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+/*
+ * 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>
+#include <asm/asm-offsets.h>
+
+ .section ".toc","aw"
+PPC64_CACHES:
+ .tc ppc64_caches[TC],ppc64_caches
+ .section ".text"
+
+/**
+ * __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
+
+ cmpdi r4,32
+ cmpdi cr1,r4,512
+ blt .Lshort_clear
+ bgt cr1,.Llong_clear
+
+.Lmedium_clear:
+ srdi r6,r4,5
+ 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
+
+.Llong_clear:
+ ld r5,PPC64_CACHES@toc(r2)
+
+ bf cr7*4+0,11f
+err2; std r0,0(r3)
+ addi r3,r3,8
+ addi r4,r4,-8
+
+ /* Destination is 16 byte aligned, need to get it cacheline aligned */
+11: lwz r7,DCACHEL1LOGLINESIZE(r5)
+ lwz r9,DCACHEL1LINESIZE(r5)
+
+ /*
+ * With worst case alignment the long clear loop takes a minimum
+ * of 1 byte less than 2 cachelines.
+ */
+ sldi r10,r9,2
+ cmpd r4,r10
+ blt .Lmedium_clear
+
+ neg r6,r3
+ addi r10,r9,-1
+ and. r5,r6,r10
+ beq 13f
+
+ srdi r6,r5,4
+ mtctr r6
+ mr r8,r3
+12:
+err1; std r0,0(r3)
+err1; std r0,8(r3)
+ addi r3,r3,16
+ bdnz 12b
+
+ sub r4,r4,r5
+
+13: srd r6,r4,r7
+ mtctr r6
+ mr r8,r3
+14:
+err1; dcbz r0,r3
+ add r3,r3,r9
+ bdnz 14b
+
+ and r4,r4,r10
+
+ cmpdi r4,32
+ blt .Lshort_clear
+ b .Lmedium_clear