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65 lines
1.6 KiB
65 lines
1.6 KiB
20 years ago
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/*
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* Add-on to transform csum_partial_copy_nocheck in checksumcopy.S into
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* csum_partial_copy_from_user by adding exception records.
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*
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* Copyright (C) 2001 Axis Communications AB.
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*
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* Author: Hans-Peter Nilsson.
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*/
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#include <asm/errno.h>
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/* Same function body, but a different name. If we just added exception
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records to _csum_partial_copy_nocheck and made it generic, we wouldn't
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know a user fault from a kernel fault and we would have overhead in
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each kernel caller for the error-pointer argument.
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unsigned int csum_partial_copy_from_user
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(const char *src, char *dst, int len, unsigned int sum, int *errptr);
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Note that the errptr argument is only set if we encounter an error.
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It is conveniently located on the stack, so the normal function body
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does not have to handle it. */
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#define csum_partial_copy_nocheck csum_partial_copy_from_user
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/* There are local labels numbered 1, 2 and 3 present to mark the
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different from-user accesses. */
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#include "checksumcopy.S"
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.section .fixup,"ax"
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;; Here from the movem loop; restore stack.
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4:
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movem [$sp+],$r8
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;; r12 is already decremented. Add back chunk_size-2.
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addq 40-2,$r12
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;; Here from the word loop; r12 is off by 2; add it back.
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5:
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addq 2,$r12
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;; Here from a failing single byte.
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6:
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;; Signal in *errptr that we had a failing access.
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moveq -EFAULT,$r9
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move.d $r9,[[$sp]]
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;; Clear the rest of the destination area using memset. Preserve the
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;; checksum for the readable bytes.
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push $srp
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push $r13
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move.d $r11,$r10
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clear.d $r11
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jsr memset
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pop $r10
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jump [$sp+]
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.previous
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.section __ex_table,"a"
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.dword 1b,4b
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.dword 2b,5b
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.dword 3b,6b
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.previous
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