[patch 14/20] x86, ds: add leakage warning

[markus . t . metzger]

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@xxxxxxxxx>
---
 arch/x86/include/asm/ds.h        |    9 	0 +	9 -	0 !
 arch/x86/include/asm/processor.h |    4 	1 +	3 -	0 !
 arch/x86/kernel/ds.c             |   10 	0 +	10 -	0 !
 arch/x86/kernel/process.c        |    5 	3 +	2 -	0 !
 arch/x86/kernel/process_32.c     |    3 	2 +	1 -	0 !
 arch/x86/kernel/process_64.c     |    3 	2 +	1 -	0 !
 6 files changed, 8 insertions(+), 26 deletions(-)

Index: b/arch/x86/kernel/ds.c
===================================================================
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -1352,16 +1352,6 @@ void ds_switch_to(struct task_struct *pr
 	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]) {
Index: b/arch/x86/include/asm/ds.h
===================================================================
--- a/arch/x86/include/asm/ds.h
+++ b/arch/x86/include/asm/ds.h
@@ -285,21 +285,12 @@ extern void __cpuinit ds_init_intel(stru
  */
 extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
 
-/*
- * Task clone/init and cleanup work
- */
-extern void ds_copy_thread(struct task_struct *tsk, struct task_struct *father);
-extern void ds_exit_thread(struct task_struct *tsk);
-
 #else /* CONFIG_X86_DS */
 
 struct cpuinfo_x86;
 static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
 static inline void ds_switch_to(struct task_struct *prev,
 				struct task_struct *next) {}
-static inline void ds_copy_thread(struct task_struct *tsk,
-				  struct task_struct *father) {}
-static inline void ds_exit_thread(struct task_struct *tsk) {}
 
 #endif /* CONFIG_X86_DS */
 #endif /* _ASM_X86_DS_H */
Index: b/arch/x86/kernel/process.c
===================================================================
--- 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_stru
 		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)
@@ -82,8 +85,6 @@ void exit_thread(void)
 		t->io_bitmap_max = 0;
 		put_cpu();
 	}
-
-	ds_exit_thread(current);
 }
 
 void flush_thread(void)
Index: b/arch/x86/include/asm/processor.h
===================================================================
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -451,10 +451,8 @@ struct thread_struct {
 	unsigned		io_bitmap_max;
 /* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set.  */
 	unsigned long	debugctlmsr;
-#ifdef CONFIG_X86_DS
-/* Debug Store context; see include/asm-x86/ds.h; goes into MSR_IA32_DS_AREA */
+	/* Debug Store context; see asm/ds.h */
 	struct ds_context	*ds_ctx;
-#endif /* CONFIG_X86_DS */
 };
 
 static inline unsigned long native_get_debugreg(int regno)
Index: b/arch/x86/kernel/process_32.c
===================================================================
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -290,7 +290,8 @@ int copy_thread(int nr, unsigned long cl
 		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;
Index: b/arch/x86/kernel/process_64.c
===================================================================
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -335,7 +335,8 @@ int copy_thread(int nr, unsigned long cl
 			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;

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