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, 3 insertions, 0 deletions

diff --git a/include/asm-x86/processor_64.h b/include/asm-x86/processor_64.h
index 0780f3e3fdfe..7b7f8a142e20 100644
--- a/include/asm-x86/processor_64.h
+++ b/include/asm-x86/processor_64.h
@@ -240,6 +240,9 @@ struct thread_struct {
         unsigned io_bitmap_max;
 /* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set.  */
         unsigned long   debugctlmsr;
+/* Debug Store - if not 0 points to a DS Save Area configuration;
+ *               goes into MSR_IA32_DS_AREA */
+        unsigned long   ds_area_msr;
 /* cached TLS descriptors. */
         u64 tls_array[GDT_ENTRY_TLS_ENTRIES];
 } __attribute__((aligned(16)));