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/*
* arch/s390/mm/fault.c
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Hartmut Penner (hp@de.ibm.com)
* Ulrich Weigand (uweigand@de.ibm.com)
*
* Derived from "arch/i386/mm/fault.c"
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/compatmac.h>
#include <linux/init.h>
#include <linux/console.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/hardirq.h>
#ifdef CONFIG_SYSCTL
extern int sysctl_userprocess_debug;
#endif
extern void die(const char *,struct pt_regs *,long);
static void force_sigsegv(struct task_struct *tsk, int code, void *address);
extern spinlock_t timerlist_lock;
/*
* Unlock any spinlocks which will prevent us from getting the
* message out (timerlist_lock is acquired through the
* console unblank code)
*/
void bust_spinlocks(int yes)
{
spin_lock_init(&timerlist_lock);
if (yes) {
oops_in_progress = 1;
} else {
int loglevel_save = console_loglevel;
oops_in_progress = 0;
console_unblank();
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
* a poke. Hold onto your hats...
*/
console_loglevel = 15;
printk(" ");
console_loglevel = loglevel_save;
}
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* error_code:
* ****0004 Protection -> Write-Protection (suprression)
* ****0010 Segment translation -> Not present (nullification)
* ****0011 Page translation -> Not present (nullification)
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long address;
unsigned long fixup;
int write;
int si_code = SEGV_MAPERR;
int kernel_address = 0;
tsk = current;
mm = tsk->mm;
/*
* Check for low-address protection. This needs to be treated
* as a special case because the translation exception code
* field is not guaranteed to contain valid data in this case.
*/
if ((error_code & 0xff) == 4 && !(S390_lowcore.trans_exc_code & 4)) {
/* Low-address protection hit in kernel mode means
NULL pointer write access in kernel mode. */
if (!(regs->psw.mask & PSW_PROBLEM_STATE)) {
address = 0;
kernel_address = 1;
goto no_context;
}
/* Low-address protection hit in user mode 'cannot happen'. */
die ("Low-address protection", regs, error_code);
do_exit(SIGKILL);
}
/*
* get the failing address
* more specific the segment and page table portion of
* the address
*/
address = S390_lowcore.trans_exc_code&0x7ffff000;
/*
* Check which address space the address belongs to
*/
switch (S390_lowcore.trans_exc_code & 3)
{
case 0: /* Primary Segment Table Descriptor */
kernel_address = 1;
goto no_context;
case 1: /* STD determined via access register */
if (S390_lowcore.exc_access_id == 0)
{
kernel_address = 1;
goto no_context;
}
if (regs && S390_lowcore.exc_access_id < NUM_ACRS)
{
if (regs->acrs[S390_lowcore.exc_access_id] == 0)
{
kernel_address = 1;
goto no_context;
}
if (regs->acrs[S390_lowcore.exc_access_id] == 1)
{
/* user space address */
break;
}
}
die("page fault via unknown access register", regs, error_code);
do_exit(SIGKILL);
break;
case 2: /* Secondary Segment Table Descriptor */
case 3: /* Home Segment Table Descriptor */
/* user space address */
break;
}
/*
* Check whether we have a user MM in the first place.
*/
if (in_interrupt() || !mm || !(regs->psw.mask & _PSW_IO_MASK_BIT))
goto no_context;
/*
* When we get here, the fault happened in the current
* task's user address space, so we can switch on the
* interrupts again and then search the VMAs
*/
__sti();
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
write = 0;
si_code = SEGV_ACCERR;
switch (error_code & 0xFF) {
case 0x04: /* write, present*/
write = 1;
break;
case 0x10: /* not present*/
case 0x11: /* not present*/
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
break;
default:
printk("code should be 4, 10 or 11 (%lX) \n",error_code&0xFF);
goto bad_area;
}
survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
case 1:
tsk->min_flt++;
break;
case 2:
tsk->maj_flt++;
break;
case 0:
goto do_sigbus;
default:
goto out_of_memory;
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
if (regs->psw.mask & PSW_PROBLEM_STATE) {
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
#ifndef CONFIG_SYSCTL
#ifdef CONFIG_PROCESS_DEBUG
printk("User process fault: interruption code 0x%lX\n",error_code);
printk("failing address: %lX\n",address);
show_regs(regs);
#endif
#else
if (sysctl_userprocess_debug) {
printk("User process fault: interruption code 0x%lX\n",
error_code);
printk("failing address: %lX\n", address);
show_regs(regs);
}
#endif
force_sigsegv(tsk, si_code, (void *)address);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if ((fixup = search_exception_table(regs->psw.addr)) != 0) {
regs->psw.addr = fixup;
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if (kernel_address)
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %08lx\n", address);
else
printk(KERN_ALERT "Unable to handle kernel paging request"
" at virtual user address %08lx\n", address);
die("Oops", regs, error_code);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (tsk->pid == 1) {
tsk->policy |= SCHED_YIELD;
schedule();
down_read(&mm->mmap_sem);
goto survive;
}
printk("VM: killing process %s\n", tsk->comm);
if (regs->psw.mask & PSW_PROBLEM_STATE)
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!(regs->psw.mask & PSW_PROBLEM_STATE))
goto no_context;
}
/*
* Send SIGSEGV to task. This is an external routine
* to keep the stack usage of do_page_fault small.
*/
static void force_sigsegv(struct task_struct *tsk, int code, void *address)
{
struct siginfo si;
si.si_signo = SIGSEGV;
si.si_code = code;
si.si_addr = address;
force_sig_info(SIGSEGV, &si, tsk);
}
typedef struct _pseudo_wait_t {
struct _pseudo_wait_t *next;
wait_queue_head_t queue;
unsigned long address;
int resolved;
} pseudo_wait_t;
static pseudo_wait_t *pseudo_lock_queue = NULL;
static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */
/*
* This routine handles 'pagex' pseudo page faults.
*/
asmlinkage void
do_pseudo_page_fault(struct pt_regs *regs, unsigned long error_code)
{
pseudo_wait_t wait_struct;
pseudo_wait_t *ptr, *last, *next;
unsigned long address;
int kernel_address;
/*
* get the failing address
* more specific the segment and page table portion of
* the address
*/
address = S390_lowcore.trans_exc_code & 0xfffff000;
if (address & 0x80000000) {
/* high bit set -> a page has been swapped in by VM */
address &= 0x7fffffff;
spin_lock(&pseudo_wait_spinlock);
last = NULL;
ptr = pseudo_lock_queue;
while (ptr != NULL) {
next = ptr->next;
if (address == ptr->address) {
/*
* This is one of the processes waiting
* for the page. Unchain from the queue.
* There can be more than one process
* waiting for the same page. VM presents
* an initial and a completion interrupt for
* every process that tries to access a
* page swapped out by VM.
*/
if (last == NULL)
pseudo_lock_queue = next;
else
last->next = next;
/* now wake up the process */
ptr->resolved = 1;
wake_up(&ptr->queue);
} else
last = ptr;
ptr = next;
}
spin_unlock(&pseudo_wait_spinlock);
} else {
/* Pseudo page faults in kernel mode is a bad idea */
if (!(regs->psw.mask & PSW_PROBLEM_STATE)) {
/*
* VM presents pseudo page faults if the interrupted
* state was not disabled for interrupts. So we can
* get pseudo page fault interrupts while running
* in kernel mode. We simply access the page here
* while we are running disabled. VM will then swap
* in the page synchronously.
*/
kernel_address = 0;
switch (S390_lowcore.trans_exc_code & 3) {
case 0: /* Primary Segment Table Descriptor */
kernel_address = 1;
break;
case 1: /* STD determined via access register */
if (S390_lowcore.exc_access_id == 0 ||
regs->acrs[S390_lowcore.exc_access_id]==0)
kernel_address = 1;
break;
case 2: /* Secondary Segment Table Descriptor */
case 3: /* Home Segment Table Descriptor */
break;
}
if (kernel_address)
/* dereference a virtual kernel address */
__asm__ __volatile__ (
" ic 0,0(%0)"
: : "a" (address) : "0");
else
/* dereference a virtual user address */
__asm__ __volatile__ (
" la 2,0(%0)\n"
" sacf 512\n"
" ic 2,0(2)\n"
"0:sacf 0\n"
".section __ex_table,\"a\"\n"
" .align 4\n"
" .long 0b,0b\n"
".previous"
: : "a" (address) : "2" );
return;
}
/* initialize and add element to pseudo_lock_queue */
init_waitqueue_head (&wait_struct.queue);
wait_struct.address = address;
wait_struct.resolved = 0;
spin_lock(&pseudo_wait_spinlock);
wait_struct.next = pseudo_lock_queue;
pseudo_lock_queue = &wait_struct;
spin_unlock(&pseudo_wait_spinlock);
/* go to sleep */
wait_event(wait_struct.queue, wait_struct.resolved);
}
}
#ifdef CONFIG_PFAULT
/*
* 'pfault' pseudo page faults routines.
*/
static int pfault_disable = 0;
static int __init nopfault(char *str)
{
pfault_disable = 1;
return 1;
}
__setup("nopfault", nopfault);
typedef struct {
__u16 refdiagc;
__u16 reffcode;
__u16 refdwlen;
__u16 refversn;
__u64 refgaddr;
__u64 refselmk;
__u64 refcmpmk;
__u64 reserved;
} __attribute__ ((packed)) pfault_refbk_t;
int pfault_init(void)
{
pfault_refbk_t refbk =
{ 0x258, 0, 5, 2, __LC_KERNEL_STACK, 1ULL << 48, 1ULL << 48, 0ULL };
int rc;
if (pfault_disable)
return -1;
__asm__ __volatile__(
" diag %1,%0,0x258\n"
"0: j 2f\n"
"1: la %0,8\n"
"2:\n"
".section __ex_table,\"a\"\n"
" .align 4\n"
" .long 0b,1b\n"
".previous"
: "=d" (rc) : "a" (&refbk) : "cc" );
__ctl_set_bit(0, 9);
return rc;
}
void pfault_fini(void)
{
pfault_refbk_t refbk =
{ 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
if (pfault_disable)
return;
__ctl_clear_bit(0,9);
__asm__ __volatile__(
" diag %0,0,0x258\n"
"0:\n"
".section __ex_table,\"a\"\n"
" .align 4\n"
" .long 0b,0b\n"
".previous"
: : "a" (&refbk) : "cc" );
}
asmlinkage void
pfault_interrupt(struct pt_regs *regs, __u16 error_code)
{
struct task_struct *tsk;
wait_queue_head_t queue;
wait_queue_head_t *qp;
__u16 subcode;
/*
* Get the external interruption subcode & pfault
* initial/completion signal bit. VM stores this
* in the 'cpu address' field associated with the
* external interrupt.
*/
subcode = S390_lowcore.cpu_addr;
if ((subcode & 0xff00) != 0x0200)
return;
/*
* Get the token (= address of kernel stack of affected task).
*/
tsk = (struct task_struct *)
(*((unsigned long *) __LC_PFAULT_INTPARM) - THREAD_SIZE);
/*
* We got all needed information from the lowcore and can
* now safely switch on interrupts.
*/
if (regs->psw.mask & PSW_PROBLEM_STATE)
__sti();
if (subcode & 0x0080) {
/* signal bit is set -> a page has been swapped in by VM */
qp = (wait_queue_head_t *)
xchg(&tsk->thread.pfault_wait, -1);
if (qp != NULL) {
/* Initial interrupt was faster than the completion
* interrupt. pfault_wait is valid. Set pfault_wait
* back to zero and wake up the process. This can
* safely be done because the task is still sleeping
* and can't procude new pfaults. */
tsk->thread.pfault_wait = 0ULL;
wake_up(qp);
}
} else {
/* signal bit not set -> a real page is missing. */
init_waitqueue_head (&queue);
qp = (wait_queue_head_t *)
xchg(&tsk->thread.pfault_wait, (addr_t) &queue);
if (qp != NULL) {
/* Completion interrupt was faster than the initial
* interrupt (swapped in a -1 for pfault_wait). Set
* pfault_wait back to zero and exit. This can be
* done safely because tsk is running in kernel
* mode and can't produce new pfaults. */
tsk->thread.pfault_wait = 0ULL;
}
/* go to sleep */
wait_event(queue, tsk->thread.pfault_wait == 0ULL);
}
}
#endif
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