x86, bts: provide in-kernel branch-trace interface
Impact: cleanup Move the BTS bits from ptrace.c into ds.c. Signed-off-by: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Markus Metzger
committed by
Ingo Molnar
Ingo Molnar
parent
b0884e25fe
commit
c2724775ce
@@ -6,13 +6,13 @@
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* precise-event based sampling (PEBS).
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*
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* It manages:
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* - per-thread and per-cpu allocation of BTS and PEBS
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* - DS and BTS hardware configuration
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* - buffer overflow handling (to be done)
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* - buffer access
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*
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* It assumes:
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* - get_task_struct on all traced tasks
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* - current is allowed to trace tasks
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* It does not do:
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* - security checking (is the caller allowed to trace the task)
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* - buffer allocation (memory accounting)
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*
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*
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* Copyright (C) 2007-2008 Intel Corporation.
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@@ -31,6 +31,7 @@
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#ifdef CONFIG_X86_DS
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struct task_struct;
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struct ds_context;
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struct ds_tracer;
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struct bts_tracer;
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struct pebs_tracer;
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@@ -38,6 +39,38 @@ struct pebs_tracer;
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typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
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typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
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/*
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* A list of features plus corresponding macros to talk about them in
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* the ds_request function's flags parameter.
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*
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* We use the enum to index an array of corresponding control bits;
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* we use the macro to index a flags bit-vector.
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*/
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enum ds_feature {
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dsf_bts = 0,
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dsf_bts_kernel,
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#define BTS_KERNEL (1 << dsf_bts_kernel)
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/* trace kernel-mode branches */
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dsf_bts_user,
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#define BTS_USER (1 << dsf_bts_user)
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/* trace user-mode branches */
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dsf_bts_overflow,
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dsf_bts_max,
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dsf_pebs = dsf_bts_max,
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dsf_pebs_max,
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dsf_ctl_max = dsf_pebs_max,
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dsf_bts_timestamps = dsf_ctl_max,
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#define BTS_TIMESTAMPS (1 << dsf_bts_timestamps)
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/* add timestamps into BTS trace */
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#define BTS_USER_FLAGS (BTS_KERNEL | BTS_USER | BTS_TIMESTAMPS)
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};
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/*
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* Request BTS or PEBS
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*
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@@ -58,92 +91,135 @@ typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
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* NULL if cyclic buffer requested
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* th: the interrupt threshold in records from the end of the buffer;
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* -1 if no interrupt threshold is requested.
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* flags: a bit-mask of the above flags
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*/
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extern struct bts_tracer *ds_request_bts(struct task_struct *task,
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void *base, size_t size,
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bts_ovfl_callback_t ovfl, size_t th);
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bts_ovfl_callback_t ovfl,
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size_t th, unsigned int flags);
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extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
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void *base, size_t size,
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pebs_ovfl_callback_t ovfl,
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size_t th);
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size_t th, unsigned int flags);
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/*
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* Release BTS or PEBS resources
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*
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* Returns 0 on success; -Eerrno otherwise
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* Suspend and resume BTS or PEBS tracing
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*
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* tracer: the tracer handle returned from ds_request_~()
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*/
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extern int ds_release_bts(struct bts_tracer *tracer);
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extern int ds_release_pebs(struct pebs_tracer *tracer);
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extern void ds_release_bts(struct bts_tracer *tracer);
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extern void ds_suspend_bts(struct bts_tracer *tracer);
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extern void ds_resume_bts(struct bts_tracer *tracer);
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extern void ds_release_pebs(struct pebs_tracer *tracer);
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extern void ds_suspend_pebs(struct pebs_tracer *tracer);
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extern void ds_resume_pebs(struct pebs_tracer *tracer);
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/*
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* Get the (array) index of the write pointer.
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* (assuming an array of BTS/PEBS records)
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* The raw DS buffer state as it is used for BTS and PEBS recording.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* pos (out): will hold the result
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* This is the low-level, arch-dependent interface for working
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* directly on the raw trace data.
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*/
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extern int ds_get_bts_index(struct bts_tracer *tracer, size_t *pos);
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extern int ds_get_pebs_index(struct pebs_tracer *tracer, size_t *pos);
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struct ds_trace {
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/* the number of bts/pebs records */
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size_t n;
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/* the size of a bts/pebs record in bytes */
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size_t size;
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/* pointers into the raw buffer:
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- to the first entry */
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void *begin;
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/* - one beyond the last entry */
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void *end;
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/* - one beyond the newest entry */
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void *top;
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/* - the interrupt threshold */
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void *ith;
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/* flags given on ds_request() */
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unsigned int flags;
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};
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/*
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* Get the (array) index one record beyond the end of the array.
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* (assuming an array of BTS/PEBS records)
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* pos (out): will hold the result
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* An arch-independent view on branch trace data.
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*/
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extern int ds_get_bts_end(struct bts_tracer *tracer, size_t *pos);
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extern int ds_get_pebs_end(struct pebs_tracer *tracer, size_t *pos);
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enum bts_qualifier {
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bts_invalid,
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#define BTS_INVALID bts_invalid
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bts_branch,
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#define BTS_BRANCH bts_branch
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bts_task_arrives,
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#define BTS_TASK_ARRIVES bts_task_arrives
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bts_task_departs,
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#define BTS_TASK_DEPARTS bts_task_departs
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bts_qual_bit_size = 4,
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bts_qual_max = (1 << bts_qual_bit_size),
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};
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struct bts_struct {
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__u64 qualifier;
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union {
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/* BTS_BRANCH */
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struct {
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__u64 from;
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__u64 to;
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} lbr;
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/* BTS_TASK_ARRIVES or BTS_TASK_DEPARTS */
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struct {
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__u64 jiffies;
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pid_t pid;
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} timestamp;
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} variant;
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};
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/*
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* Provide a pointer to the BTS/PEBS record at parameter index.
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* (assuming an array of BTS/PEBS records)
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* The BTS state.
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*
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* The pointer points directly into the buffer. The user is
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* responsible for copying the record.
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*
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* Returns the size of a single record on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* index: the index of the requested record
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* record (out): pointer to the requested record
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* This gives access to the raw DS state and adds functions to provide
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* an arch-independent view of the BTS data.
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*/
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extern int ds_access_bts(struct bts_tracer *tracer,
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size_t index, const void **record);
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extern int ds_access_pebs(struct pebs_tracer *tracer,
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size_t index, const void **record);
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struct bts_trace {
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struct ds_trace ds;
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int (*read)(struct bts_tracer *tracer, const void *at,
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struct bts_struct *out);
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int (*write)(struct bts_tracer *tracer, const struct bts_struct *in);
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};
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/*
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* Write one or more BTS/PEBS records at the write pointer index and
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* advance the write pointer.
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* The PEBS state.
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*
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* If size is not a multiple of the record size, trailing bytes are
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* zeroed out.
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* This gives access to the raw DS state and the PEBS-specific counter
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* reset value.
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*/
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struct pebs_trace {
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struct ds_trace ds;
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/* the PEBS reset value */
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unsigned long long reset_value;
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};
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/*
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* Read the BTS or PEBS trace.
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*
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* May result in one or more overflow notifications.
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* Returns a view on the trace collected for the parameter tracer.
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*
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* If called during overflow handling, that is, with index >=
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* interrupt threshold, the write will wrap around.
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*
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* An overflow notification is given if and when the interrupt
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* threshold is reached during or after the write.
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*
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* Returns the number of bytes written or -Eerrno.
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* The view remains valid as long as the traced task is not running or
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* the tracer is suspended.
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* Writes into the trace buffer are not reflected.
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*
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* tracer: the tracer handle returned from ds_request_~()
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* buffer: the buffer to write
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* size: the size of the buffer
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*/
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extern int ds_write_bts(struct bts_tracer *tracer,
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const void *buffer, size_t size);
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extern int ds_write_pebs(struct pebs_tracer *tracer,
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const void *buffer, size_t size);
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extern const struct bts_trace *ds_read_bts(struct bts_tracer *tracer);
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extern const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer);
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/*
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* Reset the write pointer of the BTS/PEBS buffer.
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@@ -155,27 +231,6 @@ extern int ds_write_pebs(struct pebs_tracer *tracer,
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extern int ds_reset_bts(struct bts_tracer *tracer);
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extern int ds_reset_pebs(struct pebs_tracer *tracer);
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/*
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* Clear the BTS/PEBS buffer and reset the write pointer.
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* The entire buffer will be zeroed out.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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*/
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extern int ds_clear_bts(struct bts_tracer *tracer);
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extern int ds_clear_pebs(struct pebs_tracer *tracer);
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/*
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* Provide the PEBS counter reset value.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_pebs()
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* value (out): the counter reset value
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*/
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extern int ds_get_pebs_reset(struct pebs_tracer *tracer, u64 *value);
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/*
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* Set the PEBS counter reset value.
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*
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@@ -192,35 +247,17 @@ extern int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value);
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struct cpuinfo_x86;
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extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
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/*
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* The DS context - part of struct thread_struct.
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* Context switch work
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*/
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#define MAX_SIZEOF_DS (12 * 8)
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struct ds_context {
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/* pointer to the DS configuration; goes into MSR_IA32_DS_AREA */
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unsigned char ds[MAX_SIZEOF_DS];
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/* the owner of the BTS and PEBS configuration, respectively */
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struct ds_tracer *owner[2];
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/* use count */
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unsigned long count;
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/* a pointer to the context location inside the thread_struct
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* or the per_cpu context array */
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struct ds_context **this;
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/* a pointer to the task owning this context, or NULL, if the
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* context is owned by a cpu */
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struct task_struct *task;
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};
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/* called by exit_thread() to free leftover contexts */
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extern void ds_free(struct ds_context *context);
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extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
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#else /* CONFIG_X86_DS */
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struct cpuinfo_x86;
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static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
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static inline void ds_switch_to(struct task_struct *prev,
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struct task_struct *next) {}
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#endif /* CONFIG_X86_DS */
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#endif /* _ASM_X86_DS_H */
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