x86, ptrace: support for branch trace store(BTS)

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Changes to the last version:
- split implementation into two layers: ds/bts and ptrace
- renamed TIF's
- save/restore ds save area msr in __switch_to_xtra()
- make block-stepping only look at BTF bit

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index ee35fd12b541..c2911a99cc32 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -123,6 +123,8 @@ static inline struct thread_info *stack_thread_info(void)
 #define TIF_FREEZE              23      /* is freezing for suspend */
 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
 #define TIF_DEBUGCTLMSR         25      /* uses thread_struct.debugctlmsr */
+#define TIF_DS_AREA_MSR 25      /* uses thread_struct.ds_area_msr */
+#define TIF_BTS_TRACE_TS        26      /* record scheduling event timestamps */
 
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
@@ -142,6 +144,8 @@ static inline struct thread_info *stack_thread_info(void)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
 #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 on interrupt/exception return */
 #define _TIF_WORK_MASK \
@@ -153,7 +157,10 @@ static inline struct thread_info *stack_thread_info(void)
         (_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED)
 
 /* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR)
+#define _TIF_WORK_CTXSW \
+    (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS)
+#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
+#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
 
 #define PREEMPT_ACTIVE     0x10000000