Merge to Fedora kernel-2.6.18-1.2224_FC5 patched with stable patch-2.6.18.1-vs2.0...

[linux-2.6.git] / arch / i386 / mm / fault-xen.c

diff --git a/arch/i386/mm/fault-xen.c b/arch/i386/mm/fault-xen.c
index 3bff39e..9561f24 100644 (file)
--- a/arch/i386/mm/fault-xen.c
+++ b/arch/i386/mm/fault-xen.c
@@ -30,6 +30,39 @@
 
 extern void die(const char *,struct pt_regs *,long);
 
+#ifdef CONFIG_KPROBES
+ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
+int register_page_fault_notifier(struct notifier_block *nb)
+{
+       vmalloc_sync_all();
+       return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
+}
+
+int unregister_page_fault_notifier(struct notifier_block *nb)
+{
+       return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
+}
+
+static inline int notify_page_fault(enum die_val val, const char *str,
+                       struct pt_regs *regs, long err, int trap, int sig)
+{
+       struct die_args args = {
+               .regs = regs,
+               .str = str,
+               .err = err,
+               .trapnr = trap,
+               .signr = sig
+       };
+       return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
+}
+#else
+static inline int notify_page_fault(enum die_val val, const char *str,
+                       struct pt_regs *regs, long err, int trap, int sig)
+{
+       return NOTIFY_DONE;
+}
+#endif
+
 /*
  * Unlock any spinlocks which will prevent us from getting the
  * message out 
@@ -77,13 +110,16 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
        unsigned seg = regs->xcs & 0xffff;
        u32 seg_ar, seg_limit, base, *desc;
 
+       /* Unlikely, but must come before segment checks. */
+       if (unlikely(regs->eflags & VM_MASK)) {
+               base = seg << 4;
+               *eip_limit = base + 0xffff;
+               return base + (eip & 0xffff);
+       }
+
        /* The standard kernel/user address space limit. */
        *eip_limit = (seg & 2) ? USER_DS.seg : KERNEL_DS.seg;
 
-       /* Unlikely, but must come before segment checks. */
-       if (unlikely((regs->eflags & VM_MASK) != 0))
-               return eip + (seg << 4);
-       
        /* By far the most common cases. */
        if (likely(seg == __USER_CS || seg == GET_KERNEL_CS()))
                return eip;
@@ -446,7 +482,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
                /* Can take a spurious fault if mapping changes R/O -> R/W. */
                if (spurious_fault(regs, address, error_code))
                        return;
-               if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+               if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
                                                SIGSEGV) == NOTIFY_STOP)
                        return;
                /*
@@ -456,7 +492,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
                goto bad_area_nosemaphore;
        }
 
-       if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+       if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
                                        SIGSEGV) == NOTIFY_STOP)
                return;
 
@@ -477,7 +513,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
        /* When running in the kernel we expect faults to occur only to
         * addresses in user space.  All other faults represent errors in the
         * kernel and should generate an OOPS.  Unfortunatly, in the case of an
-        * erroneous fault occuring in a code path which already holds mmap_sem
+        * erroneous fault occurring in a code path which already holds mmap_sem
         * we will deadlock attempting to validate the fault against the
         * address space.  Luckily the kernel only validly references user
         * space from well defined areas of code, which are listed in the
@@ -505,12 +541,12 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
                goto bad_area;
        if (error_code & 4) {
                /*
-                * accessing the stack below %esp is always a bug.
-                * The "+ 32" is there due to some instructions (like
-                * pusha) doing post-decrement on the stack and that
-                * doesn't show up until later..
+                * Accessing the stack below %esp is always a bug.
+                * The large cushion allows instructions like enter
+                * and pusha to work.  ("enter $65535,$31" pushes
+                * 32 pointers and then decrements %esp by 65535.)
                 */
-               if (address + 32 < regs->esp)
+               if (address + 65536 + 32 * sizeof(unsigned long) < regs->esp)
                        goto bad_area;
        }
        if (expand_stack(vma, address))