arch/x86/include/asm/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 branch trace store (BTS) and
   6  * precise-event based sampling (PEBS).
   7  *
   8  * It manages:
   9  * - DS and BTS hardware configuration
  10  * - buffer overflow handling (to be done)
  11  * - buffer access
  12  *
  13  * It does not do:
  14  * - security checking (is the caller allowed to trace the task)
  15  * - buffer allocation (memory accounting)
  16  *
  17  *
  18  * Copyright (C) 2007-2009 Intel Corporation.
  19  * Markus Metzger <markus.t.metzger@intel.com>, 2007-2009
  20  */
  21
  22 #ifndef _ASM_X86_DS_H
  23 #define _ASM_X86_DS_H
  24
  25
  26 #include <linux/types.h>
  27 #include <linux/init.h>
  28 #include <linux/err.h>
  29
  30
  31 #ifdef CONFIG_X86_DS
  32
  33 struct task_struct;
  34 struct ds_context;
  35 struct ds_tracer;
  36 struct bts_tracer;
  37 struct pebs_tracer;
  38
  39 typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
  40 typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
  41
  42
  43 /*
  44  * A list of features plus corresponding macros to talk about them in
  45  * the ds_request function's flags parameter.
  46  *
  47  * We use the enum to index an array of corresponding control bits;
  48  * we use the macro to index a flags bit-vector.
  49  */
  50 enum ds_feature {
  51         dsf_bts = 0,
  52         dsf_bts_kernel,
  53 #define BTS_KERNEL (1 << dsf_bts_kernel)
  54         /* trace kernel-mode branches */
  55
  56         dsf_bts_user,
  57 #define BTS_USER (1 << dsf_bts_user)
  58         /* trace user-mode branches */
  59
  60         dsf_bts_overflow,
  61         dsf_bts_max,
  62         dsf_pebs = dsf_bts_max,
  63
  64         dsf_pebs_max,
  65         dsf_ctl_max = dsf_pebs_max,
  66         dsf_bts_timestamps = dsf_ctl_max,
  67 #define BTS_TIMESTAMPS (1 << dsf_bts_timestamps)
  68         /* add timestamps into BTS trace */
  69
  70 #define BTS_USER_FLAGS (BTS_KERNEL | BTS_USER | BTS_TIMESTAMPS)
  71 };
  72
  73
  74 /*
  75  * Request BTS or PEBS
  76  *
  77  * Due to alignement constraints, the actual buffer may be slightly
  78  * smaller than the requested or provided buffer.
  79  *
  80  * Returns a pointer to a tracer structure on success, or
  81  * ERR_PTR(errcode) on failure.
  82  *
  83  * The interrupt threshold is independent from the overflow callback
  84  * to allow users to use their own overflow interrupt handling mechanism.
  85  *
  86  * The function might sleep.
  87  *
  88  * task: the task to request recording for
  89  * cpu:  the cpu to request recording for
  90  * base: the base pointer for the (non-pageable) buffer;
  91  * size: the size of the provided buffer in bytes
  92  * ovfl: pointer to a function to be called on buffer overflow;
  93  *       NULL if cyclic buffer requested
  94  * th: the interrupt threshold in records from the end of the buffer;
  95  *     -1 if no interrupt threshold is requested.
  96  * flags: a bit-mask of the above flags
  97  */
  98 extern struct bts_tracer *ds_request_bts_task(struct task_struct *task,
  99                                               void *base, size_t size,
 100                                               bts_ovfl_callback_t ovfl,
 101                                               size_t th, unsigned int flags);
 102 extern struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
 103                                              bts_ovfl_callback_t ovfl,
 104                                              size_t th, unsigned int flags);
 105 extern struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
 106                                                 void *base, size_t size,
 107                                                 pebs_ovfl_callback_t ovfl,
 108                                                 size_t th, unsigned int flags);
 109 extern struct pebs_tracer *ds_request_pebs_cpu(int cpu,
 110                                                void *base, size_t size,
 111                                                pebs_ovfl_callback_t ovfl,
 112                                                size_t th, unsigned int flags);
 113
 114 /*
 115  * Release BTS or PEBS resources
 116  * Suspend and resume BTS or PEBS tracing
 117  *
 118  * Must be called with irq's enabled.
 119  *
 120  * tracer: the tracer handle returned from ds_request_~()
 121  */
 122 extern void ds_release_bts(struct bts_tracer *tracer);
 123 extern void ds_suspend_bts(struct bts_tracer *tracer);
 124 extern void ds_resume_bts(struct bts_tracer *tracer);
 125 extern void ds_release_pebs(struct pebs_tracer *tracer);
 126 extern void ds_suspend_pebs(struct pebs_tracer *tracer);
 127 extern void ds_resume_pebs(struct pebs_tracer *tracer);
 128
 129 /*
 130  * Release BTS or PEBS resources
 131  * Suspend and resume BTS or PEBS tracing
 132  *
 133  * Cpu tracers must call this on the traced cpu.
 134  * Task tracers must call ds_release_~_noirq() for themselves.
 135  *
 136  * May be called with irq's disabled.
 137  *
 138  * Returns 0 if successful;
 139  * -EPERM if the cpu tracer does not trace the current cpu.
 140  * -EPERM if the task tracer does not trace itself.
 141  *
 142  * tracer: the tracer handle returned from ds_request_~()
 143  */
 144 extern int ds_release_bts_noirq(struct bts_tracer *tracer);
 145 extern int ds_suspend_bts_noirq(struct bts_tracer *tracer);
 146 extern int ds_resume_bts_noirq(struct bts_tracer *tracer);
 147 extern int ds_release_pebs_noirq(struct pebs_tracer *tracer);
 148 extern int ds_suspend_pebs_noirq(struct pebs_tracer *tracer);
 149 extern int ds_resume_pebs_noirq(struct pebs_tracer *tracer);
 150
 151
 152 /*
 153  * The raw DS buffer state as it is used for BTS and PEBS recording.
 154  *
 155  * This is the low-level, arch-dependent interface for working
 156  * directly on the raw trace data.
 157  */
 158 struct ds_trace {
 159         /* the number of bts/pebs records */
 160         size_t n;
 161         /* the size of a bts/pebs record in bytes */
 162         size_t size;
 163         /* pointers into the raw buffer:
 164            - to the first entry */
 165         void *begin;
 166         /* - one beyond the last entry */
 167         void *end;
 168         /* - one beyond the newest entry */
 169         void *top;
 170         /* - the interrupt threshold */
 171         void *ith;
 172         /* flags given on ds_request() */
 173         unsigned int flags;
 174 };
 175
 176 /*
 177  * An arch-independent view on branch trace data.
 178  */
 179 enum bts_qualifier {
 180         bts_invalid,
 181 #define BTS_INVALID bts_invalid
 182
 183         bts_branch,
 184 #define BTS_BRANCH bts_branch
 185
 186         bts_task_arrives,
 187 #define BTS_TASK_ARRIVES bts_task_arrives
 188
 189         bts_task_departs,
 190 #define BTS_TASK_DEPARTS bts_task_departs
 191
 192         bts_qual_bit_size = 4,
 193         bts_qual_max = (1 << bts_qual_bit_size),
 194 };
 195
 196 struct bts_struct {
 197         __u64 qualifier;
 198         union {
 199                 /* BTS_BRANCH */
 200                 struct {
 201                         __u64 from;
 202                         __u64 to;
 203                 } lbr;
 204                 /* BTS_TASK_ARRIVES or BTS_TASK_DEPARTS */
 205                 struct {
 206                         __u64 clock;
 207                         pid_t pid;
 208                 } event;
 209         } variant;
 210 };
 211
 212
 213 /*
 214  * The BTS state.
 215  *
 216  * This gives access to the raw DS state and adds functions to provide
 217  * an arch-independent view of the BTS data.
 218  */
 219 struct bts_trace {
 220         struct ds_trace ds;
 221
 222         int (*read)(struct bts_tracer *tracer, const void *at,
 223                     struct bts_struct *out);
 224         int (*write)(struct bts_tracer *tracer, const struct bts_struct *in);
 225 };
 226
 227
 228 /*
 229  * The PEBS state.
 230  *
 231  * This gives access to the raw DS state and the PEBS-specific counter
 232  * reset value.
 233  */
 234 struct pebs_trace {
 235         struct ds_trace ds;
 236
 237         /* the number of valid counters in the below array */
 238         unsigned int counters;
 239
 240 #define MAX_PEBS_COUNTERS 4
 241         /* the counter reset value */
 242         unsigned long long counter_reset[MAX_PEBS_COUNTERS];
 243 };
 244
 245
 246 /*
 247  * Read the BTS or PEBS trace.
 248  *
 249  * Returns a view on the trace collected for the parameter tracer.
 250  *
 251  * The view remains valid as long as the traced task is not running or
 252  * the tracer is suspended.
 253  * Writes into the trace buffer are not reflected.
 254  *
 255  * tracer: the tracer handle returned from ds_request_~()
 256  */
 257 extern const struct bts_trace *ds_read_bts(struct bts_tracer *tracer);
 258 extern const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer);
 259
 260
 261 /*
 262  * Reset the write pointer of the BTS/PEBS buffer.
 263  *
 264  * Returns 0 on success; -Eerrno on error
 265  *
 266  * tracer: the tracer handle returned from ds_request_~()
 267  */
 268 extern int ds_reset_bts(struct bts_tracer *tracer);
 269 extern int ds_reset_pebs(struct pebs_tracer *tracer);
 270
 271 /*
 272  * Set the PEBS counter reset value.
 273  *
 274  * Returns 0 on success; -Eerrno on error
 275  *
 276  * tracer: the tracer handle returned from ds_request_pebs()
 277  * counter: the index of the counter
 278  * value: the new counter reset value
 279  */
 280 extern int ds_set_pebs_reset(struct pebs_tracer *tracer,
 281                              unsigned int counter, u64 value);
 282
 283 /*
 284  * Initialization
 285  */
 286 struct cpuinfo_x86;
 287 extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
 288
 289 /*
 290  * Context switch work
 291  */
 292 extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
 293
 294 #else /* CONFIG_X86_DS */
 295
 296 struct cpuinfo_x86;
 297 static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
 298 static inline void ds_switch_to(struct task_struct *prev,
 299                                 struct task_struct *next) {}
 300
 301 #endif /* CONFIG_X86_DS */
 302 #endif /* _ASM_X86_DS_H */