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__("sleep 0x3");
48}
49
50asmlinkage void ret_from_fork(void);
51
52/*
53 * Copy architecture-specific thread state
54 *
55 * Layout of Child kernel mode stack as setup at the end of this function is
56 *
57 * |     ...        |
58 * |     ...        |
59 * |    unused      |
60 * |                |
61 * ------------------
62 * |     r25        |   <==== top of Stack (thread.ksp)
63 * ~                ~
64 * |    --to--      |   (CALLEE Regs of user mode)
65 * |     r13        |
66 * ------------------
67 * |     fp         |
68 * |    blink       |   @ret_from_fork
69 * ------------------
70 * |                |
71 * ~                ~
72 * ~                ~
73 * |                |
74 * ------------------
75 * |     r12        |
76 * ~                ~
77 * |    --to--      |   (scratch Regs of user mode)
78 * |     r0         |
79 * ------------------
80 * |      SP        |
81 * |    orig_r0     |
82 * |    event/ECR   |
83 * |    user_r25    |
84 * ------------------  <===== END of PAGE
85 */
86int copy_thread(unsigned long clone_flags,
87		unsigned long usp, unsigned long kthread_arg,
88		struct task_struct *p)
89{
90	struct pt_regs *c_regs;        /* child's pt_regs */
91	unsigned long *childksp;       /* to unwind out of __switch_to() */
92	struct callee_regs *c_callee;  /* child's callee regs */
93	struct callee_regs *parent_callee;  /* paren't callee */
94	struct pt_regs *regs = current_pt_regs();
95
96	/* Mark the specific anchors to begin with (see pic above) */
97	c_regs = task_pt_regs(p);
98	childksp = (unsigned long *)c_regs - 2;  /* 2 words for FP/BLINK */
99	c_callee = ((struct callee_regs *)childksp) - 1;
100
101	/*
102	 * __switch_to() uses thread.ksp to start unwinding stack
103	 * For kernel threads we don't need to create callee regs, the
104	 * stack layout nevertheless needs to remain the same.
105	 * Also, since __switch_to anyways unwinds callee regs, we use
106	 * this to populate kernel thread entry-pt/args into callee regs,
107	 * so that ret_from_kernel_thread() becomes simpler.
108	 */
109	p->thread.ksp = (unsigned long)c_callee;	/* THREAD_KSP */
110
111	/* __switch_to expects FP(0), BLINK(return addr) at top */
112	childksp[0] = 0;			/* fp */
113	childksp[1] = (unsigned long)ret_from_fork; /* blink */
114
115	if (unlikely(p->flags & PF_KTHREAD)) {
116		memset(c_regs, 0, sizeof(struct pt_regs));
117
118		c_callee->r13 = kthread_arg;
119		c_callee->r14 = usp;  /* function */
120
121		return 0;
122	}
123
124	/*--------- User Task Only --------------*/
125
126	/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
127	childksp[0] = 0;				/* for POP fp */
128	childksp[1] = (unsigned long)ret_from_fork;	/* for POP blink */
129
130	/* Copy parents pt regs on child's kernel mode stack */
131	*c_regs = *regs;
132
133	if (usp)
134		c_regs->sp = usp;
135
136	c_regs->r0 = 0;		/* fork returns 0 in child */
137
138	parent_callee = ((struct callee_regs *)regs) - 1;
139	*c_callee = *parent_callee;
140
141	if (unlikely(clone_flags & CLONE_SETTLS)) {
142		/*
143		 * set task's userland tls data ptr from 4th arg
144		 * clone C-lib call is difft from clone sys-call
145		 */
146		task_thread_info(p)->thr_ptr = regs->r3;
147	} else {
148		/* Normal fork case: set parent's TLS ptr in child */
149		task_thread_info(p)->thr_ptr =
150		task_thread_info(current)->thr_ptr;
151	}
152
153	return 0;
154}
155
156/*
157 * Do necessary setup to start up a new user task
158 */
159void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
160{
161	regs->sp = usp;
162	regs->ret = pc;
163
164	/*
165	 * [U]ser Mode bit set
166	 * [L] ZOL loop inhibited to begin with - cleared by a LP insn
167	 * Interrupts enabled
168	 */
169	regs->status32 = STATUS_U_MASK | STATUS_L_MASK |
170			 STATUS_E1_MASK | STATUS_E2_MASK;
171
172	/* bogus seed values for debugging */
173	regs->lp_start = 0x10;
174	regs->lp_end = 0x80;
175}
176
177/*
178 * Some archs flush debug and FPU info here
179 */
180void flush_thread(void)
181{
182}
183
184/*
185 * Free any architecture-specific thread data structures, etc.
186 */
187void exit_thread(void)
188{
189}
190
191int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
192{
193	return 0;
194}
195
196int elf_check_arch(const struct elf32_hdr *x)
197{
198	unsigned int eflags;
199
200	if (x->e_machine != EM_ARCOMPACT)
201		return 0;
202
203	eflags = x->e_flags;
204	if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) {
205		pr_err("ABI mismatch - you need newer toolchain\n");
206		force_sigsegv(SIGSEGV, current);
207		return 0;
208	}
209
210	return 1;
211}
212EXPORT_SYMBOL(elf_check_arch);
213