1 files changed, 42 insertions, 5 deletions

diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index 55250593d8c9..08dc696f54ee 100644
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -41,6 +41,41 @@
 #define PF_RSVD (1<<3)
 #define PF_INSTR        (1<<4)
 
+#ifdef CONFIG_KPROBES
+ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
+
+/* Hook to register for page fault notifications */
+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
+
 void bust_spinlocks(int yes)
 {
         int loglevel_save = console_loglevel;
@@ -160,7 +195,7 @@ void dump_pagetable(unsigned long address)
         printk("PGD %lx ", pgd_val(*pgd));
         if (!pgd_present(*pgd)) goto ret; 
 
-        pud = __pud_offset_k((pud_t *)pgd_page(*pgd), address);
+        pud = pud_offset(pgd, address);
         if (bad_address(pud)) goto bad;
         printk("PUD %lx ", pud_val(*pud));
         if (!pud_present(*pud)) goto ret;
@@ -348,7 +383,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
                         if (vmalloc_fault(address) >= 0)
                                 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;
                 /*
@@ -358,7 +393,7 @@ asmlinkage 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;
 
@@ -410,8 +445,10 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
         if (!(vma->vm_flags & VM_GROWSDOWN))
                 goto bad_area;
         if (error_code & 4) {
-                // XXX: align red zone size with ABI 
-                if (address + 128 < regs->rsp)
+                /* Allow userspace just enough access below the stack pointer
+                 * to let the 'enter' instruction work.
+                 */
+                if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
                         goto bad_area;
         }
         if (expand_stack(vma, address))