Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

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 00000000000..03254b9eded
--- /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;
+	}
+}