[src/trunk]: src/sys/arch/amd64/amd64 Ah. Don't use NENTRY() to declare check...

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

details:   https://anonhg.NetBSD.org/src/rev/b1549362b966
branches:  trunk
changeset: 830075:b1549362b966
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Feb 25 11:57:44 2018 +0000

description:
Ah. Don't use NENTRY() to declare check_swapgs, use LABEL() instead. NENTRY
puts the code in the .text section, so the effect of TEXT_USER_BEGIN was
overwritten, and check_swapgs was not put in the .text.user section.

As a result kernels running SVS would crash when jumping here - because we
execute this place with the user page table loaded, and in this page table
only .text.user is mapped.

While here, rename check_swapgs -> kernuser_reenter, because we do more
things than just SWAPGS.

diffstat:

 sys/arch/amd64/amd64/amd64_trap.S |  17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)

diffs (64 lines):

diff -r 7a6f6d4f895d -r b1549362b966 sys/arch/amd64/amd64/amd64_trap.S
--- a/sys/arch/amd64/amd64/amd64_trap.S Sun Feb 25 10:17:12 2018 +0000
+++ b/sys/arch/amd64/amd64/amd64_trap.S Sun Feb 25 11:57:44 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: amd64_trap.S,v 1.35 2018/02/25 08:28:55 maxv Exp $     */
+/*     $NetBSD: amd64_trap.S,v 1.36 2018/02/25 11:57:44 maxv Exp $     */
 
 /*
  * Copyright (c) 1998, 2007, 2008, 2017 The NetBSD Foundation, Inc.
@@ -273,22 +273,22 @@
  * equivalent of iret, if it does this code would be needed
  * in order to copy the user segment registers into the fault frame.
  */
-#define check_swapgs alltraps
+#define kernuser_reenter alltraps
 #endif
 
 IDTVEC(trap11)         /* #NP() Segment not present */
        TRAP_NJ(T_SEGNPFLT)
-       jmp     check_swapgs
+       jmp     kernuser_reenter
 IDTVEC_END(trap11)
 
 IDTVEC(trap12)         /* #SS() Stack exception */
        TRAP_NJ(T_STKFLT)
-       jmp     check_swapgs
+       jmp     kernuser_reenter
 IDTVEC_END(trap12)
 
 IDTVEC(trap13)         /* #GP() General protection */
        TRAP_NJ(T_PROTFLT)
-       jmp     check_swapgs
+       jmp     kernuser_reenter
 IDTVEC_END(trap13)
 
 IDTVEC(trap14)
@@ -365,7 +365,7 @@
        jmp     .Lalltraps_checkusr
 IDTVEC_END(intrspurious)
 
-#ifndef check_swapgs
+#ifndef kernuser_reenter
 /*
  * We need to worry about traps in kernel mode while the kernel %gs isn't
  * loaded. These are either faults on iretq during return to user or loads to
@@ -374,7 +374,8 @@
  * When such traps happen, we have CPL=0 and %gs=userland, and we must perform
  * an additional swapgs to get %gs=kernel.
  */
-NENTRY(check_swapgs)
+       _ALIGN_TEXT
+LABEL(kernuser_reenter)
        INTRENTRY_L(3f,1:)
 2:
        sti
@@ -406,7 +407,7 @@
 
        /* None of the above cases */
        jmp     2b      /* normal kernel fault */
-END(check_swapgs)
+END(kernuser_reenter)
 #endif
 
        TEXT_USER_END