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1da177e4 LT |
1 | /* |
2 | * Userland implementation of gettimeofday() for 64 bits processes in a | |
3 | * ppc64 kernel for use in the vDSO | |
4 | * | |
5 | * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), | |
6 | * IBM Corp. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the License, or (at your option) any later version. | |
12 | */ | |
13 | #include <linux/config.h> | |
14 | #include <asm/processor.h> | |
15 | #include <asm/ppc_asm.h> | |
16 | #include <asm/vdso.h> | |
0013a854 | 17 | #include <asm/asm-offsets.h> |
1da177e4 LT |
18 | |
19 | .text | |
20 | /* | |
21 | * Exact prototype of gettimeofday | |
22 | * | |
23 | * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); | |
24 | * | |
25 | */ | |
26 | V_FUNCTION_BEGIN(__kernel_gettimeofday) | |
27 | .cfi_startproc | |
28 | mflr r12 | |
29 | .cfi_register lr,r12 | |
30 | ||
31 | mr r11,r3 /* r11 holds tv */ | |
32 | mr r10,r4 /* r10 holds tz */ | |
33 | bl V_LOCAL_FUNC(__get_datapage) /* get data page */ | |
34 | bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */ | |
35 | lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */ | |
36 | ori r7,r7,16960 | |
37 | rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */ | |
38 | rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */ | |
39 | std r5,TVAL64_TV_SEC(r11) /* store sec in tv */ | |
40 | subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */ | |
41 | mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) / XSEC_PER_SEC */ | |
42 | rldicl r0,r0,44,20 | |
43 | cmpldi cr0,r10,0 /* check if tz is NULL */ | |
44 | std r0,TVAL64_TV_USEC(r11) /* store usec in tv */ | |
45 | beq 1f | |
46 | lwz r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */ | |
47 | lwz r5,CFG_TZ_DSTTIME(r3) | |
48 | stw r4,TZONE_TZ_MINWEST(r10) | |
49 | stw r5,TZONE_TZ_DSTTIME(r10) | |
50 | 1: mtlr r12 | |
51 | li r3,0 /* always success */ | |
52 | blr | |
53 | .cfi_endproc | |
54 | V_FUNCTION_END(__kernel_gettimeofday) | |
55 | ||
56 | ||
57 | /* | |
58 | * This is the core of gettimeofday(), it returns the xsec | |
59 | * value in r4 and expects the datapage ptr (non clobbered) | |
60 | * in r3. clobbers r0,r4,r5,r6,r7,r8 | |
61 | */ | |
62 | V_FUNCTION_BEGIN(__do_get_xsec) | |
63 | .cfi_startproc | |
64 | /* check for update count & load values */ | |
65 | 1: ld r7,CFG_TB_UPDATE_COUNT(r3) | |
66 | andi. r0,r4,1 /* pending update ? loop */ | |
67 | bne- 1b | |
68 | xor r0,r4,r4 /* create dependency */ | |
69 | add r3,r3,r0 | |
70 | ||
71 | /* Get TB & offset it */ | |
72 | mftb r8 | |
73 | ld r9,CFG_TB_ORIG_STAMP(r3) | |
74 | subf r8,r9,r8 | |
75 | ||
76 | /* Scale result */ | |
77 | ld r5,CFG_TB_TO_XS(r3) | |
78 | mulhdu r8,r8,r5 | |
79 | ||
80 | /* Add stamp since epoch */ | |
81 | ld r6,CFG_STAMP_XSEC(r3) | |
82 | add r4,r6,r8 | |
83 | ||
84 | xor r0,r4,r4 | |
85 | add r3,r3,r0 | |
86 | ld r0,CFG_TB_UPDATE_COUNT(r3) | |
87 | cmpld cr0,r0,r7 /* check if updated */ | |
88 | bne- 1b | |
89 | blr | |
90 | .cfi_endproc | |
91 | V_FUNCTION_END(__do_get_xsec) |