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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" */
18struct task_struct;
19
20extern 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 */
26struct 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
63extern unsigned long __get_wchan(struct task_struct *p);
64
65/* The following stuff is pretty HEXAGON specific. */
66
67/* This is really just here for __switch_to.
68 Offsets are pulled via asm-offsets.c */
69
70/*
71 * No real reason why VM and native switch stacks should be different.
72 * Ultimately this should merge. Note that Rev C. ABI called out only
73 * R24-27 as callee saved GPRs needing explicit attention (R29-31 being
74 * dealt with automagically by allocframe), but the current ABI has
75 * more, R16-R27. By saving more, the worst case is that we waste some
76 * cycles if building with the old compilers.
77 */
78
79struct hexagon_switch_stack {
80 union {
81 struct {
82 unsigned long r16;
83 unsigned long r17;
84 };
85 unsigned long long r1716;
86 };
87 union {
88 struct {
89 unsigned long r18;
90 unsigned long r19;
91 };
92 unsigned long long r1918;
93 };
94 union {
95 struct {
96 unsigned long r20;
97 unsigned long r21;
98 };
99 unsigned long long r2120;
100 };
101 union {
102 struct {
103 unsigned long r22;
104 unsigned long r23;
105 };
106 unsigned long long r2322;
107 };
108 union {
109 struct {
110 unsigned long r24;
111 unsigned long r25;
112 };
113 unsigned long long r2524;
114 };
115 union {
116 struct {
117 unsigned long r26;
118 unsigned long r27;
119 };
120 unsigned long long r2726;
121 };
122
123 unsigned long fp;
124 unsigned long lr;
125};
126
127#endif /* !__ASSEMBLY__ */
128
129#endif