3 files changed, 11 insertions, 1 deletions

diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 6e26c7c717a2..eaf4548a23d2 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -918,4 +918,11 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
 
 #define KSTK_EIP(task)          (task_pt_regs(task)->ip)
 
+/* Get/set a process' ability to use the timestamp counter instruction */
+#define GET_TSC_CTL(adr)        get_tsc_mode((adr))
+#define SET_TSC_CTL(val)        set_tsc_mode((val))
+
+extern int get_tsc_mode(unsigned long adr);
+extern int set_tsc_mode(unsigned int val);
+
 #endif
diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index 1e5c6f6152cd..b17f5f6c2c59 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -126,6 +126,7 @@ static inline struct thread_info *stack_thread_info(void)
 #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_NOTSC               28      /* TSC is not accessible in userland */
 
 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
@@ -147,6 +148,7 @@ static inline struct thread_info *stack_thread_info(void)
 #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)
+#define _TIF_NOTSC              (1 << TIF_NOTSC)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK                                                  \
@@ -160,7 +162,7 @@ static inline struct thread_info *stack_thread_info(void)
 
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW                                                 \
-        (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS)
+        (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS|_TIF_NOTSC)
 #define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
 
diff --git a/include/asm-x86/tsc.h b/include/asm-x86/tsc.h
index d2d8eb5b55f5..0434bd8349a7 100644
--- a/include/asm-x86/tsc.h
+++ b/include/asm-x86/tsc.h
@@ -18,6 +18,7 @@ extern unsigned int cpu_khz;
 extern unsigned int tsc_khz;
 
 extern void disable_TSC(void);
+extern void enable_TSC(void);
 
 static inline cycles_t get_cycles(void)
 {