xnu-6153.11.26.tar.gz

[apple/xnu.git] / osfmk / i386 / trap.c

diff --git a/osfmk/i386/trap.c b/osfmk/i386/trap.c
index e9ef4dea79b9c4c7dca7b45dbde1dea5a440f926..bfc24c4aa93e45faf1235cf34669a3eabfacc287 100644 (file)
--- a/osfmk/i386/trap.c
+++ b/osfmk/i386/trap.c
@@ -117,7 +117,7 @@ extern void kprint_state(x86_saved_state64_t *saved_state);
  * Forward declarations
  */
 static void user_page_fault_continue(kern_return_t kret);
-static void panic_trap(x86_saved_state64_t *saved_state, uint32_t pl, kern_return_t fault_result);
+static void panic_trap(x86_saved_state64_t *saved_state, uint32_t pl, kern_return_t fault_result) __dead2;
 static void set_recovery_ip(x86_saved_state64_t *saved_state, vm_offset_t ip);
 
 #if CONFIG_DTRACE
@@ -709,7 +709,7 @@ kernel_trap(
        case T_PAGE_FAULT:
 
 #if CONFIG_DTRACE
-               if (thread != THREAD_NULL && thread->options & TH_OPT_DTRACE) { /* Executing under dtrace_probe? */
+               if (thread != THREAD_NULL && thread->t_dtrace_inprobe) { /* Executing under dtrace_probe? */
                        if (dtrace_tally_fault(vaddr)) { /* Should a fault under dtrace be ignored? */
                                /*
                                 * DTrace has "anticipated" the possibility of this fault, and has
@@ -878,12 +878,6 @@ panic_trap(x86_saved_state64_t *regs, uint32_t pl, kern_return_t fault_result)
            potential_smap_fault ? " SMAP fault" : "",
            pl,
            fault_result);
-       /*
-        * This next statement is not executed,
-        * but it's needed to stop the compiler using tail call optimization
-        * for the panic call - which confuses the subsequent backtrace.
-        */
-       cr0 = 0;
 }
 
 #if CONFIG_DTRACE
@@ -1124,6 +1118,14 @@ user_trap(
                        /*NOTREACHED*/
                }
 
+               /*
+                * For a user trap, vm_fault() should never return KERN_FAILURE.
+                * If it does, we're leaking preemption disables somewhere in the kernel.
+                */
+               if (__improbable(kret == KERN_FAILURE)) {
+                       panic("vm_fault() KERN_FAILURE from user fault on thread %p", thread);
+               }
+
                user_page_fault_continue(kret);
        }       /* NOTREACHED */
        break;
@@ -1153,7 +1155,6 @@ user_trap(
 
        default:
                panic("Unexpected user trap, type %d", type);
-               return;
        }
        /* Note: Codepaths that directly return from user_trap() have pending
         * ASTs processed in locore