X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fi386%2Fmm%2Ffault-xen.c;fp=arch%2Fi386%2Fmm%2Ffault-xen.c;h=9561f24fe67a08a16005f8af011089c8a4c9aff5;hb=16c70f8c1b54b61c3b951b6fb220df250fe09b32;hp=3bff39ec27815cb046b6500a62e1e3664d98141a;hpb=4e76c8a9fa413ccc09d3f7f664183dcce3555d57;p=linux-2.6.git

diff --git a/arch/i386/mm/fault-xen.c b/arch/i386/mm/fault-xen.c
index 3bff39ec2..9561f24fe 100644
--- 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))