linux-kernel - [PATCH v4 1/5] coccinelle: misc: Add field

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Message-ID: <20250612-field_modify-v4-1-ae4f74da45a6@quicinc.com>
Date: Thu, 12 Jun 2025 21:46:08 +0800
From: Luo Jie <quic_luoj@...cinc.com>
To: Yury Norov <yury.norov@...il.com>,
        Rasmus Villemoes
	<linux@...musvillemoes.dk>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        "Nicolas
 Palix" <nicolas.palix@...g.fr>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Oliver Upton
	<oliver.upton@...ux.dev>,
        Joey Gouly <joey.gouly@....com>,
        Suzuki K Poulose
	<suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>
CC: <linux-kernel@...r.kernel.org>, <cocci@...ia.fr>,
        <linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
        <andrew@...n.ch>, <quic_kkumarcs@...cinc.com>,
        <quic_linchen@...cinc.com>, <quic_leiwei@...cinc.com>,
        <quic_suruchia@...cinc.com>, <quic_pavir@...cinc.com>,
        Luo Jie <quic_luoj@...cinc.com>
Subject: [PATCH v4 1/5] coccinelle: misc: Add field_modify script

Find and suggest conversions of opencoded field modify patterns with
the wrapper FIELD_MODIFY() API defined in include/linux/bitfield.h
for catching the possible parameter type error in the compile time.

Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
---
 scripts/coccinelle/misc/field_modify.cocci | 61 ++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/scripts/coccinelle/misc/field_modify.cocci b/scripts/coccinelle/misc/field_modify.cocci
new file mode 100644
index 000000000000..48b00194a265
--- /dev/null
+++ b/scripts/coccinelle/misc/field_modify.cocci
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/// Replace below code with the wrapper FIELD_MODIFY(MASK, &reg, val)
+/// - reg &= ~MASK;
+/// - reg |= FIELD_PREP(MASK, val);
+//
+// Confidence: High
+// Author: Luo Jie <quic_luoj@...cinc.com>
+// Copyright: (C) 2025 Qualcomm Innovation Center, Inc.
+// Keywords: FIELD_PREP, FIELD_MODIFY
+// Options: --include-headers
+
+virtual context
+virtual patch
+virtual org
+virtual report
+
+@ depends on context && !patch && !org && !report@
+identifier reg, val;
+constant mask;
+symbol FIELD_PREP;
+@@
+
+* reg &= ~mask;
+* reg |= FIELD_PREP(mask, val);
+
+@ depends on !context && patch && !org && !report @
+identifier reg, val;
+constant mask;
+symbol FIELD_PREP, FIELD_MODIFY;
+@@
+
+-reg &= ~mask;
+-reg |= FIELD_PREP(mask, val);
++FIELD_MODIFY(mask, &reg, val);
+
+@r depends on !context && !patch && (org || report)@
+identifier reg, val;
+constant mask;
+symbol FIELD_PREP;
+position p;
+@@
+
+ reg &= ~mask;
+ reg |= FIELD_PREP@p(mask, val);
+
+@...ipt:python depends on report@
+p << r.p;
+x << r.reg;
+@@
+
+msg="WARNING: Consider using FIELD_MODIFY helper on %s" % (x)
+coccilib.report.print_report(p[0], msg)
+
+@...ipt:python depends on org@
+p << r.p;
+x << r.reg;
+@@
+
+msg="WARNING: Consider using FIELD_MODIFY helper on %s" % (x)
+msg_safe=msg.replace("[","@(").replace("]",")")
+coccilib.org.print_todo(p[0], msg_safe)

-- 
2.34.1