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9613736d85
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 <samuel.holland@sifive.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Xuerui <git@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Test cases for using floating point operations inside a kernel module.
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*
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* This tests kernel_fpu_begin() and kernel_fpu_end() functions, especially
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* when userland has modified the floating point control registers. The kernel
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* state might depend on the state set by the userland thread that was active
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* before a syscall.
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*
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* To facilitate the test, this module registers file
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* /sys/kernel/debug/selftest_helpers/test_fpu, which when read causes a
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* sequence of floating point operations. If the operations fail, either the
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* read returns error status or the kernel crashes.
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* If the operations succeed, the read returns "1\n".
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/debugfs.h>
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#include <asm/fpu/api.h>
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#include "test_fpu.h"
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static int test_fpu_get(void *data, u64 *val)
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{
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int status = -EINVAL;
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kernel_fpu_begin();
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status = test_fpu();
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kernel_fpu_end();
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*val = 1;
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return status;
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}
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DEFINE_DEBUGFS_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n");
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static struct dentry *selftest_dir;
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static int __init test_fpu_init(void)
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{
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selftest_dir = debugfs_create_dir("selftest_helpers", NULL);
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if (!selftest_dir)
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return -ENOMEM;
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debugfs_create_file_unsafe("test_fpu", 0444, selftest_dir, NULL,
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&test_fpu_fops);
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return 0;
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}
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static void __exit test_fpu_exit(void)
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{
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debugfs_remove(selftest_dir);
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}
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module_init(test_fpu_init);
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module_exit(test_fpu_exit);
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MODULE_LICENSE("GPL");
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