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processor.h
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1 /*
2  * Process/processor support for the Hexagon architecture
3  *
4  * Copyright (c) 2010-2011, 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 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
38 extern unsigned long thread_saved_pc(struct task_struct *tsk);
39 
40 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
41 
42 /*
43  * thread_struct is supposed to be for context switch data.
44  * Specifically, to hold the state necessary to perform switch_to...
45  */
46 struct thread_struct {
47  void *switch_sp;
48 };
49 
50 /*
51  * initializes thread_struct
52  * The only thing we have in there is switch_sp
53  * which doesn't really need to be initialized.
54  */
55 
56 #define INIT_THREAD { \
57 }
58 
59 #define cpu_relax() __vmyield()
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 
104  unsigned long long r1716;
105  unsigned long long r1918;
106  unsigned long long r2120;
107  unsigned long long r2322;
108  unsigned long long r2524;
109  unsigned long long r2726;
110  unsigned long fp;
111  unsigned long lr;
112 };
113 
114 #endif /* !__ASSEMBLY__ */
115 
116 #endif