1 files changed, 63 insertions, 21 deletions

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3aaeffcfd67a..9d591c895803 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -20,6 +20,9 @@
 #include <asm/kmemcheck.h>		/* kmemcheck_*(), ...		*/
 #include <asm/fixmap.h>			/* VSYSCALL_START		*/
 
+#define CREATE_TRACE_POINTS
+#include <asm/trace/exceptions.h>
+
 /*
  * Page fault error code bits:
  *
@@ -51,7 +54,7 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr)
 	return 0;
 }
 
-static inline int __kprobes notify_page_fault(struct pt_regs *regs)
+static inline int __kprobes kprobes_fault(struct pt_regs *regs)
 {
 	int ret = 0;
 
@@ -596,7 +599,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
 
 	printk(KERN_CONT " at %p\n", (void *) address);
 	printk(KERN_ALERT "IP:");
-	printk_address(regs->ip, 1);
+	printk_address(regs->ip);
 
 	dump_pagetable(address);
 }
@@ -638,6 +641,20 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 
 	/* Are we prepared to handle this kernel fault? */
 	if (fixup_exception(regs)) {
+		/*
+		 * Any interrupt that takes a fault gets the fixup. This makes
+		 * the below recursive fault logic only apply to a faults from
+		 * task context.
+		 */
+		if (in_interrupt())
+			return;
+
+		/*
+		 * Per the above we're !in_interrupt(), aka. task context.
+		 *
+		 * In this case we need to make sure we're not recursively
+		 * faulting through the emulate_vsyscall() logic.
+		 */
 		if (current_thread_info()->sig_on_uaccess_error && signal) {
 			tsk->thread.trap_nr = X86_TRAP_PF;
 			tsk->thread.error_code = error_code | PF_USER;
@@ -646,6 +663,10 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 			/* XXX: hwpoison faults will set the wrong code. */
 			force_sig_info_fault(signal, si_code, address, tsk, 0);
 		}
+
+		/*
+		 * Barring that, we can do the fixup and be happy.
+		 */
 		return;
 	}
 
@@ -1048,7 +1069,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 			return;
 
 		/* kprobes don't want to hook the spurious faults: */
-		if (notify_page_fault(regs))
+		if (kprobes_fault(regs))
 			return;
 		/*
 		 * Don't take the mm semaphore here. If we fixup a prefetch
@@ -1060,23 +1081,8 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 	}
 
 	/* kprobes don't want to hook the spurious faults: */
-	if (unlikely(notify_page_fault(regs)))
+	if (unlikely(kprobes_fault(regs)))
 		return;
-	/*
-	 * It's safe to allow irq's after cr2 has been saved and the
-	 * vmalloc fault has been handled.
-	 *
-	 * User-mode registers count as a user access even for any
-	 * potential system fault or CPU buglet:
-	 */
-	if (user_mode_vm(regs)) {
-		local_irq_enable();
-		error_code |= PF_USER;
-		flags |= FAULT_FLAG_USER;
-	} else {
-		if (regs->flags & X86_EFLAGS_IF)
-			local_irq_enable();
-	}
 
 	if (unlikely(error_code & PF_RSVD))
 		pgtable_bad(regs, error_code, address);
@@ -1088,8 +1094,6 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		}
 	}
 
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
-
 	/*
 	 * If we're in an interrupt, have no user context or are running
 	 * in an atomic region then we must not take the fault:
@@ -1099,6 +1103,24 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		return;
 	}
 
+	/*
+	 * It's safe to allow irq's after cr2 has been saved and the
+	 * vmalloc fault has been handled.
+	 *
+	 * User-mode registers count as a user access even for any
+	 * potential system fault or CPU buglet:
+	 */
+	if (user_mode_vm(regs)) {
+		local_irq_enable();
+		error_code |= PF_USER;
+		flags |= FAULT_FLAG_USER;
+	} else {
+		if (regs->flags & X86_EFLAGS_IF)
+			local_irq_enable();
+	}
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+
 	if (error_code & PF_WRITE)
 		flags |= FAULT_FLAG_WRITE;
 
@@ -1231,3 +1253,23 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
 	__do_page_fault(regs, error_code);
 	exception_exit(prev_state);
 }
+
+static void trace_page_fault_entries(struct pt_regs *regs,
+				     unsigned long error_code)
+{
+	if (user_mode(regs))
+		trace_page_fault_user(read_cr2(), regs, error_code);
+	else
+		trace_page_fault_kernel(read_cr2(), regs, error_code);
+}
+
+dotraplinkage void __kprobes
+trace_do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
+	trace_page_fault_entries(regs, error_code);
+	__do_page_fault(regs, error_code);
+	exception_exit(prev_state);
+}