Book a Demo!
CoCalc Logo Icon
StoreFeaturesDocsShareSupportNewsAboutPoliciesSign UpSign In
torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/powerpc/lib/string_64.S
26424 views
1
/* SPDX-License-Identifier: GPL-2.0-or-later */

2
/*

3
 *

4
 * Copyright (C) IBM Corporation, 2012

5
 *

6
 * Author: Anton Blanchard <[email protected]>

7
 */

8


9
#include <linux/export.h>

10
#include <asm/ppc_asm.h>

11
#include <asm/linkage.h>

12
#include <asm/asm-offsets.h>

13


14
/**

15
 * __arch_clear_user: - Zero a block of memory in user space, with less checking.

16
 * @to:   Destination address, in user space.

17
 * @n:    Number of bytes to zero.

18
 *

19
 * Zero a block of memory in user space.  Caller must check

20
 * the specified block with access_ok() before calling this function.

21
 *

22
 * Returns number of bytes that could not be cleared.

23
 * On success, this will be zero.

24
 */

25


26
	.macro err1

27
100:

28
	EX_TABLE(100b,.Ldo_err1)

29
	.endm

30


31
	.macro err2

32
200:

33
	EX_TABLE(200b,.Ldo_err2)

34
	.endm

35


36
	.macro err3

37
300:

38
	EX_TABLE(300b,.Ldo_err3)

39
	.endm

40


41
.Ldo_err1:

42
	mr	r3,r8

43


44
.Ldo_err2:

45
	mtctr	r4

46
1:

47
err3;	stb	r0,0(r3)

48
	addi	r3,r3,1

49
	addi	r4,r4,-1

50
	bdnz	1b

51


52
.Ldo_err3:

53
	mr	r3,r4

54
	blr

55


56
_GLOBAL_TOC(__arch_clear_user)

57
	cmpdi	r4,32

58
	neg	r6,r3

59
	li	r0,0

60
	blt	.Lshort_clear

61
	mr	r8,r3

62
	mtocrf	0x01,r6

63
	clrldi	r6,r6,(64-3)

64


65
	/* Get the destination 8 byte aligned */

66
	bf	cr7*4+3,1f

67
err1;	stb	r0,0(r3)

68
	addi	r3,r3,1

69


70
1:	bf	cr7*4+2,2f

71
err1;	sth	r0,0(r3)

72
	addi	r3,r3,2

73


74
2:	bf	cr7*4+1,3f

75
err1;	stw	r0,0(r3)

76
	addi	r3,r3,4

77


78
3:	sub	r4,r4,r6

79


80
	cmpdi	r4,32

81
	cmpdi	cr1,r4,512

82
	blt	.Lshort_clear

83
	bgt	cr1,.Llong_clear

84


85
.Lmedium_clear:

86
	srdi	r6,r4,5

87
	mtctr	r6

88


89
	/* Do 32 byte chunks */

90
4:

91
err2;	std	r0,0(r3)

92
err2;	std	r0,8(r3)

93
err2;	std	r0,16(r3)

94
err2;	std	r0,24(r3)

95
	addi	r3,r3,32

96
	addi	r4,r4,-32

97
	bdnz	4b

98


99
.Lshort_clear:

100
	/* up to 31 bytes to go */

101
	cmpdi	r4,16

102
	blt	6f

103
err2;	std	r0,0(r3)

104
err2;	std	r0,8(r3)

105
	addi	r3,r3,16

106
	addi	r4,r4,-16

107


108
	/* Up to 15 bytes to go */

109
6:	mr	r8,r3

110
	clrldi	r4,r4,(64-4)

111
	mtocrf	0x01,r4

112
	bf	cr7*4+0,7f

113
err1;	std	r0,0(r3)

114
	addi	r3,r3,8

115


116
7:	bf	cr7*4+1,8f

117
err1;	stw	r0,0(r3)

118
	addi	r3,r3,4

119


120
8:	bf	cr7*4+2,9f

121
err1;	sth	r0,0(r3)

122
	addi	r3,r3,2

123


124
9:	bf	cr7*4+3,10f

125
err1;	stb	r0,0(r3)

126


127
10:	li	r3,0

128
	blr

129


130
.Llong_clear:

131
	LOAD_REG_ADDR(r5, ppc64_caches)

132


133
	bf	cr7*4+0,11f

134
err2;	std	r0,0(r3)

135
	addi	r3,r3,8

136
	addi	r4,r4,-8

137


138
	/* Destination is 16 byte aligned, need to get it cache block aligned */

139
11:	lwz	r7,DCACHEL1LOGBLOCKSIZE(r5)

140
	lwz	r9,DCACHEL1BLOCKSIZE(r5)

141


142
	/*

143
	 * With worst case alignment the long clear loop takes a minimum

144
	 * of 1 byte less than 2 cachelines.

145
	 */

146
	sldi	r10,r9,2

147
	cmpd	r4,r10

148
	blt	.Lmedium_clear

149


150
	neg	r6,r3

151
	addi	r10,r9,-1

152
	and.	r5,r6,r10

153
	beq	13f

154


155
	srdi	r6,r5,4

156
	mtctr	r6

157
	mr	r8,r3

158
12:

159
err1;	std	r0,0(r3)

160
err1;	std	r0,8(r3)

161
	addi	r3,r3,16

162
	bdnz	12b

163


164
	sub	r4,r4,r5

165


166
13:	srd	r6,r4,r7

167
	mtctr	r6

168
	mr	r8,r3

169
14:

170
err1;	dcbz	0,r3

171
	add	r3,r3,r9

172
	bdnz	14b

173


174
	and	r4,r4,r10

175


176
	cmpdi	r4,32

177
	blt	.Lshort_clear

178
	b	.Lmedium_clear

179
EXPORT_SYMBOL(__arch_clear_user)

180


181