1/*
2 * i386 semaphore implementation.
3 *
4 * (C) Copyright 1999 Linus Torvalds
5 *
6 * Portions Copyright 1999 Red Hat, Inc.
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 * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
14 */
15
16#include <linux/linkage.h>
17#include <asm/rwlock.h>
18#include <asm/alternative-asm.i>
19#include <asm/frame.i>
20#include <asm/dwarf2.h>
21
22/*
23 * The semaphore operations have a special calling sequence that
24 * allow us to do a simpler in-line version of them. These routines
25 * need to convert that sequence back into the C sequence when
26 * there is contention on the semaphore.
27 *
28 * %eax contains the semaphore pointer on entry. Save the C-clobbered
29 * registers (%eax, %edx and %ecx) except %eax whish is either a return
30 * value or just clobbered..
31 */
32	.section .sched.text
33ENTRY(__down_failed)
34	CFI_STARTPROC
35	FRAME
36	pushl %edx
37	CFI_ADJUST_CFA_OFFSET 4
38	CFI_REL_OFFSET edx,0
39	pushl %ecx
40	CFI_ADJUST_CFA_OFFSET 4
41	CFI_REL_OFFSET ecx,0
42	call __down
43	popl %ecx
44	CFI_ADJUST_CFA_OFFSET -4
45	CFI_RESTORE ecx
46	popl %edx
47	CFI_ADJUST_CFA_OFFSET -4
48	CFI_RESTORE edx
49	ENDFRAME
50	ret
51	CFI_ENDPROC
52	END(__down_failed)
53
54ENTRY(__down_failed_interruptible)
55	CFI_STARTPROC
56	FRAME
57	pushl %edx
58	CFI_ADJUST_CFA_OFFSET 4
59	CFI_REL_OFFSET edx,0
60	pushl %ecx
61	CFI_ADJUST_CFA_OFFSET 4
62	CFI_REL_OFFSET ecx,0
63	call __down_interruptible
64	popl %ecx
65	CFI_ADJUST_CFA_OFFSET -4
66	CFI_RESTORE ecx
67	popl %edx
68	CFI_ADJUST_CFA_OFFSET -4
69	CFI_RESTORE edx
70	ENDFRAME
71	ret
72	CFI_ENDPROC
73	END(__down_failed_interruptible)
74
75ENTRY(__down_failed_trylock)
76	CFI_STARTPROC
77	FRAME
78	pushl %edx
79	CFI_ADJUST_CFA_OFFSET 4
80	CFI_REL_OFFSET edx,0
81	pushl %ecx
82	CFI_ADJUST_CFA_OFFSET 4
83	CFI_REL_OFFSET ecx,0
84	call __down_trylock
85	popl %ecx
86	CFI_ADJUST_CFA_OFFSET -4
87	CFI_RESTORE ecx
88	popl %edx
89	CFI_ADJUST_CFA_OFFSET -4
90	CFI_RESTORE edx
91	ENDFRAME
92	ret
93	CFI_ENDPROC
94	END(__down_failed_trylock)
95
96ENTRY(__up_wakeup)
97	CFI_STARTPROC
98	FRAME
99	pushl %edx
100	CFI_ADJUST_CFA_OFFSET 4
101	CFI_REL_OFFSET edx,0
102	pushl %ecx
103	CFI_ADJUST_CFA_OFFSET 4
104	CFI_REL_OFFSET ecx,0
105	call __up
106	popl %ecx
107	CFI_ADJUST_CFA_OFFSET -4
108	CFI_RESTORE ecx
109	popl %edx
110	CFI_ADJUST_CFA_OFFSET -4
111	CFI_RESTORE edx
112	ENDFRAME
113	ret
114	CFI_ENDPROC
115	END(__up_wakeup)
116
117/*
118 * rw spinlock fallbacks
119 */
120#ifdef CONFIG_SMP
121ENTRY(__write_lock_failed)
122	CFI_STARTPROC simple
123	FRAME
1242: 	LOCK_PREFIX
125	addl	$ RW_LOCK_BIAS,(%eax)
1261:	rep; nop
127	cmpl	$ RW_LOCK_BIAS,(%eax)
128	jne	1b
129	LOCK_PREFIX
130	subl	$ RW_LOCK_BIAS,(%eax)
131	jnz	2b
132	ENDFRAME
133	ret
134	CFI_ENDPROC
135	END(__write_lock_failed)
136
137ENTRY(__read_lock_failed)
138	CFI_STARTPROC
139	FRAME
1402: 	LOCK_PREFIX
141	incl	(%eax)
1421:	rep; nop
143	cmpl	$1,(%eax)
144	js	1b
145	LOCK_PREFIX
146	decl	(%eax)
147	js	2b
148	ENDFRAME
149	ret
150	CFI_ENDPROC
151	END(__read_lock_failed)
152
153#endif
154
155#ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM
156
157/* Fix up special calling conventions */
158ENTRY(call_rwsem_down_read_failed)
159	CFI_STARTPROC
160	push %ecx
161	CFI_ADJUST_CFA_OFFSET 4
162	CFI_REL_OFFSET ecx,0
163	push %edx
164	CFI_ADJUST_CFA_OFFSET 4
165	CFI_REL_OFFSET edx,0
166	call rwsem_down_read_failed
167	pop %edx
168	CFI_ADJUST_CFA_OFFSET -4
169	pop %ecx
170	CFI_ADJUST_CFA_OFFSET -4
171	ret
172	CFI_ENDPROC
173	END(call_rwsem_down_read_failed)
174
175ENTRY(call_rwsem_down_write_failed)
176	CFI_STARTPROC
177	push %ecx
178	CFI_ADJUST_CFA_OFFSET 4
179	CFI_REL_OFFSET ecx,0
180	calll rwsem_down_write_failed
181	pop %ecx
182	CFI_ADJUST_CFA_OFFSET -4
183	ret
184	CFI_ENDPROC
185	END(call_rwsem_down_write_failed)
186
187ENTRY(call_rwsem_wake)
188	CFI_STARTPROC
189	decw %dx    /* do nothing if still outstanding active readers */
190	jnz 1f
191	push %ecx
192	CFI_ADJUST_CFA_OFFSET 4
193	CFI_REL_OFFSET ecx,0
194	call rwsem_wake
195	pop %ecx
196	CFI_ADJUST_CFA_OFFSET -4
1971:	ret
198	CFI_ENDPROC
199	END(call_rwsem_wake)
200
201/* Fix up special calling conventions */
202ENTRY(call_rwsem_downgrade_wake)
203	CFI_STARTPROC
204	push %ecx
205	CFI_ADJUST_CFA_OFFSET 4
206	CFI_REL_OFFSET ecx,0
207	push %edx
208	CFI_ADJUST_CFA_OFFSET 4
209	CFI_REL_OFFSET edx,0
210	call rwsem_downgrade_wake
211	pop %edx
212	CFI_ADJUST_CFA_OFFSET -4
213	pop %ecx
214	CFI_ADJUST_CFA_OFFSET -4
215	ret
216	CFI_ENDPROC
217	END(call_rwsem_downgrade_wake)
218
219#endif
220