Re: [PATCH 2/2] ptrace: fixset_task_blockstep()->update_debugctlmsr() logic

[Oleg Nesterov]

Hi.

Today I noticed by accident that starting from Aug 4 (at least)
all my emails went to nowhere. I am resending some of them...


On 08/03, Oleg Nesterov wrote:
>
> 2. It is wrong. The state of DEBUGCTLMSR_BTF bit in CPU register
>    should always match the state of current's TIF_BLOCKSTEP bit.

Yes.

But this means we should set/clear TIF_BLOCKSTEP and update
MSR_IA32_DEBUGCTLMSR "atomically" under preempt_disable().

I'll redo this patch.

Oleg.

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