[src/trunk]: src/sys/arch/x86 Error out if the higher 32 bits of DR6 and DR7 ...

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

details:   https://anonhg.NetBSD.org/src/rev/3dab8a3bcaa5
branches:  trunk
changeset: 447485:3dab8a3bcaa5
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Jan 13 10:01:07 2019 +0000

description:
Error out if the higher 32 bits of DR6 and DR7 are set. MOV DR would
fault otherwise.

diffstat:

 sys/arch/x86/include/dbregs.h |  5 +++--
 sys/arch/x86/x86/dbregs.c     |  8 +++++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diffs (55 lines):

diff -r caa8dd3b06ba -r 3dab8a3bcaa5 sys/arch/x86/include/dbregs.h
--- a/sys/arch/x86/include/dbregs.h     Sun Jan 13 06:59:15 2019 +0000
+++ b/sys/arch/x86/include/dbregs.h     Sun Jan 13 10:01:07 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dbregs.h,v 1.7 2018/09/27 13:04:22 maxv Exp $  */
+/*     $NetBSD: dbregs.h,v 1.8 2019/01/13 10:01:07 maxv Exp $  */
 
 /*
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -45,6 +45,7 @@
 #define X86_DR6_DEBUG_REGISTER_ACCESS_DETECTED         __BIT(13)
 #define X86_DR6_SINGLE_STEP                            __BIT(14)
 #define X86_DR6_TASK_SWITCH                            __BIT(15)
+#define X86_DR6_MBZ                                    __BITS(32, 63)
 
 /*
  * CPU Debug Control Register (DR7)
@@ -67,7 +68,6 @@
 #define X86_DR7_GLOBAL_EXACT_BREAKPOINT                __BIT(9)
 #define X86_DR7_RESTRICTED_TRANSACTIONAL_MEMORY        __BIT(11)
 #define X86_DR7_GENERAL_DETECT_ENABLE          __BIT(13)
-
 #define X86_DR7_DR0_CONDITION_MASK             __BITS(16, 17)
 #define X86_DR7_DR0_LENGTH_MASK                        __BITS(18, 19)
 #define X86_DR7_DR1_CONDITION_MASK             __BITS(20, 21)
@@ -76,6 +76,7 @@
 #define X86_DR7_DR2_LENGTH_MASK                        __BITS(26, 27)
 #define X86_DR7_DR3_CONDITION_MASK             __BITS(28, 29)
 #define X86_DR7_DR3_LENGTH_MASK                        __BITS(30, 31)
+#define X86_DR7_MBZ                            __BITS(32, 63)
 
 /*
  * X86_DR7_CONDITION_IO_READWRITE is currently unused. It requires DE
diff -r caa8dd3b06ba -r 3dab8a3bcaa5 sys/arch/x86/x86/dbregs.c
--- a/sys/arch/x86/x86/dbregs.c Sun Jan 13 06:59:15 2019 +0000
+++ b/sys/arch/x86/x86/dbregs.c Sun Jan 13 10:01:07 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dbregs.c,v 1.12 2018/09/27 13:04:21 maxv Exp $ */
+/*     $NetBSD: dbregs.c,v 1.13 2019/01/13 10:01:07 maxv Exp $ */
 
 /*
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -256,6 +256,12 @@
                        return EINVAL;
        }
 
+       if (regs->dr[6] & X86_DR6_MBZ) {
+               return EINVAL;
+       }
+       if (regs->dr[7] & X86_DR7_MBZ) {
+               return EINVAL;
+       }
        if (regs->dr[7] & X86_DR7_GENERAL_DETECT_ENABLE) {
                return EINVAL;
        }