/* * linux/arch/i386/kernel/process.c * * Copyright (C) 1995 Linus Torvalds * * Pentium III FXSR, SSE support * Gareth Hughes , May 2000 */ /* * This file handles the architecture-dependent parts of process handling.. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_MATH_EMULATION #include #endif #include #include #include #include asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); static int hlt_counter; unsigned long boot_option_idle_override = 0; EXPORT_SYMBOL(boot_option_idle_override); /* * Return saved PC of a blocked thread. */ unsigned long thread_saved_pc(struct task_struct *tsk) { return ((unsigned long *)tsk->thread.esp)[3]; } /* * Powermanagement idle function, if any.. */ void (*pm_idle)(void); EXPORT_SYMBOL(pm_idle); static DEFINE_PER_CPU(unsigned int, cpu_idle_state); void disable_hlt(void) { hlt_counter++; } EXPORT_SYMBOL(disable_hlt); void enable_hlt(void) { hlt_counter--; } EXPORT_SYMBOL(enable_hlt); /* * We use this if we don't have any better * idle routine.. */ void default_idle(void) { if (!hlt_counter && boot_cpu_data.hlt_works_ok) { local_irq_disable(); if (!need_resched()) safe_halt(); else local_irq_enable(); } else { cpu_relax(); } } #ifdef CONFIG_APM_MODULE EXPORT_SYMBOL(default_idle); #endif /* * On SMP it's slightly faster (but much more power-consuming!) * to poll the ->work.need_resched flag instead of waiting for the * cross-CPU IPI to arrive. Use this option with caution. */ static void poll_idle (void) { int oldval; local_irq_enable(); /* * Deal with another CPU just having chosen a thread to * run here: */ oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); if (!oldval) { set_thread_flag(TIF_POLLING_NRFLAG); asm volatile( "2:" "testl %0, %1;" "rep; nop;" "je 2b;" : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags)); clear_thread_flag(TIF_POLLING_NRFLAG); } else { set_need_resched(); } } #ifdef CONFIG_HOTPLUG_CPU #include /* We don't actually take CPU down, just spin without interrupts. */ static inline void play_dead(void) { /* This must be done before dead CPU ack */ cpu_exit_clear(); wbinvd(); mb(); /* Ack it */ __get_cpu_var(cpu_state) = CPU_DEAD; /* * With physical CPU hotplug, we should halt the cpu */ local_irq_disable(); while (1) halt(); } #else static inline void play_dead(void) { BUG(); } #endif /* CONFIG_HOTPLUG_CPU */ /* * 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 = raw_smp_processor_id(); /* endless idle loop with no priority at all */ while (1) { while (!need_resched()) { void (*idle)(void); if (__get_cpu_var(cpu_idle_state)) __get_cpu_var(cpu_idle_state) = 0; rmb(); idle = pm_idle; if (!idle) idle = default_idle; if (cpu_is_offline(cpu)) play_dead(); __get_cpu_var(irq_stat).idle_timestamp = jiffies; idle(); } schedule(); } } void cpu_idle_wait(void) { unsigned int cpu, this_cpu = get_cpu(); cpumask_t map; set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); put_cpu(); cpus_clear(map); for_each_online_cpu(cpu) { per_cpu(cpu_idle_state, cpu) = 1; cpu_set(cpu, map); } __get_cpu_var(cpu_idle_state) = 0; wmb(); do { ssleep(1); for_each_online_cpu(cpu) { if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu)) cpu_clear(cpu, map); } cpus_and(map, map, cpu_online_map); } while (!cpus_empty(map)); } EXPORT_SYMBOL_GPL(cpu_idle_wait); /* * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, * which can obviate IPI to trigger checking of need_resched. * We execute MONITOR against need_resched and enter optimized wait state * through MWAIT. Whenever someone changes need_resched, we would be woken * up from MWAIT (without an IPI). */ static void mwait_idle(void) { local_irq_enable(); if (!need_resched()) { set_thread_flag(TIF_POLLING_NRFLAG); do { __monitor((void *)¤t_thread_info()->flags, 0, 0); if (need_resched()) break; __mwait(0, 0); } while (!need_resched()); clear_thread_flag(TIF_POLLING_NRFLAG); } } void __devinit select_idle_routine(const struct cpuinfo_x86 *c) { if (cpu_has(c, X86_FEATURE_MWAIT)) { printk("monitor/mwait feature present.\n"); /* * Skip, if setup has overridden idle. * One CPU supports mwait => All CPUs supports mwait */ if (!pm_idle) { printk("using mwait in idle threads.\n"); pm_idle = mwait_idle; } } } static int __init idle_setup (char *str) { if (!strncmp(str, "poll", 4)) { printk("using polling idle threads.\n"); pm_idle = poll_idle; #ifdef CONFIG_X86_SMP if (smp_num_siblings > 1) printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); #endif } else if (!strncmp(str, "halt", 4)) { printk("using halt in idle threads.\n"); pm_idle = default_idle; } boot_option_idle_override = 1; return 1; } __setup("idle=", idle_setup); void show_regs(struct pt_regs * regs) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; printk("\n"); printk("Pid: %d, comm: %20s\n", current->pid, current->comm); printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id()); print_symbol("EIP is at %s\n", regs->eip); if (user_mode(regs)) printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp); printk(" EFLAGS: %08lx %s (%s)\n", regs->eflags, print_tainted(), system_utsname.release); printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", regs->eax,regs->ebx,regs->ecx,regs->edx); printk("ESI: %08lx EDI: %08lx EBP: %08lx", regs->esi, regs->edi, regs->ebp); printk(" DS: %04x ES: %04x\n", 0xffff & regs->xds,0xffff & regs->xes); cr0 = read_cr0(); cr2 = read_cr2(); cr3 = read_cr3(); if (current_cpu_data.x86 > 4) { cr4 = read_cr4(); } printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4); show_trace(NULL, ®s->esp); } /* * This gets run with %ebx containing the * function to call, and %edx containing * the "args". */ extern void kernel_thread_helper(void); __asm__(".section .text\n" ".align 4\n" "kernel_thread_helper:\n\t" "movl %edx,%eax\n\t" "pushl %edx\n\t" "call *%ebx\n\t" "pushl %eax\n\t" "call do_exit\n" ".previous"); /* * 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.ebx = (unsigned long) fn; regs.edx = (unsigned long) arg; regs.xds = __USER_DS; regs.xes = __USER_DS; regs.orig_eax = -1; regs.eip = (unsigned long) kernel_thread_helper; regs.xcs = __KERNEL_CS; regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; /* Ok, create the new process.. */ return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); } EXPORT_SYMBOL(kernel_thread); /* * Free current thread data structures etc.. */ void exit_thread(void) { struct task_struct *tsk = current; struct thread_struct *t = &tsk->thread; /* * Remove function-return probe instances associated with this task * and put them back on the free list. Do not insert an exit probe for * this function, it will be disabled by kprobe_flush_task if you do. */ kprobe_flush_task(tsk); /* The process may have allocated an io port bitmap... nuke it. */ if (unlikely(NULL != t->io_bitmap_ptr)) { int cpu = get_cpu(); struct tss_struct *tss = &per_cpu(init_tss, cpu); kfree(t->io_bitmap_ptr); t->io_bitmap_ptr = NULL; /* * Careful, clear this in the TSS too: */ memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); t->io_bitmap_max = 0; tss->io_bitmap_owner = NULL; tss->io_bitmap_max = 0; tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; put_cpu(); } } void flush_thread(void) { struct task_struct *tsk = current; /* * Remove function-return probe instances associated with this task * and put them back on the free list. Do not insert an exit probe for * this function, it will be disabled by kprobe_flush_task if you do. */ kprobe_flush_task(tsk); memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); /* * Forget coprocessor state.. */ clear_fpu(tsk); clear_used_math(); } void release_thread(struct task_struct *dead_task) { if (dead_task->mm) { // temporary debugging check if (dead_task->mm->context.size) { printk("WARNING: dead process %8s still has LDT? <%p/%d>\n", dead_task->comm, dead_task->mm->context.ldt, dead_task->mm->context.size); BUG(); } } release_vm86_irqs(dead_task); } /* * This gets called before we allocate a new thread and copy * the current task into it. */ void prepare_to_copy(struct task_struct *tsk) { unlazy_fpu(tsk); } int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, unsigned long unused, struct task_struct * p, struct pt_regs * regs) { struct pt_regs * childregs; struct task_struct *tsk; int err; childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1; /* * The below -8 is to reserve 8 bytes on top of the ring0 stack. * This is necessary to guarantee that the entire "struct pt_regs" * is accessable even if the CPU haven't stored the SS/ESP registers * on the stack (interrupt gate does not save these registers * when switching to the same priv ring). * Therefore beware: accessing the xss/esp fields of the * "struct pt_regs" is possible, but they may contain the * completely wrong values. */ childregs = (struct pt_regs *) ((unsigned long) childregs - 8); *childregs = *regs; childregs->eax = 0; childregs->esp = esp; p->thread.esp = (unsigned long) childregs; p->thread.esp0 = (unsigned long) (childregs+1); p->thread.eip = (unsigned long) ret_from_fork; savesegment(fs,p->thread.fs); savesegment(gs,p->thread.gs); tsk = current; if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) { p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); if (!p->thread.io_bitmap_ptr) { p->thread.io_bitmap_max = 0; return -ENOMEM; } memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr, IO_BITMAP_BYTES); } /* * Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) { struct desc_struct *desc; struct user_desc info; int idx; err = -EFAULT; if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info))) goto out; err = -EINVAL; if (LDT_empty(&info)) goto out; idx = info.entry_number; if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) goto out; desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; desc->a = LDT_entry_a(&info); desc->b = LDT_entry_b(&info); } err = 0; out: if (err && p->thread.io_bitmap_ptr) { kfree(p->thread.io_bitmap_ptr); p->thread.io_bitmap_max = 0; } return err; } /* * fill in the user structure for a core dump.. */ void dump_thread(struct pt_regs * regs, struct user * dump) { int i; /* changed the size calculations - should hopefully work better. lbt */ dump->magic = CMAGIC; dump->start_code = 0; dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; dump->u_dsize -= dump->u_tsize; dump->u_ssize = 0; for (i = 0; i < 8; i++) dump->u_debugreg[i] = current->thread.debugreg[i]; if (dump->start_stack < TASK_SIZE) dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; dump->regs.ebx = regs->ebx; dump->regs.ecx = regs->ecx; dump->regs.edx = regs->edx; dump->regs.esi = regs->esi; dump->regs.edi = regs->edi; dump->regs.ebp = regs->ebp; dump->regs.eax = regs->eax; dump->regs.ds = regs->xds; dump->regs.es = regs->xes; savesegment(fs,dump->regs.fs); savesegment(gs,dump->regs.gs); dump->regs.orig_eax = regs->orig_eax; dump->regs.eip = regs->eip; dump->regs.cs = regs->xcs; dump->regs.eflags = regs->eflags; dump->regs.esp = regs->esp; dump->regs.ss = regs->xss; dump->u_fpvalid = dump_fpu (regs, &dump->i387); } EXPORT_SYMBOL(dump_thread); /* * Capture the user space registers if the task is not running (in user space) */ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) { struct pt_regs ptregs; ptregs = *(struct pt_regs *) ((unsigned long)tsk->thread_info+THREAD_SIZE - sizeof(ptregs)); ptregs.xcs &= 0xffff; ptregs.xds &= 0xffff; ptregs.xes &= 0xffff; ptregs.xss &= 0xffff; elf_core_copy_regs(regs, &ptregs); return 1; } static inline void handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss) { if (!next->io_bitmap_ptr) { /* * Disable the bitmap via an invalid offset. We still cache * the previous bitmap owner and the IO bitmap contents: */ tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; return; } if (likely(next == tss->io_bitmap_owner)) { /* * Previous owner of the bitmap (hence the bitmap content) * matches the next task, we dont have to do anything but * to set a valid offset in the TSS: */ tss->io_bitmap_base = IO_BITMAP_OFFSET; return; } /* * Lazy TSS's I/O bitmap copy. We set an invalid offset here * and we let the task to get a GPF in case an I/O instruction * is performed. The handler of the GPF will verify that the * faulting task has a valid I/O bitmap and, it true, does the * real copy and restart the instruction. This will save us * redundant copies when the currently switched task does not * perform any I/O during its timeslice. */ tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; } /* * This function selects if the context switch from prev to next * has to tweak the TSC disable bit in the cr4. */ static inline void disable_tsc(struct task_struct *prev_p, struct task_struct *next_p) { struct thread_info *prev, *next; /* * gcc should eliminate the ->thread_info dereference if * has_secure_computing returns 0 at compile time (SECCOMP=n). */ prev = prev_p->thread_info; next = next_p->thread_info; if (has_secure_computing(prev) || has_secure_computing(next)) { /* slow path here */ if (has_secure_computing(prev) && !has_secure_computing(next)) { write_cr4(read_cr4() & ~X86_CR4_TSD); } else if (!has_secure_computing(prev) && has_secure_computing(next)) write_cr4(read_cr4() | X86_CR4_TSD); } } /* * switch_to(x,yn) should switch tasks from x to y. * * We fsave/fwait so that an exception goes off at the right time * (as a call from the fsave or fwait in effect) rather than to * the wrong process. Lazy FP saving no longer makes any sense * with modern CPU's, and this simplifies a lot of things (SMP * and UP become the same). * * NOTE! We used to use the x86 hardware context switching. The * reason for not using it any more becomes apparent when you * try to recover gracefully from saved state that is no longer * valid (stale segment register values in particular). With the * hardware task-switch, there is no way to fix up bad state in * a reasonable manner. * * The fact that Intel documents the hardware task-switching to * be slow is a fairly red herring - this code is not noticeably * faster. However, there _is_ some room for improvement here, * so the performance issues may eventually be a valid point. * More important, however, is the fact that this allows us much * more flexibility. * * The return value (in %eax) will be the "prev" task after * the task-switch, and shows up in ret_from_fork in entry.S, * for example. */ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) { struct thread_struct *prev = &prev_p->thread, *next = &next_p->thread; int cpu = smp_processor_id(); struct tss_struct *tss = &per_cpu(init_tss, cpu); /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ __unlazy_fpu(prev_p); /* * Reload esp0. */ load_esp0(tss, next); /* * Save away %fs and %gs. No need to save %es and %ds, as * those are always kernel segments while inside the kernel. * Doing this before setting the new TLS descriptors avoids * the situation where we temporarily have non-reloadable * segments in %fs and %gs. This could be an issue if the * NMI handler ever used %fs or %gs (it does not today), or * if the kernel is running inside of a hypervisor layer. */ savesegment(fs, prev->fs); savesegment(gs, prev->gs); /* * Load the per-thread Thread-Local Storage descriptor. */ load_TLS(next, cpu); /* * Restore %fs and %gs if needed. * * Glibc normally makes %fs be zero, and %gs is one of * the TLS segments. */ if (unlikely(prev->fs | next->fs)) loadsegment(fs, next->fs); if (prev->gs | next->gs) loadsegment(gs, next->gs); /* * Now maybe reload the debug registers */ if (unlikely(next->debugreg[7])) { set_debugreg(next->debugreg[0], 0); set_debugreg(next->debugreg[1], 1); set_debugreg(next->debugreg[2], 2); set_debugreg(next->debugreg[3], 3); /* no 4 and 5 */ set_debugreg(next->debugreg[6], 6); set_debugreg(next->debugreg[7], 7); } if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) handle_io_bitmap(next, tss); disable_tsc(prev_p, next_p); return prev_p; } asmlinkage int sys_fork(struct pt_regs regs) { return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL); } asmlinkage int sys_clone(struct pt_regs regs) { unsigned long clone_flags; unsigned long newsp; int __user *parent_tidptr, *child_tidptr; clone_flags = regs.ebx; newsp = regs.ecx; parent_tidptr = (int __user *)regs.edx; child_tidptr = (int __user *)regs.edi; if (!newsp) newsp = regs.esp; return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); } /* * This is trivial, and on the face of it looks like it * could equally well be done in user mode. * * Not so, for quite unobvious reasons - register pressure. * In user mode vfork() cannot have a stack frame, and if * done by calling the "clone()" system call directly, you * do not have enough call-clobbered registers to hold all * the information you need. */ asmlinkage int sys_vfork(struct pt_regs regs) { return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL); } /* * sys_execve() executes a new program. */ asmlinkage int sys_execve(struct pt_regs regs) { int error; char * filename; filename = getname((char __user *) regs.ebx); error = PTR_ERR(filename); if (IS_ERR(filename)) goto out; error = do_execve(filename, (char __user * __user *) regs.ecx, (char __user * __user *) regs.edx, ®s); if (error == 0) { task_lock(current); current->ptrace &= ~PT_DTRACE; task_unlock(current); /* Make sure we don't return using sysenter.. */ set_thread_flag(TIF_IRET); } putname(filename); out: return error; } #define top_esp (THREAD_SIZE - sizeof(unsigned long)) #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) unsigned long get_wchan(struct task_struct *p) { unsigned long ebp, esp, eip; unsigned long stack_page; int count = 0; if (!p || p == current || p->state == TASK_RUNNING) return 0; stack_page = (unsigned long)p->thread_info; esp = p->thread.esp; if (!stack_page || esp < stack_page || esp > top_esp+stack_page) return 0; /* include/asm-i386/system.h:switch_to() pushes ebp last. */ ebp = *(unsigned long *) esp; do { if (ebp < stack_page || ebp > top_ebp+stack_page) return 0; eip = *(unsigned long *) (ebp+4); if (!in_sched_functions(eip)) return eip; ebp = *(unsigned long *) ebp; } while (count++ < 16); return 0; } EXPORT_SYMBOL(get_wchan); /* * sys_alloc_thread_area: get a yet unused TLS descriptor index. */ static int get_free_idx(void) { struct thread_struct *t = ¤t->thread; int idx; for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) if (desc_empty(t->tls_array + idx)) return idx + GDT_ENTRY_TLS_MIN; return -ESRCH; } /* * Set a given TLS descriptor: */ asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) { struct thread_struct *t = ¤t->thread; struct user_desc info; struct desc_struct *desc; int cpu, idx; if (copy_from_user(&info, u_info, sizeof(info))) return -EFAULT; idx = info.entry_number; /* * index -1 means the kernel should try to find and * allocate an empty descriptor: */ if (idx == -1) { idx = get_free_idx(); if (idx < 0) return idx; if (put_user(idx, &u_info->entry_number)) return -EFAULT; } if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN; /* * We must not get preempted while modifying the TLS. */ cpu = get_cpu(); if (LDT_empty(&info)) { desc->a = 0; desc->b = 0; } else { desc->a = LDT_entry_a(&info); desc->b = LDT_entry_b(&info); } load_TLS(t, cpu); put_cpu(); return 0; } /* * Get the current Thread-Local Storage area: */ #define GET_BASE(desc) ( \ (((desc)->a >> 16) & 0x0000ffff) | \ (((desc)->b << 16) & 0x00ff0000) | \ ( (desc)->b & 0xff000000) ) #define GET_LIMIT(desc) ( \ ((desc)->a & 0x0ffff) | \ ((desc)->b & 0xf0000) ) #define GET_32BIT(desc) (((desc)->b >> 22) & 1) #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) { struct user_desc info; struct desc_struct *desc; int idx; if (get_user(idx, &u_info->entry_number)) return -EFAULT; if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; memset(&info, 0, sizeof(info)); desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; info.entry_number = idx; info.base_addr = GET_BASE(desc); info.limit = GET_LIMIT(desc); info.seg_32bit = GET_32BIT(desc); info.contents = GET_CONTENTS(desc); info.read_exec_only = !GET_WRITABLE(desc); info.limit_in_pages = GET_LIMIT_PAGES(desc); info.seg_not_present = !GET_PRESENT(desc); info.useable = GET_USEABLE(desc); if (copy_to_user(u_info, &info, sizeof(info))) return -EFAULT; return 0; } unsigned long arch_align_stack(unsigned long sp) { if (randomize_va_space) sp -= get_random_int() % 8192; return sp & ~0xf; }