Re: [RFC PATCH 3/3] coccinelle: api: add offset_in_page.cocci

[Julia Lawall <julia.lawall@lip6.fr>]

On Wed, 5 Dec 2018, Johannes Thumshirn wrote:

> Constructs like 'var & (PAGE_SIZE - 1)' or 'var & ~PAGE_MASK' can be
> replaced by the offset_in_page() macro instead of open-coding it.
>
> Add a coccinelle semantic patch to ease detection and conversion of these.
>
> This unfortunately doesn't account for the case when we want PAGE_ALIGNED()
> instead of offset_in_page() yet.
>
> Cc: Julia Lawall <julia.lawall@lip6.fr>
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> ---
>  scripts/coccinelle/api/offset_in_page.cocci | 81 +++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
>  create mode 100644 scripts/coccinelle/api/offset_in_page.cocci
>
> diff --git a/scripts/coccinelle/api/offset_in_page.cocci b/scripts/coccinelle/api/offset_in_page.cocci
> new file mode 100644
> index 000000000000..ea5b3a8e0390
> --- /dev/null
> +++ b/scripts/coccinelle/api/offset_in_page.cocci
> @@ -0,0 +1,81 @@
> +// SPDX-License-Identifier: GPL-2.0
> +///
> +/// Use offset_in_page macro on address instead of explicit computation.
> +///
> +//  Confidence: High
> +//  Keywords: offset_in_page
> +//  Comment: Based on vma_pages.cocci
> +
> +virtual context
> +virtual patch
> +virtual org
> +virtual report
> +
> +
> +//----------------------------------------------------------
> +//  For context mode
> +//----------------------------------------------------------
> +
> +@r_context depends on context && !patch && !org && !report@
> +expression E;
> +@@
> +
> +(
> +* E & ~PAGE_MASK
> +|
> +* E & (PAGE_SIZE - 1)
> +)
> +
> +
> +//----------------------------------------------------------
> +//  For patch mode
> +//----------------------------------------------------------
> +
> +@r_patch depends on !context && patch && !org && !report@
> +expression E;
> +type T;
> +@@
> +
> +(
> +- E & ~PAGE_MASK
> ++ offset_in_page(E)
> +|
> +- E & (PAGE_SIZE - 1)
> ++ offset_in_page(E)

The two lines above should be subsumed by the two lines below.  When there
is a type metavariable that has no other dependencies, an isomorphism will
consider that it is either present or absent.

Why not include the cast case for the context and org cases?

Masahiro will ultimately commit this.  I have added him to CC.

Thanks for the contribution.

julia


> +|
> +- E & ((T)PAGE_SIZE - 1)
> ++ offset_in_page(E)
> +)
> +
> +//----------------------------------------------------------
> +//  For org mode
> +//----------------------------------------------------------
> +
> +@r_org depends on !context && !patch && (org || report)@
> +expression E;
> +position p;
> +@@
> +
> +  (
> +  * E@p & ~PAGE_MASK
> +  |
> +  * E@p & (PAGE_SIZE - 1)
> +  )
> +
> +@script:python depends on report@
> +p << r_org.p;
> +x << r_org.E;
> +@@
> +
> +msg="WARNING: Consider using offset_in_page helper on %s" % (x)
> +coccilib.report.print_report(p[0], msg)
> +
> +@script:python depends on org@
> +p << r_org.p;
> +x << r_org.E;
> +@@
> +
> +msg="WARNING: Consider using offset_in_page helper on %s" % (x)
> +msg_safe=msg.replace("[","@(").replace("]",")")
> +coccilib.org.print_todo(p[0], msg_safe)
> +
> --
> 2.16.4
>
>