linux-kernel - [PATCH v4 01/15] devres: provide devm_kmemdup

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Message-Id: <20250812-pinctrl-gpio-pinfuncs-v4-1-bb3906c55e64@linaro.org>
Date: Tue, 12 Aug 2025 10:27:00 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, 
 Alexey Klimov <alexey.klimov@...aro.org>, 
 Lorenzo Bianconi <lorenzo@...nel.org>, Sean Wang <sean.wang@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Paul Cercueil <paul@...pouillou.net>, Kees Cook <kees@...nel.org>, 
 Andy Shevchenko <andy@...nel.org>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 David Hildenbrand <david@...hat.com>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>, 
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, 
 Dong Aisheng <aisheng.dong@....com>, Fabio Estevam <festevam@...il.com>, 
 Shawn Guo <shawnguo@...nel.org>, Jacky Bai <ping.bai@....com>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 NXP S32 Linux Team <s32@....com>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Tony Lindgren <tony@...mide.com>, 
 Haojian Zhuang <haojian.zhuang@...aro.org>, 
 Geert Uytterhoeven <geert+renesas@...der.be>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org, 
 linux-hardening@...r.kernel.org, linux-mm@...ck.org, imx@...ts.linux.dev, 
 linux-omap@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v4 01/15] devres: provide devm_kmemdup_const()

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

Provide a function similar to devm_strdup_const() but for copying blocks
of memory that are likely to be placed in .rodata.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/base/devres.c         | 21 +++++++++++++++++++++
 include/linux/device/devres.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index ff55e1bcfa30057849a352c577bd32f1aa196532..c948c88d395607ff511ffa6eb0a75b7847ab9239 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -1117,6 +1117,27 @@ void *devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kmemdup);

+/**
+ * devm_kmemdup_const - conditionally duplicate and manage a region of memory
+ *
+ * @dev: Device this memory belongs to
+ * @src: memory region to duplicate
+ * @len: memory region length,
+ * @gfp: GFP mask to use
+ *
+ * Return: source address if it is in .rodata or the return value of kmemdup()
+ * to which the function falls back otherwise.
+ */
+const void *
+devm_kmemdup_const(struct device *dev, const void *src, size_t len, gfp_t gfp)
+{
+	if (is_kernel_rodata((unsigned long)src))
+		return src;
+
+	return devm_kmemdup(dev, src, len, gfp);
+}
+EXPORT_SYMBOL_GPL(devm_kmemdup_const);
+
 struct pages_devres {
 	unsigned long addr;
 	unsigned int order;
diff --git a/include/linux/device/devres.h b/include/linux/device/devres.h
index ae696d10faff4468a41f37b5d5fd679d4ff11997..8c5f57e0d613492fd0b2ec97dd384181608192fc 100644
--- a/include/linux/device/devres.h
+++ b/include/linux/device/devres.h
@@ -80,6 +80,8 @@ void devm_kfree(struct device *dev, const void *p);

 void * __realloc_size(3)
 devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp);
+const void *
+devm_kmemdup_const(struct device *dev, const void *src, size_t len, gfp_t gfp);
 static inline void *devm_kmemdup_array(struct device *dev, const void *src,
 				       size_t n, size_t size, gfp_t flags)
 {

-- 
2.48.1