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, 4 insertions, 2 deletions

diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h
index 009ecc6ad38b..306fc80800e1 100644
--- a/include/asm-x86/thread_info_32.h
+++ b/include/asm-x86/thread_info_32.h
@@ -139,6 +139,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_FREEZE              19      /* is freezing for suspend */
 #define TIF_NOTSC               20      /* TSC is not accessible in userland */
 #define TIF_FORCED_TF           21      /* true if TF in eflags artificially */
+#define TIF_DEBUGCTLMSR         22      /* uses thread_struct.debugctlmsr */
 
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
@@ -155,6 +156,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
 #define _TIF_NOTSC              (1<<TIF_NOTSC)
 #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 \
@@ -164,8 +166,8 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_ALLWORK_MASK       (0x0000FFFF & ~_TIF_SECCOMP)
 
 /* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG)
-#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC)
+#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG | _TIF_DEBUGCTLMSR)
+#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUGCTLMSR)
 
 /*
  * Thread-synchronous status.