android_kernel_xiaomi_sm8350/arch/x86_64/kernel/process.c
Alan Stern e041c68341 [PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe.  There is no
protection against entries being added to or removed from a chain while the
chain is in use.  The issues were discussed in this thread:

    http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2

We noticed that notifier chains in the kernel fall into two basic usage
classes:

	"Blocking" chains are always called from a process context
	and the callout routines are allowed to sleep;

	"Atomic" chains can be called from an atomic context and
	the callout routines are not allowed to sleep.

We decided to codify this distinction and make it part of the API.  Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name).  New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain.  The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.

With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed.  For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections.  (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)

There are some limitations, which should not be too hard to live with.  For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem.  Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain.  (This did happen in a couple of places and the code
had to be changed to avoid it.)

Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.

Here is the list of chains that we adjusted and their classifications.  None
of them use the raw API, so for the moment it is only a placeholder.

  ATOMIC CHAINS
  -------------
arch/i386/kernel/traps.c:		i386die_chain
arch/ia64/kernel/traps.c:		ia64die_chain
arch/powerpc/kernel/traps.c:		powerpc_die_chain
arch/sparc64/kernel/traps.c:		sparc64die_chain
arch/x86_64/kernel/traps.c:		die_chain
drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
kernel/panic.c:				panic_notifier_list
kernel/profile.c:			task_free_notifier
net/bluetooth/hci_core.c:		hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
net/ipv6/addrconf.c:			inet6addr_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
net/netlink/af_netlink.c:		netlink_chain

  BLOCKING CHAINS
  ---------------
arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
arch/s390/kernel/process.c:		idle_chain
arch/x86_64/kernel/process.c		idle_notifier
drivers/base/memory.c:			memory_chain
drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
drivers/macintosh/adb.c:		adb_client_list
drivers/macintosh/via-pmu.c		sleep_notifier_list
drivers/macintosh/via-pmu68k.c		sleep_notifier_list
drivers/macintosh/windfarm_core.c	wf_client_list
drivers/usb/core/notify.c		usb_notifier_list
drivers/video/fbmem.c			fb_notifier_list
kernel/cpu.c				cpu_chain
kernel/module.c				module_notify_list
kernel/profile.c			munmap_notifier
kernel/profile.c			task_exit_notifier
kernel/sys.c				reboot_notifier_list
net/core/dev.c				netdev_chain
net/decnet/dn_dev.c:			dnaddr_chain
net/ipv4/devinet.c:			inetaddr_chain

It's possible that some of these classifications are wrong.  If they are,
please let us know or submit a patch to fix them.  Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)

The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.

[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 08:44:50 -08:00

831 lines
19 KiB
C

/*
* linux/arch/x86-64/kernel/process.c
*
* Copyright (C) 1995 Linus Torvalds
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*
* X86-64 port
* Andi Kleen.
*
* CPU hotplug support - ashok.raj@intel.com
* $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
*/
/*
* 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/kernel.h>
#include <linux/mm.h>
#include <linux/elfcore.h>
#include <linux/smp.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/module.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/ptrace.h>
#include <linux/utsname.h>
#include <linux/random.h>
#include <linux/notifier.h>
#include <linux/kprobes.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/mmu_context.h>
#include <asm/pda.h>
#include <asm/prctl.h>
#include <asm/kdebug.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/ia32.h>
#include <asm/idle.h>
asmlinkage extern void ret_from_fork(void);
unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
unsigned long boot_option_idle_override = 0;
EXPORT_SYMBOL(boot_option_idle_override);
/*
* Powermanagement idle function, if any..
*/
void (*pm_idle)(void);
static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
static ATOMIC_NOTIFIER_HEAD(idle_notifier);
void idle_notifier_register(struct notifier_block *n)
{
atomic_notifier_chain_register(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_register);
void idle_notifier_unregister(struct notifier_block *n)
{
atomic_notifier_chain_unregister(&idle_notifier, n);
}
EXPORT_SYMBOL(idle_notifier_unregister);
enum idle_state { CPU_IDLE, CPU_NOT_IDLE };
static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
void enter_idle(void)
{
__get_cpu_var(idle_state) = CPU_IDLE;
atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}
static void __exit_idle(void)
{
__get_cpu_var(idle_state) = CPU_NOT_IDLE;
atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
}
/* Called from interrupts to signify idle end */
void exit_idle(void)
{
if (current->pid | read_pda(irqcount))
return;
__exit_idle();
}
/*
* We use this if we don't have any better
* idle routine..
*/
static void default_idle(void)
{
local_irq_enable();
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb__after_clear_bit();
while (!need_resched()) {
local_irq_disable();
if (!need_resched())
safe_halt();
else
local_irq_enable();
}
set_thread_flag(TIF_POLLING_NRFLAG);
}
/*
* On SMP it's slightly faster (but much more power-consuming!)
* to poll the ->need_resched flag instead of waiting for the
* cross-CPU IPI to arrive. Use this option with caution.
*/
static void poll_idle (void)
{
local_irq_enable();
asm volatile(
"2:"
"testl %0,%1;"
"rep; nop;"
"je 2b;"
: :
"i" (_TIF_NEED_RESCHED),
"m" (current_thread_info()->flags));
}
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);
#ifdef CONFIG_HOTPLUG_CPU
DECLARE_PER_CPU(int, cpu_state);
#include <asm/nmi.h>
/* We halt the CPU with physical CPU hotplug */
static inline void play_dead(void)
{
idle_task_exit();
wbinvd();
mb();
/* Ack it */
__get_cpu_var(cpu_state) = CPU_DEAD;
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)
{
set_thread_flag(TIF_POLLING_NRFLAG);
/* 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(smp_processor_id()))
play_dead();
enter_idle();
idle();
__exit_idle();
}
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
/*
* 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();
while (!need_resched()) {
__monitor((void *)&current_thread_info()->flags, 0, 0);
smp_mb();
if (need_resched())
break;
__mwait(0, 0);
}
}
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
static int printed;
if (cpu_has(c, X86_FEATURE_MWAIT)) {
/*
* Skip, if setup has overridden idle.
* One CPU supports mwait => All CPUs supports mwait
*/
if (!pm_idle) {
if (!printed) {
printk("using mwait in idle threads.\n");
printed = 1;
}
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;
}
boot_option_idle_override = 1;
return 1;
}
__setup("idle=", idle_setup);
/* Prints also some state that isn't saved in the pt_regs */
void __show_regs(struct pt_regs * regs)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
unsigned int fsindex,gsindex;
unsigned int ds,cs,es;
printk("\n");
print_modules();
printk("Pid: %d, comm: %.20s %s %s %.*s\n",
current->pid, current->comm, print_tainted(),
system_utsname.release,
(int)strcspn(system_utsname.version, " "),
system_utsname.version);
printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
printk_address(regs->rip);
printk("\nRSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, regs->rsp,
regs->eflags);
printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
regs->rax, regs->rbx, regs->rcx);
printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
regs->rdx, regs->rsi, regs->rdi);
printk("RBP: %016lx R08: %016lx R09: %016lx\n",
regs->rbp, regs->r8, regs->r9);
printk("R10: %016lx R11: %016lx R12: %016lx\n",
regs->r10, regs->r11, regs->r12);
printk("R13: %016lx R14: %016lx R15: %016lx\n",
regs->r13, regs->r14, regs->r15);
asm("movl %%ds,%0" : "=r" (ds));
asm("movl %%cs,%0" : "=r" (cs));
asm("movl %%es,%0" : "=r" (es));
asm("movl %%fs,%0" : "=r" (fsindex));
asm("movl %%gs,%0" : "=r" (gsindex));
rdmsrl(MSR_FS_BASE, fs);
rdmsrl(MSR_GS_BASE, gs);
rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
asm("movq %%cr0, %0": "=r" (cr0));
asm("movq %%cr2, %0": "=r" (cr2));
asm("movq %%cr3, %0": "=r" (cr3));
asm("movq %%cr4, %0": "=r" (cr4));
printk("FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
fs,fsindex,gs,gsindex,shadowgs);
printk("CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
}
void show_regs(struct pt_regs *regs)
{
printk("CPU %d:", smp_processor_id());
__show_regs(regs);
show_trace(&regs->rsp);
}
/*
* Free current thread data structures etc..
*/
void exit_thread(void)
{
struct task_struct *me = current;
struct thread_struct *t = &me->thread;
if (me->thread.io_bitmap_ptr) {
struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
kfree(t->io_bitmap_ptr);
t->io_bitmap_ptr = NULL;
/*
* Careful, clear this in the TSS too:
*/
memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
t->io_bitmap_max = 0;
put_cpu();
}
}
void flush_thread(void)
{
struct task_struct *tsk = current;
struct thread_info *t = current_thread_info();
if (t->flags & _TIF_ABI_PENDING)
t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
tsk->thread.debugreg0 = 0;
tsk->thread.debugreg1 = 0;
tsk->thread.debugreg2 = 0;
tsk->thread.debugreg3 = 0;
tsk->thread.debugreg6 = 0;
tsk->thread.debugreg7 = 0;
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) {
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();
}
}
}
static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
{
struct user_desc ud = {
.base_addr = addr,
.limit = 0xfffff,
.seg_32bit = 1,
.limit_in_pages = 1,
.useable = 1,
};
struct n_desc_struct *desc = (void *)t->thread.tls_array;
desc += tls;
desc->a = LDT_entry_a(&ud);
desc->b = LDT_entry_b(&ud);
}
static inline u32 read_32bit_tls(struct task_struct *t, int tls)
{
struct desc_struct *desc = (void *)t->thread.tls_array;
desc += tls;
return desc->base0 |
(((u32)desc->base1) << 16) |
(((u32)desc->base2) << 24);
}
/*
* 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 rsp,
unsigned long unused,
struct task_struct * p, struct pt_regs * regs)
{
int err;
struct pt_regs * childregs;
struct task_struct *me = current;
childregs = ((struct pt_regs *)
(THREAD_SIZE + task_stack_page(p))) - 1;
*childregs = *regs;
childregs->rax = 0;
childregs->rsp = rsp;
if (rsp == ~0UL)
childregs->rsp = (unsigned long)childregs;
p->thread.rsp = (unsigned long) childregs;
p->thread.rsp0 = (unsigned long) (childregs+1);
p->thread.userrsp = me->thread.userrsp;
set_tsk_thread_flag(p, TIF_FORK);
p->thread.fs = me->thread.fs;
p->thread.gs = me->thread.gs;
asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
asm("mov %%es,%0" : "=m" (p->thread.es));
asm("mov %%ds,%0" : "=m" (p->thread.ds));
if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
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, me->thread.io_bitmap_ptr,
IO_BITMAP_BYTES);
}
/*
* Set a new TLS for the child thread?
*/
if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_IA32_EMULATION
if (test_thread_flag(TIF_IA32))
err = ia32_child_tls(p, childregs);
else
#endif
err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
if (err)
goto out;
}
err = 0;
out:
if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
return err;
}
/*
* This special macro can be used to load a debugging register
*/
#define loaddebug(thread,r) set_debugreg(thread->debugreg ## r, r)
/*
* switch_to(x,y) should switch tasks from x to y.
*
* This could still be optimized:
* - fold all the options into a flag word and test it with a single test.
* - could test fs/gs bitsliced
*
* Kprobes not supported here. Set the probe on schedule instead.
*/
__kprobes struct task_struct *
__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);
/*
* Reload esp0, LDT and the page table pointer:
*/
tss->rsp0 = next->rsp0;
/*
* Switch DS and ES.
* This won't pick up thread selector changes, but I guess that is ok.
*/
asm volatile("mov %%es,%0" : "=m" (prev->es));
if (unlikely(next->es | prev->es))
loadsegment(es, next->es);
asm volatile ("mov %%ds,%0" : "=m" (prev->ds));
if (unlikely(next->ds | prev->ds))
loadsegment(ds, next->ds);
load_TLS(next, cpu);
/*
* Switch FS and GS.
*/
{
unsigned fsindex;
asm volatile("movl %%fs,%0" : "=r" (fsindex));
/* segment register != 0 always requires a reload.
also reload when it has changed.
when prev process used 64bit base always reload
to avoid an information leak. */
if (unlikely(fsindex | next->fsindex | prev->fs)) {
loadsegment(fs, next->fsindex);
/* check if the user used a selector != 0
* if yes clear 64bit base, since overloaded base
* is always mapped to the Null selector
*/
if (fsindex)
prev->fs = 0;
}
/* when next process has a 64bit base use it */
if (next->fs)
wrmsrl(MSR_FS_BASE, next->fs);
prev->fsindex = fsindex;
}
{
unsigned gsindex;
asm volatile("movl %%gs,%0" : "=r" (gsindex));
if (unlikely(gsindex | next->gsindex | prev->gs)) {
load_gs_index(next->gsindex);
if (gsindex)
prev->gs = 0;
}
if (next->gs)
wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
prev->gsindex = gsindex;
}
/*
* Switch the PDA and FPU contexts.
*/
prev->userrsp = read_pda(oldrsp);
write_pda(oldrsp, next->userrsp);
write_pda(pcurrent, next_p);
/* This must be here to ensure both math_state_restore() and
kernel_fpu_begin() work consistently. */
unlazy_fpu(prev_p);
write_pda(kernelstack,
task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
/*
* Now maybe reload the debug registers
*/
if (unlikely(next->debugreg7)) {
loaddebug(next, 0);
loaddebug(next, 1);
loaddebug(next, 2);
loaddebug(next, 3);
/* no 4 and 5 */
loaddebug(next, 6);
loaddebug(next, 7);
}
/*
* Handle the IO bitmap
*/
if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
if (next->io_bitmap_ptr)
/*
* Copy the relevant range of the IO bitmap.
* Normally this is 128 bytes or less:
*/
memcpy(tss->io_bitmap, next->io_bitmap_ptr,
max(prev->io_bitmap_max, next->io_bitmap_max));
else {
/*
* Clear any possible leftover bits:
*/
memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
}
}
return prev_p;
}
/*
* sys_execve() executes a new program.
*/
asmlinkage
long sys_execve(char __user *name, char __user * __user *argv,
char __user * __user *envp, struct pt_regs regs)
{
long error;
char * filename;
filename = getname(name);
error = PTR_ERR(filename);
if (IS_ERR(filename))
return error;
error = do_execve(filename, argv, envp, &regs);
if (error == 0) {
task_lock(current);
current->ptrace &= ~PT_DTRACE;
task_unlock(current);
}
putname(filename);
return error;
}
void set_personality_64bit(void)
{
/* inherit personality from parent */
/* Make sure to be in 64bit mode */
clear_thread_flag(TIF_IA32);
/* TBD: overwrites user setup. Should have two bits.
But 64bit processes have always behaved this way,
so it's not too bad. The main problem is just that
32bit childs are affected again. */
current->personality &= ~READ_IMPLIES_EXEC;
}
asmlinkage long sys_fork(struct pt_regs *regs)
{
return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
}
asmlinkage long
sys_clone(unsigned long clone_flags, unsigned long newsp,
void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
{
if (!newsp)
newsp = regs->rsp;
return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
}
/*
* 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 long sys_vfork(struct pt_regs *regs)
{
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
NULL, NULL);
}
unsigned long get_wchan(struct task_struct *p)
{
unsigned long stack;
u64 fp,rip;
int count = 0;
if (!p || p == current || p->state==TASK_RUNNING)
return 0;
stack = (unsigned long)task_stack_page(p);
if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
return 0;
fp = *(u64 *)(p->thread.rsp);
do {
if (fp < (unsigned long)stack ||
fp > (unsigned long)stack+THREAD_SIZE)
return 0;
rip = *(u64 *)(fp+8);
if (!in_sched_functions(rip))
return rip;
fp = *(u64 *)fp;
} while (count++ < 16);
return 0;
}
long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
{
int ret = 0;
int doit = task == current;
int cpu;
switch (code) {
case ARCH_SET_GS:
if (addr >= TASK_SIZE_OF(task))
return -EPERM;
cpu = get_cpu();
/* handle small bases via the GDT because that's faster to
switch. */
if (addr <= 0xffffffff) {
set_32bit_tls(task, GS_TLS, addr);
if (doit) {
load_TLS(&task->thread, cpu);
load_gs_index(GS_TLS_SEL);
}
task->thread.gsindex = GS_TLS_SEL;
task->thread.gs = 0;
} else {
task->thread.gsindex = 0;
task->thread.gs = addr;
if (doit) {
load_gs_index(0);
ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
}
}
put_cpu();
break;
case ARCH_SET_FS:
/* Not strictly needed for fs, but do it for symmetry
with gs */
if (addr >= TASK_SIZE_OF(task))
return -EPERM;
cpu = get_cpu();
/* handle small bases via the GDT because that's faster to
switch. */
if (addr <= 0xffffffff) {
set_32bit_tls(task, FS_TLS, addr);
if (doit) {
load_TLS(&task->thread, cpu);
asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
}
task->thread.fsindex = FS_TLS_SEL;
task->thread.fs = 0;
} else {
task->thread.fsindex = 0;
task->thread.fs = addr;
if (doit) {
/* set the selector to 0 to not confuse
__switch_to */
asm volatile("movl %0,%%fs" :: "r" (0));
ret = checking_wrmsrl(MSR_FS_BASE, addr);
}
}
put_cpu();
break;
case ARCH_GET_FS: {
unsigned long base;
if (task->thread.fsindex == FS_TLS_SEL)
base = read_32bit_tls(task, FS_TLS);
else if (doit)
rdmsrl(MSR_FS_BASE, base);
else
base = task->thread.fs;
ret = put_user(base, (unsigned long __user *)addr);
break;
}
case ARCH_GET_GS: {
unsigned long base;
if (task->thread.gsindex == GS_TLS_SEL)
base = read_32bit_tls(task, GS_TLS);
else if (doit)
rdmsrl(MSR_KERNEL_GS_BASE, base);
else
base = task->thread.gs;
ret = put_user(base, (unsigned long __user *)addr);
break;
}
default:
ret = -EINVAL;
break;
}
return ret;
}
long sys_arch_prctl(int code, unsigned long addr)
{
return do_arch_prctl(current, code, addr);
}
/*
* 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 *pp, ptregs;
pp = task_pt_regs(tsk);
ptregs = *pp;
ptregs.cs &= 0xffff;
ptregs.ss &= 0xffff;
elf_core_copy_regs(regs, &ptregs);
return 1;
}
unsigned long arch_align_stack(unsigned long sp)
{
if (randomize_va_space)
sp -= get_random_int() % 8192;
return sp & ~0xf;
}