Re: [PATCH v4 3/5] x86: Split syscall_trace_enter into two phases

From: Oleg Nesterov
Date: Tue Jul 29 2014 - 15:28:19 EST


On 07/28, Andy Lutomirski wrote:
>
> +long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch,
> + unsigned long phase1_result)
> +{
> + long ret = 0;
> + u32 work = ACCESS_ONCE(current_thread_info()->flags) &
> + _TIF_WORK_SYSCALL_ENTRY;
> +
> + BUG_ON(regs != task_pt_regs(current));
>
> /*
> * If we stepped into a sysenter/syscall insn, it trapped in
> @@ -1463,17 +1569,20 @@ long syscall_trace_enter(struct pt_regs *regs)
> * do_debug() and we need to set it again to restore the user
> * state. If we entered on the slow path, TF was already set.
> */
> - if (test_thread_flag(TIF_SINGLESTEP))
> + if (work & _TIF_SINGLESTEP)
> regs->flags |= X86_EFLAGS_TF;

This is minor, I won't argue, but this can be moved into phase1(), afaics.

Oleg.

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