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authorVineet Gupta <vgupta@synopsys.com>2013-01-18 13:42:18 +0400
committerVineet Gupta <vgupta@synopsys.com>2013-02-11 18:30:38 +0400
commitbf90e1eab682dcb79b7765989fb65835ce9d6165 (patch)
treecb1bb4364862d878e1d361d371f8392d08f606d7 /arch/arc/kernel/process.c
parent4adeefe161a74369e44cc8e663f240ece0470dc3 (diff)
downloadlinux-bf90e1eab682dcb79b7765989fb65835ce9d6165.tar.xz
ARC: Process-creation/scheduling/idle-loop
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/arc/kernel/process.c')
-rw-r--r--arch/arc/kernel/process.c193
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index 4d14e5638c8c..279e080b6b54 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -40,3 +40,196 @@ 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);