/*
* Copyright (c) 2005-2007 Hewlett-Packard Development Company, L.P.
* Contributed by Stephane Eranian <eranian@hpl.hp.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA
*
* This file implements the sampling format to support Intel
* Precise Event Based Sampling (PEBS) feature of Pentium 4
* and other Netburst-based processors. Not to be used for
* Intel Core-based processors.
*
* What is PEBS?
* ------------
* This is a hardware feature to enhance sampling by providing
* better precision as to where a sample is taken. This avoids the
* typical skew in the instruction one can observe with any
* interrupt-based sampling technique.
*
* PEBS also lowers sampling overhead significantly by having the
* processor store samples instead of the OS. PMU interrupt are only
* generated after multiple samples are written.
*
* Another benefit of PEBS is that samples can be captured inside
* critical sections where interrupts are masked.
*
* How does it work?
* PEBS effectively implements a Hw buffer. The Os must pass a region
* of memory where samples are to be stored. The region can have any
* size. The OS must also specify the sampling period to reload. The PMU
* will interrupt when it reaches the end of the buffer or a specified
* threshold location inside the memory region.
*
* The description of the buffer is stored in the Data Save Area (DS).
* The samples are stored sequentially in the buffer. The format of the
* buffer is fixed and specified in the PEBS documentation. The sample
* format changes between 32-bit and 64-bit modes due to extended register
* file.
*
* PEBS does not work when HyperThreading is enabled due to certain MSR
* being shared being to two threads.
*
* What does the format do?
* It provides access to the PEBS feature for both 32-bit and 64-bit
* processors that support it.
*
* The same code is used for both 32-bit and 64-bit modes, but different
* format names are used because the two modes are not compatible due to
* data model and register file differences. Similarly the public data
* structures describing the samples are different.
*
* It is important to realize that the format provides a zero-copy environment
* for the samples, i.e,, the OS never touches the samples. Whatever the
* processor write is directly accessible to the user.
*
* Parameters to the buffer can be passed via pfm_create_context() in
* the pfm_pebs_smpl_arg structure.
*
* It is not possible to mix a 32-bit PEBS application on top of a 64-bit
* host kernel.
*/
#ifndef __PERFMON_PEBS_P4_SMPL_H__
#define __PERFMON_PEBS_P4_SMPL_H__ 1
#ifdef __cplusplus
extern "C" {
#endif
#include <perfmon/perfmon.h>
#ifdef __i386__
#define PFM_PEBS_P4_SMPL_NAME "pebs32_p4"
#else
#define PFM_PEBS_P4_SMPL_NAME "pebs64_p4"
#endif
/*
* format specific parameters (passed at context creation)
*/
typedef struct {
uint64_t cnt_reset; /* counter reset value */
size_t buf_size; /* size of the buffer in bytes */
size_t intr_thres; /* index of interrupt threshold entry */
uint64_t reserved[6]; /* for future use */
} pfm_pebs_p4_smpl_arg_t;
/*
* DS Save Area as described in section 15.10.5
*/
typedef struct {
unsigned long bts_buf_base;
unsigned long bts_index;
unsigned long bts_abs_max;
unsigned long bts_intr_thres;
unsigned long pebs_buf_base;
unsigned long pebs_index;
unsigned long pebs_abs_max;
unsigned long pebs_intr_thres;
uint64_t pebs_cnt_reset;
} pfm_ds_area_p4_t;
/*
* This header is at the beginning of the sampling buffer returned to the user.
*
* Because of PEBS alignement constraints, the actual PEBS buffer area does
* not necessarily begin right after the header. The hdr_start_offs must be
* used to compute the first byte of the buffer. The offset is defined as
* the number of bytes between the end of the header and the beginning of
* the buffer. As such the formula is:
* actual_buffer = (unsigned long)(hdr+1)+hdr->hdr_start_offs
*/
typedef struct {
uint64_t overflows; /* #overflows for buffer */
size_t buf_size; /* bytes in the buffer */
size_t start_offs; /* actual buffer start offset */
uint32_t version; /* smpl format version */
uint32_t reserved1; /* for future use */
uint64_t reserved2[5]; /* for future use */
pfm_ds_area_p4_t ds; /* DS management Area */
} pfm_pebs_p4_smpl_hdr_t;
/*
* PEBS record format as for both 32-bit and 64-bit modes
*/
typedef struct {
unsigned long eflags;
unsigned long ip;
unsigned long eax;
unsigned long ebx;
unsigned long ecx;
unsigned long edx;
unsigned long esi;
unsigned long edi;
unsigned long ebp;
unsigned long esp;
#ifdef __x86_64__
unsigned long r8;
unsigned long r9;
unsigned long r10;
unsigned long r11;
unsigned long r12;
unsigned long r13;
unsigned long r14;
unsigned long r15;
#endif
} pfm_pebs_p4_smpl_entry_t;
#define PFM_PEBS_P4_SMPL_VERSION_MAJ 1U
#define PFM_PEBS_P4_SMPL_VERSION_MIN 0U
#define PFM_PEBS_P4_SMPL_VERSION (((PFM_PEBS_P4_SMPL_VERSION_MAJ&0xffff)<<16)|\
(PFM_PEBS_P4_SMPL_VERSION_MIN & 0xffff))
#ifdef __cplusplus
};
#endif
#endif /* __PERFMON_PEBS_P4_SMPL_H__ */