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/*
* Debug Store (DS) 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) 2007-2008 Intel Corporation.
* Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
*/
#ifndef _ASM_X86_DS_H
#define _ASM_X86_DS_H
#include <linux/types.h>
#include <linux/init.h>
#include <linux/err.h>
#ifdef CONFIG_X86_DS
struct task_struct;
struct ds_context;
struct ds_tracer;
struct bts_tracer;
struct pebs_tracer;
typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
/*
* A list of features plus corresponding macros to talk about them in
* the ds_request function's flags parameter.
*
* We use the enum to index an array of corresponding control bits;
* we use the macro to index a flags bit-vector.
*/
enum ds_feature {
dsf_bts = 0,
dsf_bts_kernel,
#define BTS_KERNEL (1 << dsf_bts_kernel)
/* trace kernel-mode branches */
dsf_bts_user,
#define BTS_USER (1 << dsf_bts_user)
/* trace user-mode branches */
dsf_bts_overflow,
dsf_bts_max,
dsf_pebs = dsf_bts_max,
dsf_pebs_max,
dsf_ctl_max = dsf_pebs_max,
dsf_bts_timestamps = dsf_ctl_max,
#define BTS_TIMESTAMPS (1 << dsf_bts_timestamps)
/* add timestamps into BTS trace */
#define BTS_USER_FLAGS (BTS_KERNEL | BTS_USER | BTS_TIMESTAMPS)
};
/*
* Request BTS or PEBS
*
* Due to alignement constraints, the actual buffer may be slightly
* smaller than the requested or provided buffer.
*
* Returns a pointer to a tracer structure on success, or
* ERR_PTR(errcode) on failure.
*
* 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
* 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;
* NULL if cyclic buffer requested
* th: the interrupt threshold in records from the end of the buffer;
* -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);
/*
* Release BTS or PEBS resources
* Suspend and resume BTS or PEBS tracing
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern void ds_release_bts(struct bts_tracer *tracer);
extern void ds_suspend_bts(struct bts_tracer *tracer);
extern void ds_resume_bts(struct bts_tracer *tracer);
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);
/*
* The raw DS buffer state as it is used for BTS and PEBS recording.
*
* This is the low-level, arch-dependent interface for working
* directly on the raw trace data.
*/
struct ds_trace {
/* the number of bts/pebs records */
size_t n;
/* the size of a bts/pebs record in bytes */
size_t size;
/* pointers into the raw buffer:
- to the first entry */
void *begin;
/* - one beyond the last entry */
void *end;
/* - one beyond the newest entry */
void *top;
/* - the interrupt threshold */
void *ith;
/* flags given on ds_request() */
unsigned int flags;
};
/*
* An arch-independent view on branch trace data.
*/
enum bts_qualifier {
bts_invalid,
#define BTS_INVALID bts_invalid
bts_branch,
#define BTS_BRANCH bts_branch
bts_task_arrives,
#define BTS_TASK_ARRIVES bts_task_arrives
bts_task_departs,
#define BTS_TASK_DEPARTS bts_task_departs
bts_qual_bit_size = 4,
bts_qual_max = (1 << bts_qual_bit_size),
};
struct bts_struct {
__u64 qualifier;
union {
/* BTS_BRANCH */
struct {
__u64 from;
__u64 to;
} lbr;
/* BTS_TASK_ARRIVES or BTS_TASK_DEPARTS */
struct {
__u64 jiffies;
pid_t pid;
} timestamp;
} variant;
};
/*
* The BTS state.
*
* This gives access to the raw DS state and adds functions to provide
* an arch-independent view of the BTS data.
*/
struct bts_trace {
struct ds_trace ds;
int (*read)(struct bts_tracer *tracer, const void *at,
struct bts_struct *out);
int (*write)(struct bts_tracer *tracer, const struct bts_struct *in);
};
/*
* The PEBS state.
*
* This gives access to the raw DS state and the PEBS-specific counter
* reset value.
*/
struct pebs_trace {
struct ds_trace ds;
/* the PEBS reset value */
unsigned long long reset_value;
};
/*
* Read the BTS or PEBS trace.
*
* Returns a view on the trace collected for the parameter tracer.
*
* The view remains valid as long as the traced task is not running or
* the tracer is suspended.
* Writes into the trace buffer are not reflected.
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern const struct bts_trace *ds_read_bts(struct bts_tracer *tracer);
extern const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer);
/*
* Reset the write pointer of the BTS/PEBS buffer.
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern int ds_reset_bts(struct bts_tracer *tracer);
extern int ds_reset_pebs(struct pebs_tracer *tracer);
/*
* Set the PEBS counter reset value.
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_pebs()
* value: the new counter reset value
*/
extern int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value);
/*
* Initialization
*/
struct cpuinfo_x86;
extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
/*
* Context switch work
*/
extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
#else /* CONFIG_X86_DS */
struct cpuinfo_x86;
static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
static inline void ds_switch_to(struct task_struct *prev,
struct task_struct *next) {}
#endif /* CONFIG_X86_DS */
#endif /* _ASM_X86_DS_H */
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