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x86, bts: clear bts bits on fork

PATCH Applied Markus Metzger 2 participants 2 messages Dec 16, 2008

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x86 MM core Scheduler exec and binfmt
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Markus Metzger

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#0 lore raw

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]>

---

arch/x86/kernel/process_32.c +13 -2
Index: ftrace/arch/x86/kernel/process_32.c
===================================================================
@@ -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;
 }
arch/x86/kernel/process_64.c +13 -2
Index: ftrace/arch/x86/kernel/process_64.c
===================================================================
@@ -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) {
kernel/fork.c +5 -1
Index: ftrace/kernel/fork.c
===================================================================
@@ -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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#1 lore raw

arch/x86/kernel/process_32.c line 261

Quoted 10 lines · Markus Metzger
arch/x86/kernel/process_32.c +1 -2
-#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.

arch/x86/kernel/process_32.c line 353

Quoted 7 lines
arch/x86/kernel/process_32.c +7 -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

ditto.

kernel/fork.c line 1109

Quoted 5 lines
kernel/fork.c +5 -0
+#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