svn commit: r317523 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Apr 27 21:24:50 2017
New Revision: 317523
URL: https://svnweb.freebsd.org/changeset/base/317523

Log:
  Add asserts to verify stability of struct proc and struct thread layouts.
  
  Some notes:
  - Only i386 and amd64 layouts are checked, other Tier-1 (or close to
    it) architectures would benefit from the same check.
  - Unconditional enabling of the asserts depend on the stability of locks
    memory layout.  If locks are optimized to avoid bloat when some debugging
    or profiling features turned off, it makes sense to only assert layout
    for production configs.
  
  Reviewed by:	badger, emaste, jhb, vangyzen
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks
  Differential revision:	https://reviews.freebsd.org/D10526

Modified:
  head/sys/kern/kern_thread.c

Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c	Thu Apr 27 21:11:57 2017	(r317522)
+++ head/sys/kern/kern_thread.c	Thu Apr 27 21:24:50 2017	(r317523)
@@ -65,6 +65,57 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_domain.h>
 #include <sys/eventhandler.h>
 
+/*
+ * Asserts below verify the stability of struct thread and struct proc
+ * layout, as exposed by KBI to modules.  On head, the KBI is allowed
+ * to drift, change to the structures must be accompanied by the
+ * assert update.
+ *
+ * On the stable branches after KBI freeze, conditions must not be
+ * violated.  Typically new fields are moved to the end of the
+ * structures.
+ */
+#ifdef __amd64__
+_Static_assert(offsetof(struct thread, td_flags) == 0xf4,
+    "struct thread KBI td_flags");
+_Static_assert(offsetof(struct thread, td_pflags) == 0xfc,
+    "struct thread KBI td_pflags");
+_Static_assert(offsetof(struct thread, td_frame) == 0x410,
+    "struct thread KBI td_frame");
+_Static_assert(offsetof(struct thread, td_emuldata) == 0x4b8,
+    "struct thread KBI td_emuldata");
+_Static_assert(offsetof(struct proc, p_flag) == 0xb0,
+    "struct proc KBI p_flag");
+_Static_assert(offsetof(struct proc, p_pid) == 0xbc,
+    "struct proc KBI p_pid");
+_Static_assert(offsetof(struct proc, p_filemon) == 0x3d0,
+    "struct proc KBI p_filemon");
+_Static_assert(offsetof(struct proc, p_comm) == 0x3e0,
+    "struct proc KBI p_comm");
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x4b8,
+    "struct proc KBI p_emuldata");
+#endif
+#ifdef __i386__
+_Static_assert(offsetof(struct thread, td_flags) == 0x9c,
+    "struct thread KBI td_flags");
+_Static_assert(offsetof(struct thread, td_pflags) == 0xa4,
+    "struct thread KBI td_pflags");
+_Static_assert(offsetof(struct thread, td_frame) == 0x2c8,
+    "struct thread KBI td_frame");
+_Static_assert(offsetof(struct thread, td_emuldata) == 0x314,
+    "struct thread KBI td_emuldata");
+_Static_assert(offsetof(struct proc, p_flag) == 0x68,
+    "struct proc KBI p_flag");
+_Static_assert(offsetof(struct proc, p_pid) == 0x74,
+    "struct proc KBI p_pid");
+_Static_assert(offsetof(struct proc, p_filemon) == 0x27c,
+    "struct proc KBI p_filemon");
+_Static_assert(offsetof(struct proc, p_comm) == 0x288,
+    "struct proc KBI p_comm");
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x314,
+    "struct proc KBI p_emuldata");
+#endif
+
 SDT_PROVIDER_DECLARE(proc);
 SDT_PROBE_DEFINE(proc, , , lwp__exit);