1 files changed, 16 insertions, 42 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c958120fb1b6..416fb9282f4f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -39,6 +39,7 @@
 #include <linux/prctl.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
+#include <linux/ftrace.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -52,6 +53,7 @@
 #include <asm/ia32.h>
 #include <asm/idle.h>
 #include <asm/syscalls.h>
+#include <asm/ds.h>
 
 asmlinkage extern void ret_from_fork(void);
 
@@ -235,14 +237,8 @@ void exit_thread(void)
                 t->io_bitmap_max = 0;
                 put_cpu();
         }
-#ifdef CONFIG_X86_DS
-        /* Free any DS contexts that have not been properly released. */
-        if (unlikely(t->ds_ctx)) {
-                /* we clear debugctl to make sure DS is not used. */
-                update_debugctlmsr(0);
-                ds_free(t->ds_ctx);
-        }
-#endif /* CONFIG_X86_DS */
+
+        ds_exit_thread(current);
 }
 
 void flush_thread(void)
@@ -372,6 +368,12 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
                 if (err)
                         goto out;
         }
+
+        ds_copy_thread(p, me);
+
+        clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
+        p->thread.debugctlmsr = 0;
+
         err = 0;
 out:
         if (err && p->thread.io_bitmap_ptr) {
@@ -470,35 +472,14 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
                                     struct tss_struct *tss)
 {
         struct thread_struct *prev, *next;
-        unsigned long debugctl;
 
         prev = &prev_p->thread,
         next = &next_p->thread;
 
-        debugctl = prev->debugctlmsr;
-
-#ifdef CONFIG_X86_DS
-        {
-                unsigned long ds_prev = 0, ds_next = 0;
-
-                if (prev->ds_ctx)
-                        ds_prev = (unsigned long)prev->ds_ctx->ds;
-                if (next->ds_ctx)
-                        ds_next = (unsigned long)next->ds_ctx->ds;
-
-                if (ds_next != ds_prev) {
-                        /*
-                         * We clear debugctl to make sure DS
-                         * is not in use when we change it:
-                         */
-                        debugctl = 0;
-                        update_debugctlmsr(0);
-                        wrmsrl(MSR_IA32_DS_AREA, ds_next);
-                }
-        }
-#endif /* CONFIG_X86_DS */
-
-        if (next->debugctlmsr != debugctl)
+        if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
+            test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
+                ds_switch_to(prev_p, next_p);
+        else if (next->debugctlmsr != prev->debugctlmsr)
                 update_debugctlmsr(next->debugctlmsr);
 
         if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
@@ -533,14 +514,6 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
                  */
                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
         }
-
-#ifdef CONFIG_X86_PTRACE_BTS
-        if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
-                ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
-
-        if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
-                ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
-#endif /* CONFIG_X86_PTRACE_BTS */
 }
 
 /*
@@ -551,8 +524,9 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
  * - could test fs/gs bitsliced
  *
  * Kprobes not supported here. Set the probe on schedule instead.
+ * Function graph tracer not supported too.
  */
-struct task_struct *
+__notrace_funcgraph struct task_struct *
 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 {
         struct thread_struct *prev = &prev_p->thread;