Author: jhb
Date: Fri Jun 12 15:06:17 2015
New Revision: 284324
URL: https://svnweb.freebsd.org/changeset/base/284324
Log:
Ensure that the upper 16 bits of segment registers manually saved in
trapframes are cleared by explicitly pushing a zero and then moving
the segment register into the low 16 bits. Certain Intel processors
treat a push of a segment register as a move of the segment register
into the low 16 bits leaving the upper 16 bits of the word in the
stack unchanged.
Reviewed by: kib
MFC after: 1 month
Modified:
head/sys/i386/i386/exception.s
head/sys/i386/include/asmacros.h
Modified: head/sys/i386/i386/exception.s
==============================================================================
--- head/sys/i386/i386/exception.s Fri Jun 12 15:03:59 2015
(r284323)
+++ head/sys/i386/i386/exception.s Fri Jun 12 15:06:17 2015
(r284324)
@@ -157,9 +157,12 @@ IDTVEC(xmm)
.type alltraps,@function
alltraps:
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movl %ds,(%esp)
+ pushl $0
+ movl %es,(%esp)
+ pushl $0
+ movl %fs,(%esp)
alltraps_with_regs_pushed:
SET_KERNEL_SREGS
cld
@@ -233,9 +236,12 @@ IDTVEC(lcall_syscall)
pushl $7 /* sizeof "lcall 7,0" */
subl $4,%esp /* skip over tf_trapno */
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movl %ds,(%esp)
+ pushl $0
+ movl %es,(%esp)
+ pushl $0
+ movl %fs,(%esp)
SET_KERNEL_SREGS
cld
FAKE_MCOUNT(TF_EIP(%esp))
@@ -259,9 +265,12 @@ IDTVEC(int0x80_syscall)
pushl $2 /* sizeof "int 0x80" */
subl $4,%esp /* skip over tf_trapno */
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movl %ds,(%esp)
+ pushl $0
+ movl %es,(%esp)
+ pushl $0
+ movl %fs,(%esp)
SET_KERNEL_SREGS
cld
FAKE_MCOUNT(TF_EIP(%esp))
@@ -416,13 +425,16 @@ doreti_iret:
doreti_iret_fault:
subl $8,%esp
pushal
- pushl %ds
+ pushl $0
+ movl %ds,(%esp)
.globl doreti_popl_ds_fault
doreti_popl_ds_fault:
- pushl %es
+ pushl $0
+ movl %es,(%esp)
.globl doreti_popl_es_fault
doreti_popl_es_fault:
- pushl %fs
+ pushl $0
+ movl %fs,(%esp)
.globl doreti_popl_fs_fault
doreti_popl_fs_fault:
sti
Modified: head/sys/i386/include/asmacros.h
==============================================================================
--- head/sys/i386/include/asmacros.h Fri Jun 12 15:03:59 2015
(r284323)
+++ head/sys/i386/include/asmacros.h Fri Jun 12 15:06:17 2015
(r284324)
@@ -146,9 +146,12 @@
pushl $0 ; /* dummy error code */ \
pushl $0 ; /* dummy trap type */ \
pushal ; /* 8 ints */ \
- pushl %ds ; /* save data and extra segments ... */ \
- pushl %es ; \
- pushl %fs
+ pushl $0 ; /* save data and extra segments ... */ \
+ mov %ds,(%esp) ; \
+ pushl $0 ; \
+ mov %es,(%esp) ; \
+ pushl $0 ; \
+ mov %fs,(%esp)
#define POP_FRAME
\
popl %fs ; \
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