diff options
Diffstat (limited to 'arch/powerpc/lib/string_64.S')
| -rw-r--r-- | arch/powerpc/lib/string_64.S | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/arch/powerpc/lib/string_64.S b/arch/powerpc/lib/string_64.S new file mode 100644 index 00000000000..6613b904700 --- /dev/null +++ b/arch/powerpc/lib/string_64.S @@ -0,0 +1,141 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2012 + * + * Author: Anton Blanchard <anton@au.ibm.com> + */ + +#include <asm/ppc_asm.h> + +/** + * __clear_user: - Zero a block of memory in user space, with less checking. + * @to: Destination address, in user space. + * @n: Number of bytes to zero. + * + * Zero a block of memory in user space. Caller must check + * the specified block with access_ok() before calling this function. + * + * Returns number of bytes that could not be cleared. + * On success, this will be zero. + */ + + .macro err1 +100: + .section __ex_table,"a" + .align 3 + .llong 100b,.Ldo_err1 + .previous + .endm + + .macro err2 +200: + .section __ex_table,"a" + .align 3 + .llong 200b,.Ldo_err2 + .previous + .endm + + .macro err3 +300: + .section __ex_table,"a" + .align 3 + .llong 300b,.Ldo_err3 + .previous + .endm + +.Ldo_err1: + mr r3,r8 + +.Ldo_err2: + mtctr r4 +1: +err3; stb r0,0(r3) + addi r3,r3,1 + addi r4,r4,-1 + bdnz 1b + +.Ldo_err3: + mr r3,r4 + blr + +_GLOBAL(__clear_user) + cmpdi r4,32 + neg r6,r3 + li r0,0 + blt .Lshort_clear + mr r8,r3 + mtocrf 0x01,r6 + clrldi r6,r6,(64-3) + + /* Get the destination 8 byte aligned */ + bf cr7*4+3,1f +err1; stb r0,0(r3) + addi r3,r3,1 + +1: bf cr7*4+2,2f +err1; sth r0,0(r3) + addi r3,r3,2 + +2: bf cr7*4+1,3f +err1; stw r0,0(r3) + addi r3,r3,4 + +3: sub r4,r4,r6 + srdi r6,r4,5 + cmpdi r4,32 + blt .Lshort_clear + mtctr r6 + + /* Do 32 byte chunks */ +4: +err2; std r0,0(r3) +err2; std r0,8(r3) +err2; std r0,16(r3) +err2; std r0,24(r3) + addi r3,r3,32 + addi r4,r4,-32 + bdnz 4b + +.Lshort_clear: + /* up to 31 bytes to go */ + cmpdi r4,16 + blt 6f +err2; std r0,0(r3) +err2; std r0,8(r3) + addi r3,r3,16 + addi r4,r4,-16 + + /* Up to 15 bytes to go */ +6: mr r8,r3 + clrldi r4,r4,(64-4) + mtocrf 0x01,r4 + bf cr7*4+0,7f +err1; std r0,0(r3) + addi r3,r3,8 + +7: bf cr7*4+1,8f +err1; stw r0,0(r3) + addi r3,r3,4 + +8: bf cr7*4+2,9f +err1; sth r0,0(r3) + addi r3,r3,2 + +9: bf cr7*4+3,10f +err1; stb r0,0(r3) + +10: li r3,0 + blr |