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Date:   Tue, 30 Apr 2019 18:09:50 +0100
From:   Sudeep Holla <>
To:     Andy Lutomirski <>
Cc:     Sudeep Holla <>, X86 ML <>,
        linux-arm-kernel <>,
        LKML <>,
        linuxppc-dev <>,
        Catalin Marinas <>,
        Will Deacon <>,
        Oleg Nesterov <>,
        Paul Mackerras <>,
        Michael Ellerman <>,
        Thomas Gleixner <>,
        Ingo Molnar <>,
        Richard Weinberger <>,
        Jeff Dike <>,
        Steve Capper <>,
        Haibo Xu <>, Bin Lu <>,
        Borislav Petkov <>
Subject: Re: [PATCH v2 3/6] x86: clean up _TIF_SYSCALL_EMU handling using
 ptrace_syscall_enter hook

On 30/04/2019 17:46, Andy Lutomirski wrote:
> On Mon, Mar 18, 2019 at 3:49 AM Sudeep Holla <> wrote:
>> Now that we have a new hook ptrace_syscall_enter that can be called from
>> syscall entry code and it handles PTRACE_SYSEMU in generic code, we
>> can do some cleanup using the same in syscall_trace_enter.
>> Further the extra logic to find single stepping PTRACE_SYSEMU_SINGLESTEP
>> in syscall_slow_exit_work seems unnecessary. Let's remove the same.
> Unless the patch set contains a selftest that exercises all the
> interesting cases here, NAK.  To be clear, there needs to be a test
> that passes on an unmodified kernel and still passes on a patched
> kernel.  And that test case needs to *fail* if, for example, you force
> "emulated" to either true or false rather than reading out the actual
> value.

Tested using tools/testing/selftests/x86/ptrace_syscall.c

Also v3 doesn't change any logic or additional call to new function as
in v2. It's just simple cleanup as suggested by Oleg.


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