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linux-sg2042/arch/tile/kernel/process.c

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/*
* 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/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.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/nmi.h>
#include <linux/syscalls.h>
#include <linux/kernel.h>
#include <linux/tracehook.h>
#include <linux/signal.h>
#include <linux/delay.h>
#include <linux/context_tracking.h>
#include <asm/stack.h>
#include <asm/switch_to.h>
#include <asm/homecache.h>
#include <asm/syscalls.h>
#include <asm/traps.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
#ifdef CONFIG_HARDWALL
#include <asm/hardwall.h>
#endif
#include <arch/chip.h>
#include <arch/abi.h>
#include <arch/sim_def.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 __init idle_setup(char *str)
{
if (!str)
return -EINVAL;
if (!strcmp(str, "poll")) {
pr_info("using polling idle threads\n");
cpu_idle_poll_ctrl(true);
return 0;
} else if (!strcmp(str, "halt")) {
return 0;
}
return -1;
}
early_param("idle", idle_setup);
void arch_cpu_idle(void)
{
__this_cpu_write(irq_stat.idle_timestamp, jiffies);
_cpu_idle();
}
/*
* Release a thread_info structure
*/
void arch_release_thread_stack(unsigned long *stack)
{
struct thread_info *info = (void *)stack;
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);
}
}
static void save_arch_state(struct thread_struct *t);
int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p)
{
struct pt_regs *childregs = task_pt_regs(p);
unsigned long ksp;
unsigned long *callee_regs;
/*
* Set up the stack and stack pointer appropriately for the
* new child to find itself woken up in __switch_to().
* The callee-saved registers must be on the stack to be read;
* the new task will then jump to assembly support to handle
* calling schedule_tail(), etc., and (for userspace tasks)
* returning to the context set up in the pt_regs.
*/
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);
callee_regs = (unsigned long *)ksp;
ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */
((long *)ksp)[0] = ((long *)ksp)[1] = 0;
p->thread.ksp = ksp;
/* Record the pid of the task that created this one. */
p->thread.creator_pid = current->pid;
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
memset(&callee_regs[2], 0,
(CALLEE_SAVED_REGS_COUNT - 2) * sizeof(unsigned long));
callee_regs[0] = sp; /* r30 = function */
callee_regs[1] = arg; /* r31 = arg */
p->thread.pc = (unsigned long) ret_from_kernel_thread;
return 0;
}
/*
* 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;
/*
* Do not clone step state from the parent; each thread
* must make its own lazily.
*/
task_thread_info(p)->step_state = NULL;
#ifdef __tilegx__
/*
* Do not clone unalign jit fixup from the parent; each thread
* must allocate its own on demand.
*/
task_thread_info(p)->unalign_jit_base = NULL;
#endif
/*
* Copy the registers onto the kernel stack so the
* return-from-interrupt code will reload it into registers.
*/
*childregs = *current_pt_regs();
childregs->regs[0] = 0; /* return value is zero */
if (sp)
childregs->sp = sp; /* override with new user stack pointer */
memcpy(callee_regs, &childregs->regs[CALLEE_SAVED_FIRST_REG],
CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
/* Save user stack top pointer so we can ID the stack vm area later. */
p->thread.usp0 = childregs->sp;
/*
* If CLONE_SETTLS is set, set "tp" in the new task to "r4",
* which is passed in as arg #5 to sys_clone().
*/
if (clone_flags & CLONE_SETTLS)
childregs->tp = childregs->regs[4];
#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
/* New thread has its miscellaneous processor state bits clear. */
p->thread.proc_status = 0;
#ifdef CONFIG_HARDWALL
/* New thread does not own any networks. */
memset(&p->thread.hardwall[0], 0,
sizeof(struct hardwall_task) * HARDWALL_TYPES);
#endif
/*
* Start the new thread with the current architecture state
* (user interrupt masks, etc.).
*/
save_arch_state(&p->thread);
return 0;
}
int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
{
task_thread_info(tsk)->align_ctl = val;
return 0;
}
int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
{
return put_user(task_thread_info(tsk)->align_ctl,
(unsigned int __user *)adr);
}
static struct task_struct corrupt_current = { .comm = "<corrupt>" };
/*
* 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)
{
struct task_struct *tsk = current;
if (unlikely((unsigned long)tsk < PAGE_OFFSET ||
(high_memory && (void *)tsk > high_memory) ||
((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
tsk = &corrupt_current;
}
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);
t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
#if !CHIP_HAS_FIXED_INTVEC_BASE()
t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
#endif
t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
#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);
__insn_mtspr(SPR_PROC_STATUS, t->proc_status);
#if !CHIP_HAS_FIXED_INTVEC_BASE()
__insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
#endif
__insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
#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_TILE_DMA()
struct tile_dma_state *dma = &current->thread.tile_dma_state;
if (dma->enabled)
save_tile_dma_state(dma);
#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);
#ifdef CONFIG_HARDWALL
/* Enable or disable access to the network registers appropriately. */
hardwall_switch_tasks(prev, next);
#endif
/* Notify the simulator of task exit. */
if (unlikely(prev->state == TASK_DEAD))
__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
(prev->pid << _SIM_CONTROL_OPERATOR_BITS));
/*
* 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));
}
/*
* This routine is called on return from interrupt if any of the
* TIF_ALLWORK_MASK flags are set in thread_info->flags. It is
* entered with interrupts disabled so we don't miss an event that
* modified the thread_info flags. We loop until all the tested flags
* are clear. Note that the function is called on certain conditions
* that are not listed in the loop condition here (e.g. SINGLESTEP)
* which guarantees we will do those things once, and redo them if any
* of the other work items is re-done, but won't continue looping if
* all the other work is done.
*/
void prepare_exit_to_usermode(struct pt_regs *regs, u32 thread_info_flags)
{
if (WARN_ON(!user_mode(regs)))
return;
do {
local_irq_enable();
if (thread_info_flags & _TIF_NEED_RESCHED)
schedule();
#if CHIP_HAS_TILE_DMA()
if (thread_info_flags & _TIF_ASYNC_TLB)
do_async_page_fault(regs);
#endif
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
local_irq_disable();
thread_info_flags = READ_ONCE(current_thread_info()->flags);
} while (thread_info_flags & _TIF_WORK_MASK);
if (thread_info_flags & _TIF_SINGLESTEP) {
single_step_once(regs);
#ifndef __tilegx__
/*
* FIXME: on tilepro, since we enable interrupts in
* this routine, it's possible that we miss a signal
* or other asynchronous event.
*/
local_irq_disable();
#endif
}
user_enter();
}
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;
}
/* Flush thread state. */
void flush_thread(void)
{
/* Nothing */
}
/*
* Free current thread data structures etc..
*/
void exit_thread(struct task_struct *tsk)
{
#ifdef CONFIG_HARDWALL
/*
* Remove the task from the list of tasks that are associated
* with any live hardwalls. (If the task that is exiting held
* the last reference to a hardwall fd, it would already have
* been released and deactivated at this point.)
*/
hardwall_deactivate_all(tsk);
#endif
}
void tile_show_regs(struct pt_regs *regs)
{
int i;
#ifdef __tilegx__
for (i = 0; i < 17; i++)
pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
i, regs->regs[i], i+18, regs->regs[i+18],
i+36, regs->regs[i+36]);
pr_err(" r17: "REGFMT" r35: "REGFMT" tp : "REGFMT"\n",
regs->regs[17], regs->regs[35], regs->tp);
pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
#else
for (i = 0; i < 13; i++)
pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
i, regs->regs[i], i+14, regs->regs[i+14],
i+27, regs->regs[i+27], i+40, regs->regs[i+40]);
pr_err(" r13: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
regs->regs[13], regs->tp, regs->sp, regs->lr);
#endif
pr_err(" pc : "REGFMT" ex1: %ld faultnum: %ld flags:%s%s%s%s\n",
regs->pc, regs->ex1, regs->faultnum,
is_compat_task() ? " compat" : "",
(regs->flags & PT_FLAGS_DISABLE_IRQ) ? " noirq" : "",
!(regs->flags & PT_FLAGS_CALLER_SAVES) ? " nocallersave" : "",
(regs->flags & PT_FLAGS_RESTORE_REGS) ? " restoreregs" : "");
}
void show_regs(struct pt_regs *regs)
{
struct KBacktraceIterator kbt;
show_regs_print_info(KERN_DEFAULT);
tile_show_regs(regs);
KBacktraceIterator_init(&kbt, NULL, regs);
tile_show_stack(&kbt);
}
#ifdef __tilegx__
void nmi_raise_cpu_backtrace(struct cpumask *in_mask)
{
struct cpumask mask;
HV_Coord tile;
unsigned int timeout;
int cpu;
HV_NMI_Info info[NR_CPUS];
/* Tentatively dump stack on remote tiles via NMI. */
timeout = 100;
cpumask_copy(&mask, in_mask);
while (!cpumask_empty(&mask) && timeout) {
for_each_cpu(cpu, &mask) {
tile.x = cpu_x(cpu);
tile.y = cpu_y(cpu);
info[cpu] = hv_send_nmi(tile, TILE_NMI_DUMP_STACK, 0);
if (info[cpu].result == HV_NMI_RESULT_OK)
cpumask_clear_cpu(cpu, &mask);
}
mdelay(10);
touch_softlockup_watchdog();
timeout--;
}
/* Warn about cpus stuck in ICS. */
if (!cpumask_empty(&mask)) {
for_each_cpu(cpu, &mask) {
/* Clear the bit as if nmi_cpu_backtrace() ran. */
cpumask_clear_cpu(cpu, in_mask);
switch (info[cpu].result) {
case HV_NMI_RESULT_FAIL_ICS:
pr_warn("Skipping stack dump of cpu %d in ICS at pc %#llx\n",
cpu, info[cpu].pc);
break;
case HV_NMI_RESULT_FAIL_HV:
pr_warn("Skipping stack dump of cpu %d in hypervisor\n",
cpu);
break;
case HV_ENOSYS:
WARN_ONCE(1, "Hypervisor too old to allow remote stack dumps.\n");
break;
default: /* should not happen */
pr_warn("Skipping stack dump of cpu %d [%d,%#llx]\n",
cpu, info[cpu].result, info[cpu].pc);
break;
}
}
}
}
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
{
nmi_trigger_cpumask_backtrace(mask, exclude_self,
nmi_raise_cpu_backtrace);
}
#endif /* __tilegx_ */
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