1/*
2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Amit Bhor, Kanika Nema: Codito Technologies 2004
9 */
10
11#include <linux/errno.h>
12#include <linux/module.h>
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/fs.h>
16#include <linux/unistd.h>
17#include <linux/ptrace.h>
18#include <linux/slab.h>
19#include <linux/syscalls.h>
20#include <linux/elf.h>
21#include <linux/tick.h>
22
23SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
24{
25	task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
26	return 0;
27}
28
29/*
30 * We return the user space TLS data ptr as sys-call return code
31 * Ideally it should be copy to user.
32 * However we can cheat by the fact that some sys-calls do return
33 * absurdly high values
34 * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx
35 * it won't be considered a sys-call error
36 * and it will be loads better than copy-to-user, which is a definite
37 * D-TLB Miss
38 */
39SYSCALL_DEFINE0(arc_gettls)
40{
41	return task_thread_info(current)->thr_ptr;
42}
43
44void arch_cpu_idle(void)
45{
46	/* sleep, but enable all interrupts before committing */
47	__asm__ __volatile__(
48		"sleep %0	\n"
49		:
50		:"I"(ISA_SLEEP_ARG)); /* can't be "r" has to be embedded const */
51}
52
53asmlinkage void ret_from_fork(void);
54
55/*
56 * Copy architecture-specific thread state
57 *
58 * Layout of Child kernel mode stack as setup at the end of this function is
59 *
60 * |     ...        |
61 * |     ...        |
62 * |    unused      |
63 * |                |
64 * ------------------
65 * |     r25        |   <==== top of Stack (thread.ksp)
66 * ~                ~
67 * |    --to--      |   (CALLEE Regs of kernel mode)
68 * |     r13        |
69 * ------------------
70 * |     fp         |
71 * |    blink       |   @ret_from_fork
72 * ------------------
73 * |                |
74 * ~                ~
75 * ~                ~
76 * |                |
77 * ------------------
78 * |     r12        |
79 * ~                ~
80 * |    --to--      |   (scratch Regs of user mode)
81 * |     r0         |
82 * ------------------
83 * |      SP        |
84 * |    orig_r0     |
85 * |    event/ECR   |
86 * |    user_r25    |
87 * ------------------  <===== END of PAGE
88 */
89int copy_thread(unsigned long clone_flags,
90		unsigned long usp, unsigned long kthread_arg,
91		struct task_struct *p)
92{
93	struct pt_regs *c_regs;        /* child's pt_regs */
94	unsigned long *childksp;       /* to unwind out of __switch_to() */
95	struct callee_regs *c_callee;  /* child's callee regs */
96	struct callee_regs *parent_callee;  /* paren't callee */
97	struct pt_regs *regs = current_pt_regs();
98
99	/* Mark the specific anchors to begin with (see pic above) */
100	c_regs = task_pt_regs(p);
101	childksp = (unsigned long *)c_regs - 2;  /* 2 words for FP/BLINK */
102	c_callee = ((struct callee_regs *)childksp) - 1;
103
104	/*
105	 * __switch_to() uses thread.ksp to start unwinding stack
106	 * For kernel threads we don't need to create callee regs, the
107	 * stack layout nevertheless needs to remain the same.
108	 * Also, since __switch_to anyways unwinds callee regs, we use
109	 * this to populate kernel thread entry-pt/args into callee regs,
110	 * so that ret_from_kernel_thread() becomes simpler.
111	 */
112	p->thread.ksp = (unsigned long)c_callee;	/* THREAD_KSP */
113
114	/* __switch_to expects FP(0), BLINK(return addr) at top */
115	childksp[0] = 0;			/* fp */
116	childksp[1] = (unsigned long)ret_from_fork; /* blink */
117
118	if (unlikely(p->flags & PF_KTHREAD)) {
119		memset(c_regs, 0, sizeof(struct pt_regs));
120
121		c_callee->r13 = kthread_arg;
122		c_callee->r14 = usp;  /* function */
123
124		return 0;
125	}
126
127	/*--------- User Task Only --------------*/
128
129	/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
130	childksp[0] = 0;				/* for POP fp */
131	childksp[1] = (unsigned long)ret_from_fork;	/* for POP blink */
132
133	/* Copy parents pt regs on child's kernel mode stack */
134	*c_regs = *regs;
135
136	if (usp)
137		c_regs->sp = usp;
138
139	c_regs->r0 = 0;		/* fork returns 0 in child */
140
141	parent_callee = ((struct callee_regs *)regs) - 1;
142	*c_callee = *parent_callee;
143
144	if (unlikely(clone_flags & CLONE_SETTLS)) {
145		/*
146		 * set task's userland tls data ptr from 4th arg
147		 * clone C-lib call is difft from clone sys-call
148		 */
149		task_thread_info(p)->thr_ptr = regs->r3;
150	} else {
151		/* Normal fork case: set parent's TLS ptr in child */
152		task_thread_info(p)->thr_ptr =
153		task_thread_info(current)->thr_ptr;
154	}
155
156	return 0;
157}
158
159/*
160 * Do necessary setup to start up a new user task
161 */
162void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
163{
164	regs->sp = usp;
165	regs->ret = pc;
166
167	/*
168	 * [U]ser Mode bit set
169	 * [L] ZOL loop inhibited to begin with - cleared by a LP insn
170	 * Interrupts enabled
171	 */
172	regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
173
174	/* bogus seed values for debugging */
175	regs->lp_start = 0x10;
176	regs->lp_end = 0x80;
177}
178
179/*
180 * Some archs flush debug and FPU info here
181 */
182void flush_thread(void)
183{
184}
185
186/*
187 * Free any architecture-specific thread data structures, etc.
188 */
189void exit_thread(void)
190{
191}
192
193int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
194{
195	return 0;
196}
197
198int elf_check_arch(const struct elf32_hdr *x)
199{
200	unsigned int eflags;
201
202	if (x->e_machine != EM_ARC_INUSE) {
203		pr_err("ELF not built for %s ISA\n",
204			is_isa_arcompact() ? "ARCompact":"ARCv2");
205		return 0;
206	}
207
208	eflags = x->e_flags;
209	if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) {
210		pr_err("ABI mismatch - you need newer toolchain\n");
211		force_sigsegv(SIGSEGV, current);
212		return 0;
213	}
214
215	return 1;
216}
217EXPORT_SYMBOL(elf_check_arch);
218