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 /*  task_struct, defined elsewhere, is the "process descriptor" */
31 struct task_struct;
32 
33 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
34 
35 /*
36  * thread_struct is supposed to be for context switch data.
37  * Specifically, to hold the state necessary to perform switch_to...
38  */
39 struct thread_struct {
40 	void *switch_sp;
41 };
42 
43 /*
44  * initializes thread_struct
45  * The only thing we have in there is switch_sp
46  * which doesn't really need to be initialized.
47  */
48 
49 #define INIT_THREAD { \
50 }
51 
52 #define cpu_relax() __vmyield()
53 
54 /*
55  * Decides where the kernel will search for a free chunk of vm space during
56  * mmaps.
57  * See also arch_get_unmapped_area.
58  * Doesn't affect if you have MAX_FIXED in the page flags set though...
59  *
60  * Apparently the convention is that ld.so will ask for "unmapped" private
61  * memory to be allocated SOMEWHERE, but it also asks for memory explicitly
62  * via MAP_FIXED at the lower * addresses starting at VA=0x0.
63  *
64  * If the two requests collide, you get authentic segfaulting action, so
65  * you have to kick the "unmapped" base requests higher up.
66  */
67 #define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE/3))
68 
69 
70 #define task_pt_regs(task) \
71 	((struct pt_regs *)(task_stack_page(task) + THREAD_SIZE) - 1)
72 
73 #define KSTK_EIP(tsk) (pt_elr(task_pt_regs(tsk)))
74 #define KSTK_ESP(tsk) (pt_psp(task_pt_regs(tsk)))
75 
76 /*  Free all resources held by a thread; defined in process.c  */
77 extern void release_thread(struct task_struct *dead_task);
78 
79 /* Get wait channel for task P.  */
80 extern unsigned long get_wchan(struct task_struct *p);
81 
82 /*  The following stuff is pretty HEXAGON specific.  */
83 
84 /*  This is really just here for __switch_to.
85     Offsets are pulled via asm-offsets.c  */
86 
87 /*
88  * No real reason why VM and native switch stacks should be different.
89  * Ultimately this should merge.  Note that Rev C. ABI called out only
90  * R24-27 as callee saved GPRs needing explicit attention (R29-31 being
91  * dealt with automagically by allocframe), but the current ABI has
92  * more, R16-R27.  By saving more, the worst case is that we waste some
93  * cycles if building with the old compilers.
94  */
95 
96 struct hexagon_switch_stack {
97 	union {
98 		struct {
99 			unsigned long r16;
100 			unsigned long r17;
101 		};
102 		unsigned long long	r1716;
103 	};
104 	union {
105 		struct {
106 			unsigned long r18;
107 			unsigned long r19;
108 		};
109 		unsigned long long	r1918;
110 	};
111 	union {
112 		struct {
113 			unsigned long r20;
114 			unsigned long r21;
115 		};
116 		unsigned long long	r2120;
117 	};
118 	union {
119 		struct {
120 			unsigned long r22;
121 			unsigned long r23;
122 		};
123 		unsigned long long	r2322;
124 	};
125 	union {
126 		struct {
127 			unsigned long r24;
128 			unsigned long r25;
129 		};
130 		unsigned long long	r2524;
131 	};
132 	union {
133 		struct {
134 			unsigned long r26;
135 			unsigned long r27;
136 		};
137 		unsigned long long	r2726;
138 	};
139 
140 	unsigned long		fp;
141 	unsigned long		lr;
142 };
143 
144 #endif /* !__ASSEMBLY__ */
145 
146 #endif
147