30 lines
848 B
C
30 lines
848 B
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/uaccess.h>
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#include <linux/kernel.h>
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#ifdef CONFIG_X86_64
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static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
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{
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return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
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}
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bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
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{
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unsigned long vaddr = (unsigned long)unsafe_src;
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/*
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* Range covering the highest possible canonical userspace address
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* as well as non-canonical address range. For the canonical range
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* we also need to include the userspace guard page.
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*/
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return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
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canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
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}
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#else
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bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
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{
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return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
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}
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#endif
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