2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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.
8 * Amit Bhor, Kanika Nema: Codito Technologies 2004
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/sched.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>
23 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
25 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
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
39 SYSCALL_DEFINE0(arc_gettls)
41 return task_thread_info(current)->thr_ptr;
44 static inline void arch_idle(void)
46 /* sleep, but enable all interrupts before committing */
52 /* Since we SLEEP in idle loop, TIF_POLLING_NRFLAG can't be set */
54 /* endless idle loop with no priority at all */
56 tick_nohz_idle_enter();
61 if (!need_resched()) {
69 tick_nohz_idle_exit();
71 schedule_preempt_disabled();
75 asmlinkage void ret_from_fork(void);
77 /* Layout of Child kernel mode stack as setup at the end of this function is
83 * ------------------ <==== top of Stack (thread.ksp)
88 * | --to-- | (CALLEE Regs of user mode)
92 * | blink | @ret_from_fork
101 * | --to-- | (scratch Regs of user mode)
105 * ------------------ <===== END of PAGE
107 int copy_thread(unsigned long clone_flags,
108 unsigned long usp, unsigned long arg,
109 struct task_struct *p)
111 struct pt_regs *c_regs; /* child's pt_regs */
112 unsigned long *childksp; /* to unwind out of __switch_to() */
113 struct callee_regs *c_callee; /* child's callee regs */
114 struct callee_regs *parent_callee; /* paren't callee */
115 struct pt_regs *regs = current_pt_regs();
117 /* Mark the specific anchors to begin with (see pic above) */
118 c_regs = task_pt_regs(p);
119 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
120 c_callee = ((struct callee_regs *)childksp) - 1;
123 * __switch_to() uses thread.ksp to start unwinding stack
124 * For kernel threads we don't need to create callee regs, the
125 * stack layout nevertheless needs to remain the same.
126 * Also, since __switch_to anyways unwinds callee regs, we use
127 * this to populate kernel thread entry-pt/args into callee regs,
128 * so that ret_from_kernel_thread() becomes simpler.
130 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
132 /* __switch_to expects FP(0), BLINK(return addr) at top */
133 childksp[0] = 0; /* fp */
134 childksp[1] = (unsigned long)ret_from_fork; /* blink */
136 if (unlikely(p->flags & PF_KTHREAD)) {
137 memset(c_regs, 0, sizeof(struct pt_regs));
139 c_callee->r13 = arg; /* argument to kernel thread */
140 c_callee->r14 = usp; /* function */
145 /*--------- User Task Only --------------*/
147 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */
148 childksp[0] = 0; /* for POP fp */
149 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
151 /* Copy parents pt regs on child's kernel mode stack */
157 c_regs->r0 = 0; /* fork returns 0 in child */
159 parent_callee = ((struct callee_regs *)regs) - 1;
160 *c_callee = *parent_callee;
162 if (unlikely(clone_flags & CLONE_SETTLS)) {
164 * set task's userland tls data ptr from 4th arg
165 * clone C-lib call is difft from clone sys-call
167 task_thread_info(p)->thr_ptr = regs->r3;
169 /* Normal fork case: set parent's TLS ptr in child */
170 task_thread_info(p)->thr_ptr =
171 task_thread_info(current)->thr_ptr;
178 * Some archs flush debug and FPU info here
180 void flush_thread(void)
185 * Free any architecture-specific thread data structures, etc.
187 void exit_thread(void)
191 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
197 * API: expected by schedular Code: If thread is sleeping where is that.
198 * What is this good for? it will be always the scheduler or ret_from_fork.
199 * So we hard code that anyways.
201 unsigned long thread_saved_pc(struct task_struct *t)
203 struct pt_regs *regs = task_pt_regs(t);
204 unsigned long blink = 0;
207 * If the thread being queried for in not itself calling this, then it
208 * implies it is not executing, which in turn implies it is sleeping,
209 * which in turn implies it got switched OUT by the schedular.
210 * In that case, it's kernel mode blink can reliably retrieved as per
211 * the picture above (right above pt_regs).
213 if (t != current && t->state != TASK_RUNNING)
214 blink = *((unsigned int *)regs - 1);
219 int elf_check_arch(const struct elf32_hdr *x)
223 if (x->e_machine != EM_ARCOMPACT)
227 if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) {
228 pr_err("ABI mismatch - you need newer toolchain\n");
229 force_sigsegv(SIGSEGV, current);
235 EXPORT_SYMBOL(elf_check_arch);