/arch/ppc64/kernel/vdso64/datapage.S

 1/*
 2 * Access to the shared data page by the vDSO & syscall map
 3 *
 4 * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
 5 *
 6 * This program is free software; you can redistribute it and/or
 7 * modify it under the terms of the GNU General Public License
 8 * as published by the Free Software Foundation; either version
 9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/config.h>
13#include <asm/processor.h>
14#include <asm/ppc_asm.h>
15#include <asm/offsets.h>
16#include <asm/unistd.h>
17#include <asm/vdso.h>
18
19	.text
20V_FUNCTION_BEGIN(__get_datapage)
21  .cfi_startproc
22	/* We don't want that exposed or overridable as we want other objects
23	 * to be able to bl directly to here
24	 */
25	.protected __get_datapage
26	.hidden __get_datapage
27
28	mflr	r0
29  .cfi_register lr,r0
30
31	bcl	20,31,1f
32	.global	__kernel_datapage_offset;
33__kernel_datapage_offset:
34	.long	0
351:
36	mflr	r3
37	mtlr	r0
38	lwz	r0,0(r3)
39	add	r3,r0,r3
40	blr
41  .cfi_endproc
42V_FUNCTION_END(__get_datapage)
43
44/*
45 * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
46 *
47 * returns a pointer to the syscall map. the map is agnostic to the
48 * size of "long", unlike kernel bitops, it stores bits from top to
49 * bottom so that memory actually contains a linear bitmap
50 * check for syscall N by testing bit (0x80000000 >> (N & 0x1f)) of
51 * 32 bits int at N >> 5.
52 */
53V_FUNCTION_BEGIN(__kernel_get_syscall_map)
54  .cfi_startproc
55	mflr	r12
56  .cfi_register lr,r12
57
58	mr	r4,r3
59	bl	V_LOCAL_FUNC(__get_datapage)
60	mtlr	r12
61	addi	r3,r3,CFG_SYSCALL_MAP64
62	cmpli	cr0,r4,0
63	beqlr
64	li	r0,__NR_syscalls
65	stw	r0,0(r4)
66	blr
67  .cfi_endproc
68V_FUNCTION_END(__kernel_get_syscall_map)