2008-12-16 14:49:00

by Metzger, Markus T

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

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 <[email protected]>
Reported-by: Ingo Molnar <[email protected]>
---

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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2008-12-16 17:18:24

by Ingo Molnar

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

* Markus Metzger <[email protected]> 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