93 lines
2.4 KiB
C
93 lines
2.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */
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#include <linux/jump_label.h>
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#include <linux/uaccess.h>
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#include <linux/export.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <asm/mce.h>
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#ifdef CONFIG_X86_MCE
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static DEFINE_STATIC_KEY_FALSE(copy_mc_fragile_key);
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void enable_copy_mc_fragile(void)
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{
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static_branch_inc(©_mc_fragile_key);
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}
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#define copy_mc_fragile_enabled (static_branch_unlikely(©_mc_fragile_key))
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/*
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* Similar to copy_user_handle_tail, probe for the write fault point, or
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* source exception point.
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*/
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__visible notrace unsigned long
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copy_mc_fragile_handle_tail(char *to, char *from, unsigned len)
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{
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for (; len; --len, to++, from++)
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if (copy_mc_fragile(to, from, 1))
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break;
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return len;
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}
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#else
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/*
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* No point in doing careful copying, or consulting a static key when
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* there is no #MC handler in the CONFIG_X86_MCE=n case.
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*/
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void enable_copy_mc_fragile(void)
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{
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}
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#define copy_mc_fragile_enabled (0)
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#endif
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unsigned long copy_mc_enhanced_fast_string(void *dst, const void *src, unsigned len);
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/**
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* copy_mc_to_kernel - memory copy that handles source exceptions
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*
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* @dst: destination address
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* @src: source address
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* @len: number of bytes to copy
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*
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* Call into the 'fragile' version on systems that benefit from avoiding
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* corner case poison consumption scenarios, For example, accessing
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* poison across 2 cachelines with a single instruction. Almost all
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* other uses case can use copy_mc_enhanced_fast_string() for a fast
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* recoverable copy, or fallback to plain memcpy.
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*
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* Return 0 for success, or number of bytes not copied if there was an
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* exception.
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*/
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unsigned long __must_check copy_mc_to_kernel(void *dst, const void *src, unsigned len)
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{
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if (copy_mc_fragile_enabled)
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return copy_mc_fragile(dst, src, len);
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if (static_cpu_has(X86_FEATURE_ERMS))
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return copy_mc_enhanced_fast_string(dst, src, len);
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memcpy(dst, src, len);
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return 0;
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}
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EXPORT_SYMBOL_GPL(copy_mc_to_kernel);
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unsigned long __must_check copy_mc_to_user(void *dst, const void *src, unsigned len)
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{
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unsigned long ret;
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if (copy_mc_fragile_enabled) {
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__uaccess_begin();
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ret = copy_mc_fragile(dst, src, len);
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__uaccess_end();
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return ret;
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}
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if (static_cpu_has(X86_FEATURE_ERMS)) {
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__uaccess_begin();
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ret = copy_mc_enhanced_fast_string(dst, src, len);
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__uaccess_end();
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return ret;
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}
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return copy_user_generic(dst, src, len);
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}
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