On Thu, May 31, 2018 at 10:58 AM Chang S. Bae <[email protected]> wrote:
>
> With new helpers, FS/GS base access is centralized.
> Eventually, when FSGSBASE instruction enabled, it will
> be faster.
>
> The helpers are used on ptrace APIs (PTRACE_ARCH_PRCTL,
> PTRACE_SETREG, PTRACE_GETREG, etc). Idea is to keep
> the FS/GS-update mechanism organized.
>
> Notion of "active" and "inactive" are used to distinguish
> GS bases between "kernel" and "user". "inactive" GS base
> is the GS base, backed up at kernel entries, of inactive
> (user) task's.
I'm fine with the code, but the changelog entry is confusing. A bunch
of the active helpers don't contain the term "active".
> +/*
> + * Read/write an (inactive) task's fsbase or gsbase. This returns
> + * the value that the FS/GS base would have (if the task were to be
> + * resumed). The current task is also supported.
> + */
Please change to "Read/write a task's fsbase or gsbase. ... These work
on current or on a different non-running task."
> +
> +unsigned long read_task_fsbase(struct task_struct *task)
> +{
> + unsigned long fsbase;
> +
> + if (task == current)
> + fsbase = read_fsbase();
> + else
> + /*
> + * XXX: This will not behave as expected if called
> + * if fsindex != 0
> + */
> + fsbase = task->thread.fsbase;
> +
Please put braces around the if and else blocks whenever either of
them spans multiple lines. Also, maybe change add a note to the
comment and/or the changelog that this is preserving an existing bug
and that it's fixed later in the series.
