x86: debugctlmsr context switch

This adds low-level support for a per-thread value of MSR_IA32_DEBUGCTLMSR.
The per-thread value is switched in when TIF_DEBUGCTLMSR is set.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index e0f41b3deced..ee35fd12b541 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -122,6 +122,7 @@ static inline struct thread_info *stack_thread_info(void)
 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
 #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_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
@@ -140,6 +141,7 @@ static inline struct thread_info *stack_thread_info(void)
 #define _TIF_IO_BITMAP          (1<<TIF_IO_BITMAP)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
 #define _TIF_FORCED_TF          (1<<TIF_FORCED_TF)
+#define _TIF_DEBUGCTLMSR        (1<<TIF_DEBUGCTLMSR)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK \
@@ -151,7 +153,7 @@ 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)
+#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR)
 
 #define PREEMPT_ACTIVE     0x10000000