1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * arch/alpha/lib/clear_user.S 4 * Contributed by Richard Henderson <rth@tamu.edu> 5 * 6 * Zero user space, handling exceptions as we go. 7 * 8 * We have to make sure that $0 is always up-to-date and contains the 9 * right "bytes left to zero" value (and that it is updated only _after_ 10 * a successful copy). There is also some rather minor exception setup 11 * stuff. 12 */ 13#include <linux/export.h> 14 15/* Allow an exception for an insn; exit if we get one. */ 16#define EX(x,y...) \ 17 99: x,##y; \ 18 .section __ex_table,"a"; \ 19 .long 99b - .; \ 20 lda $31, $exception-99b($31); \ 21 .previous 22 23 .set noat 24 .set noreorder 25 .align 4 26 27 .globl __clear_user 28 .ent __clear_user 29 .frame $30, 0, $26 30 .prologue 0 31 32$loop: 33 and $1, 3, $4 # e0 : 34 beq $4, 1f # .. e1 : 35 360: EX( stq_u $31, 0($16) ) # e0 : zero one word 37 subq $0, 8, $0 # .. e1 : 38 subq $4, 1, $4 # e0 : 39 addq $16, 8, $16 # .. e1 : 40 bne $4, 0b # e1 : 41 unop # : 42 431: bic $1, 3, $1 # e0 : 44 beq $1, $tail # .. e1 : 45 462: EX( stq_u $31, 0($16) ) # e0 : zero four words 47 subq $0, 8, $0 # .. e1 : 48 EX( stq_u $31, 8($16) ) # e0 : 49 subq $0, 8, $0 # .. e1 : 50 EX( stq_u $31, 16($16) ) # e0 : 51 subq $0, 8, $0 # .. e1 : 52 EX( stq_u $31, 24($16) ) # e0 : 53 subq $0, 8, $0 # .. e1 : 54 subq $1, 4, $1 # e0 : 55 addq $16, 32, $16 # .. e1 : 56 bne $1, 2b # e1 : 57 58$tail: 59 bne $2, 1f # e1 : is there a tail to do? 60 ret $31, ($26), 1 # .. e1 : 61 621: EX( ldq_u $5, 0($16) ) # e0 : 63 clr $0 # .. e1 : 64 nop # e1 : 65 mskqh $5, $0, $5 # e0 : 66 EX( stq_u $5, 0($16) ) # e0 : 67 ret $31, ($26), 1 # .. e1 : 68 69__clear_user: 70 and $17, $17, $0 71 and $16, 7, $4 # e0 : find dest misalignment 72 beq $0, $zerolength # .. e1 : 73 addq $0, $4, $1 # e0 : bias counter 74 and $1, 7, $2 # e1 : number of bytes in tail 75 srl $1, 3, $1 # e0 : 76 beq $4, $loop # .. e1 : 77 78 EX( ldq_u $5, 0($16) ) # e0 : load dst word to mask back in 79 beq $1, $oneword # .. e1 : sub-word store? 80 81 mskql $5, $16, $5 # e0 : take care of misaligned head 82 addq $16, 8, $16 # .. e1 : 83 EX( stq_u $5, -8($16) ) # e0 : 84 addq $0, $4, $0 # .. e1 : bytes left -= 8 - misalignment 85 subq $1, 1, $1 # e0 : 86 subq $0, 8, $0 # .. e1 : 87 br $loop # e1 : 88 unop # : 89 90$oneword: 91 mskql $5, $16, $4 # e0 : 92 mskqh $5, $2, $5 # e0 : 93 or $5, $4, $5 # e1 : 94 EX( stq_u $5, 0($16) ) # e0 : 95 clr $0 # .. e1 : 96 97$zerolength: 98$exception: 99 ret $31, ($26), 1 # .. e1 : 100 101 .end __clear_user 102 EXPORT_SYMBOL(__clear_user) 103