1 /* SPDX-License-Identifier: GPL-2.0-only */ !! 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * linux/arch/arm/lib/clear_user.S !! 3 * arch/alpha/lib/clear_user.S
>> 4 * Contributed by Richard Henderson <rth@tamu.edu>
4 * 5 *
5 * Copyright (C) 1995, 1996,1997,1998 Russell !! 6 * Zero user space, handling exceptions as we go.
6 */ !! 7 *
7 #include <linux/linkage.h> !! 8 * We have to make sure that $0 is always up-to-date and contains the
8 #include <asm/assembler.h> !! 9 * right "bytes left to zero" value (and that it is updated only _after_
9 #include <asm/unwind.h> !! 10 * a successful copy). There is also some rather minor exception setup
10 !! 11 * stuff.
11 .text <<
12 <<
13 /* Prototype: unsigned long arm_clear_user(voi <<
14 * Purpose : clear some user memory <<
15 * Params : addr - user memory address to cl <<
16 * : sz - number of bytes to clear <<
17 * Returns : number of bytes NOT cleared <<
18 */ 12 */
19 ENTRY(__clear_user_std) !! 13 #include <linux/export.h>
20 WEAK(arm_clear_user) !! 14
21 UNWIND(.fnstart) !! 15 /* Allow an exception for an insn; exit if we get one. */
22 UNWIND(.save {r1, lr}) !! 16 #define EX(x,y...) \
23 stmfd sp!, {r1, lr} !! 17 99: x,##y; \
24 mov r2, #0 !! 18 .section __ex_table,"a"; \
25 cmp r1, #4 !! 19 .long 99b - .; \
26 blt 2f !! 20 lda $31, $exception-99b($31); \
27 ands ip, r0, #3 !! 21 .previous
28 beq 1f !! 22
29 cmp ip, #2 !! 23 .set noat
30 strusr r2, r0, 1 !! 24 .set noreorder
31 strusr r2, r0, 1, le !! 25 .align 4
32 strusr r2, r0, 1, lt !! 26
33 rsb ip, ip, #4 !! 27 .globl __clear_user
34 sub r1, r1, ip !! 28 .ent __clear_user
35 1: subs r1, r1, #8 !! 29 .frame $30, 0, $26
36 strusr r2, r0, 4, pl, rept=2 !! 30 .prologue 0
37 bpl 1b !! 31
38 adds r1, r1, #4 !! 32 $loop:
39 strusr r2, r0, 4, pl !! 33 and $1, 3, $4 # e0 :
40 2: tst r1, #2 !! 34 beq $4, 1f # .. e1 :
41 strusr r2, r0, 1, ne, rept=2 !! 35
42 tst r1, #1 !! 36 0: EX( stq_u $31, 0($16) ) # e0 : zero one word
43 it ne !! 37 subq $0, 8, $0 # .. e1 :
44 USER( strbtne r2, [r0]) !! 38 subq $4, 1, $4 # e0 :
45 mov r0, #0 !! 39 addq $16, 8, $16 # .. e1 :
46 ldmfd sp!, {r1, pc} !! 40 bne $4, 0b # e1 :
47 UNWIND(.fnend) !! 41 unop # :
48 ENDPROC(arm_clear_user) !! 42
49 ENDPROC(__clear_user_std) !! 43 1: bic $1, 3, $1 # e0 :
50 !! 44 beq $1, $tail # .. e1 :
51 .pushsection .text.fixup,"ax" !! 45
52 .align 0 !! 46 2: EX( stq_u $31, 0($16) ) # e0 : zero four words
53 9001: ldmfd sp!, {r0, pc} !! 47 subq $0, 8, $0 # .. e1 :
54 .popsection !! 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
>> 62 1: 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 :
55 100
>> 101 .end __clear_user
>> 102 EXPORT_SYMBOL(__clear_user)
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