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    Subject[PATCH v2 10/20] m68k: get rid of zeroing destination on error in csum_and_copy_from_user()
    Date
    From: Al Viro <viro@zeniv.linux.org.uk>

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    arch/m68k/lib/checksum.c | 79 +++++++++---------------------------------------
    1 file changed, 15 insertions(+), 64 deletions(-)

    diff --git a/arch/m68k/lib/checksum.c b/arch/m68k/lib/checksum.c
    index 3aeca261f622..7e6afeae6217 100644
    --- a/arch/m68k/lib/checksum.c
    +++ b/arch/m68k/lib/checksum.c
    @@ -236,82 +236,33 @@ csum_and_copy_from_user(const void __user *src, void *dst, int len)
    "clrl %5\n\t"
    "addxl %5,%0\n\t" /* add X bit */
    "7:\t"
    - "clrl %5\n" /* no error - clear return value */
    - "8:\n"
    ".section .fixup,\"ax\"\n"
    ".even\n"
    - /* If any exception occurs zero out the rest.
    - Similarities with the code above are intentional :-) */
    + /* If any exception occurs, return 0 */
    "90:\t"
    - "clrw %3@+\n\t"
    - "movel %1,%4\n\t"
    - "lsrl #5,%1\n\t"
    - "jeq 1f\n\t"
    - "subql #1,%1\n"
    - "91:\t"
    - "clrl %3@+\n"
    - "92:\t"
    - "clrl %3@+\n"
    - "93:\t"
    - "clrl %3@+\n"
    - "94:\t"
    - "clrl %3@+\n"
    - "95:\t"
    - "clrl %3@+\n"
    - "96:\t"
    - "clrl %3@+\n"
    - "97:\t"
    - "clrl %3@+\n"
    - "98:\t"
    - "clrl %3@+\n\t"
    - "dbra %1,91b\n\t"
    - "clrw %1\n\t"
    - "subql #1,%1\n\t"
    - "jcc 91b\n"
    - "1:\t"
    - "movel %4,%1\n\t"
    - "andw #0x1c,%4\n\t"
    - "jeq 1f\n\t"
    - "lsrw #2,%4\n\t"
    - "subqw #1,%4\n"
    - "99:\t"
    - "clrl %3@+\n\t"
    - "dbra %4,99b\n\t"
    - "1:\t"
    - "andw #3,%1\n\t"
    - "jeq 9f\n"
    - "100:\t"
    - "clrw %3@+\n\t"
    - "tstw %1\n\t"
    - "jeq 9f\n"
    - "101:\t"
    - "clrb %3@+\n"
    - "9:\t"
    -#define STR(X) STR1(X)
    -#define STR1(X) #X
    - "moveq #-" STR(EFAULT) ",%5\n\t"
    - "jra 8b\n"
    + "clrl %0\n"
    + "jra 7b\n"
    ".previous\n"
    ".section __ex_table,\"a\"\n"
    ".long 10b,90b\n"
    - ".long 11b,91b\n"
    - ".long 12b,92b\n"
    - ".long 13b,93b\n"
    - ".long 14b,94b\n"
    - ".long 15b,95b\n"
    - ".long 16b,96b\n"
    - ".long 17b,97b\n"
    - ".long 18b,98b\n"
    - ".long 19b,99b\n"
    - ".long 20b,100b\n"
    - ".long 21b,101b\n"
    + ".long 11b,90b\n"
    + ".long 12b,90b\n"
    + ".long 13b,90b\n"
    + ".long 14b,90b\n"
    + ".long 15b,90b\n"
    + ".long 16b,90b\n"
    + ".long 17b,90b\n"
    + ".long 18b,90b\n"
    + ".long 19b,90b\n"
    + ".long 20b,90b\n"
    + ".long 21b,90b\n"
    ".previous"
    : "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
    "=&d" (tmp1), "=d" (tmp2)
    : "0" (sum), "1" (len), "2" (src), "3" (dst)
    );

    - return tmp2 ? 0 : sum;
    + return sum;
    }

    EXPORT_SYMBOL(csum_and_copy_from_user);
    --
    2.11.0
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