in include/asm/uaccess.h [616:656]
static inline unsigned long __arc_clear_user(void __user *to, unsigned long n)
{
long res = n;
unsigned char *d_char = to;
__asm__ __volatile__(
" bbit0 %0, 0, 1f \n"
"75: stb.ab %2, [%0,1] \n"
" sub %1, %1, 1 \n"
"1: bbit0 %0, 1, 2f \n"
"76: stw.ab %2, [%0,2] \n"
" sub %1, %1, 2 \n"
"2: asr.f lp_count, %1, 2 \n"
" lpnz 3f \n"
"77: st.ab %2, [%0,4] \n"
" sub %1, %1, 4 \n"
"3: bbit0 %1, 1, 4f \n"
"78: stw.ab %2, [%0,2] \n"
" sub %1, %1, 2 \n"
"4: bbit0 %1, 0, 5f \n"
"79: stb.ab %2, [%0,1] \n"
" sub %1, %1, 1 \n"
"5: \n"
" .section .fixup, \"ax\" \n"
" .align 4 \n"
"3: j 5b \n"
" .previous \n"
" .section __ex_table, \"a\" \n"
" .align 4 \n"
" .word 75b, 3b \n"
" .word 76b, 3b \n"
" .word 77b, 3b \n"
" .word 78b, 3b \n"
" .word 79b, 3b \n"
" .previous \n"
: "+r"(d_char), "+r"(res)
: "i"(0)
: "lp_count", "memory");
return res;
}