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
 44SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new)
 45{
 46	struct pt_regs *regs = current_pt_regs();
 47	int uval = -EFAULT;
 48
 49	/*
 50	 * This is only for old cores lacking LLOCK/SCOND, which by defintion
 51	 * can't possibly be SMP. Thus doesn't need to be SMP safe.
 52	 * And this also helps reduce the overhead for serializing in
 53	 * the UP case
 54	 */
 55	WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP));
 56
 57	/* Z indicates to userspace if operation succeded */
 58	regs->status32 &= ~STATUS_Z_MASK;
 59
 60	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 61		return -EFAULT;
 62
 63	preempt_disable();
 64
 65	if (__get_user(uval, uaddr))
 66		goto done;
 67
 68	if (uval == expected) {
 69		if (!__put_user(new, uaddr))
 70			regs->status32 |= STATUS_Z_MASK;
 71	}
 72
 73done:
 74	preempt_enable();
 75
 76	return uval;
 77}
 78
 79void arch_cpu_idle(void)
 80{
 81	/* sleep, but enable all interrupts before committing */
 82	__asm__ __volatile__(
 83		"sleep %0	\n"
 84		:
 85		:"I"(ISA_SLEEP_ARG)); /* can't be "r" has to be embedded const */
 86}
 87
 88asmlinkage void ret_from_fork(void);
 89
 90/*
 91 * Copy architecture-specific thread state
 92 *
 93 * Layout of Child kernel mode stack as setup at the end of this function is
 94 *
 95 * |     ...        |
 96 * |     ...        |
 97 * |    unused      |
 98 * |                |
 99 * ------------------
100 * |     r25        |   <==== top of Stack (thread.ksp)
101 * ~                ~
102 * |    --to--      |   (CALLEE Regs of kernel mode)
103 * |     r13        |
104 * ------------------
105 * |     fp         |
106 * |    blink       |   @ret_from_fork
107 * ------------------
108 * |                |
109 * ~                ~
110 * ~                ~
111 * |                |
112 * ------------------
113 * |     r12        |
114 * ~                ~
115 * |    --to--      |   (scratch Regs of user mode)
116 * |     r0         |
117 * ------------------
118 * |      SP        |
119 * |    orig_r0     |
120 * |    event/ECR   |
121 * |    user_r25    |
122 * ------------------  <===== END of PAGE
123 */
124int copy_thread(unsigned long clone_flags,
125		unsigned long usp, unsigned long kthread_arg,
126		struct task_struct *p)
127{
128	struct pt_regs *c_regs;        /* child's pt_regs */
129	unsigned long *childksp;       /* to unwind out of __switch_to() */
130	struct callee_regs *c_callee;  /* child's callee regs */
131	struct callee_regs *parent_callee;  /* paren't callee */
132	struct pt_regs *regs = current_pt_regs();
133
134	/* Mark the specific anchors to begin with (see pic above) */
135	c_regs = task_pt_regs(p);
136	childksp = (unsigned long *)c_regs - 2;  /* 2 words for FP/BLINK */
137	c_callee = ((struct callee_regs *)childksp) - 1;
138
139	/*
140	 * __switch_to() uses thread.ksp to start unwinding stack
141	 * For kernel threads we don't need to create callee regs, the
142	 * stack layout nevertheless needs to remain the same.
143	 * Also, since __switch_to anyways unwinds callee regs, we use
144	 * this to populate kernel thread entry-pt/args into callee regs,
145	 * so that ret_from_kernel_thread() becomes simpler.
146	 */
147	p->thread.ksp = (unsigned long)c_callee;	/* THREAD_KSP */
148
149	/* __switch_to expects FP(0), BLINK(return addr) at top */
150	childksp[0] = 0;			/* fp */
151	childksp[1] = (unsigned long)ret_from_fork; /* blink */
152
153	if (unlikely(p->flags & PF_KTHREAD)) {
154		memset(c_regs, 0, sizeof(struct pt_regs));
155
156		c_callee->r13 = kthread_arg;
157		c_callee->r14 = usp;  /* function */
158
159		return 0;
160	}
161
162	/*--------- User Task Only --------------*/
163
164	/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
165	childksp[0] = 0;				/* for POP fp */
166	childksp[1] = (unsigned long)ret_from_fork;	/* for POP blink */
167
168	/* Copy parents pt regs on child's kernel mode stack */
169	*c_regs = *regs;
170
171	if (usp)
172		c_regs->sp = usp;
173
174	c_regs->r0 = 0;		/* fork returns 0 in child */
175
176	parent_callee = ((struct callee_regs *)regs) - 1;
177	*c_callee = *parent_callee;
178
179	if (unlikely(clone_flags & CLONE_SETTLS)) {
180		/*
181		 * set task's userland tls data ptr from 4th arg
182		 * clone C-lib call is difft from clone sys-call
183		 */
184		task_thread_info(p)->thr_ptr = regs->r3;
185	} else {
186		/* Normal fork case: set parent's TLS ptr in child */
187		task_thread_info(p)->thr_ptr =
188		task_thread_info(current)->thr_ptr;
189	}
190
191	return 0;
192}
193
194/*
195 * Do necessary setup to start up a new user task
196 */
197void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
198{
199	regs->sp = usp;
200	regs->ret = pc;
201
202	/*
203	 * [U]ser Mode bit set
204	 * [L] ZOL loop inhibited to begin with - cleared by a LP insn
205	 * Interrupts enabled
206	 */
207	regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
208
209	/* bogus seed values for debugging */
210	regs->lp_start = 0x10;
211	regs->lp_end = 0x80;
212}
213
214/*
215 * Some archs flush debug and FPU info here
216 */
217void flush_thread(void)
218{
219}
220
221int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
222{
223	return 0;
224}
225
226int elf_check_arch(const struct elf32_hdr *x)
227{
228	unsigned int eflags;
229
230	if (x->e_machine != EM_ARC_INUSE) {
231		pr_err("ELF not built for %s ISA\n",
232			is_isa_arcompact() ? "ARCompact":"ARCv2");
233		return 0;
234	}
235
236	eflags = x->e_flags;
237	if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
238		pr_err("ABI mismatch - you need newer toolchain\n");
239		force_sigsegv(SIGSEGV, current);
240		return 0;
241	}
242
243	return 1;
244}
245EXPORT_SYMBOL(elf_check_arch);