| /* | |
| * S390 version | |
| * Copyright IBM Corp. 1999 | |
| * 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/kernel_stat.h> | |
| #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/extable.h> | |
| #include <linux/hardirq.h> | |
| #include <linux/kprobes.h> | |
| #include <linux/uaccess.h> | |
| #include <linux/hugetlb.h> | |
| #include <asm/asm-offsets.h> | |
| #include <asm/diag.h> | |
| #include <asm/pgtable.h> | |
| #include <asm/gmap.h> | |
| #include <asm/irq.h> | |
| #include <asm/mmu_context.h> | |
| #include <asm/facility.h> | |
| #include "../kernel/entry.h" | |
| #define __FAIL_ADDR_MASK -4096L | |
| #define __SUBCODE_MASK 0x0600 | |
| #define __PF_RES_FIELD 0x8000000000000000ULL | |
| #define VM_FAULT_BADCONTEXT 0x010000 | |
| #define VM_FAULT_BADMAP 0x020000 | |
| #define VM_FAULT_BADACCESS 0x040000 | |
| #define VM_FAULT_SIGNAL 0x080000 | |
| #define VM_FAULT_PFAULT 0x100000 | |
| static unsigned long store_indication __read_mostly; | |
| static int __init fault_init(void) | |
| { | |
| if (test_facility(75)) | |
| store_indication = 0xc00; | |
| return 0; | |
| } | |
| early_initcall(fault_init); | |
| static inline int notify_page_fault(struct pt_regs *regs) | |
| { | |
| int ret = 0; | |
| /* kprobe_running() needs smp_processor_id() */ | |
| if (kprobes_built_in() && !user_mode(regs)) { | |
| preempt_disable(); | |
| if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
| ret = 1; | |
| preempt_enable(); | |
| } | |
| 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(struct pt_regs *regs) | |
| { | |
| unsigned long trans_exc_code; | |
| /* | |
| * The lowest two bits of the translation exception | |
| * identification indicate which paging table was used. | |
| */ | |
| trans_exc_code = regs->int_parm_long & 3; | |
| if (trans_exc_code == 3) /* home space -> kernel */ | |
| return 0; | |
| if (user_mode(regs)) | |
| return 1; | |
| if (trans_exc_code == 2) /* secondary space -> set_fs */ | |
| return current->thread.mm_segment.ar4; | |
| if (current->flags & PF_VCPU) | |
| return 1; | |
| return 0; | |
| } | |
| static int bad_address(void *p) | |
| { | |
| unsigned long dummy; | |
| return probe_kernel_address((unsigned long *)p, dummy); | |
| } | |
| static void dump_pagetable(unsigned long asce, unsigned long address) | |
| { | |
| unsigned long *table = __va(asce & PAGE_MASK); | |
| pr_alert("AS:%016lx ", asce); | |
| switch (asce & _ASCE_TYPE_MASK) { | |
| case _ASCE_TYPE_REGION1: | |
| table = table + ((address >> 53) & 0x7ff); | |
| if (bad_address(table)) | |
| goto bad; | |
| pr_cont("R1:%016lx ", *table); | |
| if (*table & _REGION_ENTRY_INVALID) | |
| goto out; | |
| table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
| /* fallthrough */ | |
| case _ASCE_TYPE_REGION2: | |
| table = table + ((address >> 42) & 0x7ff); | |
| if (bad_address(table)) | |
| goto bad; | |
| pr_cont("R2:%016lx ", *table); | |
| if (*table & _REGION_ENTRY_INVALID) | |
| goto out; | |
| table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
| /* fallthrough */ | |
| case _ASCE_TYPE_REGION3: | |
| table = table + ((address >> 31) & 0x7ff); | |
| if (bad_address(table)) | |
| goto bad; | |
| pr_cont("R3:%016lx ", *table); | |
| if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) | |
| goto out; | |
| table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
| /* fallthrough */ | |
| case _ASCE_TYPE_SEGMENT: | |
| table = table + ((address >> 20) & 0x7ff); | |
| if (bad_address(table)) | |
| goto bad; | |
| pr_cont("S:%016lx ", *table); | |
| if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) | |
| goto out; | |
| table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); | |
| } | |
| table = table + ((address >> 12) & 0xff); | |
| if (bad_address(table)) | |
| goto bad; | |
| pr_cont("P:%016lx ", *table); | |
| out: | |
| pr_cont("\n"); | |
| return; | |
| bad: | |
| pr_cont("BAD\n"); | |
| } | |
| static void dump_fault_info(struct pt_regs *regs) | |
| { | |
| unsigned long asce; | |
| pr_alert("Failing address: %016lx TEID: %016lx\n", | |
| regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); | |
| pr_alert("Fault in "); | |
| switch (regs->int_parm_long & 3) { | |
| case 3: | |
| pr_cont("home space "); | |
| break; | |
| case 2: | |
| pr_cont("secondary space "); | |
| break; | |
| case 1: | |
| pr_cont("access register "); | |
| break; | |
| case 0: | |
| pr_cont("primary space "); | |
| break; | |
| } | |
| pr_cont("mode while using "); | |
| if (!user_space_fault(regs)) { | |
| asce = S390_lowcore.kernel_asce; | |
| pr_cont("kernel "); | |
| } | |
| #ifdef CONFIG_PGSTE | |
| else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { | |
| struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; | |
| asce = gmap->asce; | |
| pr_cont("gmap "); | |
| } | |
| #endif | |
| else { | |
| asce = S390_lowcore.user_asce; | |
| pr_cont("user "); | |
| } | |
| pr_cont("ASCE.\n"); | |
| dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); | |
| } | |
| int show_unhandled_signals = 1; | |
| void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) | |
| { | |
| if ((task_pid_nr(current) > 1) && !show_unhandled_signals) | |
| return; | |
| if (!unhandled_signal(current, signr)) | |
| return; | |
| if (!printk_ratelimit()) | |
| return; | |
| printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", | |
| regs->int_code & 0xffff, regs->int_code >> 17); | |
| print_vma_addr(KERN_CONT "in ", regs->psw.addr); | |
| printk(KERN_CONT "\n"); | |
| if (is_mm_fault) | |
| dump_fault_info(regs); | |
| show_regs(regs); | |
| } | |
| /* | |
| * 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, int si_code) | |
| { | |
| struct siginfo si; | |
| report_user_fault(regs, SIGSEGV, 1); | |
| si.si_signo = SIGSEGV; | |
| si.si_errno = 0; | |
| si.si_code = si_code; | |
| si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); | |
| force_sig_info(SIGSEGV, &si, current); | |
| } | |
| static noinline void do_no_context(struct pt_regs *regs) | |
| { | |
| const struct exception_table_entry *fixup; | |
| /* Are we prepared to handle this kernel fault? */ | |
| fixup = search_exception_tables(regs->psw.addr); | |
| if (fixup) { | |
| regs->psw.addr = extable_fixup(fixup); | |
| return; | |
| } | |
| /* | |
| * Oops. The kernel tried to access some bad page. We'll have to | |
| * terminate things with extreme prejudice. | |
| */ | |
| if (!user_space_fault(regs)) | |
| printk(KERN_ALERT "Unable to handle kernel pointer dereference" | |
| " in virtual kernel address space\n"); | |
| else | |
| printk(KERN_ALERT "Unable to handle kernel paging request" | |
| " in virtual user address space\n"); | |
| dump_fault_info(regs); | |
| die(regs, "Oops"); | |
| do_exit(SIGKILL); | |
| } | |
| static noinline void do_low_address(struct pt_regs *regs) | |
| { | |
| /* 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 (regs, "Low-address protection"); | |
| do_exit(SIGKILL); | |
| } | |
| do_no_context(regs); | |
| } | |
| static noinline void do_sigbus(struct pt_regs *regs) | |
| { | |
| struct task_struct *tsk = current; | |
| struct siginfo si; | |
| /* | |
| * Send a sigbus, regardless of whether we were in kernel | |
| * or user mode. | |
| */ | |
| si.si_signo = SIGBUS; | |
| si.si_errno = 0; | |
| si.si_code = BUS_ADRERR; | |
| si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); | |
| force_sig_info(SIGBUS, &si, tsk); | |
| } | |
| static noinline void do_fault_error(struct pt_regs *regs, int fault) | |
| { | |
| int si_code; | |
| switch (fault) { | |
| case VM_FAULT_BADACCESS: | |
| case VM_FAULT_BADMAP: | |
| /* Bad memory access. Check if it is kernel or user space. */ | |
| if (user_mode(regs)) { | |
| /* User mode accesses just cause a SIGSEGV */ | |
| si_code = (fault == VM_FAULT_BADMAP) ? | |
| SEGV_MAPERR : SEGV_ACCERR; | |
| do_sigsegv(regs, si_code); | |
| return; | |
| } | |
| case VM_FAULT_BADCONTEXT: | |
| case VM_FAULT_PFAULT: | |
| do_no_context(regs); | |
| break; | |
| case VM_FAULT_SIGNAL: | |
| if (!user_mode(regs)) | |
| do_no_context(regs); | |
| break; | |
| default: /* fault & VM_FAULT_ERROR */ | |
| if (fault & VM_FAULT_OOM) { | |
| if (!user_mode(regs)) | |
| do_no_context(regs); | |
| else | |
| pagefault_out_of_memory(); | |
| } else if (fault & VM_FAULT_SIGSEGV) { | |
| /* Kernel mode? Handle exceptions or die */ | |
| if (!user_mode(regs)) | |
| do_no_context(regs); | |
| else | |
| do_sigsegv(regs, SEGV_MAPERR); | |
| } else if (fault & VM_FAULT_SIGBUS) { | |
| /* Kernel mode? Handle exceptions or die */ | |
| if (!user_mode(regs)) | |
| do_no_context(regs); | |
| else | |
| do_sigbus(regs); | |
| } 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) | |
| { | |
| #ifdef CONFIG_PGSTE | |
| struct gmap *gmap; | |
| #endif | |
| struct task_struct *tsk; | |
| struct mm_struct *mm; | |
| struct vm_area_struct *vma; | |
| unsigned long trans_exc_code; | |
| unsigned long address; | |
| unsigned int flags; | |
| int fault; | |
| tsk = current; | |
| /* | |
| * The instruction that caused the program check has | |
| * been nullified. Don't signal single step via SIGTRAP. | |
| */ | |
| clear_pt_regs_flag(regs, PIF_PER_TRAP); | |
| if (notify_page_fault(regs)) | |
| return 0; | |
| mm = tsk->mm; | |
| trans_exc_code = regs->int_parm_long; | |
| /* | |
| * 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(regs) || faulthandler_disabled() || !mm)) | |
| goto out; | |
| address = trans_exc_code & __FAIL_ADDR_MASK; | |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); | |
| flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; | |
| if (user_mode(regs)) | |
| flags |= FAULT_FLAG_USER; | |
| if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) | |
| flags |= FAULT_FLAG_WRITE; | |
| down_read(&mm->mmap_sem); | |
| #ifdef CONFIG_PGSTE | |
| gmap = (current->flags & PF_VCPU) ? | |
| (struct gmap *) S390_lowcore.gmap : NULL; | |
| if (gmap) { | |
| current->thread.gmap_addr = address; | |
| current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); | |
| current->thread.gmap_int_code = regs->int_code & 0xffff; | |
| address = __gmap_translate(gmap, address); | |
| if (address == -EFAULT) { | |
| fault = VM_FAULT_BADMAP; | |
| goto out_up; | |
| } | |
| if (gmap->pfault_enabled) | |
| flags |= FAULT_FLAG_RETRY_NOWAIT; | |
| } | |
| #endif | |
| retry: | |
| 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(vma, address, flags); | |
| /* No reason to continue if interrupted by SIGKILL. */ | |
| if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { | |
| fault = VM_FAULT_SIGNAL; | |
| goto out; | |
| } | |
| if (unlikely(fault & VM_FAULT_ERROR)) | |
| goto out_up; | |
| /* | |
| * Major/minor page fault accounting is only done on the | |
| * initial attempt. If we go through a retry, it is extremely | |
| * likely that the page will be found in page cache at that point. | |
| */ | |
| if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
| if (fault & VM_FAULT_MAJOR) { | |
| tsk->maj_flt++; | |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, | |
| regs, address); | |
| } else { | |
| tsk->min_flt++; | |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, | |
| regs, address); | |
| } | |
| if (fault & VM_FAULT_RETRY) { | |
| #ifdef CONFIG_PGSTE | |
| if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
| /* FAULT_FLAG_RETRY_NOWAIT has been set, | |
| * mmap_sem has not been released */ | |
| current->thread.gmap_pfault = 1; | |
| fault = VM_FAULT_PFAULT; | |
| goto out_up; | |
| } | |
| #endif | |
| /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk | |
| * of starvation. */ | |
| flags &= ~(FAULT_FLAG_ALLOW_RETRY | | |
| FAULT_FLAG_RETRY_NOWAIT); | |
| flags |= FAULT_FLAG_TRIED; | |
| down_read(&mm->mmap_sem); | |
| goto retry; | |
| } | |
| } | |
| #ifdef CONFIG_PGSTE | |
| if (gmap) { | |
| address = __gmap_link(gmap, current->thread.gmap_addr, | |
| address); | |
| if (address == -EFAULT) { | |
| fault = VM_FAULT_BADMAP; | |
| goto out_up; | |
| } | |
| if (address == -ENOMEM) { | |
| fault = VM_FAULT_OOM; | |
| goto out_up; | |
| } | |
| } | |
| #endif | |
| fault = 0; | |
| out_up: | |
| up_read(&mm->mmap_sem); | |
| out: | |
| return fault; | |
| } | |
| void do_protection_exception(struct pt_regs *regs) | |
| { | |
| unsigned long trans_exc_code; | |
| int fault; | |
| trans_exc_code = regs->int_parm_long; | |
| /* | |
| * Protection exceptions are suppressing, decrement psw address. | |
| * The exception to this rule are aborted transactions, for these | |
| * the PSW already points to the correct location. | |
| */ | |
| if (!(regs->int_code & 0x200)) | |
| regs->psw.addr = __rewind_psw(regs->psw, regs->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); | |
| return; | |
| } | |
| fault = do_exception(regs, VM_WRITE); | |
| if (unlikely(fault)) | |
| do_fault_error(regs, fault); | |
| } | |
| NOKPROBE_SYMBOL(do_protection_exception); | |
| void do_dat_exception(struct pt_regs *regs) | |
| { | |
| int access, fault; | |
| access = VM_READ | VM_EXEC | VM_WRITE; | |
| fault = do_exception(regs, access); | |
| if (unlikely(fault)) | |
| do_fault_error(regs, fault); | |
| } | |
| NOKPROBE_SYMBOL(do_dat_exception); | |
| #ifdef CONFIG_PFAULT | |
| /* | |
| * 'pfault' pseudo page faults routines. | |
| */ | |
| static int pfault_disable; | |
| static int __init nopfault(char *str) | |
| { | |
| pfault_disable = 1; | |
| return 1; | |
| } | |
| __setup("nopfault", nopfault); | |
| struct pfault_refbk { | |
| u16 refdiagc; | |
| u16 reffcode; | |
| u16 refdwlen; | |
| u16 refversn; | |
| u64 refgaddr; | |
| u64 refselmk; | |
| u64 refcmpmk; | |
| u64 reserved; | |
| } __attribute__ ((packed, aligned(8))); | |
| int pfault_init(void) | |
| { | |
| struct pfault_refbk refbk = { | |
| .refdiagc = 0x258, | |
| .reffcode = 0, | |
| .refdwlen = 5, | |
| .refversn = 2, | |
| .refgaddr = __LC_LPP, | |
| .refselmk = 1ULL << 48, | |
| .refcmpmk = 1ULL << 48, | |
| .reserved = __PF_RES_FIELD }; | |
| int rc; | |
| if (pfault_disable) | |
| return -1; | |
| diag_stat_inc(DIAG_STAT_X258); | |
| 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"); | |
| return rc; | |
| } | |
| void pfault_fini(void) | |
| { | |
| struct pfault_refbk refbk = { | |
| .refdiagc = 0x258, | |
| .reffcode = 1, | |
| .refdwlen = 5, | |
| .refversn = 2, | |
| }; | |
| if (pfault_disable) | |
| return; | |
| diag_stat_inc(DIAG_STAT_X258); | |
| asm volatile( | |
| " diag %0,0,0x258\n" | |
| "0: nopr %%r7\n" | |
| EX_TABLE(0b,0b) | |
| : : "a" (&refbk), "m" (refbk) : "cc"); | |
| } | |
| static DEFINE_SPINLOCK(pfault_lock); | |
| static LIST_HEAD(pfault_list); | |
| #define PF_COMPLETE 0x0080 | |
| /* | |
| * The mechanism of our pfault code: if Linux is running as guest, runs a user | |
| * space process and the user space process accesses a page that the host has | |
| * paged out we get a pfault interrupt. | |
| * | |
| * This allows us, within the guest, to schedule a different process. Without | |
| * this mechanism the host would have to suspend the whole virtual cpu until | |
| * the page has been paged in. | |
| * | |
| * So when we get such an interrupt then we set the state of the current task | |
| * to uninterruptible and also set the need_resched flag. Both happens within | |
| * interrupt context(!). If we later on want to return to user space we | |
| * recognize the need_resched flag and then call schedule(). It's not very | |
| * obvious how this works... | |
| * | |
| * Of course we have a lot of additional fun with the completion interrupt (-> | |
| * host signals that a page of a process has been paged in and the process can | |
| * continue to run). This interrupt can arrive on any cpu and, since we have | |
| * virtual cpus, actually appear before the interrupt that signals that a page | |
| * is missing. | |
| */ | |
| static void pfault_interrupt(struct ext_code ext_code, | |
| unsigned int param32, unsigned long param64) | |
| { | |
| struct task_struct *tsk; | |
| __u16 subcode; | |
| pid_t pid; | |
| /* | |
| * Get the external interruption subcode & pfault initial/completion | |
| * signal bit. VM stores this in the 'cpu address' field associated | |
| * with the external interrupt. | |
| */ | |
| subcode = ext_code.subcode; | |
| if ((subcode & 0xff00) != __SUBCODE_MASK) | |
| return; | |
| inc_irq_stat(IRQEXT_PFL); | |
| /* Get the token (= pid of the affected task). */ | |
| pid = param64 & LPP_PFAULT_PID_MASK; | |
| rcu_read_lock(); | |
| tsk = find_task_by_pid_ns(pid, &init_pid_ns); | |
| if (tsk) | |
| get_task_struct(tsk); | |
| rcu_read_unlock(); | |
| if (!tsk) | |
| return; | |
| spin_lock(&pfault_lock); | |
| if (subcode & PF_COMPLETE) { | |
| /* signal bit is set -> a page has been swapped in by VM */ | |
| if (tsk->thread.pfault_wait == 1) { | |
| /* 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; | |
| list_del(&tsk->thread.list); | |
| wake_up_process(tsk); | |
| put_task_struct(tsk); | |
| } else { | |
| /* Completion interrupt was faster than initial | |
| * interrupt. Set pfault_wait to -1 so the initial | |
| * interrupt doesn't put the task to sleep. | |
| * If the task is not running, ignore the completion | |
| * interrupt since it must be a leftover of a PFAULT | |
| * CANCEL operation which didn't remove all pending | |
| * completion interrupts. */ | |
| if (tsk->state == TASK_RUNNING) | |
| tsk->thread.pfault_wait = -1; | |
| } | |
| } else { | |
| /* signal bit not set -> a real page is missing. */ | |
| if (WARN_ON_ONCE(tsk != current)) | |
| goto out; | |
| if (tsk->thread.pfault_wait == 1) { | |
| /* Already on the list with a reference: put to sleep */ | |
| goto block; | |
| } else if (tsk->thread.pfault_wait == -1) { | |
| /* Completion interrupt was faster than the initial | |
| * interrupt (pfault_wait == -1). Set pfault_wait | |
| * back to zero and exit. */ | |
| tsk->thread.pfault_wait = 0; | |
| } else { | |
| /* Initial interrupt arrived before completion | |
| * interrupt. Let the task sleep. | |
| * An extra task reference is needed since a different | |
| * cpu may set the task state to TASK_RUNNING again | |
| * before the scheduler is reached. */ | |
| get_task_struct(tsk); | |
| tsk->thread.pfault_wait = 1; | |
| list_add(&tsk->thread.list, &pfault_list); | |
| block: | |
| /* Since this must be a userspace fault, there | |
| * is no kernel task state to trample. Rely on the | |
| * return to userspace schedule() to block. */ | |
| __set_current_state(TASK_UNINTERRUPTIBLE); | |
| set_tsk_need_resched(tsk); | |
| } | |
| } | |
| out: | |
| spin_unlock(&pfault_lock); | |
| put_task_struct(tsk); | |
| } | |
| static int pfault_cpu_dead(unsigned int cpu) | |
| { | |
| struct thread_struct *thread, *next; | |
| struct task_struct *tsk; | |
| spin_lock_irq(&pfault_lock); | |
| list_for_each_entry_safe(thread, next, &pfault_list, list) { | |
| thread->pfault_wait = 0; | |
| list_del(&thread->list); | |
| tsk = container_of(thread, struct task_struct, thread); | |
| wake_up_process(tsk); | |
| put_task_struct(tsk); | |
| } | |
| spin_unlock_irq(&pfault_lock); | |
| return 0; | |
| } | |
| static int __init pfault_irq_init(void) | |
| { | |
| int rc; | |
| rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); | |
| if (rc) | |
| goto out_extint; | |
| rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; | |
| if (rc) | |
| goto out_pfault; | |
| irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); | |
| cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", | |
| NULL, pfault_cpu_dead); | |
| return 0; | |
| out_pfault: | |
| unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); | |
| out_extint: | |
| pfault_disable = 1; | |
| return rc; | |
| } | |
| early_initcall(pfault_irq_init); | |
| #endif /* CONFIG_PFAULT */ |