612 lines
15 KiB
C
612 lines
15 KiB
C
/*
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* arch/s390/mm/fault.c
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*
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* S390 version
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* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Hartmut Penner (hp@de.ibm.com)
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* Ulrich Weigand (uweigand@de.ibm.com)
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*
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* Derived from "arch/i386/mm/fault.c"
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* Copyright (C) 1995 Linus Torvalds
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kdebug.h>
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#include <linux/smp_lock.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/module.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <asm/system.h>
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#include <asm/pgtable.h>
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#include <asm/s390_ext.h>
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#include <asm/mmu_context.h>
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#include "../kernel/entry.h"
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#ifndef CONFIG_64BIT
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#define __FAIL_ADDR_MASK 0x7ffff000
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#define __FIXUP_MASK 0x7fffffff
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#define __SUBCODE_MASK 0x0200
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#define __PF_RES_FIELD 0ULL
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#else /* CONFIG_64BIT */
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#define __FAIL_ADDR_MASK -4096L
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#define __FIXUP_MASK ~0L
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#define __SUBCODE_MASK 0x0600
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#define __PF_RES_FIELD 0x8000000000000000ULL
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#endif /* CONFIG_64BIT */
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#ifdef CONFIG_SYSCTL
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extern int sysctl_userprocess_debug;
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#endif
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#ifdef CONFIG_KPROBES
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static inline int notify_page_fault(struct pt_regs *regs, long err)
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{
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int ret = 0;
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/* kprobe_running() needs smp_processor_id() */
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if (!user_mode(regs)) {
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, 14))
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ret = 1;
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preempt_enable();
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}
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return ret;
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}
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#else
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static inline int notify_page_fault(struct pt_regs *regs, long err)
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{
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return 0;
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}
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#endif
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/*
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* Unlock any spinlocks which will prevent us from getting the
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* message out.
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*/
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void bust_spinlocks(int yes)
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{
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if (yes) {
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oops_in_progress = 1;
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} else {
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int loglevel_save = console_loglevel;
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console_unblank();
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oops_in_progress = 0;
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/*
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* OK, the message is on the console. Now we call printk()
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* without oops_in_progress set so that printk will give klogd
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* a poke. Hold onto your hats...
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*/
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console_loglevel = 15;
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printk(" ");
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console_loglevel = loglevel_save;
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}
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}
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/*
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* Returns the address space associated with the fault.
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* Returns 0 for kernel space, 1 for user space and
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* 2 for code execution in user space with noexec=on.
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*/
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static inline int check_space(struct task_struct *tsk)
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{
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/*
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* The lowest two bits of S390_lowcore.trans_exc_code
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* indicate which paging table was used.
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*/
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int desc = S390_lowcore.trans_exc_code & 3;
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if (desc == 3) /* Home Segment Table Descriptor */
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return switch_amode == 0;
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if (desc == 2) /* Secondary Segment Table Descriptor */
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return tsk->thread.mm_segment.ar4;
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#ifdef CONFIG_S390_SWITCH_AMODE
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if (unlikely(desc == 1)) { /* STD determined via access register */
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/* %a0 always indicates primary space. */
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if (S390_lowcore.exc_access_id != 0) {
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save_access_regs(tsk->thread.acrs);
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/*
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* An alet of 0 indicates primary space.
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* An alet of 1 indicates secondary space.
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* Any other alet values generate an
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* alen-translation exception.
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*/
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if (tsk->thread.acrs[S390_lowcore.exc_access_id])
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return tsk->thread.mm_segment.ar4;
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}
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}
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#endif
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/* Primary Segment Table Descriptor */
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return switch_amode << s390_noexec;
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}
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/*
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* Send SIGSEGV to task. This is an external routine
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* to keep the stack usage of do_page_fault small.
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*/
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static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
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int si_code, unsigned long address)
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{
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struct siginfo si;
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#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
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#if defined(CONFIG_SYSCTL)
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if (sysctl_userprocess_debug)
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#endif
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{
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printk("User process fault: interruption code 0x%lX\n",
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error_code);
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printk("failing address: %lX\n", address);
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show_regs(regs);
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}
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#endif
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si.si_signo = SIGSEGV;
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si.si_code = si_code;
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si.si_addr = (void __user *) address;
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force_sig_info(SIGSEGV, &si, current);
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}
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static void do_no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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const struct exception_table_entry *fixup;
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/* Are we prepared to handle this kernel fault? */
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fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK);
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if (fixup) {
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regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
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return;
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}
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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if (check_space(current) == 0)
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printk(KERN_ALERT "Unable to handle kernel pointer dereference"
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" at virtual kernel address %p\n", (void *)address);
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else
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printk(KERN_ALERT "Unable to handle kernel paging request"
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" at virtual user address %p\n", (void *)address);
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die("Oops", regs, error_code);
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do_exit(SIGKILL);
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}
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static void do_low_address(struct pt_regs *regs, unsigned long error_code)
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{
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/* Low-address protection hit in kernel mode means
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NULL pointer write access in kernel mode. */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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/* Low-address protection hit in user mode 'cannot happen'. */
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die ("Low-address protection", regs, error_code);
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do_exit(SIGKILL);
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}
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do_no_context(regs, error_code, 0);
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}
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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static int do_out_of_memory(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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up_read(&mm->mmap_sem);
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if (is_global_init(tsk)) {
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yield();
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down_read(&mm->mmap_sem);
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return 1;
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}
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printk("VM: killing process %s\n", tsk->comm);
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if (regs->psw.mask & PSW_MASK_PSTATE)
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do_group_exit(SIGKILL);
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do_no_context(regs, error_code, address);
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return 0;
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}
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static void do_sigbus(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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tsk->thread.prot_addr = address;
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tsk->thread.trap_no = error_code;
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force_sig(SIGBUS, tsk);
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/* Kernel mode? Handle exceptions or die */
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if (!(regs->psw.mask & PSW_MASK_PSTATE))
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do_no_context(regs, error_code, address);
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}
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#ifdef CONFIG_S390_EXEC_PROTECT
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static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
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unsigned long address, unsigned long error_code)
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{
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u16 instruction;
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int rc;
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#ifdef CONFIG_COMPAT
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int compat;
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#endif
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pagefault_disable();
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rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
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pagefault_enable();
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if (rc)
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return -EFAULT;
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up_read(&mm->mmap_sem);
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clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
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#ifdef CONFIG_COMPAT
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compat = test_tsk_thread_flag(current, TIF_31BIT);
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if (compat && instruction == 0x0a77)
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sys32_sigreturn();
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else if (compat && instruction == 0x0aad)
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sys32_rt_sigreturn();
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else
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#endif
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if (instruction == 0x0a77)
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sys_sigreturn();
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else if (instruction == 0x0aad)
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sys_rt_sigreturn();
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else {
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current->thread.prot_addr = address;
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current->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, SEGV_MAPERR, address);
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}
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return 0;
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}
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#endif /* CONFIG_S390_EXEC_PROTECT */
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* error_code:
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* 04 Protection -> Write-Protection (suprression)
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* 10 Segment translation -> Not present (nullification)
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* 11 Page translation -> Not present (nullification)
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* 3b Region third trans. -> Not present (nullification)
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*/
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static inline void
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do_exception(struct pt_regs *regs, unsigned long error_code, int write)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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unsigned long address;
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int space;
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int si_code;
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int fault;
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if (notify_page_fault(regs, error_code))
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return;
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tsk = current;
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mm = tsk->mm;
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/* get the failing address and the affected space */
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address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;
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space = check_space(tsk);
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/*
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* Verify that the fault happened in user space, that
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* we are not in an interrupt and that there is a
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* user context.
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*/
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if (unlikely(space == 0 || in_atomic() || !mm))
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goto no_context;
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/*
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* When we get here, the fault happened in the current
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* task's user address space, so we can switch on the
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* interrupts again and then search the VMAs
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*/
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local_irq_enable();
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down_read(&mm->mmap_sem);
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si_code = SEGV_MAPERR;
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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#ifdef CONFIG_S390_EXEC_PROTECT
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if (unlikely((space == 2) && !(vma->vm_flags & VM_EXEC)))
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if (!signal_return(mm, regs, address, error_code))
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/*
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* signal_return() has done an up_read(&mm->mmap_sem)
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* if it returns 0.
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*/
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return;
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#endif
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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si_code = SEGV_ACCERR;
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if (!write) {
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/* page not present, check vm flags */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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}
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survive:
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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fault = handle_mm_fault(mm, vma, address, write);
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM) {
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if (do_out_of_memory(regs, error_code, address))
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goto survive;
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return;
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} else if (fault & VM_FAULT_SIGBUS) {
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do_sigbus(regs, error_code, address);
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return;
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}
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BUG();
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}
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if (fault & VM_FAULT_MAJOR)
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tsk->maj_flt++;
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else
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tsk->min_flt++;
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up_read(&mm->mmap_sem);
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/*
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* The instruction that caused the program check will
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* be repeated. Don't signal single step via SIGTRAP.
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*/
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clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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/* User mode accesses just cause a SIGSEGV */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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tsk->thread.prot_addr = address;
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tsk->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, si_code, address);
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return;
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}
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no_context:
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do_no_context(regs, error_code, address);
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}
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void __kprobes do_protection_exception(struct pt_regs *regs,
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long error_code)
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{
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/* Protection exception is supressing, decrement psw address. */
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regs->psw.addr -= (error_code >> 16);
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/*
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* Check for low-address protection. This needs to be treated
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* as a special case because the translation exception code
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* field is not guaranteed to contain valid data in this case.
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*/
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if (unlikely(!(S390_lowcore.trans_exc_code & 4))) {
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do_low_address(regs, error_code);
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return;
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}
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do_exception(regs, 4, 1);
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}
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void __kprobes do_dat_exception(struct pt_regs *regs, long error_code)
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{
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do_exception(regs, error_code & 0xff, 0);
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}
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#ifdef CONFIG_64BIT
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void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code)
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{
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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unsigned long address;
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int space;
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mm = current->mm;
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address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;
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space = check_space(current);
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if (unlikely(space == 0 || in_atomic() || !mm))
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goto no_context;
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local_irq_enable();
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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up_read(&mm->mmap_sem);
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if (vma) {
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update_mm(mm, current);
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return;
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}
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/* User mode accesses just cause a SIGSEGV */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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current->thread.prot_addr = address;
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current->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, SEGV_MAPERR, address);
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return;
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}
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no_context:
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do_no_context(regs, error_code, address);
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}
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#endif
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#ifdef CONFIG_PFAULT
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/*
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* 'pfault' pseudo page faults routines.
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*/
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static ext_int_info_t ext_int_pfault;
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static int pfault_disable = 0;
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static int __init nopfault(char *str)
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{
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pfault_disable = 1;
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return 1;
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}
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__setup("nopfault", nopfault);
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typedef struct {
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__u16 refdiagc;
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__u16 reffcode;
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__u16 refdwlen;
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__u16 refversn;
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__u64 refgaddr;
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__u64 refselmk;
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__u64 refcmpmk;
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__u64 reserved;
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} __attribute__ ((packed, aligned(8))) pfault_refbk_t;
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int pfault_init(void)
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{
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pfault_refbk_t refbk =
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{ 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
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__PF_RES_FIELD };
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int rc;
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if (!MACHINE_IS_VM || pfault_disable)
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return -1;
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asm volatile(
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" diag %1,%0,0x258\n"
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"0: j 2f\n"
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"1: la %0,8\n"
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"2:\n"
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EX_TABLE(0b,1b)
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: "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
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__ctl_set_bit(0, 9);
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return rc;
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}
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void pfault_fini(void)
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{
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pfault_refbk_t refbk =
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{ 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
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if (!MACHINE_IS_VM || pfault_disable)
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return;
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__ctl_clear_bit(0,9);
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asm volatile(
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" diag %0,0,0x258\n"
|
|
"0:\n"
|
|
EX_TABLE(0b,0b)
|
|
: : "a" (&refbk), "m" (refbk) : "cc");
|
|
}
|
|
|
|
static void pfault_interrupt(__u16 error_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
|