cfg.sizeof_bts);
switch (in->qualifier) {
case BTS_INVALID:
break;
case BTS_BRANCH:
set_from_ip((void *)bts, in->variant.lbr.from_ip);
set_to_ip((void *)bts, in->variant.lbr.to_ip);
break;
case BTS_TASK_ARRIVES:
case BTS_TASK_DEPARTS:
set_from_ip((void *)bts, BTS_ESCAPE_ADDRESS);
set_info_type((void *)bts, in->qualifier);
set_info_data((void *)bts, in->variant.jiffies);
break;
default:
return -EINVAL;
}
bts = bts + ds_cfg.sizeof_bts;
if (bts >= get_bts_absolute_maximum(ds))
bts = get_bts_buffer_base(ds);
set_bts_index(ds, bts);
return ds_cfg.sizeof_bts;
}
unsigned long ds_debugctl_mask(void)
{
return ds_cfg.debugctl_mask;
}
#ifdef __i386__
static const struct ds_configuration ds_cfg_netburst = {
.sizeof_ds = 9 * 4,
.bts_buffer_base = { 0, 4 },
.bts_index = { 4, 4 },
.bts_absolute_maximum = { 8, 4 },
.bts_interrupt_threshold = { 12, 4 },
.sizeof_bts = 3 * 4,
.from_ip = { 0, 4 },
.to_ip = { 4, 4 },
.info_type = { 4, 1 },
.info_data = { 8, 4 },
.debugctl_mask = (1<<2)|(1<<3)
};
static const struct ds_configuration ds_cfg_pentium_m = {
.sizeof_ds = 9 * 4,
.bts_buffer_base = { 0, 4 },
.bts_index = { 4, 4 },
.bts_absolute_maximum = { 8, 4 },
.bts_interrupt_threshold = { 12, 4 },
.sizeof_bts = 3 * 4,
.from_ip = { 0, 4 },
.to_ip = { 4, 4 },
.info_type = { 4, 1 },
.info_data = { 8, 4 },
.debugctl_mask = (1<<6)|(1<<7)
};
#endif /* _i386_ */
static const struct ds_configuration ds_cfg_core2 = {
.sizeof_ds = 9 * 8,
.bts_buffer_base = { 0, 8 },
.bts_index = { 8, 8 },
.bts_absolute_maximum = { 16, 8 },
.bts_interrupt_threshold = { 24, 8 },
.sizeof_bts = 3 * 8,
.from_ip = { 0, 8 },
.to_ip = { 8, 8 },
.info_type = { 8, 1 },
.info_data = { 16, 8 },
.debugctl_mask = (1<<6)|(1<<7)|(1<<9)
};
static inline void
ds_configure(const struct ds_configuration *cfg)
{
ds_cfg = *cfg;
}
void __cpuinit ds_init_intel(struct cpuinfo_x86 *c)
{
switch (c->x86) {
case 0x6:
switch (c->x86_model) {
#ifdef __i386__
case 0xD:
case 0xE: /* Pentium M */
ds_configure(&ds_cfg_pentium_m);
break;
#endif /* _i386_ */
case 0xF: /* Core2 */
ds_configure(&ds_cfg_core2);
break;
default:
/* sorry, don't know about them */
break;
}
break;
case 0xF:
switch (c->x86_model) {
#ifdef __i386__
case 0x0:
case 0x1:
case 0x2: /* Netburst */
ds_configure(&ds_cfg_netburst);
break;
#endif /* _i386_ */
default:
/* sorry, don't know about them */
break;
}
break;
default:
/* sorry, don't know about them */
break;
}
}