2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
15 #include <linux/sched.h>
16 #include <linux/preempt.h>
17 #include <linux/module.h>
19 #include <linux/kprobes.h>
20 #include <linux/elfcore.h>
21 #include <linux/tick.h>
22 #include <linux/init.h>
24 #include <linux/compat.h>
25 #include <linux/hardirq.h>
26 #include <linux/syscalls.h>
27 #include <linux/kernel.h>
28 #include <asm/system.h>
29 #include <asm/stack.h>
30 #include <asm/homecache.h>
31 #include <asm/syscalls.h>
32 #ifdef CONFIG_HARDWALL
33 #include <asm/hardwall.h>
35 #include <arch/chip.h>
40 * Use the (x86) "idle=poll" option to prefer low latency when leaving the
41 * idle loop over low power while in the idle loop, e.g. if we have
42 * one thread per core and we want to get threads out of futex waits fast.
44 static int no_idle_nap;
45 static int __init idle_setup(char *str)
50 if (!strcmp(str, "poll")) {
51 pr_info("using polling idle threads.\n");
53 } else if (!strcmp(str, "halt"))
60 early_param("idle", idle_setup);
63 * The idle thread. There's no useful work to be
64 * done, so just try to conserve power and have a
65 * low exit latency (ie sit in a loop waiting for
66 * somebody to say that they'd like to reschedule)
70 int cpu = smp_processor_id();
73 current_thread_info()->status |= TS_POLLING;
77 while (!need_resched())
83 /* endless idle loop with no priority at all */
85 tick_nohz_stop_sched_tick(1);
86 while (!need_resched()) {
87 if (cpu_is_offline(cpu))
88 BUG(); /* no HOTPLUG_CPU */
91 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
92 current_thread_info()->status &= ~TS_POLLING;
94 * TS_POLLING-cleared state must be visible before we
103 current_thread_info()->status |= TS_POLLING;
105 tick_nohz_restart_sched_tick();
106 preempt_enable_no_resched();
112 struct thread_info *alloc_thread_info(struct task_struct *task)
115 gfp_t flags = GFP_KERNEL;
117 #ifdef CONFIG_DEBUG_STACK_USAGE
121 page = alloc_pages(flags, THREAD_SIZE_ORDER);
125 return (struct thread_info *)page_address(page);
129 * Free a thread_info node, and all of its derivative
132 void free_thread_info(struct thread_info *info)
134 struct single_step_state *step_state = info->step_state;
136 #ifdef CONFIG_HARDWALL
138 * We free a thread_info from the context of the task that has
139 * been scheduled next, so the original task is already dead.
140 * Calling deactivate here just frees up the data structures.
141 * If the task we're freeing held the last reference to a
142 * hardwall fd, it would have been released prior to this point
143 * anyway via exit_files(), and "hardwall" would be NULL by now.
145 if (info->task->thread.hardwall)
146 hardwall_deactivate(info->task);
152 * FIXME: we don't munmap step_state->buffer
153 * because the mm_struct for this process (info->task->mm)
154 * has already been zeroed in exit_mm(). Keeping a
155 * reference to it here seems like a bad move, so this
156 * means we can't munmap() the buffer, and therefore if we
157 * ptrace multiple threads in a process, we will slowly
158 * leak user memory. (Note that as soon as the last
159 * thread in a process dies, we will reclaim all user
160 * memory including single-step buffers in the usual way.)
161 * We should either assign a kernel VA to this buffer
162 * somehow, or we should associate the buffer(s) with the
163 * mm itself so we can clean them up that way.
168 free_page((unsigned long)info);
171 static void save_arch_state(struct thread_struct *t);
173 int copy_thread(unsigned long clone_flags, unsigned long sp,
174 unsigned long stack_size,
175 struct task_struct *p, struct pt_regs *regs)
177 struct pt_regs *childregs;
181 * When creating a new kernel thread we pass sp as zero.
182 * Assign it to a reasonable value now that we have the stack.
184 if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0))
188 * Do not clone step state from the parent; each thread
189 * must make its own lazily.
191 task_thread_info(p)->step_state = NULL;
194 * Start new thread in ret_from_fork so it schedules properly
195 * and then return from interrupt like the parent.
197 p->thread.pc = (unsigned long) ret_from_fork;
199 /* Save user stack top pointer so we can ID the stack vm area later. */
202 /* Record the pid of the process that created this one. */
203 p->thread.creator_pid = current->pid;
206 * Copy the registers onto the kernel stack so the
207 * return-from-interrupt code will reload it into registers.
209 childregs = task_pt_regs(p);
211 childregs->regs[0] = 0; /* return value is zero */
212 childregs->sp = sp; /* override with new user stack pointer */
215 * Copy the callee-saved registers from the passed pt_regs struct
216 * into the context-switch callee-saved registers area.
217 * We have to restore the callee-saved registers since we may
218 * be cloning a userspace task with userspace register state,
219 * and we won't be unwinding the same kernel frames to restore them.
220 * Zero out the C ABI save area to mark the top of the stack.
222 ksp = (unsigned long) childregs;
223 ksp -= C_ABI_SAVE_AREA_SIZE; /* interrupt-entry save area */
224 ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
225 ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
226 memcpy((void *)ksp, ®s->regs[CALLEE_SAVED_FIRST_REG],
227 CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
228 ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */
229 ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
232 #if CHIP_HAS_TILE_DMA()
234 * No DMA in the new thread. We model this on the fact that
235 * fork() clears the pending signals, alarms, and aio for the child.
237 memset(&p->thread.tile_dma_state, 0, sizeof(struct tile_dma_state));
238 memset(&p->thread.dma_async_tlb, 0, sizeof(struct async_tlb));
241 #if CHIP_HAS_SN_PROC()
242 /* Likewise, the new thread is not running static processor code. */
243 p->thread.sn_proc_running = 0;
244 memset(&p->thread.sn_async_tlb, 0, sizeof(struct async_tlb));
247 #if CHIP_HAS_PROC_STATUS_SPR()
248 /* New thread has its miscellaneous processor state bits clear. */
249 p->thread.proc_status = 0;
252 #ifdef CONFIG_HARDWALL
253 /* New thread does not own any networks. */
254 p->thread.hardwall = NULL;
259 * Start the new thread with the current architecture state
260 * (user interrupt masks, etc.).
262 save_arch_state(&p->thread);
268 * Return "current" if it looks plausible, or else a pointer to a dummy.
269 * This can be helpful if we are just trying to emit a clean panic.
271 struct task_struct *validate_current(void)
273 static struct task_struct corrupt = { .comm = "<corrupt>" };
274 struct task_struct *tsk = current;
275 if (unlikely((unsigned long)tsk < PAGE_OFFSET ||
276 (void *)tsk > high_memory ||
277 ((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
278 pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
284 /* Take and return the pointer to the previous task, for schedule_tail(). */
285 struct task_struct *sim_notify_fork(struct task_struct *prev)
287 struct task_struct *tsk = current;
288 __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK_PARENT |
289 (tsk->thread.creator_pid << _SIM_CONTROL_OPERATOR_BITS));
290 __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK |
291 (tsk->pid << _SIM_CONTROL_OPERATOR_BITS));
295 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
297 struct pt_regs *ptregs = task_pt_regs(tsk);
298 elf_core_copy_regs(regs, ptregs);
302 #if CHIP_HAS_TILE_DMA()
304 /* Allow user processes to access the DMA SPRs */
305 void grant_dma_mpls(void)
307 __insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
308 __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
311 /* Forbid user processes from accessing the DMA SPRs */
312 void restrict_dma_mpls(void)
314 __insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
315 __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
318 /* Pause the DMA engine, then save off its state registers. */
319 static void save_tile_dma_state(struct tile_dma_state *dma)
321 unsigned long state = __insn_mfspr(SPR_DMA_USER_STATUS);
322 unsigned long post_suspend_state;
324 /* If we're running, suspend the engine. */
325 if ((state & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK)
326 __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK);
329 * Wait for the engine to idle, then save regs. Note that we
330 * want to record the "running" bit from before suspension,
331 * and the "done" bit from after, so that we can properly
332 * distinguish a case where the user suspended the engine from
333 * the case where the kernel suspended as part of the context
337 post_suspend_state = __insn_mfspr(SPR_DMA_USER_STATUS);
338 } while (post_suspend_state & SPR_DMA_STATUS__BUSY_MASK);
340 dma->src = __insn_mfspr(SPR_DMA_SRC_ADDR);
341 dma->src_chunk = __insn_mfspr(SPR_DMA_SRC_CHUNK_ADDR);
342 dma->dest = __insn_mfspr(SPR_DMA_DST_ADDR);
343 dma->dest_chunk = __insn_mfspr(SPR_DMA_DST_CHUNK_ADDR);
344 dma->strides = __insn_mfspr(SPR_DMA_STRIDE);
345 dma->chunk_size = __insn_mfspr(SPR_DMA_CHUNK_SIZE);
346 dma->byte = __insn_mfspr(SPR_DMA_BYTE);
347 dma->status = (state & SPR_DMA_STATUS__RUNNING_MASK) |
348 (post_suspend_state & SPR_DMA_STATUS__DONE_MASK);
351 /* Restart a DMA that was running before we were context-switched out. */
352 static void restore_tile_dma_state(struct thread_struct *t)
354 const struct tile_dma_state *dma = &t->tile_dma_state;
357 * The only way to restore the done bit is to run a zero
358 * length transaction.
360 if ((dma->status & SPR_DMA_STATUS__DONE_MASK) &&
361 !(__insn_mfspr(SPR_DMA_USER_STATUS) & SPR_DMA_STATUS__DONE_MASK)) {
362 __insn_mtspr(SPR_DMA_BYTE, 0);
363 __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
364 while (__insn_mfspr(SPR_DMA_USER_STATUS) &
365 SPR_DMA_STATUS__BUSY_MASK)
369 __insn_mtspr(SPR_DMA_SRC_ADDR, dma->src);
370 __insn_mtspr(SPR_DMA_SRC_CHUNK_ADDR, dma->src_chunk);
371 __insn_mtspr(SPR_DMA_DST_ADDR, dma->dest);
372 __insn_mtspr(SPR_DMA_DST_CHUNK_ADDR, dma->dest_chunk);
373 __insn_mtspr(SPR_DMA_STRIDE, dma->strides);
374 __insn_mtspr(SPR_DMA_CHUNK_SIZE, dma->chunk_size);
375 __insn_mtspr(SPR_DMA_BYTE, dma->byte);
378 * Restart the engine if we were running and not done.
379 * Clear a pending async DMA fault that we were waiting on return
380 * to user space to execute, since we expect the DMA engine
381 * to regenerate those faults for us now. Note that we don't
382 * try to clear the TIF_ASYNC_TLB flag, since it's relatively
383 * harmless if set, and it covers both DMA and the SN processor.
385 if ((dma->status & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK) {
386 t->dma_async_tlb.fault_num = 0;
387 __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
393 static void save_arch_state(struct thread_struct *t)
395 #if CHIP_HAS_SPLIT_INTR_MASK()
396 t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0_0) |
397 ((u64)__insn_mfspr(SPR_INTERRUPT_MASK_0_1) << 32);
399 t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0);
401 t->ex_context[0] = __insn_mfspr(SPR_EX_CONTEXT_0_0);
402 t->ex_context[1] = __insn_mfspr(SPR_EX_CONTEXT_0_1);
403 t->system_save[0] = __insn_mfspr(SPR_SYSTEM_SAVE_0_0);
404 t->system_save[1] = __insn_mfspr(SPR_SYSTEM_SAVE_0_1);
405 t->system_save[2] = __insn_mfspr(SPR_SYSTEM_SAVE_0_2);
406 t->system_save[3] = __insn_mfspr(SPR_SYSTEM_SAVE_0_3);
407 t->intctrl_0 = __insn_mfspr(SPR_INTCTRL_0_STATUS);
408 #if CHIP_HAS_PROC_STATUS_SPR()
409 t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
413 static void restore_arch_state(const struct thread_struct *t)
415 #if CHIP_HAS_SPLIT_INTR_MASK()
416 __insn_mtspr(SPR_INTERRUPT_MASK_0_0, (u32) t->interrupt_mask);
417 __insn_mtspr(SPR_INTERRUPT_MASK_0_1, t->interrupt_mask >> 32);
419 __insn_mtspr(SPR_INTERRUPT_MASK_0, t->interrupt_mask);
421 __insn_mtspr(SPR_EX_CONTEXT_0_0, t->ex_context[0]);
422 __insn_mtspr(SPR_EX_CONTEXT_0_1, t->ex_context[1]);
423 __insn_mtspr(SPR_SYSTEM_SAVE_0_0, t->system_save[0]);
424 __insn_mtspr(SPR_SYSTEM_SAVE_0_1, t->system_save[1]);
425 __insn_mtspr(SPR_SYSTEM_SAVE_0_2, t->system_save[2]);
426 __insn_mtspr(SPR_SYSTEM_SAVE_0_3, t->system_save[3]);
427 __insn_mtspr(SPR_INTCTRL_0_STATUS, t->intctrl_0);
428 #if CHIP_HAS_PROC_STATUS_SPR()
429 __insn_mtspr(SPR_PROC_STATUS, t->proc_status);
431 #if CHIP_HAS_TILE_RTF_HWM()
433 * Clear this whenever we switch back to a process in case
434 * the previous process was monkeying with it. Even if enabled
435 * in CBOX_MSR1 via TILE_RTF_HWM_MIN, it's still just a
436 * performance hint, so isn't worth a full save/restore.
438 __insn_mtspr(SPR_TILE_RTF_HWM, 0);
443 void _prepare_arch_switch(struct task_struct *next)
445 #if CHIP_HAS_SN_PROC()
448 #if CHIP_HAS_TILE_DMA()
449 struct tile_dma_state *dma = ¤t->thread.tile_dma_state;
451 save_tile_dma_state(dma);
453 #if CHIP_HAS_SN_PROC()
455 * Suspend the static network processor if it was running.
456 * We do not suspend the fabric itself, just like we don't
457 * try to suspend the UDN.
459 snctl = __insn_mfspr(SPR_SNCTL);
460 current->thread.sn_proc_running =
461 (snctl & SPR_SNCTL__FRZPROC_MASK) == 0;
462 if (current->thread.sn_proc_running)
463 __insn_mtspr(SPR_SNCTL, snctl | SPR_SNCTL__FRZPROC_MASK);
468 struct task_struct *__sched _switch_to(struct task_struct *prev,
469 struct task_struct *next)
471 /* DMA state is already saved; save off other arch state. */
472 save_arch_state(&prev->thread);
474 #if CHIP_HAS_TILE_DMA()
476 * Restore DMA in new task if desired.
477 * Note that it is only safe to restart here since interrupts
478 * are disabled, so we can't take any DMATLB miss or access
479 * interrupts before we have finished switching stacks.
481 if (next->thread.tile_dma_state.enabled) {
482 restore_tile_dma_state(&next->thread);
489 /* Restore other arch state. */
490 restore_arch_state(&next->thread);
492 #if CHIP_HAS_SN_PROC()
494 * Restart static network processor in the new process
495 * if it was running before.
497 if (next->thread.sn_proc_running) {
498 int snctl = __insn_mfspr(SPR_SNCTL);
499 __insn_mtspr(SPR_SNCTL, snctl & ~SPR_SNCTL__FRZPROC_MASK);
503 #ifdef CONFIG_HARDWALL
504 /* Enable or disable access to the network registers appropriately. */
505 if (prev->thread.hardwall != NULL) {
506 if (next->thread.hardwall == NULL)
507 restrict_network_mpls();
508 } else if (next->thread.hardwall != NULL) {
509 grant_network_mpls();
514 * Switch kernel SP, PC, and callee-saved registers.
515 * In the context of the new task, return the old task pointer
516 * (i.e. the task that actually called __switch_to).
517 * Pass the value to use for SYSTEM_SAVE_1_0 when we reset our sp.
519 return __switch_to(prev, next, next_current_ksp0(next));
522 long _sys_fork(struct pt_regs *regs)
524 return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
527 long _sys_clone(unsigned long clone_flags, unsigned long newsp,
528 void __user *parent_tidptr, void __user *child_tidptr,
529 struct pt_regs *regs)
533 return do_fork(clone_flags, newsp, regs, 0,
534 parent_tidptr, child_tidptr);
537 long _sys_vfork(struct pt_regs *regs)
539 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp,
540 regs, 0, NULL, NULL);
544 * sys_execve() executes a new program.
546 long _sys_execve(char __user *path, char __user *__user *argv,
547 char __user *__user *envp, struct pt_regs *regs)
552 filename = getname(path);
553 error = PTR_ERR(filename);
554 if (IS_ERR(filename))
556 error = do_execve(filename, argv, envp, regs);
563 long _compat_sys_execve(char __user *path, compat_uptr_t __user *argv,
564 compat_uptr_t __user *envp, struct pt_regs *regs)
569 filename = getname(path);
570 error = PTR_ERR(filename);
571 if (IS_ERR(filename))
573 error = compat_do_execve(filename, argv, envp, regs);
580 unsigned long get_wchan(struct task_struct *p)
582 struct KBacktraceIterator kbt;
584 if (!p || p == current || p->state == TASK_RUNNING)
587 for (KBacktraceIterator_init(&kbt, p, NULL);
588 !KBacktraceIterator_end(&kbt);
589 KBacktraceIterator_next(&kbt)) {
590 if (!in_sched_functions(kbt.it.pc))
598 * We pass in lr as zero (cleared in kernel_thread) and the caller
599 * part of the backtrace ABI on the stack also zeroed (in copy_thread)
600 * so that backtraces will stop with this function.
601 * Note that we don't use r0, since copy_thread() clears it.
603 static void start_kernel_thread(int dummy, int (*fn)(int), int arg)
609 * Create a kernel thread
611 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
615 memset(®s, 0, sizeof(regs));
616 regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0); /* run at kernel PL, no ICS */
617 regs.pc = (long) start_kernel_thread;
618 regs.flags = PT_FLAGS_CALLER_SAVES; /* need to restore r1 and r2 */
619 regs.regs[1] = (long) fn; /* function pointer */
620 regs.regs[2] = (long) arg; /* parameter register */
622 /* Ok, create the new process.. */
623 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s,
626 EXPORT_SYMBOL(kernel_thread);
628 /* Flush thread state. */
629 void flush_thread(void)
635 * Free current thread data structures etc..
637 void exit_thread(void)
642 void show_regs(struct pt_regs *regs)
644 struct task_struct *tsk = validate_current();
648 pr_err(" Pid: %d, comm: %20s, CPU: %d\n",
649 tsk->pid, tsk->comm, smp_processor_id());
651 for (i = 0; i < 51; i += 3)
652 pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
653 i, regs->regs[i], i+1, regs->regs[i+1],
654 i+2, regs->regs[i+2]);
655 pr_err(" r51: "REGFMT" r52: "REGFMT" tp : "REGFMT"\n",
656 regs->regs[51], regs->regs[52], regs->tp);
657 pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
659 for (i = 0; i < 52; i += 3)
660 pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
661 " r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
662 i, regs->regs[i], i+1, regs->regs[i+1],
663 i+2, regs->regs[i+2], i+3, regs->regs[i+3]);
664 pr_err(" r52: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
665 regs->regs[52], regs->tp, regs->sp, regs->lr);
667 pr_err(" pc : "REGFMT" ex1: %ld faultnum: %ld\n",
668 regs->pc, regs->ex1, regs->faultnum);
670 dump_stack_regs(regs);