Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * arch/alpha/lib/clear_user.S | |
3 | * Contributed by Richard Henderson <rth@tamu.edu> | |
4 | * | |
5 | * Zero user space, handling exceptions as we go. | |
6 | * | |
7 | * We have to make sure that $0 is always up-to-date and contains the | |
8 | * right "bytes left to zero" value (and that it is updated only _after_ | |
9 | * a successful copy). There is also some rather minor exception setup | |
10 | * stuff. | |
11 | * | |
12 | * NOTE! This is not directly C-callable, because the calling semantics | |
13 | * are different: | |
14 | * | |
15 | * Inputs: | |
16 | * length in $0 | |
17 | * destination address in $6 | |
18 | * exception pointer in $7 | |
19 | * return address in $28 (exceptions expect it there) | |
20 | * | |
21 | * Outputs: | |
22 | * bytes left to copy in $0 | |
23 | * | |
24 | * Clobbers: | |
25 | * $1,$2,$3,$4,$5,$6 | |
26 | */ | |
00fc0e0d | 27 | #include <asm/export.h> |
1da177e4 LT |
28 | |
29 | /* Allow an exception for an insn; exit if we get one. */ | |
30 | #define EX(x,y...) \ | |
31 | 99: x,##y; \ | |
32 | .section __ex_table,"a"; \ | |
33 | .long 99b - .; \ | |
34 | lda $31, $exception-99b($31); \ | |
35 | .previous | |
36 | ||
37 | .set noat | |
38 | .set noreorder | |
39 | .align 4 | |
40 | ||
41 | .globl __do_clear_user | |
42 | .ent __do_clear_user | |
43 | .frame $30, 0, $28 | |
44 | .prologue 0 | |
45 | ||
46 | $loop: | |
47 | and $1, 3, $4 # e0 : | |
48 | beq $4, 1f # .. e1 : | |
49 | ||
50 | 0: EX( stq_u $31, 0($6) ) # e0 : zero one word | |
51 | subq $0, 8, $0 # .. e1 : | |
52 | subq $4, 1, $4 # e0 : | |
53 | addq $6, 8, $6 # .. e1 : | |
54 | bne $4, 0b # e1 : | |
55 | unop # : | |
56 | ||
57 | 1: bic $1, 3, $1 # e0 : | |
58 | beq $1, $tail # .. e1 : | |
59 | ||
60 | 2: EX( stq_u $31, 0($6) ) # e0 : zero four words | |
61 | subq $0, 8, $0 # .. e1 : | |
62 | EX( stq_u $31, 8($6) ) # e0 : | |
63 | subq $0, 8, $0 # .. e1 : | |
64 | EX( stq_u $31, 16($6) ) # e0 : | |
65 | subq $0, 8, $0 # .. e1 : | |
66 | EX( stq_u $31, 24($6) ) # e0 : | |
67 | subq $0, 8, $0 # .. e1 : | |
68 | subq $1, 4, $1 # e0 : | |
69 | addq $6, 32, $6 # .. e1 : | |
70 | bne $1, 2b # e1 : | |
71 | ||
72 | $tail: | |
73 | bne $2, 1f # e1 : is there a tail to do? | |
74 | ret $31, ($28), 1 # .. e1 : | |
75 | ||
76 | 1: EX( ldq_u $5, 0($6) ) # e0 : | |
77 | clr $0 # .. e1 : | |
78 | nop # e1 : | |
79 | mskqh $5, $0, $5 # e0 : | |
80 | EX( stq_u $5, 0($6) ) # e0 : | |
81 | ret $31, ($28), 1 # .. e1 : | |
82 | ||
83 | __do_clear_user: | |
84 | and $6, 7, $4 # e0 : find dest misalignment | |
85 | beq $0, $zerolength # .. e1 : | |
86 | addq $0, $4, $1 # e0 : bias counter | |
87 | and $1, 7, $2 # e1 : number of bytes in tail | |
88 | srl $1, 3, $1 # e0 : | |
89 | beq $4, $loop # .. e1 : | |
90 | ||
91 | EX( ldq_u $5, 0($6) ) # e0 : load dst word to mask back in | |
92 | beq $1, $oneword # .. e1 : sub-word store? | |
93 | ||
94 | mskql $5, $6, $5 # e0 : take care of misaligned head | |
95 | addq $6, 8, $6 # .. e1 : | |
96 | EX( stq_u $5, -8($6) ) # e0 : | |
97 | addq $0, $4, $0 # .. e1 : bytes left -= 8 - misalignment | |
98 | subq $1, 1, $1 # e0 : | |
99 | subq $0, 8, $0 # .. e1 : | |
100 | br $loop # e1 : | |
101 | unop # : | |
102 | ||
103 | $oneword: | |
104 | mskql $5, $6, $4 # e0 : | |
105 | mskqh $5, $2, $5 # e0 : | |
106 | or $5, $4, $5 # e1 : | |
107 | EX( stq_u $5, 0($6) ) # e0 : | |
108 | clr $0 # .. e1 : | |
109 | ||
110 | $zerolength: | |
111 | $exception: | |
112 | ret $31, ($28), 1 # .. e1 : | |
113 | ||
114 | .end __do_clear_user | |
00fc0e0d | 115 | EXPORT_SYMBOL(__do_clear_user) |