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linux/arch/i386/kernel/process.c

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/*
* linux/arch/i386/kernel/process.c
*
* Copyright (C) 1995 Linus Torvalds
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
/*
* This file handles the architecture-dependent parts of process handling..
*/
#include <stdarg.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elfcore.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/utsname.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
#include <linux/random.h>
#include <linux/personality.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/ldt.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/desc.h>
#include <asm/vm86.h>
#ifdef CONFIG_MATH_EMULATION
#include <asm/math_emu.h>
#endif
#include <linux/err.h>
#include <asm/tlbflush.h>
#include <asm/cpu.h>
#include <asm/pda.h>
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) {
current_thread_info()->status &= ~TS_POLLING;
/*
* TS_POLLING-cleared state must be visible before we
* test NEED_RESCHED:
*/
smp_mb();
local_irq_disable();
if (!need_resched())
safe_halt(); /* enables interrupts racelessly */
else
local_irq_enable();
current_thread_info()->status |= TS_POLLING;
} else {
/* loop is done by the caller */
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)
{
cpu_relax();
}
#ifdef CONFIG_HOTPLUG_CPU
#include <asm/nmi.h>
/* 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 = smp_processor_id();
current_thread_info()->status |= TS_POLLING;
/* 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();
}
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
void cpu_idle_wait(void)
{
unsigned int cpu, this_cpu = get_cpu();
cpumask_t map, tmp = current->cpus_allowed;
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));
set_cpus_allowed(current, tmp);
}
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).
*
* New with Core Duo processors, MWAIT can take some hints based on CPU
* capability.
*/
void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
{
if (!need_resched()) {
__monitor((void *)&current_thread_info()->flags, 0, 0);
smp_mb();
if (!need_resched())
__mwait(eax, ecx);
}
}
/* Default MONITOR/MWAIT with no hints, used for default C1 state */
static void mwait_idle(void)
{
local_irq_enable();
mwait_idle_with_hints(0, 0);
}
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_vm(regs))
printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp);
printk(" EFLAGS: %08lx %s (%s %.*s)\n",
regs->eflags, print_tainted(), init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
init_utsname()->version);
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 FS: %04x\n",
0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xfs);
cr0 = read_cr0();
cr2 = read_cr2();
cr3 = read_cr3();
cr4 = read_cr4_safe();
printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
show_trace(NULL, regs, &regs->esp);
}
/*
* This gets run with %ebx containing the
* function to call, and %edx containing
* the "args".
*/
extern void kernel_thread_helper(void);
/*
* Create a kernel thread
*/
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
struct pt_regs regs;
memset(&regs, 0, sizeof(regs));
regs.ebx = (unsigned long) fn;
regs.edx = (unsigned long) arg;
regs.xds = __USER_DS;
regs.xes = __USER_DS;
regs.xfs = __KERNEL_PDA;
regs.orig_eax = -1;
regs.eip = (unsigned long) kernel_thread_helper;
regs.xcs = __KERNEL_CS | get_kernel_rpl();
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, &regs, 0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);
/*
* Free current thread data structures etc..
*/
void exit_thread(void)
{
/* The process may have allocated an io port bitmap... nuke it. */
if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
struct task_struct *tsk = current;
struct thread_struct *t = &tsk->thread;
int cpu = get_cpu();
struct tss_struct *tss = &per_cpu(init_tss, cpu);
kfree(t->io_bitmap_ptr);
t->io_bitmap_ptr = NULL;
clear_thread_flag(TIF_IO_BITMAP);
/*
* 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;
memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
clear_tsk_thread_flag(tsk, TIF_DEBUG);
/*
* Forget coprocessor state..
*/
clear_fpu(tsk);
clear_used_math();
}
void release_thread(struct task_struct *dead_task)
{
BUG_ON(dead_task->mm);
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 = task_pt_regs(p);
*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(gs,p->thread.gs);
tsk = current;
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);
if (!p->thread.io_bitmap_ptr) {
p->thread.io_bitmap_max = 0;
return -ENOMEM;
}
set_tsk_thread_flag(p, TIF_IO_BITMAP);
}
/*
* 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;
dump->regs.fs = regs->xfs;
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 = *task_pt_regs(tsk);
ptregs.xcs &= 0xffff;
ptregs.xds &= 0xffff;
ptregs.xes &= 0xffff;
ptregs.xss &= 0xffff;
elf_core_copy_regs(regs, &ptregs);
return 1;
}
static noinline void __switch_to_xtra(struct task_struct *next_p,
struct tss_struct *tss)
{
struct thread_struct *next;
next = &next_p->thread;
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
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 (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* 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 = task_thread_info(prev_p);
next = task_thread_info(next_p);
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);
/* we're going to use this soon, after a few expensive things */
if (next_p->fpu_counter > 5)
prefetch(&next->i387.fxsave);
/*
* Reload esp0.
*/
load_esp0(tss, next);
/*
* Save away %gs. No need to save %fs, as it was saved on the
* stack on entry. 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(gs, prev->gs);
/*
* Load the per-thread Thread-Local Storage descriptor.
*/
load_TLS(next, cpu);
/*
* Restore IOPL if needed. In normal use, the flags restore
* in the switch assembly will handle this. But if the kernel
* is running virtualized at a non-zero CPL, the popf will
* not restore flags, so it must be done in a separate step.
*/
if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
set_iopl_mask(next->iopl);
/*
* Now maybe handle debug registers and/or IO bitmaps
*/
if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)
|| test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)))
__switch_to_xtra(next_p, tss);
disable_tsc(prev_p, next_p);
/*
* Leave lazy mode, flushing any hypercalls made here.
* This must be done before restoring TLS segments so
* the GDT and LDT are properly updated, and must be
* done before math_state_restore, so the TS bit is up
* to date.
*/
arch_leave_lazy_cpu_mode();
/* If the task has used fpu the last 5 timeslices, just do a full
* restore of the math state immediately to avoid the trap; the
* chances of needing FPU soon are obviously high now
*/
if (next_p->fpu_counter > 5)
math_state_restore();
/*
* Restore %gs if needed (which is common)
*/
if (prev->gs | next->gs)
loadsegment(gs, next->gs);
write_pda(pcurrent, next_p);
return prev_p;
}
asmlinkage int sys_fork(struct pt_regs regs)
{
return do_fork(SIGCHLD, regs.esp, &regs, 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, &regs, 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, &regs, 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,
&regs);
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)task_stack_page(p);
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;
}
/*
* sys_alloc_thread_area: get a yet unused TLS descriptor index.
*/
static int get_free_idx(void)
{
struct thread_struct *t = &current->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 = &current->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 (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
sp -= get_random_int() % 8192;
return sp & ~0xf;
}
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