diff options
Diffstat (limited to 'arch/arc/kernel/process.c')
| -rw-r--r-- | arch/arc/kernel/process.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c index 4d14e56..279e080 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); |