x86, ds: add leakage warning

Add a warning in case a debug store context is not removed before
the task it is attached to is freed.

Remove the old warning at thread exit. It is too early.

Declare the debug store context field in thread_struct unconditionally.

Remove ds_copy_thread() and ds_exit_thread() and do the work directly
in process*.c.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144601.254472000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 7 insertions, 14 deletions

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 21a3852abf68..71cab3b62dce 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -1352,16 +1352,6 @@ void ds_switch_to(struct task_struct *prev, struct task_struct *next)
         update_debugctlmsr(debugctlmsr);
 }
 
-void ds_copy_thread(struct task_struct *tsk, struct task_struct *father)
-{
-        clear_tsk_thread_flag(tsk, TIF_DS_AREA_MSR);
-        tsk->thread.ds_ctx = NULL;
-}
-
-void ds_exit_thread(struct task_struct *tsk)
-{
-}
-
 static __init int ds_selftest(void)
 {
         if (ds_cfg.sizeof_rec[ds_bts]) {
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index ca989158e847..fb5dfb891f0f 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -14,6 +14,7 @@
 #include <asm/idle.h>
 #include <asm/uaccess.h>
 #include <asm/i387.h>
+#include <asm/ds.h>
 
 unsigned long idle_halt;
 EXPORT_SYMBOL(idle_halt);
@@ -45,6 +46,8 @@ void free_thread_xstate(struct task_struct *tsk)
                 kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
                 tsk->thread.xstate = NULL;
         }
+
+        WARN(tsk->thread.ds_ctx, "leaking DS context\n");
 }
 
 void free_thread_info(struct thread_info *ti)
@@ -83,8 +86,6 @@ void exit_thread(void)
                 put_cpu();
                 kfree(bp);
         }
-
-        ds_exit_thread(current);
 }
 
 void flush_thread(void)
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 76f8f84043a2..b5e4bfef4472 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -290,7 +290,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
                 p->thread.io_bitmap_max = 0;
         }
 
-        ds_copy_thread(p, current);
+        clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
+        p->thread.ds_ctx = NULL;
 
         clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
         p->thread.debugctlmsr = 0;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b751a41392b1..5a1a1de292ec 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -335,7 +335,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
                         goto out;
         }
 
-        ds_copy_thread(p, me);
+        clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
+        p->thread.ds_ctx = NULL;
 
         clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
         p->thread.debugctlmsr = 0;