--- /dev/null
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1995 - 2000 by Ralf Baechle
+ */
+#include <linux/context_tracking.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/ratelimit.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/perf_event.h>
+#include <linux/uaccess.h>
+
+#include <asm/branch.h>
+#include <asm/mmu_context.h>
+#include <asm/ptrace.h>
+#include <asm/highmem.h> /* For VMALLOC_END */
+#include <linux/kdebug.h>
+
+int show_unhandled_signals = 1;
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
+ unsigned long address)
+{
+ struct vm_area_struct * vma = NULL;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
+ const int field = sizeof(unsigned long) * 2;
+ siginfo_t info;
+ int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+
+ static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+
+#if 0
+ printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
+ current->comm, current->pid, field, address, write,
+ field, regs->cp0_epc);
+#endif
+
+#ifdef CONFIG_KPROBES
+ /*
+ * This is to notify the fault handler of the kprobes. The
+ * exception code is redundant as it is also carried in REGS,
+ * but we pass it anyhow.
+ */
+ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
+ (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
+ return;
+#endif
+
+ info.si_code = SEGV_MAPERR;
+
+ /*
+ * We fault-in kernel-space virtual memory on-demand. The
+ * 'reference' page table is init_mm.pgd.
+ *
+ * NOTE! We MUST NOT take any locks for this case. We may
+ * be in an interrupt or a critical region, and should
+ * only copy the information from the master page table,
+ * nothing more.
+ */
+#ifdef CONFIG_64BIT
+# define VMALLOC_FAULT_TARGET no_context
+#else
+# define VMALLOC_FAULT_TARGET vmalloc_fault
+#endif
+
+ if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
+ goto VMALLOC_FAULT_TARGET;
+#ifdef MODULE_START
+ if (unlikely(address >= MODULE_START && address < MODULE_END))
+ goto VMALLOC_FAULT_TARGET;
+#endif
+
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (faulthandler_disabled() || !mm)
+ goto bad_area_nosemaphore;
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+retry:
+ 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:
+ info.si_code = SEGV_ACCERR;
+
+ if (write) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
+ } else {
+ if (cpu_has_rixi) {
+ if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
+#if 0
+ pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
+ raw_smp_processor_id(),
+ current->comm, current->pid,
+ field, address, write,
+ field, regs->cp0_epc);
+#endif
+ goto bad_area;
+ }
+ if (!(vma->vm_flags & VM_READ)) {
+#if 0
+ pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
+ raw_smp_processor_id(),
+ current->comm, current->pid,
+ field, address, write,
+ field, regs->cp0_epc);
+#endif
+ goto bad_area;
+ }
+ } else {
+ if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+ goto bad_area;
+ }
+ }
+
+ /*
+ * 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, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return;
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ if (fault & VM_FAULT_OOM)
+ goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
+ else if (fault & VM_FAULT_SIGBUS)
+ goto do_sigbus;
+ BUG();
+ }
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR) {
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+ regs, address);
+ tsk->maj_flt++;
+ } else {
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+ regs, address);
+ tsk->min_flt++;
+ }
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
+
+ /*
+ * No need to up_read(&mm->mmap_sem) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+
+ goto retry;
+ }
+ }
+
+ up_read(&mm->mmap_sem);
+ return;
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+ up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+ /* User mode accesses just cause a SIGSEGV */
+ if (user_mode(regs)) {
+ tsk->thread.cp0_badvaddr = address;
+ tsk->thread.error_code = write;
+ if (show_unhandled_signals &&
+ unhandled_signal(tsk, SIGSEGV) &&
+ __ratelimit(&ratelimit_state)) {
+ pr_info("\ndo_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx",
+ tsk->comm,
+ write ? "write access to" : "read access from",
+ field, address);
+ pr_info("epc = %0*lx in", field,
+ (unsigned long) regs->cp0_epc);
+ print_vma_addr(" ", regs->cp0_epc);
+ pr_info("ra = %0*lx in", field,
+ (unsigned long) regs->regs[31]);
+ print_vma_addr(" ", regs->regs[31]);
+ pr_info("\n");
+ }
+ info.si_signo = SIGSEGV;
+ info.si_errno = 0;
+ /* info.si_code has been set above */
+ info.si_addr = (void __user *) address;
+ force_sig_info(SIGSEGV, &info, tsk);
+ return;
+ }
+
+no_context:
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs)) {
+ current->thread.cp0_baduaddr = address;
+ return;
+ }
+
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+
+ printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
+ "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
+ raw_smp_processor_id(), field, address, field, regs->cp0_epc,
+ field, regs->regs[31]);
+ die("Oops", regs);
+
+out_of_memory:
+ /*
+ * We ran out of memory, call the OOM killer, and return the userspace
+ * (which will retry the fault, or kill us if we got oom-killed).
+ */
+ up_read(&mm->mmap_sem);
+ if (!user_mode(regs))
+ goto no_context;
+ pagefault_out_of_memory();
+ return;
+
+do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs))
+ goto no_context;
+ else
+ /*
+ * Send a sigbus, regardless of whether we were in kernel
+ * or user mode.
+ */
+#if 0
+ printk("do_page_fault() #3: sending SIGBUS to %s for "
+ "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
+ tsk->comm,
+ write ? "write access to" : "read access from",
+ field, address,
+ field, (unsigned long) regs->cp0_epc,
+ field, (unsigned long) regs->regs[31]);
+#endif
+ tsk->thread.cp0_badvaddr = address;
+ info.si_signo = SIGBUS;
+ info.si_errno = 0;
+ info.si_code = BUS_ADRERR;
+ info.si_addr = (void __user *) address;
+ force_sig_info(SIGBUS, &info, tsk);
+
+ return;
+#ifndef CONFIG_64BIT
+vmalloc_fault:
+ {
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Do _not_ use "tsk" here. We might be inside
+ * an interrupt in the middle of a task switch..
+ */
+ int offset = __pgd_offset(address);
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+ pte_t *pte_k;
+
+ pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ if (!pgd_present(*pgd_k))
+ goto no_context;
+ set_pgd(pgd, *pgd_k);
+
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ goto no_context;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ goto no_context;
+ set_pmd(pmd, *pmd_k);
+
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ goto no_context;
+ return;
+ }
+#endif
+}
+
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+ unsigned long write, unsigned long address)
+{
+ enum ctx_state prev_state;
+
+ prev_state = exception_enter();
+ __do_page_fault(regs, write, address);
+ exception_exit(prev_state);
+}
Code Review / kvmfornfv.git / blobdiff