include/asm-x86/ds.h

   1 /*
   2  * Debug Store (DS) support
   3  *
   4  * This provides a low-level interface to the hardware's Debug Store
   5  * feature that is used for last branch recording (LBR) and
   6  * precise-event based sampling (PEBS).
   7  *
   8  * Different architectures use a different DS layout/pointer size.
   9  * The below functions therefore work on a void*.
  10  *
  11  *
  12  * Since there is no user for PEBS, yet, only LBR (or branch
  13  * trace store, BTS) is supported.
  14  *
  15  *
  16  * Copyright (C) 2007 Intel Corporation.
  17  * Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
  18  */
  19
  20 #ifndef _ASM_X86_DS_H
  21 #define _ASM_X86_DS_H
  22
  23 #include <linux/types.h>
  24 #include <linux/init.h>
  25
  26 struct cpuinfo_x86;
  27
  28
  29 /* a branch trace record entry
  30  *
  31  * In order to unify the interface between various processor versions,
  32  * we use the below data structure for all processors.
  33  */
  34 enum bts_qualifier {
  35         BTS_INVALID = 0,
  36         BTS_BRANCH,
  37         BTS_TASK_ARRIVES,
  38         BTS_TASK_DEPARTS
  39 };
  40
  41 struct bts_struct {
  42         u64 qualifier;
  43         union {
  44                 /* BTS_BRANCH */
  45                 struct {
  46                         u64 from_ip;
  47                         u64 to_ip;
  48                 } lbr;
  49                 /* BTS_TASK_ARRIVES or
  50                    BTS_TASK_DEPARTS */
  51                 u64 jiffies;
  52         } variant;
  53 };
  54
  55 /* Overflow handling mechanisms */
  56 #define DS_O_SIGNAL     1 /* send overflow signal */
  57 #define DS_O_WRAP       2 /* wrap around */
  58
  59 extern int ds_allocate(void **, size_t);
  60 extern int ds_free(void **);
  61 extern int ds_get_bts_size(void *);
  62 extern int ds_get_bts_end(void *);
  63 extern int ds_get_bts_index(void *);
  64 extern int ds_set_overflow(void *, int);
  65 extern int ds_get_overflow(void *);
  66 extern int ds_clear(void *);
  67 extern int ds_read_bts(void *, int, struct bts_struct *);
  68 extern int ds_write_bts(void *, const struct bts_struct *);
  69 extern unsigned long ds_debugctl_mask(void);
  70 extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *c);
  71
  72 #endif /* _ASM_X86_DS_H */