1 /*
2  * Process/processor support for the Hexagon architecture
3  *
4  * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 and
8  * only version 2 as published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18  * 02110-1301, USA.
19  */
20 
21 #ifndef _ASM_PROCESSOR_H
22 #define _ASM_PROCESSOR_H
23 
24 #ifndef __ASSEMBLY__
25 
26 #include <asm/mem-layout.h>
27 #include <asm/registers.h>
28 #include <asm/hexagon_vm.h>
29 
30 /*  must be a macro  */
31 #define current_text_addr() ({ __label__ _l; _l: &&_l; })
32 
33 /*  task_struct, defined elsewhere, is the "process descriptor" */
34 struct task_struct;
35 
36 /*  this is defined in arch/process.c  */
37 extern unsigned long thread_saved_pc(struct task_struct *tsk);
38 
39 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
40 
41 /*
42  * thread_struct is supposed to be for context switch data.
43  * Specifically, to hold the state necessary to perform switch_to...
44  */
45 struct thread_struct {
46 	void *switch_sp;
47 };
48 
49 /*
50  * initializes thread_struct
51  * The only thing we have in there is switch_sp
52  * which doesn't really need to be initialized.
53  */
54 
55 #define INIT_THREAD { \
56 }
57 
58 #define cpu_relax() __vmyield()
59 #define cpu_relax_lowlatency() cpu_relax()
60 
61 /*
62  * Decides where the kernel will search for a free chunk of vm space during
63  * mmaps.
64  * See also arch_get_unmapped_area.
65  * Doesn't affect if you have MAX_FIXED in the page flags set though...
66  *
67  * Apparently the convention is that ld.so will ask for "unmapped" private
68  * memory to be allocated SOMEWHERE, but it also asks for memory explicitly
69  * via MAP_FIXED at the lower * addresses starting at VA=0x0.
70  *
71  * If the two requests collide, you get authentic segfaulting action, so
72  * you have to kick the "unmapped" base requests higher up.
73  */
74 #define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE/3))
75 
76 
77 #define task_pt_regs(task) \
78 	((struct pt_regs *)(task_stack_page(task) + THREAD_SIZE) - 1)
79 
80 #define KSTK_EIP(tsk) (pt_elr(task_pt_regs(tsk)))
81 #define KSTK_ESP(tsk) (pt_psp(task_pt_regs(tsk)))
82 
83 /*  Free all resources held by a thread; defined in process.c  */
84 extern void release_thread(struct task_struct *dead_task);
85 
86 /* Get wait channel for task P.  */
87 extern unsigned long get_wchan(struct task_struct *p);
88 
89 /*  The following stuff is pretty HEXAGON specific.  */
90 
91 /*  This is really just here for __switch_to.
92     Offsets are pulled via asm-offsets.c  */
93 
94 /*
95  * No real reason why VM and native switch stacks should be different.
96  * Ultimately this should merge.  Note that Rev C. ABI called out only
97  * R24-27 as callee saved GPRs needing explicit attention (R29-31 being
98  * dealt with automagically by allocframe), but the current ABI has
99  * more, R16-R27.  By saving more, the worst case is that we waste some
100  * cycles if building with the old compilers.
101  */
102 
103 struct hexagon_switch_stack {
104 	union {
105 		struct {
106 			unsigned long r16;
107 			unsigned long r17;
108 		};
109 		unsigned long long	r1716;
110 	};
111 	union {
112 		struct {
113 			unsigned long r18;
114 			unsigned long r19;
115 		};
116 		unsigned long long	r1918;
117 	};
118 	union {
119 		struct {
120 			unsigned long r20;
121 			unsigned long r21;
122 		};
123 		unsigned long long	r2120;
124 	};
125 	union {
126 		struct {
127 			unsigned long r22;
128 			unsigned long r23;
129 		};
130 		unsigned long long	r2322;
131 	};
132 	union {
133 		struct {
134 			unsigned long r24;
135 			unsigned long r25;
136 		};
137 		unsigned long long	r2524;
138 	};
139 	union {
140 		struct {
141 			unsigned long r26;
142 			unsigned long r27;
143 		};
144 		unsigned long long	r2726;
145 	};
146 
147 	unsigned long		fp;
148 	unsigned long		lr;
149 };
150 
151 #endif /* !__ASSEMBLY__ */
152 
153 #endif
154