linux-kernel - [PATCH 06/15] tools/nolibc: add abs() and friends

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Message-Id: <20250423-nolibc-misc-v1-6-a925bf40297b@linutronix.de>
Date: Wed, 23 Apr 2025 17:01:36 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Willy Tarreau <w@....eu>, 
 Thomas Weißschuh <linux@...ssschuh.net>, 
 Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH 06/15] tools/nolibc: add abs() and friends

This is used in various selftests and will be handy when integrating
those with nolibc.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 tools/include/nolibc/Makefile                |  1 +
 tools/include/nolibc/math.h                  | 31 ++++++++++++++++++++++++++++
 tools/include/nolibc/nolibc.h                |  1 +
 tools/include/nolibc/stdlib.h                | 18 ++++++++++++++++
 tools/testing/selftests/nolibc/nolibc-test.c |  2 ++
 5 files changed, 53 insertions(+)

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
index b22ff1e268b2e4bd788e974d6d8f2e1ef96dfc5f..3a82e036a2c1762da5c3916ff9f4e158fb6106ff 100644
--- a/tools/include/nolibc/Makefile
+++ b/tools/include/nolibc/Makefile
@@ -35,6 +35,7 @@ all_files := \
 		fcntl.h \
 		getopt.h \
 		limits.h \
+		math.h \
 		nolibc.h \
 		signal.h \
 		stackprotector.h \
diff --git a/tools/include/nolibc/math.h b/tools/include/nolibc/math.h
new file mode 100644
index 0000000000000000000000000000000000000000..4906d3eb7c1aed0c402d3ab39526dd1c93b5df2a
--- /dev/null
+++ b/tools/include/nolibc/math.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * math definitions for NOLIBC
+ * Copyright (C) 2025 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
+ */
+
+#ifndef _NOLIBC_SYS_MATH_H
+#define _NOLIBC_SYS_MATH_H
+
+static __inline__
+double fabs(double x)
+{
+	return x >= 0 ? x : -x;
+}
+
+static __inline__
+float fabsf(float x)
+{
+	return x >= 0 ? x : -x;
+}
+
+static __inline__
+long double fabsl(long double x)
+{
+	return x >= 0 ? x : -x;
+}
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#endif /* _NOLIBC_SYS_MATH_H */
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 3f329feb379c4c808d2e56fbb2b7a6c4b08a7c0d..2207f3d3c5cf92b96150149050f0bde0ed7e7147 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -115,6 +115,7 @@
 #include "dirent.h"
 #include "fcntl.h"
 #include "getopt.h"
+#include "math.h"
 
 /* Used by programs to avoid std includes */
 #define NOLIBC
diff --git a/tools/include/nolibc/stdlib.h b/tools/include/nolibc/stdlib.h
index 69cf1d4418f1c1f59192aee40ea3a5b684d2709a..c8c44859aee20e2b9eb55ddae488f1f70b710fbb 100644
--- a/tools/include/nolibc/stdlib.h
+++ b/tools/include/nolibc/stdlib.h
@@ -29,6 +29,24 @@ static __attribute__((unused)) char itoa_buffer[21];
  * As much as possible, please keep functions alphabetically sorted.
  */
 
+static __inline__
+int abs(int j)
+{
+	return j >= 0 ? j : -j;
+}
+
+static __inline__
+long labs(long j)
+{
+	return j >= 0 ? j : -j;
+}
+
+static __inline__
+long long llabs(long long j)
+{
+	return j >= 0 ? j : -j;
+}
+
 /* must be exported, as it's used by libgcc for various divide functions */
 void abort(void);
 __attribute__((weak,unused,noreturn,section(".text.nolibc_abort")))
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 95d08e9ccf5b3be924548100e9621cd47f39e8c2..b6724c314766b0cf34d7cae5cac28a9102ebe66e 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -1315,6 +1315,8 @@ int run_stdlib(int min, int max)
 		CASE_TEST(tolower_noop);            EXPECT_EQ(1, tolower('a'), 'a'); break;
 		CASE_TEST(toupper);                 EXPECT_EQ(1, toupper('a'), 'A'); break;
 		CASE_TEST(toupper_noop);            EXPECT_EQ(1, toupper('A'), 'A'); break;
+		CASE_TEST(abs);                     EXPECT_EQ(1, abs(-10), 10); break;
+		CASE_TEST(abs_noop);                EXPECT_EQ(1, abs(10), 10); break;
 
 		case __LINE__:
 			return ret; /* must be last */

-- 
2.49.0