diff options
Diffstat (limited to 'arch/tile/kernel/process.c')
| -rw-r--r-- | arch/tile/kernel/process.c | 647 |
1 files changed, 647 insertions, 0 deletions
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c new file mode 100644 index 000000000000..824f230e6d1a --- /dev/null +++ b/arch/tile/kernel/process.c @@ -0,0 +1,647 @@ +/* + * Copyright 2010 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/sched.h> +#include <linux/preempt.h> +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/kprobes.h> +#include <linux/elfcore.h> +#include <linux/tick.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/compat.h> +#include <linux/hardirq.h> +#include <linux/syscalls.h> +#include <asm/system.h> +#include <asm/stack.h> +#include <asm/homecache.h> +#include <arch/chip.h> +#include <arch/abi.h> + + +/* + * Use the (x86) "idle=poll" option to prefer low latency when leaving the + * idle loop over low power while in the idle loop, e.g. if we have + * one thread per core and we want to get threads out of futex waits fast. + */ +static int no_idle_nap; +static int __init idle_setup(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "poll")) { + printk("using polling idle threads.\n"); + no_idle_nap = 1; + } else if (!strcmp(str, "halt")) + no_idle_nap = 0; + else + return -1; + + return 0; +} +early_param("idle", idle_setup); + +/* + * The idle thread. There's no useful work to be + * done, so just try to conserve power and have a + * low exit latency (ie sit in a loop waiting for + * somebody to say that they'd like to reschedule) + */ +void cpu_idle(void) +{ + extern void _cpu_idle(void); + int cpu = smp_processor_id(); + + + current_thread_info()->status |= TS_POLLING; + + if (no_idle_nap) { + while (1) { + while (!need_resched()) + cpu_relax(); + schedule(); + } + } + + /* endless idle loop with no priority at all */ + while (1) { + tick_nohz_stop_sched_tick(1); + while (!need_resched()) { + if (cpu_is_offline(cpu)) + BUG(); /* no HOTPLUG_CPU */ + + local_irq_disable(); + __get_cpu_var(irq_stat).idle_timestamp = jiffies; + current_thread_info()->status &= ~TS_POLLING; + /* + * TS_POLLING-cleared state must be visible before we + * test NEED_RESCHED: + */ + smp_mb(); + + if (!need_resched()) + _cpu_idle(); + else + local_irq_enable(); + current_thread_info()->status |= TS_POLLING; + } + tick_nohz_restart_sched_tick(); + preempt_enable_no_resched(); + schedule(); + preempt_disable(); + } +} + +struct thread_info *alloc_thread_info(struct task_struct *task) +{ + struct page *page; + int flags = GFP_KERNEL; + +#ifdef CONFIG_DEBUG_STACK_USAGE + flags |= __GFP_ZERO; +#endif + + page = alloc_pages(flags, THREAD_SIZE_ORDER); + if (!page) + return 0; + + return (struct thread_info *)page_address(page); +} + +/* + * Free a thread_info node, and all of its derivative + * data structures. + */ +void free_thread_info(struct thread_info *info) +{ + struct single_step_state *step_state = info->step_state; + + + if (step_state) { + + /* + * FIXME: we don't munmap step_state->buffer + * because the mm_struct for this process (info->task->mm) + * has already been zeroed in exit_mm(). Keeping a + * reference to it here seems like a bad move, so this + * means we can't munmap() the buffer, and therefore if we + * ptrace multiple threads in a process, we will slowly + * leak user memory. (Note that as soon as the last + * thread in a process dies, we will reclaim all user + * memory including single-step buffers in the usual way.) + * We should either assign a kernel VA to this buffer + * somehow, or we should associate the buffer(s) with the + * mm itself so we can clean them up that way. + */ + kfree(step_state); + } + + free_page((unsigned long)info); +} + +static void save_arch_state(struct thread_struct *t); + +extern void ret_from_fork(void); + +int copy_thread(unsigned long clone_flags, unsigned long sp, + unsigned long stack_size, + struct task_struct *p, struct pt_regs *regs) +{ + struct pt_regs *childregs; + unsigned long ksp; + + /* + * When creating a new kernel thread we pass sp as zero. + * Assign it to a reasonable value now that we have the stack. + */ + if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0)) + sp = KSTK_TOP(p); + + /* + * Do not clone step state from the parent; each thread + * must make its own lazily. + */ + task_thread_info(p)->step_state = NULL; + + /* + * Start new thread in ret_from_fork so it schedules properly + * and then return from interrupt like the parent. + */ + p->thread.pc = (unsigned long) ret_from_fork; + + /* Save user stack top pointer so we can ID the stack vm area later. */ + p->thread.usp0 = sp; + + /* Record the pid of the process that created this one. */ + p->thread.creator_pid = current->pid; + + /* + * Copy the registers onto the kernel stack so the + * return-from-interrupt code will reload it into registers. + */ + childregs = task_pt_regs(p); + *childregs = *regs; + childregs->regs[0] = 0; /* return value is zero */ + childregs->sp = sp; /* override with new user stack pointer */ + + /* + * Copy the callee-saved registers from the passed pt_regs struct + * into the context-switch callee-saved registers area. + * We have to restore the callee-saved registers since we may + * be cloning a userspace task with userspace register state, + * and we won't be unwinding the same kernel frames to restore them. + * Zero out the C ABI save area to mark the top of the stack. + */ + ksp = (unsigned long) childregs; + ksp -= C_ABI_SAVE_AREA_SIZE; /* interrupt-entry save area */ + ((long *)ksp)[0] = ((long *)ksp)[1] = 0; + ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long); + memcpy((void *)ksp, ®s->regs[CALLEE_SAVED_FIRST_REG], + CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long)); + ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */ + ((long *)ksp)[0] = ((long *)ksp)[1] = 0; + p->thread.ksp = ksp; + +#if CHIP_HAS_TILE_DMA() + /* + * No DMA in the new thread. We model this on the fact that + * fork() clears the pending signals, alarms, and aio for the child. + */ + memset(&p->thread.tile_dma_state, 0, sizeof(struct tile_dma_state)); + memset(&p->thread.dma_async_tlb, 0, sizeof(struct async_tlb)); +#endif + +#if CHIP_HAS_SN_PROC() + /* Likewise, the new thread is not running static processor code. */ + p->thread.sn_proc_running = 0; + memset(&p->thread.sn_async_tlb, 0, sizeof(struct async_tlb)); +#endif + +#if CHIP_HAS_PROC_STATUS_SPR() + /* New thread has its miscellaneous processor state bits clear. */ + p->thread.proc_status = 0; +#endif + + + + /* + * Start the new thread with the current architecture state + * (user interrupt masks, etc.). + */ + save_arch_state(&p->thread); + + return 0; +} + +/* + * Return "current" if it looks plausible, or else a pointer to a dummy. + * This can be helpful if we are just trying to emit a clean panic. + */ +struct task_struct *validate_current(void) +{ + static struct task_struct corrupt = { .comm = "<corrupt>" }; + struct task_struct *tsk = current; + if (unlikely((unsigned long)tsk < PAGE_OFFSET || + (void *)tsk > high_memory || + ((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) { + printk("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer); + tsk = &corrupt; + } + return tsk; +} + +/* Take and return the pointer to the previous task, for schedule_tail(). */ +struct task_struct *sim_notify_fork(struct task_struct *prev) +{ + struct task_struct *tsk = current; + __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK_PARENT | + (tsk->thread.creator_pid << _SIM_CONTROL_OPERATOR_BITS)); + __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK | + (tsk->pid << _SIM_CONTROL_OPERATOR_BITS)); + return prev; +} + +int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) +{ + struct pt_regs *ptregs = task_pt_regs(tsk); + elf_core_copy_regs(regs, ptregs); + return 1; +} + +#if CHIP_HAS_TILE_DMA() + +/* Allow user processes to access the DMA SPRs */ +void grant_dma_mpls(void) +{ + __insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1); + __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1); +} + +/* Forbid user processes from accessing the DMA SPRs */ +void restrict_dma_mpls(void) +{ + __insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1); + __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1); +} + +/* Pause the DMA engine, then save off its state registers. */ +static void save_tile_dma_state(struct tile_dma_state *dma) +{ + unsigned long state = __insn_mfspr(SPR_DMA_USER_STATUS); + unsigned long post_suspend_state; + + /* If we're running, suspend the engine. */ + if ((state & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK) + __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK); + + /* + * Wait for the engine to idle, then save regs. Note that we + * want to record the "running" bit from before suspension, + * and the "done" bit from after, so that we can properly + * distinguish a case where the user suspended the engine from + * the case where the kernel suspended as part of the context + * swap. + */ + do { + post_suspend_state = __insn_mfspr(SPR_DMA_USER_STATUS); + } while (post_suspend_state & SPR_DMA_STATUS__BUSY_MASK); + + dma->src = __insn_mfspr(SPR_DMA_SRC_ADDR); + dma->src_chunk = __insn_mfspr(SPR_DMA_SRC_CHUNK_ADDR); + dma->dest = __insn_mfspr(SPR_DMA_DST_ADDR); + dma->dest_chunk = __insn_mfspr(SPR_DMA_DST_CHUNK_ADDR); + dma->strides = __insn_mfspr(SPR_DMA_STRIDE); + dma->chunk_size = __insn_mfspr(SPR_DMA_CHUNK_SIZE); + dma->byte = __insn_mfspr(SPR_DMA_BYTE); + dma->status = (state & SPR_DMA_STATUS__RUNNING_MASK) | + (post_suspend_state & SPR_DMA_STATUS__DONE_MASK); +} + +/* Restart a DMA that was running before we were context-switched out. */ +static void restore_tile_dma_state(struct thread_struct *t) +{ + const struct tile_dma_state *dma = &t->tile_dma_state; + + /* + * The only way to restore the done bit is to run a zero + * length transaction. + */ + if ((dma->status & SPR_DMA_STATUS__DONE_MASK) && + !(__insn_mfspr(SPR_DMA_USER_STATUS) & SPR_DMA_STATUS__DONE_MASK)) { + __insn_mtspr(SPR_DMA_BYTE, 0); + __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK); + while (__insn_mfspr(SPR_DMA_USER_STATUS) & + SPR_DMA_STATUS__BUSY_MASK) + ; + } + + __insn_mtspr(SPR_DMA_SRC_ADDR, dma->src); + __insn_mtspr(SPR_DMA_SRC_CHUNK_ADDR, dma->src_chunk); + __insn_mtspr(SPR_DMA_DST_ADDR, dma->dest); + __insn_mtspr(SPR_DMA_DST_CHUNK_ADDR, dma->dest_chunk); + __insn_mtspr(SPR_DMA_STRIDE, dma->strides); + __insn_mtspr(SPR_DMA_CHUNK_SIZE, dma->chunk_size); + __insn_mtspr(SPR_DMA_BYTE, dma->byte); + + /* + * Restart the engine if we were running and not done. + * Clear a pending async DMA fault that we were waiting on return + * to user space to execute, since we expect the DMA engine + * to regenerate those faults for us now. Note that we don't + * try to clear the TIF_ASYNC_TLB flag, since it's relatively + * harmless if set, and it covers both DMA and the SN processor. + */ + if ((dma->status & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK) { + t->dma_async_tlb.fault_num = 0; + __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK); + } +} + +#endif + +static void save_arch_state(struct thread_struct *t) +{ +#if CHIP_HAS_SPLIT_INTR_MASK() + t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0_0) | + ((u64)__insn_mfspr(SPR_INTERRUPT_MASK_0_1) << 32); +#else + t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0); +#endif + t->ex_context[0] = __insn_mfspr(SPR_EX_CONTEXT_0_0); + t->ex_context[1] = __insn_mfspr(SPR_EX_CONTEXT_0_1); + t->system_save[0] = __insn_mfspr(SPR_SYSTEM_SAVE_0_0); + t->system_save[1] = __insn_mfspr(SPR_SYSTEM_SAVE_0_1); + t->system_save[2] = __insn_mfspr(SPR_SYSTEM_SAVE_0_2); + t->system_save[3] = __insn_mfspr(SPR_SYSTEM_SAVE_0_3); + t->intctrl_0 = __insn_mfspr(SPR_INTCTRL_0_STATUS); +#if CHIP_HAS_PROC_STATUS_SPR() + t->proc_status = __insn_mfspr(SPR_PROC_STATUS); +#endif +} + +static void restore_arch_state(const struct thread_struct *t) +{ +#if CHIP_HAS_SPLIT_INTR_MASK() + __insn_mtspr(SPR_INTERRUPT_MASK_0_0, (u32) t->interrupt_mask); + __insn_mtspr(SPR_INTERRUPT_MASK_0_1, t->interrupt_mask >> 32); +#else + __insn_mtspr(SPR_INTERRUPT_MASK_0, t->interrupt_mask); +#endif + __insn_mtspr(SPR_EX_CONTEXT_0_0, t->ex_context[0]); + __insn_mtspr(SPR_EX_CONTEXT_0_1, t->ex_context[1]); + __insn_mtspr(SPR_SYSTEM_SAVE_0_0, t->system_save[0]); + __insn_mtspr(SPR_SYSTEM_SAVE_0_1, t->system_save[1]); + __insn_mtspr(SPR_SYSTEM_SAVE_0_2, t->system_save[2]); + __insn_mtspr(SPR_SYSTEM_SAVE_0_3, t->system_save[3]); + __insn_mtspr(SPR_INTCTRL_0_STATUS, t->intctrl_0); +#if CHIP_HAS_PROC_STATUS_SPR() + __insn_mtspr(SPR_PROC_STATUS, t->proc_status); +#endif +#if CHIP_HAS_TILE_RTF_HWM() + /* + * Clear this whenever we switch back to a process in case + * the previous process was monkeying with it. Even if enabled + * in CBOX_MSR1 via TILE_RTF_HWM_MIN, it's still just a + * performance hint, so isn't worth a full save/restore. + */ + __insn_mtspr(SPR_TILE_RTF_HWM, 0); +#endif +} + + +void _prepare_arch_switch(struct task_struct *next) +{ +#if CHIP_HAS_SN_PROC() + int snctl; +#endif +#if CHIP_HAS_TILE_DMA() + struct tile_dma_state *dma = ¤t->thread.tile_dma_state; + if (dma->enabled) + save_tile_dma_state(dma); +#endif +#if CHIP_HAS_SN_PROC() + /* + * Suspend the static network processor if it was running. + * We do not suspend the fabric itself, just like we don't + * try to suspend the UDN. + */ + snctl = __insn_mfspr(SPR_SNCTL); + current->thread.sn_proc_running = + (snctl & SPR_SNCTL__FRZPROC_MASK) == 0; + if (current->thread.sn_proc_running) + __insn_mtspr(SPR_SNCTL, snctl | SPR_SNCTL__FRZPROC_MASK); +#endif +} + + +extern struct task_struct *__switch_to(struct task_struct *prev, + struct task_struct *next, + unsigned long new_system_save_1_0); + +struct task_struct *__sched _switch_to(struct task_struct *prev, + struct task_struct *next) +{ + /* DMA state is already saved; save off other arch state. */ + save_arch_state(&prev->thread); + +#if CHIP_HAS_TILE_DMA() + /* + * Restore DMA in new task if desired. + * Note that it is only safe to restart here since interrupts + * are disabled, so we can't take any DMATLB miss or access + * interrupts before we have finished switching stacks. + */ + if (next->thread.tile_dma_state.enabled) { + restore_tile_dma_state(&next->thread); + grant_dma_mpls(); + } else { + restrict_dma_mpls(); + } +#endif + + /* Restore other arch state. */ + restore_arch_state(&next->thread); + +#if CHIP_HAS_SN_PROC() + /* + * Restart static network processor in the new process + * if it was running before. + */ + if (next->thread.sn_proc_running) { + int snctl = __insn_mfspr(SPR_SNCTL); + __insn_mtspr(SPR_SNCTL, snctl & ~SPR_SNCTL__FRZPROC_MASK); + } +#endif + + + /* + * Switch kernel SP, PC, and callee-saved registers. + * In the context of the new task, return the old task pointer + * (i.e. the task that actually called __switch_to). + * Pass the value to use for SYSTEM_SAVE_1_0 when we reset our sp. + */ + return __switch_to(prev, next, next_current_ksp0(next)); +} + +int _sys_fork(struct pt_regs *regs) +{ + return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL); +} + +int _sys_clone(unsigned long clone_flags, unsigned long newsp, + int __user *parent_tidptr, int __user *child_tidptr, + struct pt_regs *regs) +{ + if (!newsp) + newsp = regs->sp; + return do_fork(clone_flags, newsp, regs, 0, + parent_tidptr, child_tidptr); +} + +int _sys_vfork(struct pt_regs *regs) +{ + return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, + regs, 0, NULL, NULL); +} + +/* + * sys_execve() executes a new program. + */ +int _sys_execve(char __user *path, char __user *__user *argv, + char __user *__user *envp, struct pt_regs *regs) +{ + int error; + char *filename; + + filename = getname(path); + error = PTR_ERR(filename); + if (IS_ERR(filename)) + goto out; + error = do_execve(filename, argv, envp, regs); + putname(filename); +out: + return error; +} + +#ifdef CONFIG_COMPAT +int _compat_sys_execve(char __user *path, compat_uptr_t __user *argv, + compat_uptr_t __user *envp, struct pt_regs *regs) +{ + int error; + char *filename; + + filename = getname(path); + error = PTR_ERR(filename); + if (IS_ERR(filename)) + goto out; + error = compat_do_execve(filename, argv, envp, regs); + putname(filename); +out: + return error; +} +#endif + +unsigned long get_wchan(struct task_struct *p) +{ + struct KBacktraceIterator kbt; + + if (!p || p == current || p->state == TASK_RUNNING) + return 0; + + for (KBacktraceIterator_init(&kbt, p, NULL); + !KBacktraceIterator_end(&kbt); + KBacktraceIterator_next(&kbt)) { + if (!in_sched_functions(kbt.it.pc)) + return kbt.it.pc; + } + + return 0; +} + +/* + * We pass in lr as zero (cleared in kernel_thread) and the caller + * part of the backtrace ABI on the stack also zeroed (in copy_thread) + * so that backtraces will stop with this function. + * Note that we don't use r0, since copy_thread() clears it. + */ +static void start_kernel_thread(int dummy, int (*fn)(int), int arg) +{ + do_exit(fn(arg)); +} + +/* + * Create a kernel thread + */ +int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) +{ + struct pt_regs regs; + + memset(®s, 0, sizeof(regs)); + regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0); /* run at kernel PL, no ICS */ + regs.pc = (long) start_kernel_thread; + regs.flags = PT_FLAGS_CALLER_SAVES; /* need to restore r1 and r2 */ + regs.regs[1] = (long) fn; /* function pointer */ + regs.regs[2] = (long) arg; /* parameter register */ + + /* Ok, create the new process.. */ + return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, + 0, NULL, NULL); +} +EXPORT_SYMBOL(kernel_thread); + +/* Flush thread state. */ +void flush_thread(void) +{ + /* Nothing */ +} + +/* + * Free current thread data structures etc.. + */ +void exit_thread(void) +{ + /* Nothing */ +} + +#ifdef __tilegx__ +# define LINECOUNT 3 +# define EXTRA_NL "\n" +#else +# define LINECOUNT 4 +# define EXTRA_NL "" +#endif + +void show_regs(struct pt_regs *regs) +{ + struct task_struct *tsk = validate_current(); + int i, linebreak; + printk("\n"); + printk(" Pid: %d, comm: %20s, CPU: %d\n", + tsk->pid, tsk->comm, smp_processor_id()); + for (i = linebreak = 0; i < 53; ++i) { + printk(" r%-2d: "REGFMT, i, regs->regs[i]); + if (++linebreak == LINECOUNT) { + linebreak = 0; + printk("\n"); + } + } + printk(" tp : "REGFMT EXTRA_NL " sp : "REGFMT" lr : "REGFMT"\n", + regs->tp, regs->sp, regs->lr); + printk(" pc : "REGFMT" ex1: %ld faultnum: %ld\n", + regs->pc, regs->ex1, regs->faultnum); + + dump_stack_regs(regs); +} |