diff options
Diffstat (limited to 'arch/s390/mm/fault.c')
| -rw-r--r-- | arch/s390/mm/fault.c | 877 |
1 files changed, 586 insertions, 291 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 64e32da7775..3f3b35403d0 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -1,8 +1,6 @@ /* - * arch/s390/mm/fault.c - * * S390 version - * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation + * Copyright IBM Corp. 1999 * Author(s): Hartmut Penner (hp@de.ibm.com) * Ulrich Weigand (uweigand@de.ibm.com) * @@ -10,7 +8,8 @@ * Copyright (C) 1995 Linus Torvalds */ -#include <linux/config.h> +#include <linux/kernel_stat.h> +#include <linux/perf_event.h> #include <linux/signal.h> #include <linux/sched.h> #include <linux/kernel.h> @@ -20,41 +19,69 @@ #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/mm.h> +#include <linux/compat.h> #include <linux/smp.h> -#include <linux/smp_lock.h> +#include <linux/kdebug.h> #include <linux/init.h> #include <linux/console.h> #include <linux/module.h> #include <linux/hardirq.h> - -#include <asm/system.h> -#include <asm/uaccess.h> +#include <linux/kprobes.h> +#include <linux/uaccess.h> +#include <linux/hugetlb.h> +#include <asm/asm-offsets.h> #include <asm/pgtable.h> +#include <asm/irq.h> +#include <asm/mmu_context.h> +#include <asm/facility.h> +#include "../kernel/entry.h" -#ifndef CONFIG_ARCH_S390X +#ifndef CONFIG_64BIT #define __FAIL_ADDR_MASK 0x7ffff000 -#define __FIXUP_MASK 0x7fffffff #define __SUBCODE_MASK 0x0200 #define __PF_RES_FIELD 0ULL -#else /* CONFIG_ARCH_S390X */ +#else /* CONFIG_64BIT */ #define __FAIL_ADDR_MASK -4096L -#define __FIXUP_MASK ~0L #define __SUBCODE_MASK 0x0600 #define __PF_RES_FIELD 0x8000000000000000ULL -#endif /* CONFIG_ARCH_S390X */ +#endif /* CONFIG_64BIT */ + +#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 -#ifdef CONFIG_SYSCTL -extern int sysctl_userprocess_debug; +static unsigned long store_indication __read_mostly; + +#ifdef CONFIG_64BIT +static int __init fault_init(void) +{ + if (test_facility(75)) + store_indication = 0xc00; + return 0; +} +early_initcall(fault_init); #endif -extern void die(const char *,struct pt_regs *,long); +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; +} -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) + * message out. */ void bust_spinlocks(int yes) { @@ -76,287 +103,482 @@ void bust_spinlocks(int yes) } /* - * Check which address space is addressed by the access - * register in S390_lowcore.exc_access_id. - * Returns 1 for user space and 0 for kernel space. + * Returns the address space associated with the fault. + * Returns 0 for kernel space and 1 for user space. */ -static int __check_access_register(struct pt_regs *regs, int error_code) +static inline int user_space_fault(struct pt_regs *regs) { - int areg = S390_lowcore.exc_access_id; + unsigned long trans_exc_code; - if (areg == 0) - /* Access via access register 0 -> kernel address */ + /* + * 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; - save_access_regs(current->thread.acrs); - if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1) - /* - * access register contains 0 -> kernel address, - * access register contains 1 -> user space address - */ - return current->thread.acrs[areg]; - - /* Something unhealthy was done with the access registers... */ - die("page fault via unknown access register", regs, error_code); - do_exit(SIGKILL); + 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; } -/* - * Check which address space the address belongs to. - * Returns 1 for user space and 0 for kernel space. - */ -static inline int check_user_space(struct pt_regs *regs, int error_code) +static int bad_address(void *p) { - /* - * The lowest two bits of S390_lowcore.trans_exc_code indicate - * which paging table was used: - * 0: Primary Segment Table Descriptor - * 1: STD determined via access register - * 2: Secondary Segment Table Descriptor - * 3: Home Segment Table Descriptor - */ - int descriptor = S390_lowcore.trans_exc_code & 3; - if (unlikely(descriptor == 1)) - return __check_access_register(regs, error_code); - if (descriptor == 2) - return current->thread.mm_segment.ar4; - return descriptor != 0; + unsigned long dummy; + + return probe_kernel_address((unsigned long *)p, dummy); +} + +#ifdef CONFIG_64BIT +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(KERN_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"); +} + +#else /* CONFIG_64BIT */ + +static void dump_pagetable(unsigned long asce, unsigned long address) +{ + unsigned long *table = __va(asce & PAGE_MASK); + + pr_alert("AS:%08lx ", asce); + table = table + ((address >> 20) & 0x7ff); + if (bad_address(table)) + goto bad; + pr_cont("S:%08lx ", *table); + if (*table & _SEGMENT_ENTRY_INVALID) + goto out; + table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); + table = table + ((address >> 12) & 0xff); + if (bad_address(table)) + goto bad; + pr_cont("P:%08lx ", *table); +out: + pr_cont("\n"); + return; +bad: + pr_cont("BAD\n"); +} + +#endif /* CONFIG_64BIT */ + +static void dump_fault_info(struct pt_regs *regs) +{ + unsigned long asce; + + 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); +} + +static inline void report_user_fault(struct pt_regs *regs, long signr) +{ + 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 0x%X ", + regs->int_code); + print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN); + printk(KERN_CONT "\n"); + printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n", + regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); + 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 void do_sigsegv(struct pt_regs *regs, unsigned long error_code, - int si_code, unsigned long address) +static noinline void do_sigsegv(struct pt_regs *regs, int si_code) { struct siginfo si; -#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", - error_code); - printk("failing address: %lX\n", address); - show_regs(regs); - } -#endif + report_user_fault(regs, SIGSEGV); si.si_signo = SIGSEGV; si.si_code = si_code; - si.si_addr = (void *) address; + 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; + 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 = extable_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 = regs->int_parm_long & __FAIL_ADDR_MASK; + 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"); + printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n", + regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); + 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_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. * - * error_code: + * 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) */ -extern inline void -do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) +static inline int do_exception(struct pt_regs *regs, int access) { - struct task_struct *tsk; - struct mm_struct *mm; - struct vm_area_struct * vma; - unsigned long address; - int user_address; - const struct exception_table_entry *fixup; - int si_code = SEGV_MAPERR; - - 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. +#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. */ - if (is_protection && !(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_MASK_PSTATE)) { - address = 0; - user_address = 0; - goto no_context; - } + clear_pt_regs_flag(regs, PIF_PER_TRAP); - /* Low-address protection hit in user mode 'cannot happen'. */ - die ("Low-address protection", regs, error_code); - do_exit(SIGKILL); - } + if (notify_page_fault(regs)) + return 0; - /* - * get the failing address - * more specific the segment and page table portion of - * the address - */ - address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; - user_address = check_user_space(regs, error_code); + 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. */ - if (user_address == 0 || in_atomic() || !mm) - goto no_context; + fault = VM_FAULT_BADCONTEXT; + if (unlikely(!user_space_fault(regs) || in_atomic() || !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 = (struct gmap *) + ((current->flags & PF_VCPU) ? S390_lowcore.gmap : 0); + if (gmap) { + address = __gmap_fault(address, gmap); + if (address == -EFAULT) { + fault = VM_FAULT_BADMAP; + goto out_up; + } + if (address == -ENOMEM) { + fault = VM_FAULT_OOM; + 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; + } /* - * 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 + * Ok, we have a good vm_area for this memory access, so + * we can handle it.. */ - local_irq_enable(); - - 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: - si_code = SEGV_ACCERR; - if (!is_protection) { - /* page not present, check vm flags */ - if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) - goto bad_area; - } else { - if (!(vma->vm_flags & VM_WRITE)) - goto bad_area; - } + fault = VM_FAULT_BADACCESS; + if (unlikely(!(vma->vm_flags & access))) + goto out_up; -survive: + 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. */ - switch (handle_mm_fault(mm, vma, address, is_protection)) { - case VM_FAULT_MINOR: - tsk->min_flt++; - break; - case VM_FAULT_MAJOR: - tsk->maj_flt++; - break; - case VM_FAULT_SIGBUS: - goto do_sigbus; - case VM_FAULT_OOM: - goto out_of_memory; - default: - BUG(); + fault = handle_mm_fault(mm, 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; - up_read(&mm->mmap_sem); /* - * The instruction that caused the program check will - * be repeated. Don't signal single step via SIGTRAP. + * 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. */ - clear_tsk_thread_flag(current, TIF_SINGLE_STEP); - 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_MASK_PSTATE) { - tsk->thread.prot_addr = address; - tsk->thread.trap_no = error_code; - do_sigsegv(regs, error_code, si_code, address); - return; + 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; + } } - -no_context: - /* Are we prepared to handle this kernel fault? */ - fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); - 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. - */ - if (user_address == 0) - 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, 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: + fault = 0; +out_up: up_read(&mm->mmap_sem); - if (tsk->pid == 1) { - yield(); - goto survive; - } - printk("VM: killing process %s\n", tsk->comm); - if (regs->psw.mask & PSW_MASK_PSTATE) - do_exit(SIGKILL); - goto no_context; +out: + return fault; +} -do_sigbus: - up_read(&mm->mmap_sem); +void __kprobes do_protection_exception(struct pt_regs *regs) +{ + unsigned long trans_exc_code; + int fault; + trans_exc_code = regs->int_parm_long; /* - * Send a sigbus, regardless of whether we were in kernel - * or user mode. + * 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. */ - 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_MASK_PSTATE)) - goto no_context; + 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); } -void do_protection_exception(struct pt_regs *regs, unsigned long error_code) +void __kprobes do_dat_exception(struct pt_regs *regs) { - regs->psw.addr -= (error_code >> 16); - do_exception(regs, 4, 1); -} + int access, fault; -void do_dat_exception(struct pt_regs *regs, unsigned long error_code) -{ - do_exception(regs, error_code & 0xff, 0); + access = VM_READ | VM_EXEC | VM_WRITE; + fault = do_exception(regs, access); + if (unlikely(fault)) + do_fault_error(regs, fault); } #ifdef CONFIG_PFAULT /* * 'pfault' pseudo page faults routines. */ -static int pfault_disable = 0; +static int pfault_disable; static int __init nopfault(char *str) { @@ -366,71 +588,69 @@ static int __init nopfault(char *str) __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; +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) { - pfault_refbk_t refbk = - { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48, - __PF_RES_FIELD }; + struct pfault_refbk refbk = { + .refdiagc = 0x258, + .reffcode = 0, + .refdwlen = 5, + .refversn = 2, + .refgaddr = __LC_CURRENT_PID, + .refselmk = 1ULL << 48, + .refcmpmk = 1ULL << 48, + .reserved = __PF_RES_FIELD }; int rc; if (pfault_disable) return -1; - __asm__ __volatile__( - " diag %1,%0,0x258\n" - "0: j 2f\n" - "1: la %0,8\n" + 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" -#ifndef CONFIG_ARCH_S390X - " .long 0b,1b\n" -#else /* CONFIG_ARCH_S390X */ - " .quad 0b,1b\n" -#endif /* CONFIG_ARCH_S390X */ - ".previous" - : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc" ); - __ctl_set_bit(0, 9); + EX_TABLE(0b,1b) + : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); return rc; } void pfault_fini(void) { - pfault_refbk_t refbk = - { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; + struct pfault_refbk refbk = { + .refdiagc = 0x258, + .reffcode = 1, + .refdwlen = 5, + .refversn = 2, + }; if (pfault_disable) return; - __ctl_clear_bit(0,9); - __asm__ __volatile__( - " diag %0,0,0x258\n" + asm volatile( + " diag %0,0,0x258\n" "0:\n" - ".section __ex_table,\"a\"\n" - " .align 4\n" -#ifndef CONFIG_ARCH_S390X - " .long 0b,0b\n" -#else /* CONFIG_ARCH_S390X */ - " .quad 0b,0b\n" -#endif /* CONFIG_ARCH_S390X */ - ".previous" - : : "a" (&refbk), "m" (refbk) : "cc" ); + EX_TABLE(0b,0b) + : : "a" (&refbk), "m" (refbk) : "cc"); } -asmlinkage void -pfault_interrupt(struct pt_regs *regs, __u16 error_code) +static DEFINE_SPINLOCK(pfault_lock); +static LIST_HEAD(pfault_list); + +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 @@ -438,43 +658,118 @@ pfault_interrupt(struct pt_regs *regs, __u16 error_code) * in the 'cpu address' field associated with the * external interrupt. */ - subcode = S390_lowcore.cpu_addr; + subcode = ext_code.subcode; 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; - + inc_irq_stat(IRQEXT_PFL); + /* Get the token (= pid of the affected task). */ + pid = sizeof(void *) == 4 ? param32 : param64; + 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 & 0x0080) { /* signal bit is set -> a page has been swapped in by VM */ - if (xchg(&tsk->thread.pfault_wait, -1) != 0) { + 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. */ - get_task_struct(tsk); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - if (xchg(&tsk->thread.pfault_wait, 1) != 0) { + if (WARN_ON_ONCE(tsk != current)) + goto out; + if (tsk->thread.pfault_wait == 1) { + /* Already on the list with a reference: put to sleep */ + __set_task_state(tsk, TASK_UNINTERRUPTIBLE); + set_tsk_need_resched(tsk); + } else if (tsk->thread.pfault_wait == -1) { /* 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. */ + * interrupt (pfault_wait == -1). Set pfault_wait + * back to zero and exit. */ tsk->thread.pfault_wait = 0; - set_task_state(tsk, TASK_RUNNING); - put_task_struct(tsk); - } else + } 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); + __set_task_state(tsk, TASK_UNINTERRUPTIBLE); set_tsk_need_resched(tsk); + } } +out: + spin_unlock(&pfault_lock); + put_task_struct(tsk); } -#endif +static int pfault_cpu_notify(struct notifier_block *self, unsigned long action, + void *hcpu) +{ + struct thread_struct *thread, *next; + struct task_struct *tsk; + + switch (action & ~CPU_TASKS_FROZEN) { + case CPU_DEAD: + 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); + break; + default: + break; + } + return NOTIFY_OK; +} + +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); + hotcpu_notifier(pfault_cpu_notify, 0); + 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 */ |