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![Eric W. Biederman](/assets/img/avatar_default.png)
Add fn and fn_arg members into struct kernel_clone_args and test for them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER). This allows any task that wants to be a user space task that only runs in kernel mode to use this functionality. The code on x86 is an exception and still retains a PF_KTHREAD test because x86 unlikely everything else handles kthreads slightly differently than user space tasks that start with a function. The functions that created tasks that start with a function have been updated to set ".fn" and ".fn_arg" instead of ".stack" and ".stack_size". These functions are fork_idle(), create_io_thread(), kernel_thread(), and user_mode_thread(). Link: https://lkml.kernel.org/r/20220506141512.516114-4-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
232 lines
5.9 KiB
C
232 lines
5.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file handles the architecture dependent parts of process handling.
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*
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* Copyright IBM Corp. 1999, 2009
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
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* Hartmut Penner <hp@de.ibm.com>,
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* Denis Joseph Barrow,
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*/
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#include <linux/elf-randomize.h>
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#include <linux/compiler.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task.h>
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#include <linux/sched/task_stack.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/elfcore.h>
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#include <linux/smp.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/tick.h>
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#include <linux/personality.h>
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#include <linux/syscalls.h>
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#include <linux/compat.h>
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#include <linux/kprobes.h>
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#include <linux/random.h>
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#include <linux/export.h>
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#include <linux/init_task.h>
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#include <linux/entry-common.h>
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#include <asm/cpu_mf.h>
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#include <asm/io.h>
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#include <asm/processor.h>
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#include <asm/vtimer.h>
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#include <asm/exec.h>
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#include <asm/irq.h>
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#include <asm/nmi.h>
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#include <asm/smp.h>
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#include <asm/stacktrace.h>
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#include <asm/switch_to.h>
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#include <asm/runtime_instr.h>
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#include <asm/unwind.h>
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#include "entry.h"
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void ret_from_fork(void) asm("ret_from_fork");
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void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
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{
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void (*func)(void *arg);
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schedule_tail(prev);
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if (!user_mode(regs)) {
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/* Kernel thread */
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func = (void *)regs->gprs[9];
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func((void *)regs->gprs[10]);
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}
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clear_pt_regs_flag(regs, PIF_SYSCALL);
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syscall_exit_to_user_mode(regs);
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}
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void flush_thread(void)
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{
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}
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void arch_setup_new_exec(void)
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{
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if (S390_lowcore.current_pid != current->pid) {
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S390_lowcore.current_pid = current->pid;
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if (test_facility(40))
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lpp(&S390_lowcore.lpp);
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}
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}
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void arch_release_task_struct(struct task_struct *tsk)
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{
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runtime_instr_release(tsk);
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guarded_storage_release(tsk);
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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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/*
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* Save the floating-point or vector register state of the current
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* task and set the CIF_FPU flag to lazy restore the FPU register
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* state when returning to user space.
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*/
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save_fpu_regs();
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memcpy(dst, src, arch_task_struct_size);
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dst->thread.fpu.regs = dst->thread.fpu.fprs;
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return 0;
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}
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int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
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{
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unsigned long clone_flags = args->flags;
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unsigned long new_stackp = args->stack;
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unsigned long tls = args->tls;
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struct fake_frame
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{
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struct stack_frame sf;
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struct pt_regs childregs;
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} *frame;
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frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
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p->thread.ksp = (unsigned long) frame;
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/* Save access registers to new thread structure. */
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save_access_regs(&p->thread.acrs[0]);
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/* start new process with ar4 pointing to the correct address space */
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/* Don't copy debug registers */
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memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
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memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
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clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
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p->thread.per_flags = 0;
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/* Initialize per thread user and system timer values */
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p->thread.user_timer = 0;
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p->thread.guest_timer = 0;
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p->thread.system_timer = 0;
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p->thread.hardirq_timer = 0;
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p->thread.softirq_timer = 0;
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p->thread.last_break = 1;
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frame->sf.back_chain = 0;
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frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame);
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frame->sf.gprs[6] = (unsigned long)p;
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/* new return point is ret_from_fork */
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frame->sf.gprs[8] = (unsigned long)ret_from_fork;
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/* fake return stack for resume(), don't go back to schedule */
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frame->sf.gprs[9] = (unsigned long)frame;
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/* Store access registers to kernel stack of new process. */
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if (unlikely(args->fn)) {
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/* kernel thread */
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memset(&frame->childregs, 0, sizeof(struct pt_regs));
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frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
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PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
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frame->childregs.psw.addr =
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(unsigned long)__ret_from_fork;
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frame->childregs.gprs[9] = (unsigned long)args->fn;
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frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
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frame->childregs.orig_gpr2 = -1;
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frame->childregs.last_break = 1;
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return 0;
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}
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frame->childregs = *current_pt_regs();
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frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
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frame->childregs.flags = 0;
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if (new_stackp)
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frame->childregs.gprs[15] = new_stackp;
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/* Don't copy runtime instrumentation info */
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p->thread.ri_cb = NULL;
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frame->childregs.psw.mask &= ~PSW_MASK_RI;
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/* Don't copy guarded storage control block */
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p->thread.gs_cb = NULL;
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p->thread.gs_bc_cb = NULL;
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/* Set a new TLS ? */
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if (clone_flags & CLONE_SETTLS) {
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if (is_compat_task()) {
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p->thread.acrs[0] = (unsigned int)tls;
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} else {
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p->thread.acrs[0] = (unsigned int)(tls >> 32);
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p->thread.acrs[1] = (unsigned int)tls;
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}
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}
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/*
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* s390 stores the svc return address in arch_data when calling
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* sigreturn()/restart_syscall() via vdso. 1 means no valid address
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* stored.
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*/
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p->restart_block.arch_data = 1;
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return 0;
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}
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void execve_tail(void)
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{
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current->thread.fpu.fpc = 0;
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asm volatile("sfpc %0" : : "d" (0));
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}
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unsigned long __get_wchan(struct task_struct *p)
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{
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struct unwind_state state;
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unsigned long ip = 0;
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if (!task_stack_page(p))
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return 0;
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if (!try_get_task_stack(p))
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return 0;
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unwind_for_each_frame(&state, p, NULL, 0) {
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if (state.stack_info.type != STACK_TYPE_TASK) {
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ip = 0;
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break;
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}
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ip = unwind_get_return_address(&state);
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if (!ip)
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break;
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if (!in_sched_functions(ip))
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break;
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}
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put_task_stack(p);
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return ip;
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}
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unsigned long arch_align_stack(unsigned long sp)
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{
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if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
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sp -= get_random_int() & ~PAGE_MASK;
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return sp & ~0xf;
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}
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static inline unsigned long brk_rnd(void)
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{
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return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
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}
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unsigned long arch_randomize_brk(struct mm_struct *mm)
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{
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unsigned long ret;
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ret = PAGE_ALIGN(mm->brk + brk_rnd());
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return (ret > mm->brk) ? ret : mm->brk;
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}
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