linux-kernel - [PATCH v4 14/15] selftests/fpu: Move FP code to a separate translation unit

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Message-ID: <20240329072441.591471-15-samuel.holland@sifive.com>
Date: Fri, 29 Mar 2024 00:18:29 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-riscv@...ts.infradead.org,
	Christoph Hellwig <hch@....de>,
	loongarch@...ts.linux.dev,
	amd-gfx@...ts.freedesktop.org,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v4 14/15] selftests/fpu: Move FP code to a separate translation unit

This ensures no compiler-generated floating-point code can appear
outside kernel_fpu_{begin,end}() sections, and some architectures
enforce this separation.

Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

(no changes since v2)

Changes in v2:
 - Declare test_fpu() in a header

 lib/Makefile                        |  3 ++-
 lib/test_fpu.h                      |  8 +++++++
 lib/{test_fpu.c => test_fpu_glue.c} | 32 +------------------------
 lib/test_fpu_impl.c                 | 37 +++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 32 deletions(-)
 create mode 100644 lib/test_fpu.h
 rename lib/{test_fpu.c => test_fpu_glue.c} (71%)
 create mode 100644 lib/test_fpu_impl.c

diff --git a/lib/Makefile b/lib/Makefile
index ffc6b2341b45..fcb35bf50979 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -133,7 +133,8 @@ FPU_CFLAGS += $(call cc-option,-msse -mpreferred-stack-boundary=3,-mpreferred-st
 endif
 
 obj-$(CONFIG_TEST_FPU) += test_fpu.o
-CFLAGS_test_fpu.o += $(FPU_CFLAGS)
+test_fpu-y := test_fpu_glue.o test_fpu_impl.o
+CFLAGS_test_fpu_impl.o += $(FPU_CFLAGS)
 
 # Some KUnit files (hooks.o) need to be built-in even when KUnit is a module,
 # so we can't just use obj-$(CONFIG_KUNIT).
diff --git a/lib/test_fpu.h b/lib/test_fpu.h
new file mode 100644
index 000000000000..4459807084bc
--- /dev/null
+++ b/lib/test_fpu.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef _LIB_TEST_FPU_H
+#define _LIB_TEST_FPU_H
+
+int test_fpu(void);
+
+#endif
diff --git a/lib/test_fpu.c b/lib/test_fpu_glue.c
similarity index 71%
rename from lib/test_fpu.c
rename to lib/test_fpu_glue.c
index e82db19fed84..85963d7be826 100644
--- a/lib/test_fpu.c
+++ b/lib/test_fpu_glue.c
@@ -19,37 +19,7 @@
 #include <linux/debugfs.h>
 #include <asm/fpu/api.h>
 
-static int test_fpu(void)
-{
-	/*
-	 * This sequence of operations tests that rounding mode is
-	 * to nearest and that denormal numbers are supported.
-	 * Volatile variables are used to avoid compiler optimizing
-	 * the calculations away.
-	 */
-	volatile double a, b, c, d, e, f, g;
-
-	a = 4.0;
-	b = 1e-15;
-	c = 1e-310;
-
-	/* Sets precision flag */
-	d = a + b;
-
-	/* Result depends on rounding mode */
-	e = a + b / 2;
-
-	/* Denormal and very large values */
-	f = b / c;
-
-	/* Depends on denormal support */
-	g = a + c * f;
-
-	if (d > a && e > a && g > a)
-		return 0;
-	else
-		return -EINVAL;
-}
+#include "test_fpu.h"
 
 static int test_fpu_get(void *data, u64 *val)
 {
diff --git a/lib/test_fpu_impl.c b/lib/test_fpu_impl.c
new file mode 100644
index 000000000000..777894dbbe86
--- /dev/null
+++ b/lib/test_fpu_impl.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/errno.h>
+
+#include "test_fpu.h"
+
+int test_fpu(void)
+{
+	/*
+	 * This sequence of operations tests that rounding mode is
+	 * to nearest and that denormal numbers are supported.
+	 * Volatile variables are used to avoid compiler optimizing
+	 * the calculations away.
+	 */
+	volatile double a, b, c, d, e, f, g;
+
+	a = 4.0;
+	b = 1e-15;
+	c = 1e-310;
+
+	/* Sets precision flag */
+	d = a + b;
+
+	/* Result depends on rounding mode */
+	e = a + b / 2;
+
+	/* Denormal and very large values */
+	f = b / c;
+
+	/* Depends on denormal support */
+	g = a + c * f;
+
+	if (d > a && e > a && g > a)
+		return 0;
+	else
+		return -EINVAL;
+}
-- 
2.44.0