linux-hardening - [PATCH 00/10] compiler.h: refactor __is_constexpr() into is_const{,_true,

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Message-Id: <20241203-is_constexpr-refactor-v1-0-4e4cbaecc216@wanadoo.fr>
Date: Tue, 03 Dec 2024 02:33:22 +0900
From: Vincent Mailhol via B4 Relay <devnull+mailhol.vincent.wanadoo.fr@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>, 
 David Laight <David.Laight@...lab.com>, 
 Luc Van Oostenryck <luc.vanoostenryck@...il.com>, 
 Nathan Chancellor <nathan@...nel.org>, 
 Nick Desaulniers <ndesaulniers@...gle.com>, 
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
 Yury Norov <yury.norov@...il.com>, 
 Rasmus Villemoes <linux@...musvillemoes.dk>, Kees Cook <kees@...nel.org>, 
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
 Jani Nikula <jani.nikula@...ux.intel.com>, 
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, 
 Rodrigo Vivi <rodrigo.vivi@...el.com>, 
 Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Rikard Falkeborn <rikard.falkeborn@...il.com>, 
 Martin Uecker <Martin.Uecker@....uni-goettingen.de>
Cc: linux-sparse@...r.kernel.org, linux-kernel@...r.kernel.org, 
 llvm@...ts.linux.dev, linux-hardening@...r.kernel.org, 
 intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, 
 coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 Vincent Mailhol <mailhol.vincent@...adoo.fr>
Subject: [PATCH 00/10] compiler.h: refactor __is_constexpr() into
 is_const{,_true,_false}()

This series is the spiritual successor of [1] which introduced
const_true(). In [1], following a comment from David Laight, Linus
came with a suggestion to simplify __is_constexpr() and its derived
macros using a _Generic() selection. Because of the total change of
scope, I am starting a new series.

The goal is to introduce a set of three macros:

  - is_const(): a one to one replacement of __is_constexpr() in term
    of features but written in a less hacky way thanks to _Generic().

  - is_const_true(): tells whether or not the argument is a true
    integer constant expression.

  - is_const_false(): tells whether or not the argument is a false
    integer constant expression.

Once defined, apply them tree-wide.

All those three macros will rely on a single building block:
__is_const_zero().

Patch 1 adds statically_false(). This is just done so that at the end
of this series, the full set of statically_true/false() and
is_const_true/false() is present.

Patch 2 adds __is_const_zero() and is_const().

Patch 3 adds is_const_true() and is_const_false().

Patch 4 to 9 do a tree-wide replacement to remove all the usages of
__is_constexpr() and replace them by is_const_true() or
is_const_false() whenever feasible, or by is_const() otherwise.

Patch 10 finally remove __is_constexpr(). RIP!

[1] add const_true() to simplify GENMASK_INPUT_CHECK()
Link: https://lore.kernel.org/all/20241113172939.747686-4-mailhol.vincent@wanadoo.fr/

Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
Vincent Mailhol (10):
      compiler.h: add statically_false()
      compiler.h: add is_const() as a replacement of __is_constexpr()
      compiler.h: add is_const_true() and is_const_false()
      linux/bits.h: simplify GENMASK_INPUT_CHECK() by using is_const_true()
      minmax: simplify __clamp_once() by using is_const_false()
      fortify: replace __is_constexpr() by is_const() in strlen()
      overflow: replace __is_constexpr() by is_const()
      drm/i915/reg: replace __is_const_expr() by is_const_true() or is_const()
      coresight: etm4x: replace __is_const_expr() by is_const()
      compiler.h: remove __is_constexpr()

 drivers/gpu/drm/i915/i915_reg_defs.h          |  47 +++++------
 drivers/hwtracing/coresight/coresight-etm4x.h |   2 +-
 include/linux/bits.h                          |   5 +-
 include/linux/compiler.h                      | 112 +++++++++++++++-----------
 include/linux/fortify-string.h                |   4 +-
 include/linux/minmax.h                        |   3 +-
 include/linux/overflow.h                      |   8 +-
 7 files changed, 97 insertions(+), 84 deletions(-)
---
base-commit: e70140ba0d2b1a30467d4af6bcfe761327b9ec95
change-id: 20241129-is_constexpr-refactor-19460adedc48

Best regards,
-- 
Vincent Mailhol <mailhol.vincent@...adoo.fr>