Commit c2724775 authored by Markus Metzger's avatar Markus Metzger Committed by Ingo Molnar

x86, bts: provide in-kernel branch-trace interface

Impact: cleanup

Move the BTS bits from ptrace.c into ds.c.
Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b0884e25
......@@ -6,13 +6,13 @@
* precise-event based sampling (PEBS).
*
* It manages:
* - per-thread and per-cpu allocation of BTS and PEBS
* - DS and BTS hardware configuration
* - buffer overflow handling (to be done)
* - buffer access
*
* It assumes:
* - get_task_struct on all traced tasks
* - current is allowed to trace tasks
* It does not do:
* - security checking (is the caller allowed to trace the task)
* - buffer allocation (memory accounting)
*
*
* Copyright (C) 2007-2008 Intel Corporation.
......@@ -31,6 +31,7 @@
#ifdef CONFIG_X86_DS
struct task_struct;
struct ds_context;
struct ds_tracer;
struct bts_tracer;
struct pebs_tracer;
......@@ -38,6 +39,38 @@ struct pebs_tracer;
typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
/*
* A list of features plus corresponding macros to talk about them in
* the ds_request function's flags parameter.
*
* We use the enum to index an array of corresponding control bits;
* we use the macro to index a flags bit-vector.
*/
enum ds_feature {
dsf_bts = 0,
dsf_bts_kernel,
#define BTS_KERNEL (1 << dsf_bts_kernel)
/* trace kernel-mode branches */
dsf_bts_user,
#define BTS_USER (1 << dsf_bts_user)
/* trace user-mode branches */
dsf_bts_overflow,
dsf_bts_max,
dsf_pebs = dsf_bts_max,
dsf_pebs_max,
dsf_ctl_max = dsf_pebs_max,
dsf_bts_timestamps = dsf_ctl_max,
#define BTS_TIMESTAMPS (1 << dsf_bts_timestamps)
/* add timestamps into BTS trace */
#define BTS_USER_FLAGS (BTS_KERNEL | BTS_USER | BTS_TIMESTAMPS)
};
/*
* Request BTS or PEBS
*
......@@ -58,92 +91,135 @@ typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
* NULL if cyclic buffer requested
* th: the interrupt threshold in records from the end of the buffer;
* -1 if no interrupt threshold is requested.
* flags: a bit-mask of the above flags
*/
extern struct bts_tracer *ds_request_bts(struct task_struct *task,
void *base, size_t size,
bts_ovfl_callback_t ovfl, size_t th);
bts_ovfl_callback_t ovfl,
size_t th, unsigned int flags);
extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
void *base, size_t size,
pebs_ovfl_callback_t ovfl,
size_t th);
size_t th, unsigned int flags);
/*
* Release BTS or PEBS resources
*
* Returns 0 on success; -Eerrno otherwise
* Suspend and resume BTS or PEBS tracing
*
* 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);
extern void ds_release_bts(struct bts_tracer *tracer);
extern void ds_suspend_bts(struct bts_tracer *tracer);
extern void ds_resume_bts(struct bts_tracer *tracer);
extern void ds_release_pebs(struct pebs_tracer *tracer);
extern void ds_suspend_pebs(struct pebs_tracer *tracer);
extern void ds_resume_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
* The raw DS buffer state as it is used for BTS and PEBS recording.
*
* tracer: the tracer handle returned from ds_request_~()
* pos (out): will hold the result
* This is the low-level, arch-dependent interface for working
* directly on the raw trace data.
*/
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);
struct ds_trace {
/* the number of bts/pebs records */
size_t n;
/* the size of a bts/pebs record in bytes */
size_t size;
/* pointers into the raw buffer:
- to the first entry */
void *begin;
/* - one beyond the last entry */
void *end;
/* - one beyond the newest entry */
void *top;
/* - the interrupt threshold */
void *ith;
/* flags given on ds_request() */
unsigned int flags;
};
/*
* 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
* An arch-independent view on branch trace data.
*/
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);
enum bts_qualifier {
bts_invalid,
#define BTS_INVALID bts_invalid
bts_branch,
#define BTS_BRANCH bts_branch
bts_task_arrives,
#define BTS_TASK_ARRIVES bts_task_arrives
bts_task_departs,
#define BTS_TASK_DEPARTS bts_task_departs
bts_qual_bit_size = 4,
bts_qual_max = (1 << bts_qual_bit_size),
};
struct bts_struct {
__u64 qualifier;
union {
/* BTS_BRANCH */
struct {
__u64 from;
__u64 to;
} lbr;
/* BTS_TASK_ARRIVES or BTS_TASK_DEPARTS */
struct {
__u64 jiffies;
pid_t pid;
} timestamp;
} variant;
};
/*
* 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
* The BTS state.
*
* tracer: the tracer handle returned from ds_request_~()
* index: the index of the requested record
* record (out): pointer to the requested record
* This gives access to the raw DS state and adds functions to provide
* an arch-independent view of the BTS data.
*/
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);
struct bts_trace {
struct ds_trace ds;
int (*read)(struct bts_tracer *tracer, const void *at,
struct bts_struct *out);
int (*write)(struct bts_tracer *tracer, const struct bts_struct *in);
};
/*
* Write one or more BTS/PEBS records at the write pointer index and
* advance the write pointer.
* The PEBS state.
*
* 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.
* This gives access to the raw DS state and the PEBS-specific counter
* reset value.
*/
struct pebs_trace {
struct ds_trace ds;
/* the PEBS reset value */
unsigned long long reset_value;
};
/*
* Read the BTS or PEBS trace.
*
* An overflow notification is given if and when the interrupt
* threshold is reached during or after the write.
* Returns a view on the trace collected for the parameter tracer.
*
* Returns the number of bytes written or -Eerrno.
* The view remains valid as long as the traced task is not running or
* the tracer is suspended.
* Writes into the trace buffer are not reflected.
*
* 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);
extern const struct bts_trace *ds_read_bts(struct bts_tracer *tracer);
extern const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer);
/*
* Reset the write pointer of the BTS/PEBS buffer.
......@@ -155,27 +231,6 @@ extern int ds_write_pebs(struct pebs_tracer *tracer,
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.
*
......@@ -192,35 +247,17 @@ extern int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value);
struct cpuinfo_x86;
extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
/*
* The DS context - part of struct thread_struct.
* Context switch work
*/
#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);
extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
#else /* CONFIG_X86_DS */
struct cpuinfo_x86;
static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
static inline void ds_switch_to(struct task_struct *prev,
struct task_struct *next) {}
#endif /* CONFIG_X86_DS */
#endif /* _ASM_X86_DS_H */
......@@ -752,6 +752,19 @@ extern void switch_to_new_gdt(void);
extern void cpu_init(void);
extern void init_gdt(int cpu);
static inline unsigned long get_debugctlmsr(void)
{
unsigned long debugctlmsr = 0;
#ifndef CONFIG_X86_DEBUGCTLMSR
if (boot_cpu_data.x86 < 6)
return 0;
#endif
rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctlmsr);
return debugctlmsr;
}
static inline void update_debugctlmsr(unsigned long debugctlmsr)
{
#ifndef CONFIG_X86_DEBUGCTLMSR
......
......@@ -6,7 +6,6 @@
#include <asm/processor-flags.h>
#ifdef __KERNEL__
#include <asm/ds.h> /* the DS BTS struct is used for ptrace too */
#include <asm/segment.h>
#endif
......@@ -128,34 +127,6 @@ struct pt_regs {
#endif /* !__i386__ */
#ifdef CONFIG_X86_PTRACE_BTS
/* a branch trace record entry
*
* In order to unify the interface between various processor versions,
* we use the below data structure for all processors.
*/
enum bts_qualifier {
BTS_INVALID = 0,
BTS_BRANCH,
BTS_TASK_ARRIVES,
BTS_TASK_DEPARTS
};
struct bts_struct {
__u64 qualifier;
union {
/* BTS_BRANCH */
struct {
__u64 from_ip;
__u64 to_ip;
} lbr;
/* BTS_TASK_ARRIVES or
BTS_TASK_DEPARTS */
__u64 jiffies;
} variant;
};
#endif /* CONFIG_X86_PTRACE_BTS */
#ifdef __KERNEL__
#include <linux/init.h>
......@@ -163,13 +134,6 @@ struct bts_struct {
struct cpuinfo_x86;
struct task_struct;
#ifdef CONFIG_X86_PTRACE_BTS
extern void __cpuinit ptrace_bts_init_intel(struct cpuinfo_x86 *);
extern void ptrace_bts_take_timestamp(struct task_struct *, enum bts_qualifier);
#else
#define ptrace_bts_init_intel(config) do {} while (0)
#endif /* CONFIG_X86_PTRACE_BTS */
extern unsigned long profile_pc(struct pt_regs *regs);
extern unsigned long
......
......@@ -93,7 +93,6 @@ struct thread_info {
#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
#define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
#define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
#define TIF_BTS_TRACE_TS 27 /* record scheduling event timestamps */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
......@@ -115,7 +114,6 @@ struct thread_info {
#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
#define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
#define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
#define _TIF_BTS_TRACE_TS (1 << TIF_BTS_TRACE_TS)
/* work to do in syscall_trace_enter() */
#define _TIF_WORK_SYSCALL_ENTRY \
......@@ -141,8 +139,7 @@ struct thread_info {
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW \
(_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS| \
_TIF_NOTSC)
(_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_NOTSC)
#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
......
......@@ -11,7 +11,6 @@
#include <asm/pgtable.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/ds.h>
#include <asm/bugs.h>
......@@ -309,9 +308,6 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
set_cpu_cap(c, X86_FEATURE_P3);
#endif
if (cpu_has_bts)
ptrace_bts_init_intel(c);
detect_extended_topology(c);
if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
/*
......
This diff is collapsed.
......@@ -252,11 +252,14 @@ void exit_thread(void)
put_cpu();
}
#ifdef CONFIG_X86_DS
/* Free any DS contexts that have not been properly released. */
if (unlikely(current->thread.ds_ctx)) {
/* we clear debugctl to make sure DS is not used. */
update_debugctlmsr(0);
ds_free(current->thread.ds_ctx);
/* Free any BTS tracers that have not been properly released. */
if (unlikely(current->bts)) {
ds_release_bts(current->bts);
current->bts = NULL;
kfree(current->bts_buffer);
current->bts_buffer = NULL;
current->bts_size = 0;
}
#endif /* CONFIG_X86_DS */
}
......@@ -420,48 +423,19 @@ int set_tsc_mode(unsigned int val)
return 0;
}
#ifdef CONFIG_X86_DS
static int update_debugctl(struct thread_struct *prev,
struct thread_struct *next, unsigned long debugctl)
{
unsigned long ds_prev = 0;
unsigned long ds_next = 0;
if (prev->ds_ctx)
ds_prev = (unsigned long)prev->ds_ctx->ds;
if (next->ds_ctx)
ds_next = (unsigned long)next->ds_ctx->ds;
if (ds_next != ds_prev) {
/* we clear debugctl to make sure DS
* is not in use when we change it */
debugctl = 0;
update_debugctlmsr(0);
wrmsr(MSR_IA32_DS_AREA, ds_next, 0);
}
return debugctl;
}
#else
static int update_debugctl(struct thread_struct *prev,
struct thread_struct *next, unsigned long debugctl)
{
return debugctl;
}
#endif /* CONFIG_X86_DS */
static noinline void
__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
struct tss_struct *tss)
{
struct thread_struct *prev, *next;
unsigned long debugctl;
prev = &prev_p->thread;
next = &next_p->thread;
debugctl = update_debugctl(prev, next, prev->debugctlmsr);
if (next->debugctlmsr != debugctl)
if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
ds_switch_to(prev_p, next_p);
else if (next->debugctlmsr != prev->debugctlmsr)
update_debugctlmsr(next->debugctlmsr);
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
......@@ -483,15 +457,6 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
hard_enable_TSC();
}
#ifdef CONFIG_X86_PTRACE_BTS
if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
#endif /* CONFIG_X86_PTRACE_BTS */
if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* Disable the bitmap via an invalid offset. We still cache
......
......@@ -237,11 +237,14 @@ void exit_thread(void)
put_cpu();
}
#ifdef CONFIG_X86_DS
/* Free any DS contexts that have not been properly released. */
if (unlikely(t->ds_ctx)) {
/* we clear debugctl to make sure DS is not used. */
update_debugctlmsr(0);
ds_free(t->ds_ctx);
/* Free any BTS tracers that have not been properly released. */
if (unlikely(current->bts)) {
ds_release_bts(current->bts);
current->bts = NULL;
kfree(current->bts_buffer);
current->bts_buffer = NULL;
current->bts_size = 0;
}
#endif /* CONFIG_X86_DS */
}
......@@ -471,35 +474,14 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
struct tss_struct *tss)
{
struct thread_struct *prev, *next;
unsigned long debugctl;
prev = &prev_p->thread,
next = &next_p->thread;
debugctl = prev->debugctlmsr;
#ifdef CONFIG_X86_DS
{
unsigned long ds_prev = 0, ds_next = 0;
if (prev->ds_ctx)
ds_prev = (unsigned long)prev->ds_ctx->ds;
if (next->ds_ctx)
ds_next = (unsigned long)next->ds_ctx->ds;
if (ds_next != ds_prev) {
/*
* We clear debugctl to make sure DS
* is not in use when we change it:
*/
debugctl = 0;
update_debugctlmsr(0);
wrmsrl(MSR_IA32_DS_AREA, ds_next);
}
}
#endif /* CONFIG_X86_DS */
if (next->debugctlmsr != debugctl)
if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
ds_switch_to(prev_p, next_p);
else if (next->debugctlmsr != prev->debugctlmsr)
update_debugctlmsr(next->debugctlmsr);
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
......@@ -534,14 +516,6 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
*/
memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
}
#ifdef CONFIG_X86_PTRACE_BTS
if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
#endif /* CONFIG_X86_PTRACE_BTS */
}
/*
......
This diff is collapsed.
......@@ -1176,6 +1176,7 @@ struct task_struct {
* The buffer to hold the BTS data.
*/
void *bts_buffer;
size_t bts_size;
#endif /* CONFIG_X86_PTRACE_BTS */
/* PID/PID hash table linkage. */
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment