xref: /linux/arch/hexagon/include/asm/processor.h (revision 44f57d78) 
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Process/processor support for the Hexagon architecture
4  *
5  * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
6  */
7 
8 #ifndef _ASM_PROCESSOR_H
9 #define _ASM_PROCESSOR_H
10 
11 #ifndef __ASSEMBLY__
12 
13 #include <asm/mem-layout.h>
14 #include <asm/registers.h>
15 #include <asm/hexagon_vm.h>
16 
17 /*  task_struct, defined elsewhere, is the "process descriptor" */
18 struct task_struct;
19 
20 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
21 
22 /*
23  * thread_struct is supposed to be for context switch data.
24  * Specifically, to hold the state necessary to perform switch_to...
25  */
26 struct thread_struct {
27 	void *switch_sp;
28 };
29 
30 /*
31  * initializes thread_struct
32  * The only thing we have in there is switch_sp
33  * which doesn't really need to be initialized.
34  */
35 
36 #define INIT_THREAD { \
37 }
38 
39 #define cpu_relax() __vmyield()
40 
41 /*
42  * Decides where the kernel will search for a free chunk of vm space during
43  * mmaps.
44  * See also arch_get_unmapped_area.
45  * Doesn't affect if you have MAX_FIXED in the page flags set though...
46  *
47  * Apparently the convention is that ld.so will ask for "unmapped" private
48  * memory to be allocated SOMEWHERE, but it also asks for memory explicitly
49  * via MAP_FIXED at the lower * addresses starting at VA=0x0.
50  *
51  * If the two requests collide, you get authentic segfaulting action, so
52  * you have to kick the "unmapped" base requests higher up.
53  */
54 #define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE/3))
55 
56 
57 #define task_pt_regs(task) \
58 	((struct pt_regs *)(task_stack_page(task) + THREAD_SIZE) - 1)
59 
60 #define KSTK_EIP(tsk) (pt_elr(task_pt_regs(tsk)))
61 #define KSTK_ESP(tsk) (pt_psp(task_pt_regs(tsk)))
62 
63 /*  Free all resources held by a thread; defined in process.c  */
64 extern void release_thread(struct task_struct *dead_task);
65 
66 /* Get wait channel for task P.  */
67 extern unsigned long get_wchan(struct task_struct *p);
68 
69 /*  The following stuff is pretty HEXAGON specific.  */
70 
71 /*  This is really just here for __switch_to.
72     Offsets are pulled via asm-offsets.c  */
73 
74 /*
75  * No real reason why VM and native switch stacks should be different.
76  * Ultimately this should merge.  Note that Rev C. ABI called out only
77  * R24-27 as callee saved GPRs needing explicit attention (R29-31 being
78  * dealt with automagically by allocframe), but the current ABI has
79  * more, R16-R27.  By saving more, the worst case is that we waste some
80  * cycles if building with the old compilers.
81  */
82 
83 struct hexagon_switch_stack {
84 	union {
85 		struct {
86 			unsigned long r16;
87 			unsigned long r17;
88 		};
89 		unsigned long long	r1716;
90 	};
91 	union {
92 		struct {
93 			unsigned long r18;
94 			unsigned long r19;
95 		};
96 		unsigned long long	r1918;
97 	};
98 	union {
99 		struct {
100 			unsigned long r20;
101 			unsigned long r21;
102 		};
103 		unsigned long long	r2120;
104 	};
105 	union {
106 		struct {
107 			unsigned long r22;
108 			unsigned long r23;
109 		};
110 		unsigned long long	r2322;
111 	};
112 	union {
113 		struct {
114 			unsigned long r24;
115 			unsigned long r25;
116 		};
117 		unsigned long long	r2524;
118 	};
119 	union {
120 		struct {
121 			unsigned long r26;
122 			unsigned long r27;
123 		};
124 		unsigned long long	r2726;
125 	};
126 
127 	unsigned long		fp;
128 	unsigned long		lr;
129 };
130 
131 #endif /* !__ASSEMBLY__ */
132 
133 #endif
134