357 lines
9.5 KiB
C
357 lines
9.5 KiB
C
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/*
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* arch/xtensa/kernel/process.c
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*
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* Xtensa Processor version.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2001 - 2005 Tensilica Inc.
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*
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* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
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* Chris Zankel <chris@zankel.net>
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* Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
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* Kevin Chea
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*/
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/ptrace.h>
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#include <linux/elf.h>
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#include <linux/init.h>
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#include <linux/prctl.h>
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#include <linux/init_task.h>
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#include <linux/module.h>
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#include <linux/mqueue.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/rcupdate.h>
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#include <asm/pgtable.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <asm/processor.h>
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#include <asm/platform.h>
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#include <asm/mmu.h>
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#include <asm/irq.h>
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#include <linux/atomic.h>
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#include <asm/asm-offsets.h>
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#include <asm/regs.h>
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extern void ret_from_fork(void);
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extern void ret_from_kernel_thread(void);
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struct task_struct *current_set[NR_CPUS] = {&init_task, };
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void (*pm_power_off)(void) = NULL;
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EXPORT_SYMBOL(pm_power_off);
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#if XTENSA_HAVE_COPROCESSORS
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void coprocessor_release_all(struct thread_info *ti)
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{
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unsigned long cpenable;
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int i;
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/* Make sure we don't switch tasks during this operation. */
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preempt_disable();
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/* Walk through all cp owners and release it for the requested one. */
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cpenable = ti->cpenable;
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for (i = 0; i < XCHAL_CP_MAX; i++) {
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if (coprocessor_owner[i] == ti) {
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coprocessor_owner[i] = 0;
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cpenable &= ~(1 << i);
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}
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}
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ti->cpenable = cpenable;
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coprocessor_clear_cpenable();
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preempt_enable();
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}
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void coprocessor_flush_all(struct thread_info *ti)
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{
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unsigned long cpenable;
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int i;
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preempt_disable();
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cpenable = ti->cpenable;
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for (i = 0; i < XCHAL_CP_MAX; i++) {
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if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
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coprocessor_flush(ti, i);
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cpenable >>= 1;
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}
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preempt_enable();
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}
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#endif
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/*
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* Powermanagement idle function, if any is provided by the platform.
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*/
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void arch_cpu_idle(void)
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{
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platform_idle();
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}
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/*
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* This is called when the thread calls exit().
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*/
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void exit_thread(void)
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{
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#if XTENSA_HAVE_COPROCESSORS
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coprocessor_release_all(current_thread_info());
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#endif
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}
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/*
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* Flush thread state. This is called when a thread does an execve()
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* Note that we flush coprocessor registers for the case execve fails.
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*/
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void flush_thread(void)
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{
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#if XTENSA_HAVE_COPROCESSORS
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struct thread_info *ti = current_thread_info();
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coprocessor_flush_all(ti);
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coprocessor_release_all(ti);
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#endif
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}
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/*
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* this gets called so that we can store coprocessor state into memory and
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* copy the current task into the new thread.
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*/
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int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
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{
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#if XTENSA_HAVE_COPROCESSORS
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coprocessor_flush_all(task_thread_info(src));
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#endif
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*dst = *src;
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return 0;
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}
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/*
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* Copy thread.
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*
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* There are two modes in which this function is called:
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* 1) Userspace thread creation,
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* regs != NULL, usp_thread_fn is userspace stack pointer.
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* It is expected to copy parent regs (in case CLONE_VM is not set
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* in the clone_flags) and set up passed usp in the childregs.
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* 2) Kernel thread creation,
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* regs == NULL, usp_thread_fn is the function to run in the new thread
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* and thread_fn_arg is its parameter.
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* childregs are not used for the kernel threads.
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*
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* The stack layout for the new thread looks like this:
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*
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* +------------------------+
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* | childregs |
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* +------------------------+ <- thread.sp = sp in dummy-frame
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* | dummy-frame | (saved in dummy-frame spill-area)
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* +------------------------+
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*
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* We create a dummy frame to return to either ret_from_fork or
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* ret_from_kernel_thread:
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* a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
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* sp points to itself (thread.sp)
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* a2, a3 are unused for userspace threads,
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* a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
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*
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* Note: This is a pristine frame, so we don't need any spill region on top of
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* childregs.
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*
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* The fun part: if we're keeping the same VM (i.e. cloning a thread,
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* not an entire process), we're normally given a new usp, and we CANNOT share
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* any live address register windows. If we just copy those live frames over,
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* the two threads (parent and child) will overflow the same frames onto the
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* parent stack at different times, likely corrupting the parent stack (esp.
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* if the parent returns from functions that called clone() and calls new
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* ones, before the child overflows its now old copies of its parent windows).
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* One solution is to spill windows to the parent stack, but that's fairly
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* involved. Much simpler to just not copy those live frames across.
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*/
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int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
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unsigned long thread_fn_arg, struct task_struct *p)
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{
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struct pt_regs *childregs = task_pt_regs(p);
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#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
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struct thread_info *ti;
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#endif
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/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
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*((int*)childregs - 3) = (unsigned long)childregs;
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*((int*)childregs - 4) = 0;
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p->thread.sp = (unsigned long)childregs;
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if (!(p->flags & PF_KTHREAD)) {
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struct pt_regs *regs = current_pt_regs();
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unsigned long usp = usp_thread_fn ?
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usp_thread_fn : regs->areg[1];
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p->thread.ra = MAKE_RA_FOR_CALL(
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(unsigned long)ret_from_fork, 0x1);
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/* This does not copy all the regs.
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* In a bout of brilliance or madness,
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* ARs beyond a0-a15 exist past the end of the struct.
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*/
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*childregs = *regs;
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childregs->areg[1] = usp;
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childregs->areg[2] = 0;
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/* When sharing memory with the parent thread, the child
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usually starts on a pristine stack, so we have to reset
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windowbase, windowstart and wmask.
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(Note that such a new thread is required to always create
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an initial call4 frame)
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The exception is vfork, where the new thread continues to
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run on the parent's stack until it calls execve. This could
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be a call8 or call12, which requires a legal stack frame
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of the previous caller for the overflow handlers to work.
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(Note that it's always legal to overflow live registers).
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In this case, ensure to spill at least the stack pointer
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of that frame. */
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if (clone_flags & CLONE_VM) {
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/* check that caller window is live and same stack */
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int len = childregs->wmask & ~0xf;
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if (regs->areg[1] == usp && len != 0) {
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int callinc = (regs->areg[0] >> 30) & 3;
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int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
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put_user(regs->areg[caller_ars+1],
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(unsigned __user*)(usp - 12));
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}
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childregs->wmask = 1;
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childregs->windowstart = 1;
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childregs->windowbase = 0;
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} else {
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int len = childregs->wmask & ~0xf;
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memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
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®s->areg[XCHAL_NUM_AREGS - len/4], len);
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}
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/* The thread pointer is passed in the '4th argument' (= a5) */
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if (clone_flags & CLONE_SETTLS)
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childregs->threadptr = childregs->areg[5];
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} else {
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p->thread.ra = MAKE_RA_FOR_CALL(
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(unsigned long)ret_from_kernel_thread, 1);
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/* pass parameters to ret_from_kernel_thread:
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* a2 = thread_fn, a3 = thread_fn arg
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*/
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*((int *)childregs - 1) = thread_fn_arg;
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*((int *)childregs - 2) = usp_thread_fn;
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/* Childregs are only used when we're going to userspace
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* in which case start_thread will set them up.
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*/
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}
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#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
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ti = task_thread_info(p);
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ti->cpenable = 0;
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#endif
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return 0;
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}
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/*
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* These bracket the sleeping functions..
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*/
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unsigned long get_wchan(struct task_struct *p)
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{
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unsigned long sp, pc;
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unsigned long stack_page = (unsigned long) task_stack_page(p);
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int count = 0;
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if (!p || p == current || p->state == TASK_RUNNING)
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return 0;
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sp = p->thread.sp;
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pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
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do {
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if (sp < stack_page + sizeof(struct task_struct) ||
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sp >= (stack_page + THREAD_SIZE) ||
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pc == 0)
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return 0;
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if (!in_sched_functions(pc))
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return pc;
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/* Stack layout: sp-4: ra, sp-3: sp' */
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pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
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sp = *(unsigned long *)sp - 3;
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} while (count++ < 16);
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return 0;
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}
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/*
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* xtensa_gregset_t and 'struct pt_regs' are vastly different formats
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* of processor registers. Besides different ordering,
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* xtensa_gregset_t contains non-live register information that
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* 'struct pt_regs' does not. Exception handling (primarily) uses
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* 'struct pt_regs'. Core files and ptrace use xtensa_gregset_t.
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*
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*/
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void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
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{
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unsigned long wb, ws, wm;
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int live, last;
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wb = regs->windowbase;
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ws = regs->windowstart;
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wm = regs->wmask;
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ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
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/* Don't leak any random bits. */
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memset(elfregs, 0, sizeof(*elfregs));
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/* Note: PS.EXCM is not set while user task is running; its
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* being set in regs->ps is for exception handling convenience.
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*/
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elfregs->pc = regs->pc;
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elfregs->ps = (regs->ps & ~(1 << PS_EXCM_BIT));
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elfregs->lbeg = regs->lbeg;
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elfregs->lend = regs->lend;
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elfregs->lcount = regs->lcount;
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elfregs->sar = regs->sar;
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elfregs->windowstart = ws;
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live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
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last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
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memcpy(elfregs->a, regs->areg, live * 4);
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memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
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}
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int dump_fpu(void)
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{
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return 0;
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}
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