/*
* 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:
* - per-thread and per-cpu allocation of BTS and PEBS
* - buffer overflow handling (to be done)
* - buffer access
*
* It assumes:
* - get_task_struct on all traced tasks
* - current is allowed to trace tasks
*
*
* 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_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 *);
/*
* 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.
*/
extern struct bts_tracer *ds_request_bts(struct task_struct *task,
void *base, size_t size,
bts_ovfl_callback_t ovfl, size_t th);
extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
void *base, size_t size,
pebs_ovfl_callback_t ovfl,
size_t th);
/*
* Release BTS or PEBS resources
*
* Returns 0 on success; -Eerrno otherwise
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern int ds_release_bts(struct bts_tracer *tracer);
extern int ds_release_pebs(struct pebs_tracer *tracer);
/*
* Get the (array) index of the write pointer.
* (assuming an array of BTS/PEBS records)
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_~()
* pos (out): will hold the result
*/
extern int ds_get_bts_index(struct bts_tracer *tracer, size_t *pos);
extern int ds_get_pebs_index(struct pebs_tracer *tracer, size_t *pos);
/*
* Get the (array) index one record beyond the end of the array.
* (assuming an array of BTS/PEBS records)
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_~()
* pos (out): will hold the result
*/
extern int ds_get_bts_end(struct bts_tracer *tracer, size_t *pos);
extern int ds_get_pebs_end(struct pebs_tracer *tracer, size_t *pos);
/*
* Provide a pointer to the BTS/PEBS record at parameter index.
* (assuming an array of BTS/PEBS records)
*
* The pointer points directly into the buffer. The user is
* responsible for copying the record.
*
* Returns the size of a single record on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_~()
* index: the index of the requested record
* record (out): pointer to the requested record
*/
extern int ds_access_bts(struct bts_tracer *tracer,
size_t index, const void **record);
extern int ds_access_pebs(struct pebs_tracer *tracer,
size_t index, const void **record);
/*
* Write one or more BTS/PEBS records at the write pointer index and
* advance the write pointer.
*
* If size is not a multiple of the record size, trailing bytes are
* zeroed out.
*
* May result in one or more overflow notifications.
*
* If called during overflow handling, that is, with index >=
* interrupt threshold, the write will wrap around.
*
* An overflow notification is given if and when the interrupt
* threshold is reached during or after the write.
*
* Returns the number of bytes written or -Eerrno.
*
* tracer: the tracer handle returned from ds_request_~()
* buffer: the buffer to write
* size: the size of the buffer
*/
extern int ds_write_bts(struct bts_tracer *tracer,
const void *buffer, size_t size);
extern int ds_write_pebs(struct pebs_tracer *tracer,
const void *buffer, size_t size);
/*
* 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);
/*
* Clear the BTS/PEBS buffer and reset the write pointer.
* The entire buffer will be zeroed out.
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_~()
*/
extern int ds_clear_bts(struct bts_tracer *tracer);
extern int ds_clear_pebs(struct pebs_tracer *tracer);
/*
* Provide the PEBS counter reset value.
*
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_pebs()
* value (out): the counter reset value
*/
extern int ds_get_pebs_reset(struct pebs_tracer *tracer, u64 *value);
/*
* 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 *);
/*
* The DS context - part of struct thread_struct.
*/
#define MAX_SIZEOF_DS (12 * 8)
struct ds_context {
/* pointer to 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 ds_tracer *owner[2];
/* use count */
unsigned long count;
/* a pointer to the context location inside the thread_struct
* or the per_cpu context array */
struct ds_context **this;
/* a pointer to the task owning this context, or NULL, if the
* context is owned by a cpu */
struct task_struct *task;
};
/* called by exit_thread() to free leftover contexts */
extern void ds_free(struct ds_context *context);
#else /* CONFIG_X86_DS */
struct cpuinfo_x86;
static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
#endif /* CONFIG_X86_DS */
#endif /* _ASM_X86_DS_H */
