[src/trunk]: src/sys/arch/amd64/amd64 Don't fall through functions, explicitl...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6d6fef7a71be
branches:  trunk
changeset: 827531:6d6fef7a71be
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Nov 01 09:17:28 2017 +0000

description:
Don't fall through functions, explicitly jump instead. While here don't
call smap_enable twice (harmless), and add END() markers.

diffstat:

 sys/arch/amd64/amd64/copy.S    |  19 +++++++++++--------
 sys/arch/amd64/amd64/cpufunc.S |  15 ++++++++-------
 2 files changed, 19 insertions(+), 15 deletions(-)

diffs (111 lines):

diff -r 2a0423bc019f -r 6d6fef7a71be sys/arch/amd64/amd64/copy.S
--- a/sys/arch/amd64/amd64/copy.S       Wed Nov 01 08:44:34 2017 +0000
+++ b/sys/arch/amd64/amd64/copy.S       Wed Nov 01 09:17:28 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: copy.S,v 1.27 2017/10/30 17:06:42 maxv Exp $   */
+/*     $NetBSD: copy.S,v 1.28 2017/11/01 09:17:28 maxv Exp $   */
 
 /*
  * Copyright (c) 2001 Wasabi Systems, Inc.
@@ -258,19 +258,17 @@
 
 NENTRY(copy_efault)
        movq    $EFAULT,%rax
-
-/*
- * kcopy_fault is used by kcopy and copy_fault is used by copyin/out.
- *
- * they're distinguished for lazy pmap switching.  see trap().
- */
+       ret
+END(copy_efault)
 
 NENTRY(kcopy_fault)
        ret
+END(kcopy_fault)
 
 NENTRY(copy_fault)
        callq   smap_enable
        ret
+END(copy_fault)
 
 ENTRY(copyoutstr)
        DEFERRED_SWITCH_CHECK
@@ -362,6 +360,8 @@
 
 ENTRY(copystr_efault)
        movl    $EFAULT,%eax
+       jmp     copystr_return
+END(copystr_efault)
 
 ENTRY(copystr_fault)
        callq   smap_enable
@@ -371,8 +371,8 @@
        jz      8f
        subq    %rdx,%r8
        movq    %r8,(%r9)
-
 8:     ret
+END(copystr_fault)
 
 ENTRY(copystr)
        xchgq   %rdi,%rsi
@@ -564,10 +564,13 @@
 
 ENTRY(ucas_efault)
        movq    $EFAULT,%rax
+       ret
+END(ucas_efault)
 
 NENTRY(ucas_fault)
        callq   smap_enable
        ret
+END(ucas_fault)
 
 /*
  * int ucas_ptr(volatile void **uptr, void *old, void *new, void **ret);
diff -r 2a0423bc019f -r 6d6fef7a71be sys/arch/amd64/amd64/cpufunc.S
--- a/sys/arch/amd64/amd64/cpufunc.S    Wed Nov 01 08:44:34 2017 +0000
+++ b/sys/arch/amd64/amd64/cpufunc.S    Wed Nov 01 09:17:28 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cpufunc.S,v 1.30 2017/10/30 17:06:42 maxv Exp $        */
+/*     $NetBSD: cpufunc.S,v 1.31 2017/11/01 09:17:28 maxv Exp $        */
 
 /*
  * Copyright (c) 1998, 2007, 2008 The NetBSD Foundation, Inc.
@@ -424,8 +424,7 @@
  * Load a new GDT pointer (and do any necessary cleanup).
  * XXX It's somewhat questionable whether reloading all the segment registers
  * is necessary, since the actual descriptor data is not changed except by
- * process creation and exit, both of which clean up via task switches.  OTOH,
- * this only happens at run time when the GDT is resized.
+ * process creation and exit, both of which clean up via task switches.
  */
 #ifndef XEN
 ENTRY(lgdt)
@@ -435,19 +434,21 @@
        /* Flush the prefetch q. */
        jmp     1f
        nop
-1:     /* Reload "stale" selectors. */
-#else /* XEN */
+1:     jmp     _C_LABEL(lgdt_finish)
+END(lgdt)
+#endif
+
 /*
  * void lgdt_finish(void);
  * Reload segments after a GDT change
  */
 ENTRY(lgdt_finish)
-#endif /* XEN */
        movl    $GSEL(GDATA_SEL, SEL_KPL),%eax
        movl    %eax,%ds
        movl    %eax,%es
        movl    %eax,%ss
-       /* FALLTHROUGH */
+       jmp     _C_LABEL(x86_flush)
+END(lgdt_finish)
 
 /*
  * void x86_flush()