diff options
Diffstat (limited to 'arch/cris/mm/fault.c')
| -rw-r--r-- | arch/cris/mm/fault.c | 387 |
1 files changed, 387 insertions, 0 deletions
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c new file mode 100644 index 0000000..03254b9 --- /dev/null +++ b/arch/cris/mm/fault.c @@ -0,0 +1,387 @@ +/* + * linux/arch/cris/mm/fault.c + * + * Copyright (C) 2000, 2001 Axis Communications AB + * + * Authors: Bjorn Wesen + * + * $Log: fault.c,v $ + * 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); + +/* 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 pgd_t *current_pgd; + +/* + * 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 %X at %X, prot %d write %d\n", + address, regs->erp, 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; + + /* we can and should enable interrupts at this point */ + sti(); + + 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) { + 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)) { + 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) + printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); + else + printk(KERN_ALERT "Unable to handle kernel access"); + 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; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + + pgd = (pgd_t *)current_pgd + 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. + */ + + pmd = pmd_offset(pgd, address); + pmd_k = pmd_offset(pgd_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; + } +} |
