/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Amit Bhor, Kanika Nema: Codito Technologies 2004
*/
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/elf.h>
#include <linux/tick.h>
SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
{
task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
return 0;
}
/*
* We return the user space TLS data ptr as sys-call return code
* Ideally it should be copy to user.
* However we can cheat by the fact that some sys-calls do return
* absurdly high values
* Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx
* it won't be considered a sys-call error
* and it will be loads better than copy-to-user, which is a definite
* D-TLB Miss
*/
SYSCALL_DEFINE0(arc_gettls)
{
return task_thread_info(current)->thr_ptr;
}
static inline void arch_idle(void)
{
/* sleep, but enable all interrupts before committing */
__asm__("sleep 0x3");
}
void cpu_idle(void)
{
/* Since we SLEEP in idle loop, TIF_POLLING_NRFLAG can't be set */
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_idle_enter();
rcu_idle_enter();
doze:
local_irq_disable();
if (!need_resched()) {
arch_idle();
goto doze;
} else {
local_irq_enable();
}
rcu_idle_exit();
tick_nohz_idle_exit();
schedule_preempt_disabled();
}
}
asmlinkage void ret_from_fork(void);
/* Layout of Child kernel mode stack as setup at the end of this function is
*
* | ... |
* | ... |
* | unused |
* | |
* ------------------ <==== top of Stack (thread.ksp)
* | UNUSED 1 word|
* ------------------
* | r25 |
* ~ ~
* | --to-- | (CALLEE Regs of user mode)
* | r13 |
* ------------------
* | fp |
* | blink | @ret_from_fork
* ------------------
* | |
* ~ ~
* ~ ~
* | |
* ------------------
* | r12 |
* ~ ~
* | --to-- | (scratch Regs of user mode)
* | r0 |
* ------------------
* | UNUSED 1 word|
* ------------------ <===== END of PAGE
*/
int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long arg,
struct task_struct *p)
{
struct pt_regs *c_regs; /* child's pt_regs */
unsigned long *childksp; /* to unwind out of __switch_to() */
struct callee_regs *c_callee; /* child's callee regs */
struct callee_regs *parent_callee; /* paren't callee */
struct pt_regs *regs = current_pt_regs();
/* Mark the specific anchors to begin with (see pic above) */
c_regs = task_pt_regs(p);
childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
c_callee = ((struct callee_regs *)childksp) - 1;
/*
* __switch_to() uses thread.ksp to start unwinding stack
* For kernel threads we don't need to create callee regs, the
* stack layout nevertheless needs to remain the same.
* Also, since __switch_to anyways unwinds callee regs, we use
* this to populate kernel thread entry-pt/args into callee regs,
* so that ret_from_kernel_thread() becomes simpler.
*/
p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
/* __switch_to expects FP(0), BLINK(return addr) at top */
childksp[0] = 0; /* fp */
childksp[1] = (unsigned long)ret_from_fork; /* blink */
if (unlikely(p->flags & PF_KTHREAD)) {
memset(c_regs, 0, sizeof(struct pt_regs));
c_callee->r13 = arg; /* argument to kernel thread */
c_callee->r14 = usp; /* function */
return 0;
}
/*--------- User Task Only --------------*/
/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
childksp[0] = 0; /* for POP fp */
childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
/* Copy parents pt regs on child's kernel mode stack */
*c_regs = *regs;
if (usp)
c_regs->sp = usp;
c_regs->r0 = 0; /* fork returns 0 in child */
parent_callee = ((struct callee_regs *)regs) - 1;
*c_callee = *parent_callee;
if (unlikely(clone_flags & CLONE_SETTLS)) {
/*
* set task's userland tls data ptr from 4th arg
* clone C-lib call is difft from clone sys-call
*/
task_thread_info(p)->thr_ptr = regs->r3;
} else {
/* Normal fork case: set parent's TLS ptr in child */
task_thread_info(p)->thr_ptr =
task_thread_info(current)->thr_ptr;
}
return 0;
}
/*
* Some archs flush debug and FPU info here
*/
void flush_thread(void)
{
}
/*
* Free any architecture-specific thread data structures, etc.
*/
void exit_thread(void)
{
}
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
return 0;
}
/*
* API: expected by schedular Code: If thread is sleeping where is that.
* What is this good for? it will be always the scheduler or ret_from_fork.
* So we hard code that anyways.
*/
unsigned long thread_saved_pc(struct task_struct *t)
{
struct pt_regs *regs = task_pt_regs(t);
unsigned long blink = 0;
/*
* If the thread being queried for in not itself calling this, then it
* implies it is not executing, which in turn implies it is sleeping,
* which in turn implies it got switched OUT by the schedular.
* In that case, it's kernel mode blink can reliably retrieved as per
* the picture above (right above pt_regs).
*/
if (t != current && t->state != TASK_RUNNING)
blink = *((unsigned int *)regs - 1);
return blink;
}
int elf_check_arch(const struct elf32_hdr *x)
{
unsigned int eflags;
if (x->e_machine != EM_ARCOMPACT)
return 0;
eflags = x->e_flags;
if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_V2) {
pr_err("ABI mismatch - you need newer toolchain\n");
force_sigsegv(SIGSEGV, current);
return 0;
}
return 1;
}
EXPORT_SYMBOL(elf_check_arch);
