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m68k: get rid of zeroing destination on error in csum_and_copy_from_user() 

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-07-12 23:01:10 -04:00
parent 1d60be3c25
commit 66aa38801a
1 changed files with 15 additions and 64 deletions
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79
arch/m68k/lib/checksum.c
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@ -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);