/* * __clear_user_page, __clear_user, clear_page implementation of SuperH * * Copyright (C) 2001 Kaz Kojima * Copyright (C) 2001, 2002 Niibe Yutaka * Copyright (C) 2006 Paul Mundt */ #include <linux/linkage.h> #include <asm/page.h> ENTRY(__clear_user) ! mov #0, r0 mov #0xffffffe0, r1 ! ! r4..(r4+31)&~32 -------- not aligned [ Area 0 ] ! (r4+31)&~32..(r4+r5)&~32 -------- aligned [ Area 1 ] ! (r4+r5)&~32..r4+r5 -------- not aligned [ Area 2 ] ! ! Clear area 0 mov r4, r2 ! tst r1, r5 ! length < 32 bt .Larea2 ! skip to remainder ! add #31, r2 and r1, r2 cmp/eq r4, r2 bt .Larea1 mov r2, r3 sub r4, r3 mov r3, r7 mov r4, r2 ! .L0: dt r3 0: mov.b r0, @r2 bf/s .L0 add #1, r2 ! sub r7, r5 mov r2, r4 .Larea1: mov r4, r3 add r5, r3 and r1, r3 cmp/hi r2, r3 bf .Larea2 ! ! Clear area 1 #if defined(CONFIG_CPU_SH4) 1: movca.l r0, @r2 #else 1: mov.l r0, @r2 #endif add #4, r2 2: mov.l r0, @r2 add #4, r2 3: mov.l r0, @r2 add #4, r2 4: mov.l r0, @r2 add #4, r2 5: mov.l r0, @r2 add #4, r2 6: mov.l r0, @r2 add #4, r2 7: mov.l r0, @r2 add #4, r2 8: mov.l r0, @r2 add #4, r2 cmp/hi r2, r3 bt/s 1b nop ! ! Clear area 2 .Larea2: mov r4, r3 add r5, r3 cmp/hs r3, r2 bt/s .Ldone sub r2, r3 .L2: dt r3 9: mov.b r0, @r2 bf/s .L2 add #1, r2 ! .Ldone: rts mov #0, r0 ! return 0 as normal return ! return the number of bytes remained .Lbad_clear_user: mov r4, r0 add r5, r0 rts sub r2, r0 .section __ex_table,"a" .align 2 .long 0b, .Lbad_clear_user .long 1b, .Lbad_clear_user .long 2b, .Lbad_clear_user .long 3b, .Lbad_clear_user .long 4b, .Lbad_clear_user .long 5b, .Lbad_clear_user .long 6b, .Lbad_clear_user .long 7b, .Lbad_clear_user .long 8b, .Lbad_clear_user .long 9b, .Lbad_clear_user .previous