| /* |
| * linux/arch/cris/mm/fault.c |
| * |
| * Copyright (C) 2000, 2001 Axis Communications AB |
| * |
| * Authors: Bjorn Wesen |
| * |
| * $Log: fault.c,v $ |
| * Revision 1.20 2005/03/04 08:16:18 starvik |
| * Merge of Linux 2.6.11. |
| * |
| * Revision 1.19 2005/01/14 10:07:59 starvik |
| * Fixed warning. |
| * |
| * Revision 1.18 2005/01/12 08:10:14 starvik |
| * Readded the change of frametype when handling kernel page fault fixup |
| * for v10. This is necessary to avoid that the CPU remakes the faulting |
| * access. |
| * |
| * Revision 1.17 2005/01/11 13:53:05 starvik |
| * Use raw_printk. |
| * |
| * Revision 1.16 2004/12/17 11:39:41 starvik |
| * SMP support. |
| * |
| * Revision 1.15 2004/11/23 18:36:18 starvik |
| * Stack is now non-executable. |
| * Signal handler trampolines are placed in a reserved page mapped into all |
| * processes. |
| * |
| * Revision 1.14 2004/11/23 07:10:21 starvik |
| * Moved find_fixup_code to generic code. |
| * |
| * Revision 1.13 2004/11/23 07:00:54 starvik |
| * Actually use the execute permission bit in the MMU. This makes it possible |
| * to prevent e.g. attacks where executable code is put on the stack. |
| * |
| * Revision 1.12 2004/09/29 06:16:04 starvik |
| * Use instruction_pointer |
| * |
| * Revision 1.11 2004/05/14 07:58:05 starvik |
| * Merge of changes from 2.4 |
| * |
| * Revision 1.10 2003/10/27 14:51:24 starvik |
| * Removed debugcode |
| * |
| * Revision 1.9 2003/10/27 14:50:42 starvik |
| * Changed do_page_fault signature |
| * |
| * Revision 1.8 2003/07/04 13:02:48 tobiasa |
| * Moved code snippet from arch/cris/mm/fault.c that searches for fixup code |
| * to seperate function in arch-specific files. |
| * |
| * Revision 1.7 2003/01/22 06:48:38 starvik |
| * Fixed warnings issued by GCC 3.2.1 |
| * |
| * Revision 1.6 2003/01/09 14:42:52 starvik |
| * Merge of Linux 2.5.55 |
| * |
| * Revision 1.5 2002/12/11 14:44:48 starvik |
| * Extracted v10 (ETRAX 100LX) specific stuff to arch/cris/arch-v10/mm |
| * |
| * Revision 1.4 2002/11/13 15:10:28 starvik |
| * pte_offset has been renamed to pte_offset_kernel |
| * |
| * Revision 1.3 2002/11/05 06:45:13 starvik |
| * Merge of Linux 2.5.45 |
| * |
| * Revision 1.2 2001/12/18 13:35:22 bjornw |
| * Applied the 2.4.13->2.4.16 CRIS patch to 2.5.1 (is a copy of 2.4.15). |
| * |
| * Revision 1.20 2001/11/22 13:34:06 bjornw |
| * * Bug workaround (LX TR89): force a rerun of the whole of an interrupted |
| * unaligned write, because the second half of the write will be corrupted |
| * otherwise. Affected unaligned writes spanning not-yet mapped pages. |
| * * Optimization: use the wr_rd bit in R_MMU_CAUSE to know whether a miss |
| * was due to a read or a write (before we didn't know this until the next |
| * restart of the interrupted instruction, thus wasting one fault-irq) |
| * |
| * Revision 1.19 2001/11/12 19:02:10 pkj |
| * Fixed compiler warnings. |
| * |
| * Revision 1.18 2001/07/18 22:14:32 bjornw |
| * Enable interrupts in the bulk of do_page_fault |
| * |
| * Revision 1.17 2001/07/18 13:07:23 bjornw |
| * * Detect non-existant PTE's in vmalloc pmd synchronization |
| * * Remove comment about fast-paths for VMALLOC_START etc, because all that |
| * was totally bogus anyway it turned out :) |
| * * Fix detection of vmalloc-area synchronization |
| * * Add some comments |
| * |
| * Revision 1.16 2001/06/13 00:06:08 bjornw |
| * current_pgd should be volatile |
| * |
| * Revision 1.15 2001/06/13 00:02:23 bjornw |
| * Use a separate variable to store the current pgd to avoid races in schedule |
| * |
| * Revision 1.14 2001/05/16 17:41:07 hp |
| * Last comment tweak further tweaked. |
| * |
| * Revision 1.13 2001/05/15 00:58:44 hp |
| * Expand a bit on the comment why we compare address >= TASK_SIZE rather |
| * than >= VMALLOC_START. |
| * |
| * Revision 1.12 2001/04/04 10:51:14 bjornw |
| * mmap_sem is grabbed for reading |
| * |
| * Revision 1.11 2001/03/23 07:36:07 starvik |
| * Corrected according to review remarks |
| * |
| * Revision 1.10 2001/03/21 16:10:11 bjornw |
| * CRIS_FRAME_FIXUP not needed anymore, use FRAME_NORMAL |
| * |
| * Revision 1.9 2001/03/05 13:22:20 bjornw |
| * Spell-fix and fix in vmalloc_fault handling |
| * |
| * Revision 1.8 2000/11/22 14:45:31 bjornw |
| * * 2.4.0-test10 removed the set_pgdir instantaneous kernel global mapping |
| * into all processes. Instead we fill in the missing PTE entries on demand. |
| * |
| * Revision 1.7 2000/11/21 16:39:09 bjornw |
| * fixup switches frametype |
| * |
| * Revision 1.6 2000/11/17 16:54:08 bjornw |
| * More detailed siginfo reporting |
| * |
| * |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/interrupt.h> |
| #include <linux/module.h> |
| #include <asm/uaccess.h> |
| |
| extern int find_fixup_code(struct pt_regs *); |
| extern void die_if_kernel(const char *, struct pt_regs *, long); |
| extern int raw_printk(const char *fmt, ...); |
| |
| /* debug of low-level TLB reload */ |
| #undef DEBUG |
| |
| #ifdef DEBUG |
| #define D(x) x |
| #else |
| #define D(x) |
| #endif |
| |
| /* debug of higher-level faults */ |
| #define DPG(x) |
| |
| /* current active page directory */ |
| |
| volatile DEFINE_PER_CPU(pgd_t *,current_pgd); |
| unsigned long cris_signal_return_page; |
| |
| /* |
| * This routine handles page faults. It determines the address, |
| * and the problem, and then passes it off to one of the appropriate |
| * routines. |
| * |
| * Notice that the address we're given is aligned to the page the fault |
| * occurred in, since we only get the PFN in R_MMU_CAUSE not the complete |
| * address. |
| * |
| * error_code: |
| * bit 0 == 0 means no page found, 1 means protection fault |
| * bit 1 == 0 means read, 1 means write |
| * |
| * If this routine detects a bad access, it returns 1, otherwise it |
| * returns 0. |
| */ |
| |
| asmlinkage void |
| do_page_fault(unsigned long address, struct pt_regs *regs, |
| int protection, int writeaccess) |
| { |
| struct task_struct *tsk; |
| struct mm_struct *mm; |
| struct vm_area_struct * vma; |
| siginfo_t info; |
| |
| D(printk("Page fault for %lX on %X at %lX, prot %d write %d\n", |
| address, smp_processor_id(), instruction_pointer(regs), |
| protection, writeaccess)); |
| |
| tsk = current; |
| |
| /* |
| * 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. |
| * |
| * NOTE2: This is done so that, when updating the vmalloc |
| * mappings we don't have to walk all processes pgdirs and |
| * add the high mappings all at once. Instead we do it as they |
| * are used. However vmalloc'ed page entries have the PAGE_GLOBAL |
| * bit set so sometimes the TLB can use a lingering entry. |
| * |
| * This verifies that the fault happens in kernel space |
| * and that the fault was not a protection error (error_code & 1). |
| */ |
| |
| if (address >= VMALLOC_START && |
| !protection && |
| !user_mode(regs)) |
| goto vmalloc_fault; |
| |
| /* When stack execution is not allowed we store the signal |
| * trampolines in the reserved cris_signal_return_page. |
| * Handle this in the exact same way as vmalloc (we know |
| * that the mapping is there and is valid so no need to |
| * call handle_mm_fault). |
| */ |
| if (cris_signal_return_page && |
| address == cris_signal_return_page && |
| !protection && user_mode(regs)) |
| goto vmalloc_fault; |
| |
| /* we can and should enable interrupts at this point */ |
| local_irq_enable(); |
| |
| mm = tsk->mm; |
| info.si_code = SEGV_MAPERR; |
| |
| /* |
| * If we're in an interrupt or have no user |
| * context, we must not take the fault.. |
| */ |
| |
| if (in_interrupt() || !mm) |
| goto no_context; |
| |
| 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 (user_mode(regs)) { |
| /* |
| * accessing the stack below usp is always a bug. |
| * we get page-aligned addresses so we can only check |
| * if we're within a page from usp, but that might be |
| * enough to catch brutal errors at least. |
| */ |
| if (address + PAGE_SIZE < rdusp()) |
| 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; |
| |
| /* first do some preliminary protection checks */ |
| |
| if (writeaccess == 2){ |
| if (!(vma->vm_flags & VM_EXEC)) |
| goto bad_area; |
| } else if (writeaccess == 1) { |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto bad_area; |
| } else { |
| if (!(vma->vm_flags & (VM_READ | 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. |
| */ |
| |
| switch (handle_mm_fault(mm, vma, address, writeaccess & 1)) { |
| case 1: |
| tsk->min_flt++; |
| break; |
| case 2: |
| tsk->maj_flt++; |
| break; |
| case 0: |
| goto do_sigbus; |
| default: |
| goto out_of_memory; |
| } |
| |
| 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: |
| DPG(show_registers(regs)); |
| |
| /* User mode accesses just cause a SIGSEGV */ |
| |
| if (user_mode(regs)) { |
| info.si_signo = SIGSEGV; |
| info.si_errno = 0; |
| /* info.si_code has been set above */ |
| info.si_addr = (void *)address; |
| force_sig_info(SIGSEGV, &info, tsk); |
| return; |
| } |
| |
| no_context: |
| |
| /* Are we prepared to handle this kernel fault? |
| * |
| * (The kernel has valid exception-points in the source |
| * when it acesses user-memory. When it fails in one |
| * of those points, we find it in a table and do a jump |
| * to some fixup code that loads an appropriate error |
| * code) |
| */ |
| |
| if (find_fixup_code(regs)) |
| return; |
| |
| /* |
| * Oops. The kernel tried to access some bad page. We'll have to |
| * terminate things with extreme prejudice. |
| */ |
| |
| if ((unsigned long) (address) < PAGE_SIZE) |
| raw_printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); |
| else |
| raw_printk(KERN_ALERT "Unable to handle kernel access"); |
| raw_printk(" at virtual address %08lx\n",address); |
| |
| die_if_kernel("Oops", regs, (writeaccess << 1) | protection); |
| |
| 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: |
| up_read(&mm->mmap_sem); |
| printk("VM: killing process %s\n", tsk->comm); |
| if (user_mode(regs)) |
| do_exit(SIGKILL); |
| goto no_context; |
| |
| do_sigbus: |
| up_read(&mm->mmap_sem); |
| |
| /* |
| * Send a sigbus, regardless of whether we were in kernel |
| * or user mode. |
| */ |
| info.si_signo = SIGBUS; |
| info.si_errno = 0; |
| info.si_code = BUS_ADRERR; |
| info.si_addr = (void *)address; |
| force_sig_info(SIGBUS, &info, tsk); |
| |
| /* Kernel mode? Handle exceptions or die */ |
| if (!user_mode(regs)) |
| goto no_context; |
| return; |
| |
| vmalloc_fault: |
| { |
| /* |
| * Synchronize this task's top level page-table |
| * with the 'reference' page table. |
| * |
| * Use current_pgd instead of tsk->active_mm->pgd |
| * since the latter might be unavailable if this |
| * code is executed in a misfortunately run irq |
| * (like inside schedule() between switch_mm and |
| * switch_to...). |
| */ |
| |
| int offset = pgd_index(address); |
| pgd_t *pgd, *pgd_k; |
| pud_t *pud, *pud_k; |
| pmd_t *pmd, *pmd_k; |
| pte_t *pte_k; |
| |
| pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset; |
| pgd_k = init_mm.pgd + offset; |
| |
| /* Since we're two-level, we don't need to do both |
| * set_pgd and set_pmd (they do the same thing). If |
| * we go three-level at some point, do the right thing |
| * with pgd_present and set_pgd here. |
| * |
| * Also, since the vmalloc area is global, we don't |
| * need to copy individual PTE's, it is enough to |
| * copy the pgd pointer into the pte page of the |
| * root task. If that is there, we'll find our pte if |
| * it exists. |
| */ |
| |
| 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 bad_area_nosemaphore; |
| |
| set_pmd(pmd, *pmd_k); |
| |
| /* Make sure the actual PTE exists as well to |
| * catch kernel vmalloc-area accesses to non-mapped |
| * addresses. If we don't do this, this will just |
| * silently loop forever. |
| */ |
| |
| pte_k = pte_offset_kernel(pmd_k, address); |
| if (!pte_present(*pte_k)) |
| goto no_context; |
| |
| return; |
| } |
| } |
| |
| /* Find fixup code. */ |
| int |
| find_fixup_code(struct pt_regs *regs) |
| { |
| const struct exception_table_entry *fixup; |
| |
| if ((fixup = search_exception_tables(instruction_pointer(regs))) != 0) { |
| /* Adjust the instruction pointer in the stackframe. */ |
| instruction_pointer(regs) = fixup->fixup; |
| arch_fixup(regs); |
| return 1; |
| } |
| |
| return 0; |
| } |