xnu-4903.241.1.tar.gz

[apple/xnu.git] / pexpert / i386 / pe_init.c

diff --git a/pexpert/i386/pe_init.c b/pexpert/i386/pe_init.c
index 2a82b7f36d65335af56a70b5707edfe376299181..49f9caecf02be7c05c8fb58e592bdefd24cb9173 100644 (file)
--- a/pexpert/i386/pe_init.c
+++ b/pexpert/i386/pe_init.c
@@ -49,7 +49,7 @@
 
 /* extern references */
 extern void pe_identify_machine(void * args);
-
+extern int kdb_printf(const char *format, ...) __printflike(1,2);
 /* private globals */
 PE_state_t  PE_state;
 
@@ -344,6 +344,12 @@ PE_sync_panic_buffers(void)
 uint32_t
 PE_i_can_has_debugger(uint32_t *debug_flags)
 {
+#if DEVELOPMENT || DEBUG
+       if (debug_flags) {
+               assert(debug_boot_arg_inited);
+       }
+#endif
+
 #if CONFIG_CSR
        if (csr_check(CSR_ALLOW_KERNEL_DEBUGGER) != 0) {
                if (debug_flags)
@@ -363,7 +369,7 @@ PE_get_offset_into_panic_region(char *location)
        assert(panic_info != NULL);
        assert(location > (char *) panic_info);
 
-       return (uint32_t) (location - debug_buf);
+       return (uint32_t) (location - (char *) panic_info);
 }
 
 void
@@ -383,6 +389,9 @@ PE_init_panicheader()
  *
  * NOTE: The purpose of this function is NOT to detect/correct corruption in the panic region,
  *       it is to update the panic header to make it consistent when we nest panics.
+ *
+ * We try to avoid nested panics/asserts on x86 because they are difficult to debug, so log any
+ * inconsistencies we find.
  */
 void
 PE_update_panicheader_nestedpanic()
@@ -396,7 +405,27 @@ PE_update_panicheader_nestedpanic()
 
        panic_info->mph_panic_flags |= MACOS_PANIC_HEADER_FLAG_NESTED_PANIC;
 
-       /* macOS panic logs include nested panic data, so don't touch the panic log length here */
+       /* Usually indicative of corruption in the panic region */
+       if(!(((panic_info->mph_stackshot_offset == 0) && (panic_info->mph_stackshot_len == 0)) ||
+                       ((panic_info->mph_stackshot_offset != 0) && (panic_info->mph_stackshot_len != 0)))) {
+               kdb_printf("panic_info contains invalid stackshot metadata: mph_stackshot_offset 0x%x mph_stackshot_len 0x%x\n",
+                               panic_info->mph_stackshot_offset, panic_info->mph_stackshot_len);
+       }
+
+       /*
+        * macOS panic logs contain nested panic data, if we've already closed the panic log,
+        * begin the other log.
+        */
+       if ((panic_info->mph_panic_log_len != 0) && (panic_info->mph_other_log_offset == 0)) {
+               panic_info->mph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
+
+               /* Usually indicative of corruption in the panic region */
+               if (panic_info->mph_other_log_len != 0) {
+                       kdb_printf("panic_info contains invalid other log metadata (zero offset but non-zero length), length was 0x%x, zeroing value\n",
+                                       panic_info->mph_other_log_len);
+                       panic_info->mph_other_log_len = 0;
+               }
+       }
 
        return;
 }