/*
* 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 <linux/kernel.h>
#include <asm/system.h>
#include <asm/stack.h>
#include <asm/homecache.h>
#include <asm/syscalls.h>
#ifdef CONFIG_HARDWALL
#include <asm/hardwall.h>
#endif
#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")) {
pr_info("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)
{
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;
gfp_t flags = GFP_KERNEL;
#ifdef CONFIG_DEBUG_STACK_USAGE
flags |= __GFP_ZERO;
#endif
page = alloc_pages(flags, THREAD_SIZE_ORDER);
if (!page)
return NULL;
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;
#ifdef CONFIG_HARDWALL
/*
* We free a thread_info from the context of the task that has
* been scheduled next, so the original task is already dead.
* Calling deactivate here just frees up the data structures.
* If the task we're freeing held the last reference to a
* hardwall fd, it would have been released prior to this point
* anyway via exit_files(), and "hardwall" would be NULL by now.
*/
if (info->task->thread.hardwall)
hardwall_deactivate(info->task);
#endif
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);
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.
* This way when we start the interrupt-return sequence, the
* callee-save registers will be correctly in registers, which
* is how we assume the compiler leaves them as we start doing
* the normal return-from-interrupt path after calling C code.
* 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
#ifdef CONFIG_HARDWALL
/* New thread does not own any networks. */
p->thread.hardwall = NULL;
#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)) {
pr_err("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)
{
#if CONFIG_KERNEL_PL == 2
__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
#else
__insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
#endif
}
/* Forbid user processes from accessing the DMA SPRs */
void restrict_dma_mpls(void)
{
#if CONFIG_KERNEL_PL == 2
__insn_mtspr(SPR_MPL_DMA_CPL_SET_2, 1);
__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_2, 1);
#else
__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
#endif
}
/* 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
#if !CHIP_HAS_FIXED_INTVEC_BASE()
t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
#endif
#if CHIP_HAS_TILE_RTF_HWM()
t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
#endif
#if CHIP_HAS_DSTREAM_PF()
t->dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
#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_FIXED_INTVEC_BASE()
__insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
#endif
#if CHIP_HAS_TILE_RTF_HWM()
__insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
#endif
#if CHIP_HAS_DSTREAM_PF()
__insn_mtspr(SPR_DSTREAM_PF, t->dstream_pf);
#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
}
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
#ifdef CONFIG_HARDWALL
/* Enable or disable access to the network registers appropriately. */
if (prev->thread.hardwall != NULL) {
if (next->thread.hardwall == NULL)
restrict_network_mpls();
} else if (next->thread.hardwall != NULL) {
grant_network_mpls();
}
#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_K_0 when we reset our sp.
*/
return __switch_to(prev, next, next_current_ksp0(next));
}
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
void __user *, parent_tidptr, void __user *, child_tidptr,
struct pt_regs *, regs)
{
if (!newsp)
newsp = regs->sp;
return do_fork(clone_flags, newsp, regs, 0,
parent_tidptr, child_tidptr);
}
/*
* sys_execve() executes a new program.
*/
SYSCALL_DEFINE4(execve, const char __user *, path,
const char __user *const __user *, argv,
const char __user *const __user *, envp,
struct pt_regs *, regs)
{
long 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
long compat_sys_execve(const char __user *path,
const compat_uptr_t __user *argv,
const compat_uptr_t __user *envp,
struct pt_regs *regs)
{
long 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 */
}
void show_regs(struct pt_regs *regs)
{
struct task_struct *tsk = validate_current();
int i;
pr_err("\n");
pr_err(" Pid: %d, comm: %20s, CPU: %d\n",
tsk->pid, tsk->comm, smp_processor_id());
#ifdef __tilegx__
for (i = 0; i < 51; i += 3)
pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
i, regs->regs[i], i+1, regs->regs[i+1],
i+2, regs->regs[i+2]);
pr_err(" r51: "REGFMT" r52: "REGFMT" tp : "REGFMT"\n",
regs->regs[51], regs->regs[52], regs->tp);
pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
#else
for (i = 0; i < 52; i += 4)
pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
i, regs->regs[i], i+1, regs->regs[i+1],
i+2, regs->regs[i+2], i+3, regs->regs[i+3]);
pr_err(" r52: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
regs->regs[52], regs->tp, regs->sp, regs->lr);
#endif
pr_err(" pc : "REGFMT" ex1: %ld faultnum: %ld\n",
regs->pc, regs->ex1, regs->faultnum);
dump_stack_regs(regs);
}
