[patch 1/3] x86, bts: clear bts bits on fork

[patch 1/3] x86, bts: clear bts bits on fork

[Markus Metzger]

Clear the DS context as well as the bts tracer and corresponding
fields in task_struct on fork.

Correct the CONFIG guard.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Reported-by: Ingo Molnar <mingo@elte.hu>
---

Index: ftrace/arch/x86/kernel/process_32.c
===================================================================
--- ftrace.orig/arch/x86/kernel/process_32.c	2008-12-12 14:02:24.000000000 +0100
+++ ftrace/arch/x86/kernel/process_32.c	2008-12-12 14:33:19.000000000 +0100
@@ -251,7 +251,7 @@
 		tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
 		put_cpu();
 	}
-#ifdef CONFIG_X86_DS
+#ifdef CONFIG_X86_PTRACE_BTS
 	/* Free any BTS tracers that have not been properly released. */
 	if (unlikely(current->bts)) {
 		ds_release_bts(current->bts);
@@ -261,7 +261,7 @@
 		current->bts_buffer = NULL;
 		current->bts_size = 0;
 	}
-#endif /* CONFIG_X86_DS */
+#endif /* CONFIG_X86_PTRACE_BTS */
 }
 
 void flush_thread(void)
@@ -343,6 +343,17 @@
 		kfree(p->thread.io_bitmap_ptr);
 		p->thread.io_bitmap_max = 0;
 	}
+
+#ifdef CONFIG_X86_DS
+	clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
+	p->thread.ds_ctx = NULL;
+#endif
+#ifdef CONFIG_X86_PTRACE_BTS
+	p->thread.bts_ovfl_signal = 0;
+#endif
+	clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
+	p->thread.debugctlmsr = 0;
+
 	return err;
 }
 
Index: ftrace/arch/x86/kernel/process_64.c
===================================================================
--- ftrace.orig/arch/x86/kernel/process_64.c	2008-12-12 14:02:24.000000000 +0100
+++ ftrace/arch/x86/kernel/process_64.c	2008-12-12 14:32:38.000000000 +0100
@@ -248,7 +248,7 @@
 		t->io_bitmap_max = 0;
 		put_cpu();
 	}
-#ifdef CONFIG_X86_DS
+#ifdef CONFIG_X86_PTRACE_BTS
 	/* Free any BTS tracers that have not been properly released. */
 	if (unlikely(current->bts)) {
 		ds_release_bts(current->bts);
@@ -258,7 +258,7 @@
 		current->bts_buffer = NULL;
 		current->bts_size = 0;
 	}
-#endif /* CONFIG_X86_DS */
+#endif /* CONFIG_X86_PTRACE_BTS */
 }
 
 void flush_thread(void)
@@ -388,6 +388,17 @@
 		if (err)
 			goto out;
 	}
+
+#ifdef CONFIG_X86_DS
+	clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
+	p->thread.ds_ctx = NULL;
+#endif
+#ifdef CONFIG_X86_PTRACE_BTS
+	p->thread.bts_ovfl_signal = 0;
+#endif
+	clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
+	p->thread.debugctlmsr = 0;
+
 	err = 0;
 out:
 	if (err && p->thread.io_bitmap_ptr) {
Index: ftrace/kernel/fork.c
===================================================================
--- ftrace.orig/kernel/fork.c	2008-12-12 14:02:24.000000000 +0100
+++ ftrace/kernel/fork.c	2008-12-12 14:29:43.000000000 +0100
@@ -1102,7 +1102,11 @@
 #ifdef CONFIG_DEBUG_MUTEXES
 	p->blocked_on = NULL; /* not blocked yet */
 #endif
-
+#ifdef CONFIG_X86_PTRACE_BTS
+	p->bts = NULL;
+	p->bts_buffer = NULL;
+	p->bts_size = 0;
+#endif
 	/* Perform scheduler related setup. Assign this task to a CPU. */
 	sched_fork(p, clone_flags);
 
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Re: [patch 1/3] x86, bts: clear bts bits on fork

[Ingo Molnar]

* Markus Metzger <markus.t.metzger@intel.com> wrote:

> -#ifdef CONFIG_X86_DS
> +#ifdef CONFIG_X86_PTRACE_BTS
>  	/* Free any BTS tracers that have not been properly released. */
>  	if (unlikely(current->bts)) {
>  		ds_release_bts(current->bts);
> @@ -258,7 +258,7 @@
>  		current->bts_buffer = NULL;
>  		current->bts_size = 0;
>  	}
> -#endif /* CONFIG_X86_DS */

Please eliminate the #ifdef from here by introducing a helper function - 
possibly inlined.

> +#ifdef CONFIG_X86_DS
> +	clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
> +	p->thread.ds_ctx = NULL;
> +#endif
> +#ifdef CONFIG_X86_PTRACE_BTS
> +	p->thread.bts_ovfl_signal = 0;
> +#endif

ditto.

> +#ifdef CONFIG_X86_PTRACE_BTS
> +	p->bts = NULL;
> +	p->bts_buffer = NULL;
> +	p->bts_size = 0;
> +#endif

this one too please.

There's generally little reason to put #ifdefs into .c files.

	Ingo