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
63/*  Free all resources held by a thread; defined in process.c  */
64extern void release_thread(struct task_struct *dead_task);
65
66/* Get wait channel for task P.  */
67extern 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
83struct 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