1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (C) 2012 Regents of the University of California
4  */
5 
6 #ifndef _ASM_RISCV_PROCESSOR_H
7 #define _ASM_RISCV_PROCESSOR_H
8 
9 #include <linux/const.h>
10 
11 #include <asm/ptrace.h>
12 
13 /*
14  * This decides where the kernel will search for a free chunk of vm
15  * space during mmap's.
16  */
17 #define TASK_UNMAPPED_BASE	PAGE_ALIGN(TASK_SIZE / 3)
18 
19 #define STACK_TOP		TASK_SIZE
20 #define STACK_TOP_MAX		STACK_TOP
21 #define STACK_ALIGN		16
22 
23 #ifndef __ASSEMBLY__
24 
25 struct task_struct;
26 struct pt_regs;
27 
28 /* CPU-specific state of a task */
29 struct thread_struct {
30 	/* Callee-saved registers */
31 	unsigned long ra;
32 	unsigned long sp;	/* Kernel mode stack */
33 	unsigned long s[12];	/* s[0]: frame pointer */
34 	struct __riscv_d_ext_state fstate;
35 };
36 
37 #define INIT_THREAD {					\
38 	.sp = sizeof(init_stack) + (long)&init_stack,	\
39 }
40 
41 #define task_pt_regs(tsk)						\
42 	((struct pt_regs *)(task_stack_page(tsk) + THREAD_SIZE		\
43 			    - ALIGN(sizeof(struct pt_regs), STACK_ALIGN)))
44 
45 #define KSTK_EIP(tsk)		(task_pt_regs(tsk)->sepc)
46 #define KSTK_ESP(tsk)		(task_pt_regs(tsk)->sp)
47 
48 
49 /* Do necessary setup to start up a newly executed thread. */
50 extern void start_thread(struct pt_regs *regs,
51 			unsigned long pc, unsigned long sp);
52 
53 /* Free all resources held by a thread. */
release_thread(struct task_struct * dead_task)54 static inline void release_thread(struct task_struct *dead_task)
55 {
56 }
57 
58 extern unsigned long get_wchan(struct task_struct *p);
59 
60 
cpu_relax(void)61 static inline void cpu_relax(void)
62 {
63 #ifdef __riscv_muldiv
64 	int dummy;
65 	/* In lieu of a halt instruction, induce a long-latency stall. */
66 	__asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy));
67 #endif
68 	barrier();
69 }
70 
wait_for_interrupt(void)71 static inline void wait_for_interrupt(void)
72 {
73 	__asm__ __volatile__ ("wfi");
74 }
75 
76 struct device_node;
77 int riscv_of_processor_hartid(struct device_node *node);
78 
79 extern void riscv_fill_hwcap(void);
80 
81 #endif /* __ASSEMBLY__ */
82 
83 #endif /* _ASM_RISCV_PROCESSOR_H */
84