linux-hardening - [PATCH v2 03/14] lib/string: extract generic strchr() into __generic

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Message-Id: <20260113082748.250916-4-jiangfeng@kylinos.cn>
Date: Tue, 13 Jan 2026 16:27:37 +0800
From: Feng Jiang <jiangfeng@...inos.cn>
To: pjw@...nel.org,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	alex@...ti.fr,
	kees@...nel.org,
	andy@...nel.org,
	akpm@...ux-foundation.org,
	jiangfeng@...inos.cn,
	ebiggers@...nel.org,
	martin.petersen@...cle.com,
	ardb@...nel.org,
	ajones@...tanamicro.com,
	conor.dooley@...rochip.com,
	samuel.holland@...ive.com,
	linus.walleij@...aro.org,
	nathan@...nel.org
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v2 03/14] lib/string: extract generic strchr() into __generic_strchr()

To support performance benchmarking in KUnit tests, extract the
generic C implementation of strchr() into a standalone function
__generic_strchr(). This allows tests to compare architecture-optimized
versions against the generic baseline without duplicating code.

Suggested-by: Andy Shevchenko <andy@...nel.org>
Signed-off-by: Feng Jiang <jiangfeng@...inos.cn>
---
 include/linux/string.h |  1 +
 lib/string.c           | 14 ++++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 04b5fef7a4ec..57f8bf543891 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -169,6 +169,7 @@ extern int strcasecmp(const char *s1, const char *s2);
 #ifndef __HAVE_ARCH_STRNCASECMP
 extern int strncasecmp(const char *s1, const char *s2, size_t n);
 #endif
+extern char *__generic_strchr(const char *, int);
 #ifndef __HAVE_ARCH_STRCHR
 extern char * strchr(const char *,int);
 #endif
diff --git a/lib/string.c b/lib/string.c
index 9dfe7177e290..8ad9b73ffe4e 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -317,6 +317,15 @@ int strncmp(const char *cs, const char *ct, size_t count)
 EXPORT_SYMBOL(strncmp);
 #endif
 
+char *__generic_strchr(const char *s, int c)
+{
+	for (; *s != (char)c; ++s)
+		if (*s == '\0')
+			return NULL;
+	return (char *)s;
+}
+EXPORT_SYMBOL(__generic_strchr);
+
 #ifndef __HAVE_ARCH_STRCHR
 /**
  * strchr - Find the first occurrence of a character in a string
@@ -328,10 +337,7 @@ EXPORT_SYMBOL(strncmp);
  */
 char *strchr(const char *s, int c)
 {
-	for (; *s != (char)c; ++s)
-		if (*s == '\0')
-			return NULL;
-	return (char *)s;
+	return __generic_strchr(s, c);
 }
 EXPORT_SYMBOL(strchr);
 #endif
-- 
2.25.1