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x86, ptrace: Fix block-step

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Implement ptrace-block-step using TIF_BLOCKSTEP which will set
DEBUGCTLMSR_BTF when set for a task while preserving any other
DEBUGCTLMSR bits.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100325135414.017536066@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
2010-03-25 14:51:51 +01:00
committed by Ingo Molnar
parent faa4602e47
commit ea8e61b7bb
6 changed files with 53 additions and 9 deletions
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11
arch/x86/kernel/process.c
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@@ -195,6 +195,17 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
prev = &prev_p->thread;
next = &next_p->thread;
if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
unsigned long debugctl = get_debugctlmsr();
debugctl &= ~DEBUGCTLMSR_BTF;
if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
debugctl |= DEBUGCTLMSR_BTF;
update_debugctlmsr(debugctl);
}
if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
test_tsk_thread_flag(next_p, TIF_NOTSC)) {
/* prev and next are different */