x86, ptrace: Fix block-step

Implement ptrace-block-step using TIF_BLOCKSTEP which will set
DEBUGCTLMSR_BTF when set for a task while preserving any other
DEBUGCTLMSR bits.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100325135414.017536066@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index dc85e12d140..d017ed5502e 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -92,6 +92,7 @@ struct thread_info {
 #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_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
 
@@ -113,6 +114,7 @@ struct thread_info {
 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 #define _TIF_FREEZE             (1 << TIF_FREEZE)
 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
+#define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 
@@ -143,7 +145,7 @@ struct thread_info {
 
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW                                                 \
-        (_TIF_IO_BITMAP|_TIF_NOTSC)
+        (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
 
 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)