From: Samuel Holland Date: Fri, 29 Mar 2024 07:18:29 +0000 (-0700) Subject: selftests/fpu: move FP code to a separate translation unit X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9613736d852dce2376a848e6e9af091c422a947e;p=linux.git 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. Link: https://lkml.kernel.org/r/20240329072441.591471-15-samuel.holland@sifive.com Signed-off-by: Samuel Holland Reviewed-by: Christoph Hellwig Acked-by: Christian König Cc: Alex Deucher Cc: Borislav Petkov (AMD) Cc: Catalin Marinas Cc: Dave Hansen Cc: Huacai Chen Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Masahiro Yamada Cc: Michael Ellerman Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Palmer Dabbelt Cc: Russell King Cc: Thomas Gleixner Cc: WANG Xuerui Cc: Will Deacon Signed-off-by: Andrew Morton --- diff --git a/lib/Makefile b/lib/Makefile index 7a1fdd1cce7a0..87f8803587ae0 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.c b/lib/test_fpu.c deleted file mode 100644 index e82db19fed84a..0000000000000 --- a/lib/test_fpu.c +++ /dev/null @@ -1,89 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0+ -/* - * Test cases for using floating point operations inside a kernel module. - * - * This tests kernel_fpu_begin() and kernel_fpu_end() functions, especially - * when userland has modified the floating point control registers. The kernel - * state might depend on the state set by the userland thread that was active - * before a syscall. - * - * To facilitate the test, this module registers file - * /sys/kernel/debug/selftest_helpers/test_fpu, which when read causes a - * sequence of floating point operations. If the operations fail, either the - * read returns error status or the kernel crashes. - * If the operations succeed, the read returns "1\n". - */ - -#include -#include -#include -#include - -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; -} - -static int test_fpu_get(void *data, u64 *val) -{ - int status = -EINVAL; - - kernel_fpu_begin(); - status = test_fpu(); - kernel_fpu_end(); - - *val = 1; - return status; -} - -DEFINE_DEBUGFS_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n"); -static struct dentry *selftest_dir; - -static int __init test_fpu_init(void) -{ - selftest_dir = debugfs_create_dir("selftest_helpers", NULL); - if (!selftest_dir) - return -ENOMEM; - - debugfs_create_file_unsafe("test_fpu", 0444, selftest_dir, NULL, - &test_fpu_fops); - - return 0; -} - -static void __exit test_fpu_exit(void) -{ - debugfs_remove(selftest_dir); -} - -module_init(test_fpu_init); -module_exit(test_fpu_exit); - -MODULE_LICENSE("GPL"); diff --git a/lib/test_fpu.h b/lib/test_fpu.h new file mode 100644 index 0000000000000..4459807084bce --- /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_glue.c b/lib/test_fpu_glue.c new file mode 100644 index 0000000000000..85963d7be826f --- /dev/null +++ b/lib/test_fpu_glue.c @@ -0,0 +1,59 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Test cases for using floating point operations inside a kernel module. + * + * This tests kernel_fpu_begin() and kernel_fpu_end() functions, especially + * when userland has modified the floating point control registers. The kernel + * state might depend on the state set by the userland thread that was active + * before a syscall. + * + * To facilitate the test, this module registers file + * /sys/kernel/debug/selftest_helpers/test_fpu, which when read causes a + * sequence of floating point operations. If the operations fail, either the + * read returns error status or the kernel crashes. + * If the operations succeed, the read returns "1\n". + */ + +#include +#include +#include +#include + +#include "test_fpu.h" + +static int test_fpu_get(void *data, u64 *val) +{ + int status = -EINVAL; + + kernel_fpu_begin(); + status = test_fpu(); + kernel_fpu_end(); + + *val = 1; + return status; +} + +DEFINE_DEBUGFS_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n"); +static struct dentry *selftest_dir; + +static int __init test_fpu_init(void) +{ + selftest_dir = debugfs_create_dir("selftest_helpers", NULL); + if (!selftest_dir) + return -ENOMEM; + + debugfs_create_file_unsafe("test_fpu", 0444, selftest_dir, NULL, + &test_fpu_fops); + + return 0; +} + +static void __exit test_fpu_exit(void) +{ + debugfs_remove(selftest_dir); +} + +module_init(test_fpu_init); +module_exit(test_fpu_exit); + +MODULE_LICENSE("GPL"); diff --git a/lib/test_fpu_impl.c b/lib/test_fpu_impl.c new file mode 100644 index 0000000000000..777894dbbe86f --- /dev/null +++ b/lib/test_fpu_impl.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#include + +#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; +}