Linux-2.6.33.2/arch/s390/mm/fault.c
/*
* 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/perf_event.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/compat.h>
#include <linux/smp.h>
#include <linux/kdebug.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/hardirq.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hugetlb.h>
#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/s390_ext.h>
#include <asm/mmu_context.h>
#include <asm/compat.h>
#include "../kernel/entry.h"
#ifndef CONFIG_64BIT
#define __FAIL_ADDR_MASK 0x7ffff000
#define __SUBCODE_MASK 0x0200
#define __PF_RES_FIELD 0ULL
#else /* CONFIG_64BIT */
#define __FAIL_ADDR_MASK -4096L
#define __SUBCODE_MASK 0x0600
#define __PF_RES_FIELD 0x8000000000000000ULL
#endif /* CONFIG_64BIT */
#ifdef CONFIG_SYSCTL
extern int sysctl_userprocess_debug;
#endif
#define VM_FAULT_BADCONTEXT 0x010000
#define VM_FAULT_BADMAP 0x020000
#define VM_FAULT_BADACCESS 0x040000
static inline int notify_page_fault(struct pt_regs *regs)
{
int ret = 0;
#ifdef CONFIG_KPROBES
/* kprobe_running() needs smp_processor_id() */
if (!user_mode(regs)) {
preempt_disable();
if (kprobe_running() && kprobe_fault_handler(regs, 14))
ret = 1;
preempt_enable();
}
#endif
return ret;
}
/*
* Unlock any spinlocks which will prevent us from getting the
* message out.
*/
void bust_spinlocks(int yes)
{
if (yes) {
oops_in_progress = 1;
} else {
int loglevel_save = console_loglevel;
console_unblank();
oops_in_progress = 0;
/*
* 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;
}
}
/*
* Returns the address space associated with the fault.
* Returns 0 for kernel space and 1 for user space.
*/
static inline int user_space_fault(unsigned long trans_exc_code)
{
/*
* The lowest two bits of the translation exception
* identification indicate which paging table was used.
*/
trans_exc_code &= 3;
if (trans_exc_code == 2)
/* Access via secondary space, set_fs setting decides */
return current->thread.mm_segment.ar4;
if (user_mode == HOME_SPACE_MODE)
/* User space if the access has been done via home space. */
return trans_exc_code == 3;
/*
* If the user space is not the home space the kernel runs in home
* space. Access via secondary space has already been covered,
* access via primary space or access register is from user space
* and access via home space is from the kernel.
*/
return trans_exc_code != 3;
}
/*
* Send SIGSEGV to task. This is an external routine
* to keep the stack usage of do_page_fault small.
*/
static noinline void do_sigsegv(struct pt_regs *regs, long int_code,
int si_code, unsigned long trans_exc_code)
{
struct siginfo si;
unsigned long address;
address = trans_exc_code & __FAIL_ADDR_MASK;
current->thread.prot_addr = address;
current->thread.trap_no = int_code;
#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
#if defined(CONFIG_SYSCTL)
if (sysctl_userprocess_debug)
#endif
{
printk("User process fault: interruption code 0x%lX\n",
int_code);
printk("failing address: %lX\n", address);
show_regs(regs);
}
#endif
si.si_signo = SIGSEGV;
si.si_code = si_code;
si.si_addr = (void __user *) address;
force_sig_info(SIGSEGV, &si, current);
}
static noinline void do_no_context(struct pt_regs *regs, long int_code,
unsigned long trans_exc_code)
{
const struct exception_table_entry *fixup;
unsigned long address;
/* Are we prepared to handle this kernel fault? */
fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
if (fixup) {
regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
address = trans_exc_code & __FAIL_ADDR_MASK;
if (!user_space_fault(trans_exc_code))
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %p\n", (void *)address);
else
printk(KERN_ALERT "Unable to handle kernel paging request"
" at virtual user address %p\n", (void *)address);
die("Oops", regs, int_code);
do_exit(SIGKILL);
}
static noinline void do_low_address(struct pt_regs *regs, long int_code,
unsigned long trans_exc_code)
{
/* Low-address protection hit in kernel mode means
NULL pointer write access in kernel mode. */
if (regs->psw.mask & PSW_MASK_PSTATE) {
/* Low-address protection hit in user mode 'cannot happen'. */
die ("Low-address protection", regs, int_code);
do_exit(SIGKILL);
}
do_no_context(regs, int_code, trans_exc_code);
}
static noinline void do_sigbus(struct pt_regs *regs, long int_code,
unsigned long trans_exc_code)
{
struct task_struct *tsk = current;
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->thread.prot_addr = trans_exc_code & __FAIL_ADDR_MASK;
tsk->thread.trap_no = int_code;
force_sig(SIGBUS, tsk);
}
#ifdef CONFIG_S390_EXEC_PROTECT
static noinline int signal_return(struct pt_regs *regs, long int_code,
unsigned long trans_exc_code)
{
u16 instruction;
int rc;
rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
if (!rc && instruction == 0x0a77) {
clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
if (is_compat_task())
sys32_sigreturn();
else
sys_sigreturn();
} else if (!rc && instruction == 0x0aad) {
clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
if (is_compat_task())
sys32_rt_sigreturn();
else
sys_rt_sigreturn();
} else
do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
return 0;
}
#endif /* CONFIG_S390_EXEC_PROTECT */
static noinline void do_fault_error(struct pt_regs *regs, long int_code,
unsigned long trans_exc_code, int fault)
{
int si_code;
switch (fault) {
case VM_FAULT_BADACCESS:
#ifdef CONFIG_S390_EXEC_PROTECT
if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
(trans_exc_code & 3) == 0) {
signal_return(regs, int_code, trans_exc_code);
break;
}
#endif /* CONFIG_S390_EXEC_PROTECT */
case VM_FAULT_BADMAP:
/* Bad memory access. Check if it is kernel or user space. */
if (regs->psw.mask & PSW_MASK_PSTATE) {
/* User mode accesses just cause a SIGSEGV */
si_code = (fault == VM_FAULT_BADMAP) ?
SEGV_MAPERR : SEGV_ACCERR;
do_sigsegv(regs, int_code, si_code, trans_exc_code);
return;
}
case VM_FAULT_BADCONTEXT:
do_no_context(regs, int_code, trans_exc_code);
break;
default: /* fault & VM_FAULT_ERROR */
if (fault & VM_FAULT_OOM)
pagefault_out_of_memory();
else if (fault & VM_FAULT_SIGBUS) {
do_sigbus(regs, int_code, trans_exc_code);
/* Kernel mode? Handle exceptions or die */
if (!(regs->psw.mask & PSW_MASK_PSTATE))
do_no_context(regs, int_code, trans_exc_code);
} else
BUG();
break;
}
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* interruption code (int_code):
* 04 Protection -> Write-Protection (suprression)
* 10 Segment translation -> Not present (nullification)
* 11 Page translation -> Not present (nullification)
* 3b Region third trans. -> Not present (nullification)
*/
static inline int do_exception(struct pt_regs *regs, int access,
unsigned long trans_exc_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long address;
int fault;
if (notify_page_fault(regs))
return 0;
tsk = current;
mm = tsk->mm;
/*
* Verify that the fault happened in user space, that
* we are not in an interrupt and that there is a
* user context.
*/
fault = VM_FAULT_BADCONTEXT;
if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
goto out;
address = trans_exc_code & __FAIL_ADDR_MASK;
/*
* 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
*/
local_irq_enable();
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
down_read(&mm->mmap_sem);
fault = VM_FAULT_BADMAP;
vma = find_vma(mm, address);
if (!vma)
goto out_up;
if (unlikely(vma->vm_start > address)) {
if (!(vma->vm_flags & VM_GROWSDOWN))
goto out_up;
if (expand_stack(vma, address))
goto out_up;
}
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
fault = VM_FAULT_BADACCESS;
if (unlikely(!(vma->vm_flags & access)))
goto out_up;
if (is_vm_hugetlb_page(vma))
address &= HPAGE_MASK;
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address,
(access == VM_WRITE) ? FAULT_FLAG_WRITE : 0);
if (unlikely(fault & VM_FAULT_ERROR))
goto out_up;
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
regs, address);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
regs, address);
}
/*
* The instruction that caused the program check will
* be repeated. Don't signal single step via SIGTRAP.
*/
clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
fault = 0;
out_up:
up_read(&mm->mmap_sem);
out:
return fault;
}
void __kprobes do_protection_exception(struct pt_regs *regs, long int_code)
{
unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
int fault;
/* Protection exception is supressing, decrement psw address. */
regs->psw.addr -= (int_code >> 16);
/*
* 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 (unlikely(!(trans_exc_code & 4))) {
do_low_address(regs, int_code, trans_exc_code);
return;
}
fault = do_exception(regs, VM_WRITE, trans_exc_code);
if (unlikely(fault))
do_fault_error(regs, 4, trans_exc_code, fault);
}
void __kprobes do_dat_exception(struct pt_regs *regs, long int_code)
{
unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
int access, fault;
access = VM_READ | VM_EXEC | VM_WRITE;
#ifdef CONFIG_S390_EXEC_PROTECT
if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
(trans_exc_code & 3) == 0)
access = VM_EXEC;
#endif
fault = do_exception(regs, access, trans_exc_code);
if (unlikely(fault))
do_fault_error(regs, int_code & 255, trans_exc_code, fault);
}
#ifdef CONFIG_64BIT
void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
{
unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
goto no_context;
local_irq_enable();
down_read(&mm->mmap_sem);
vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
up_read(&mm->mmap_sem);
if (vma) {
update_mm(mm, current);
return;
}
/* User mode accesses just cause a SIGSEGV */
if (regs->psw.mask & PSW_MASK_PSTATE) {
do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
return;
}
no_context:
do_no_context(regs, int_code, trans_exc_code);
}
#endif
int __handle_fault(unsigned long uaddr, unsigned long int_code, int write_user)
{
struct pt_regs regs;
int access, fault;
regs.psw.mask = psw_kernel_bits;
if (!irqs_disabled())
regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
regs.psw.addr = (unsigned long) __builtin_return_address(0);
regs.psw.addr |= PSW_ADDR_AMODE;
uaddr &= PAGE_MASK;
access = write_user ? VM_WRITE : VM_READ;
fault = do_exception(®s, access, uaddr | 2);
if (unlikely(fault)) {
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
fault = 0;
} else if (fault & VM_FAULT_SIGBUS)
do_sigbus(®s, int_code, uaddr);
}
return fault ? -EFAULT : 0;
}
#ifdef CONFIG_PFAULT
/*
* 'pfault' pseudo page faults routines.
*/
static ext_int_info_t ext_int_pfault;
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, aligned(8))) pfault_refbk_t;
int pfault_init(void)
{
pfault_refbk_t refbk =
{ 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
__PF_RES_FIELD };
int rc;
if (!MACHINE_IS_VM || pfault_disable)
return -1;
asm volatile(
" diag %1,%0,0x258\n"
"0: j 2f\n"
"1: la %0,8\n"
"2:\n"
EX_TABLE(0b,1b)
: "=d" (rc) : "a" (&refbk), "m" (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 (!MACHINE_IS_VM || pfault_disable)
return;
__ctl_clear_bit(0,9);
asm volatile(
" diag %0,0,0x258\n"
"0:\n"
EX_TABLE(0b,0b)
: : "a" (&refbk), "m" (refbk) : "cc");
}
static void pfault_interrupt(__u16 int_code)
{
struct task_struct *tsk;
__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) != __SUBCODE_MASK)
return;
/*
* Get the token (= address of the task structure of the affected task).
*/
tsk = *(struct task_struct **) __LC_PFAULT_INTPARM;
if (subcode & 0x0080) {
/* signal bit is set -> a page has been swapped in by VM */
if (xchg(&tsk->thread.pfault_wait, -1) != 0) {
/* 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 produce new pfaults. */
tsk->thread.pfault_wait = 0;
wake_up_process(tsk);
put_task_struct(tsk);
}
} else {
/* signal bit not set -> a real page is missing. */
get_task_struct(tsk);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
/* 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 = 0;
set_task_state(tsk, TASK_RUNNING);
put_task_struct(tsk);
} else
set_tsk_need_resched(tsk);
}
}
void __init pfault_irq_init(void)
{
if (!MACHINE_IS_VM)
return;
/*
* Try to get pfault pseudo page faults going.
*/
if (register_early_external_interrupt(0x2603, pfault_interrupt,
&ext_int_pfault) != 0)
panic("Couldn't request external interrupt 0x2603");
if (pfault_init() == 0)
return;
/* Tough luck, no pfault. */
pfault_disable = 1;
unregister_early_external_interrupt(0x2603, pfault_interrupt,
&ext_int_pfault);
}
#endif